Home » Public Forums » GMCnet » [GMCnet] Speedometer Gear Reducer Adapter
| [GMCnet] Speedometer Gear Reducer Adapter [message #359929] |
Mon, 02 November 2020 09:29  |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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Good Morning If I recall someone on here is knowledgeable of speedometer gear adapters. Can anyone connect me with that person?ThanksRaySent from my U.S.Cellular© Smartphone
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359934 is a reply to message #359929] |
Mon, 02 November 2020 10:33  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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Call Jim Kanomata at Applied GMC. He stocks them.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359946 is a reply to message #359945] |
Tue, 03 November 2020 09:30 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
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Summitt has these gears:
https://www.summitracing.com/parts/tci-880031
880029 41 tooth
880030 42 tooth
880031 43 tooth
880032 45 tooth
880013 44 tooth
On Tue, Nov 3, 2020 at 7:49 AM John Wright via Gmclist <
gmclist@list.gmcnet.org> wrote:
> There are at least 3 speedometer gears available from your GMC dealer for
> the 425 trans. There is a yellow, white and I think a light blue
> available. One is stock, one is a lower gear and one is a higher gear. I
> look for the information this morning and came up short. Call Jim K and he
> may be able to help you or call Manny.
>
> J.R. Wright
> GMC Great Laker MHC
> GMCGL Tech Editor
> GMC Eastern States Charter Member
> GMCMI
> 78 GMC Buskirk 29.5’ Stretch
> 75 GMC Avion (Under Reconstruction)
> Michigan
>
>
>> On Nov 3, 2020, at 8:24 AM, Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> It may be an option to change the driven gear, on the transmission, to
> one with more teeth so that it will slow the turn rate of the cable.
>>
>> They are about $10.
>> --
>> Todd Snyder, Buffalo NY
>> 1976 Eleganza II
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
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--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359947 is a reply to message #359946] |
Tue, 03 November 2020 10:41 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
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Bruce,
Yes, the gears are available, but those teeth counts way off what we need
to correct.
I can get the odometer to read within 2-4% by ordering in the right gear
combination in the reducer.
I help lot of people with them.
On Tue, Nov 3, 2020 at 7:31 AM Bruce Hart via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Summitt has these gears:
>
> https://www.summitracing.com/parts/tci-880031
> 880029 41 tooth
> 880030 42 tooth
> 880031 43 tooth
> 880032 45 tooth
> 880013 44 tooth
>
>
>
> On Tue, Nov 3, 2020 at 7:49 AM John Wright via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> There are at least 3 speedometer gears available from your GMC dealer for
>> the 425 trans. There is a yellow, white and I think a light blue
>> available. One is stock, one is a lower gear and one is a higher gear. I
>> look for the information this morning and came up short. Call Jim K and
> he
>> may be able to help you or call Manny.
>>
>> J.R. Wright
>> GMC Great Laker MHC
>> GMCGL Tech Editor
>> GMC Eastern States Charter Member
>> GMCMI
>> 78 GMC Buskirk 29.5’ Stretch
>> 75 GMC Avion (Under Reconstruction)
>> Michigan
>>
>>
>>> On Nov 3, 2020, at 8:24 AM, Todd Snyder via Gmclist > gmclist@list.gmcnet.org> wrote:
>>>
>>> It may be an option to change the driven gear, on the transmission, to
>> one with more teeth so that it will slow the turn rate of the cable.
>>>
>>> They are about $10.
>>> --
>>> Todd Snyder, Buffalo NY
>>> 1976 Eleganza II
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
> Bruce Hart
> 1976 Palm Beach
> Milliken, Co
> GMC=Got More Class
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359949 is a reply to message #359946] |
Tue, 03 November 2020 14:53 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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How many teeth does the stock gear have?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Bruce Hart via Gmclist Date: 11/3/20 9:31 AM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Bruce Hart Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter Summitt has these gears: https://www.summitracing.com/parts/tci-880031880029 41 tooth880030 42 tooth880031 43 tooth880032 45 tooth880013 44 toothOn Tue, Nov 3, 2020 at 7:49 AM John Wright via Gmclist wrote:> There are at least 3 speedometer gears available from your GMC dealer for> the 425 trans. There is a yellow, white and I think a light blue> available. One is stock, one is a lower gear and one is a higher gear. I> look for the information this morning and came up short. Call Jim K and he> may be able to help you or call Manny.>> J.R. Wright> GMC Great Laker MHC> GMCGL Tech Editor> GMC Eastern States Charter Member> GMCMI> 78 GMC Buskirk 29.5’ Stretch> 75 GMC Avion (Under Reconstruction)> Michigan>>> > On Nov 3, 2020, at 8:24 AM, Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:> >> > It may be an option to change the driven gear, on the transmission, to> one with more teeth so that it will slow the turn rate of the cable.> >> > They are about $10.> > --> > Todd Snyder, Buffalo NY> > 1976 Eleganza II> >> > _______________________________________________> > GMCnet mailing list> > Unsubscribe or Change List Options:> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>>> _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>-- Bruce Hart1976 Palm BeachMilliken, CoGMC=Got More Class_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359952 is a reply to message #359947] |
Tue, 03 November 2020 15:13 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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Right now I'm running a .944 gear reducer and my speedo reads 4.2% fast. If I'm correct I think I need a .879 reducer.Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Jim Kanomata via Gmclist Date: 11/3/20 10:42 AM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Jim Kanomata Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter Bruce,Yes, the gears are available, but those teeth counts way off what we needto correct.I can get the odometer to read within 2-4% by ordering in the right gearcombination in the reducer.I help lot of people with them.On Tue, Nov 3, 2020 at 7:31 AM Bruce Hart via Gmclist wrote:> Summitt has these gears:>> https://www.summitracing.com/parts/tci-880031> 880029 41 tooth> 880030 42 tooth> 880031 43 tooth> 880032 45 tooth> 880013 44 tooth>>>> On Tue, Nov 3, 2020 at 7:49 AM John Wright via Gmclist gmclist@list.gmcnet.org> wrote:>> > There are at least 3 speedometer gears available from your GMC dealer for> > the 425 trans. There is a yellow, white and I think a light blue> > available. One is stock, one is a lower gear and one is a higher gear. I> > look for the information this morning and came up short. Call Jim K and> he> > may be able to help you or call Manny.> >> > J.R. Wright> > GMC Great Laker MHC> > GMCGL Tech Editor> > GMC Eastern States Charter Member> > GMCMI> > 78 GMC Buskirk 29.5’ Stretch> > 75 GMC Avion (Under Reconstruction)> > Michigan> >> >> > > On Nov 3, 2020, at 8:24 AM, Todd Snyder via Gmclist > gmclist@list.gmcnet.org> wrote:> > >> > > It may be an option to change the driven gear, on the transmission, to> > one with more teeth so that it will slow the turn rate of the cable.> > >> > > They are about $10.> > > --> > > Todd Snyder, Buffalo NY> > > 1976 Eleganza II> > >> > > _______________________________________________> > > GMCnet mailing list> > > Unsubscribe or Change List Options:> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org> >> >> > _______________________________________________> > GMCnet mailing list> > Unsubscribe or Change List Options:> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org> >>>> --> Bruce Hart> 1976 Palm Beach> Milliken, Co> GMC=Got More Class> _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>-- Jim KanomataApplied/GMC, Newark,CAjimk@appliedairfilters.comhttp://www.gmcrvparts.com1-800-752-7502_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359988 is a reply to message #359952] |
Thu, 05 November 2020 15:51 |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout of distance traveled. It needs to be correct before the speedometer reading can be addressed if needed.
You could get on the highway, take note of the odometer as you pass a mile marker. Drive 10 miles and note the odometer reading. Subtract one reading from the other, figure out the % difference and get a driven gear with that % more or less teeth, depending on which way you need it to go.
Then pull your current driven gear out and count the teeth.
If the odometer is reading low, you need fewer teeth on the driven gear. If the odometer reads high, you need more teeth. You may or may not be able to get it corrected with the driven gear though, the drive gear only works for a certain range of tooth numbers. Looking online there are transmission parts stores that offer assistance with this. They'll know what range of teeth numbers will fit with what you have and sell you the gear
There are also online calculators that can determine the correct driven gear to use but you need to know the number of teeth on the drive gear so they won't be much help unless you use them to figure out what's in there by trial and error, which you can do.
Todd Snyder, Buffalo NY
1976 Eleganza II
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359989 is a reply to message #359929] |
Thu, 05 November 2020 17:55 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Todd, your correct on what you say.
Majority of the customers care mainly for what the speed reads, so I do as
they want.
On Thu, Nov 5, 2020 at 3:47 PM Emery Stora via Gmclist <
gmclist@list.gmcnet.org> wrote:
> You are correct. Set things by the odometer. I used my gps rather than a
> mile marker. I have found that mile marked often are off by .2 miles. After
> setting it I checked it by mile markers 100 miles apart. It was within 0.1
> miles.
> Once you have the gps for ten miles record the odometer reading at that
> point. I had an adapter from Jim Kanometer and I just sent it back to him
> and gave him my odometer reading for 10 miles on the gps. He changed gears
> in it and it was right on
>
> Emery Stora
>
>> On Nov 5, 2020, at 2:52 PM, Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> I don't think the mph reading is the first thing to correct. The
> first thing to get right is the odometer. That's a direct geared readout of
>> distance traveled. It needs to be correct before the speedometer
> reading can be addressed if needed.
>>
>> You could get on the highway, take note of the odometer as you pass a
> mile marker. Drive 10 miles and note the odometer reading. Subtract one
>> reading from the other, figure out the % difference and get a driven
> gear with that % more or less teeth, depending on which way you need it to
> go.
>>
>> Then pull your current driven gear out and count the teeth.
>>
>> If the odometer is reading low, you need fewer teeth on the driven
> gear. If the odometer reads high, you need more teeth. You may or may
> not be
>> able to get it corrected with the driven gear though, the drive gear
> only works for a certain range of tooth numbers. Looking online there are
>> transmission parts stores that offer assistance with this. They'll know
> what range of teeth numbers will fit with what you have and sell you the
>> gear
>>
>> There are also online calculators that can determine the correct driven
> gear to use but you need to know the number of teeth on the drive gear so
> they
>> won't be much help unless you use them to figure out what's in there by
> trial and error, which you can do.
>>
>>
>>
>> --
>> Todd Snyder, Buffalo NY
>> 1976 Eleganza II
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #359990 is a reply to message #359988] |
Thu, 05 November 2020 17:47 |
stu@97381.com, Emery
Messages: 232
Registered: June 2020
Karma: 2
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Senior Member |
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You are correct. Set things by the odometer. I used my gps rather than a mile marker. I have found that mile marked often are off by .2 miles. After setting it I checked it by mile markers 100 miles apart. It was within 0.1 miles.
Once you have the gps for ten miles record the odometer reading at that point. I had an adapter from Jim Kanometer and I just sent it back to him and gave him my odometer reading for 10 miles on the gps. He changed gears in it and it was right on
Emery Stora
> On Nov 5, 2020, at 2:52 PM, Todd Snyder via Gmclist wrote:
>
> I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout of
> distance traveled. It needs to be correct before the speedometer reading can be addressed if needed.
>
> You could get on the highway, take note of the odometer as you pass a mile marker. Drive 10 miles and note the odometer reading. Subtract one
> reading from the other, figure out the % difference and get a driven gear with that % more or less teeth, depending on which way you need it to go.
>
> Then pull your current driven gear out and count the teeth.
>
> If the odometer is reading low, you need fewer teeth on the driven gear. If the odometer reads high, you need more teeth. You may or may not be
> able to get it corrected with the driven gear though, the drive gear only works for a certain range of tooth numbers. Looking online there are
> transmission parts stores that offer assistance with this. They'll know what range of teeth numbers will fit with what you have and sell you the
> gear
>
> There are also online calculators that can determine the correct driven gear to use but you need to know the number of teeth on the drive gear so they
> won't be much help unless you use them to figure out what's in there by trial and error, which you can do.
>
>
>
> --
> Todd Snyder, Buffalo NY
> 1976 Eleganza II
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360000 is a reply to message #359990] |
Sat, 07 November 2020 09:36 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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This makes sense. I haven't changed anything yet and now the coach is in winter storage. I'll continue in spring starting with correcting the miles.Thanks everyone Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Emery Stora via Gmclist Date: 11/5/20 5:47 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Emery Stora Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter You are correct. Set things by the odometer. I used my gps rather than a mile marker. I have found that mile marked often are off by .2 miles. After setting it I checked it by mile markers 100 miles apart. It was within 0.1 miles. Once you have the gps for ten miles record the odometer reading at that point. I had an adapter from Jim Kanometer and I just sent it back to him and gave him my odometer reading for 10 miles on the gps. He changed gears in it and it was right on Emery Stora> On Nov 5, 2020, at 2:52 PM, Todd Snyder via Gmclist wrote:> > I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout of> distance traveled. It needs to be correct before the speedometer reading can be addressed if needed. > > You could get on the highway, take note of the odometer as you pass a mile marker. Drive 10 miles and note the odometer reading. Subtract one> reading from the other, figure out the % difference and get a driven gear with that % more or less teeth, depending on which way you need it to go. > > Then pull your current driven gear out and count the teeth. > > If the odometer is reading low, you need fewer teeth on the driven gear. If the odometer reads high, you need more teeth. You may or may not be> able to get it corrected with the driven gear though, the drive gear only works for a certain range of tooth numbers. Looking online there are> transmission parts stores that offer assistance with this. They'll know what range of teeth numbers will fit with what you have and sell you the> gear> > There are also online calculators that can determine the correct driven gear to use but you need to know the number of teeth on the drive gear so they> won't be much help unless you use them to figure out what's in there by trial and error, which you can do. > > > > -- > Todd Snyder, Buffalo NY > 1976 Eleganza II> > _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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Unsubscribe or Change List Options:
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360001 is a reply to message #359988] |
Sat, 07 November 2020 09:39 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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Senior Member |
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Quick question.....how many teeth does the oem gear have?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Todd Snyder via Gmclist Date: 11/5/20 3:52 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Todd Snyder Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout ofdistance traveled. It needs to be correct before the speedometer reading can be addressed if needed. You could get on the highway, take note of the odometer as you pass a mile marker. Drive 10 miles and note the odometer reading. Subtract onereading from the other, figure out the % difference and get a driven gear with that % more or less teeth, depending on which way you need it to go. Then pull your current driven gear out and count the teeth. If the odometer is reading low, you need fewer teeth on the driven gear. If the odometer reads high, you need more teeth. You may or may not beable to get it corrected with the driven gear though, the drive gear only works for a certain range of tooth numbers. Looking online there aretransmission parts stores that offer assistance with this. They'll know what range of teeth numbers will fit with what you have and sell you thegearThere are also online calculators that can determine the correct driven gear to use but you need to know the number of teeth on the drive gear so theywon't be much help unless you use them to figure out what's in there by trial and error, which you can do. -- Todd Snyder, Buffalo NY 1976 Eleganza II_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360005 is a reply to message #360001] |
Sat, 07 November 2020 15:43 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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OEM ones are light tan/white 31 teeth
On Sat, Nov 7, 2020 at 7:40 AM 78gmcroyale via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Quick question.....how many teeth does the oem gear have?Sent from my
> U.S.Cellular© Smartphone
> -------- Original message --------From: Todd Snyder via Gmclist gmclist@list.gmcnet.org> Date: 11/5/20 3:52 PM (GMT-06:00) To:
> gmclist@list.gmcnet.org Cc: Todd Snyder Subject:
> Re: [GMCnet] Speedometer Gear Reducer Adapter I don't think the mph reading
> is the first thing to correct. The first thing to get right is the
> odometer. That's a direct geared readout ofdistance traveled. It needs to
> be correct before the speedometer reading can be addressed if needed. You
> could get on the highway, take note of the odometer as you pass a mile
> marker. Drive 10 miles and note the odometer reading. Subtract onereading
> from the other, figure out the % difference and get a driven gear with that
> % more or less teeth, depending on which way you need it to go. Then pull
> your current driven gear out and count the teeth. If the odometer is
> reading low, you need fewer teeth on the driven gear. If the odometer
> reads high, you need more teeth. You may or may not beable to get it
> corrected with the driven gear though, the drive gear only works for a
> certain range of tooth numbers. Looking online there aretransmission parts
> stores that offer assistance with this. They'll know what range of teeth
> numbers will fit with what you have and sell you thegearThere are also
> online calculators that can determine the correct driven gear to use but
> you need to know the number of teeth on the drive gear so theywon't be much
> help unless you use them to figure out what's in there by trial and error,
> which you can do. -- Todd Snyder, Buffalo NY 1976 Eleganza
> II_______________________________________________GMCnet mailing
> listUnsubscribe or Change List Options:
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360007 is a reply to message #359990] |
Sun, 08 November 2020 09:53 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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Senior Member |
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I'm very confused by this statement.... "I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout ofdistance traveled. It needs to be correct before the speedometer reading can be addressed if needed."The speedometer cable feeds the speedometer and it's rate of spinning determines miles and mph. It can't differentiate between the two. If mph is correct then mileage should be correct and if mileage is correct then mph should be correct. I don't understand how you can first fix one and then fix the other.What am I missing?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Emery Stora via Gmclist Date: 11/5/20 5:47 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Emery Stora Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter You are correct. Set things by the odometer. I used my gps rather than a mile marker. I have found that mile marked often are off by .2 miles. After setting it I checked it by mile markers 100 miles apart. It was within 0.1 miles. Once you have the gps for ten miles record the odometer reading at that point. I had an adapter from Jim Kanometer and I just sent it back to him and gave him my odometer reading for 10 miles on the gps. He changed gears in it and it was right on Emery Stora> On Nov 5, 2020, at 2:52 PM, Todd Snyder via Gmclist wrote:> > I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout of> distance traveled. It needs to be correct before the speedometer reading can be addressed if needed. > > You could get on the highway, take note of the odometer as you pass a mile marker. Drive 10 miles and note the odometer reading. Subtract one> reading from the other, figure out the % difference and get a driven gear with that % more or less teeth, depending on which way you need it to go. > > Then pull your current driven gear out and count the teeth. > > If the odometer is reading low, you need fewer teeth on the driven gear. If the odometer reads high, you need more teeth. You may or may not be> able to get it corrected with the driven gear though, the drive gear only works for a certain range of tooth numbers. Looking online there are> transmission parts stores that offer assistance with this. They'll know what range of teeth numbers will fit with what you have and sell you the> gear> > There are also online calculators that can determine the correct driven gear to use but you need to know the number of teeth on the drive gear so they> won't be much help unless you use them to figure out what's in there by trial and error, which you can do. > > > > -- > Todd Snyder, Buffalo NY > 1976 Eleganza II> > _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360008 is a reply to message #360007] |
Sun, 08 November 2020 10:23 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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The odometer is connected to the tires through a series of mechanical
connections (gears, shafts), so it must correspond exactly to the rotation
of the tires. When adjusted for the effective circumference of the tires,
it should yield an exact distance travelled. The Speedometer, on the other
hand, is driven through that same sequence of mechanical devices, but the
last stage is a magnet rotating past a disk which is attached to the
spring-loaded needle. That is NOT a solid or certain way of connecting
devices together. If the magnet and disk are slightly too close, the speed
will read high (a weak spring will have that same effect); too far apart
yields a slow speed indication.
HTH,
Ken H.
On Sun, Nov 8, 2020 at 10:54 AM 78gmcroyale via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm very confused by this statement.... "I don't think the mph reading is
> the first thing to correct. The first thing to get right is the
> odometer. That's a direct geared readout ofdistance traveled. It needs to
> be correct before the speedometer reading can be addressed if needed."The
> speedometer cable feeds the speedometer and it's rate of spinning
> determines miles and mph. It can't differentiate between the two. If mph
> is correct then mileage should be correct and if mileage is correct then
> mph should be correct. I don't understand how you can first fix one and
> then fix the other.What am I missing?Sent from my U.S.Cellular© Smartphone
> -------- Original message --------From: Emery Stora via Gmclist gmclist@list.gmcnet.org> Date: 11/5/20 5:47 PM (GMT-06:00) To:
> gmclist@list.gmcnet.org Cc: Emery Stora Subject:
> Re: [GMCnet] Speedometer Gear Reducer Adapter You are correct. Set things
> by the odometer. I used my gps rather than a mile marker. I have found that
> mile marked often are off by .2 miles. After setting it I checked it by
> mile markers 100 miles apart. It was within 0.1 miles. Once you have the
> gps for ten miles record the odometer reading at that point. I had an
> adapter from Jim Kanometer and I just sent it back to him and gave him my
> odometer reading for 10 miles on the gps. He changed gears in it and it was
> right on Emery Stora> On Nov 5, 2020, at 2:52 PM, Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:> > I don't think the mph reading is the
> first thing to correct. The first thing to get right is the odometer.
> That's a direct geared readout of> distance traveled. It needs to be
> correct before the speedometer reading can be addressed if needed. > > You
> could get on the highway, take note of the odometer as you pass a mile
> marker. Drive 10 miles and note the odometer reading. Subtract one>
> reading from the other, figure out the % difference and get a driven gear
> with that % more or less teeth, depending on which way you need it to go.
>>> Then pull your current driven gear out and count the teeth. > > If the
> odometer is reading low, you need fewer teeth on the driven gear. If the
> odometer reads high, you need more teeth. You may or may not be> able to
> get it corrected with the driven gear though, the drive gear only works for
> a certain range of tooth numbers. Looking online there are> transmission
> parts stores that offer assistance with this. They'll know what range of
> teeth numbers will fit with what you have and sell you the> gear> > There
> are also online calculators that can determine the correct driven gear to
> use but you need to know the number of teeth on the drive gear so they>
> won't be much help unless you use them to figure out what's in there by
> trial and error, which you can do. > > > > -- > Todd Snyder, Buffalo NY >
> 1976 Eleganza II> > _______________________________________________> GMCnet
> mailing list> Unsubscribe or Change List Options:>
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org_______________________________________________GMCnet
> mailing listUnsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360009 is a reply to message #360005] |
Sun, 08 November 2020 13:14 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
|
Senior Member |
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Thanks JimWould you know how much decrease there is for each tooth added?RaySent from my U.S.Cellular© Smartphone
-------- Original message --------From: Jim Kanomata via Gmclist Date: 11/7/20 3:44 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Jim Kanomata Subject: Re: [GMCnet] Speedometer Gear Reducer Adapter OEM ones are light tan/white 31 teethOn Sat, Nov 7, 2020 at 7:40 AM 78gmcroyale via Gmclist wrote:> Quick question.....how many teeth does the oem gear have?Sent from my> U.S.Cellular© Smartphone> -------- Original message --------From: Todd Snyder via Gmclist gmclist@list.gmcnet.org> Date: 11/5/20 3:52 PM (GMT-06:00) To:> gmclist@list.gmcnet.org Cc: Todd Snyder Subject:> Re: [GMCnet] Speedometer Gear Reducer Adapter I don't think the mph reading> is the first thing to correct. The first thing to get right is the> odometer. That's a direct geared readout ofdistance traveled. It needs to> be correct before the speedometer reading can be addressed if needed. You> could get on the highway, take note of the odometer as you pass a mile> marker. Drive 10 miles and note the odometer reading. Subtract onereading> from the other, figure out the % difference and get a driven gear with that> % more or less teeth, depending on which way you need it to go. Then pull> your current driven gear out and count the teeth. If the odometer is> reading low, you need fewer teeth on the driven gear. If the odometer> reads high, you need more teeth. You may or may not beable to get it> corrected with the driven gear though, the drive gear only works for a> certain range of tooth numbers. Looking online there aretransmission parts> stores that offer assistance with this. They'll know what range of teeth> numbers will fit with what you have and sell you thegearThere are also> online calculators that can determine the correct driven gear to use but> you need to know the number of teeth on the drive gear so theywon't be much> help unless you use them to figure out what's in there by trial and error,> which you can do. -- Todd Snyder, Buffalo NY 1976 Eleganza> II_______________________________________________GMCnet mailing> listUnsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org> _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>-- Jim KanomataApplied/GMC, Newark,CAjimk@appliedairfilters.comhttp://www.gmcrvparts.com1-800-752-7502_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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Unsubscribe or Change List Options:
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Speedometer Gear Reducer Adapter [message #360021 is a reply to message #360007] |
Mon, 09 November 2020 10:29 |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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Senior Member |
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Ray Erspamer wrote on Sun, 08 November 2020 09:53I'm very confused by this statement.... "I don't think the mph reading is the first thing to correct. The first thing to get right is the odometer. That's a direct geared readout ofdistance traveled. It needs to be correct before the speedometer reading can be addressed if needed."The speedometer cable feeds the speedometer and it's rate of spinning determines miles and mph. It can't differentiate between the two. If mph is correct then mileage should be correct and if mileage is correct then mph should be correct. I don't understand how you can first fix one and then fix the other.What am I missing?
Hi Ray,
Yes that's how it _should_ work if your speedometer (only considering the mechanical unit in the dash) is calibrated correctly. After 40 years, I would not make that assumption.
On mine, the odometer reads almost perfect b/c it is the OEM (31 tooth?) driven gear, OEM 3.07FD, and OEM diameter tires. Nothing has been been changed. So as designed, the cable rotates 1000? turns per mile. That's a direct gear driven mechanism that turns the odometer. There's no calibration other than getting the gearing ratios correct between the odometer and the output shaft of the transmission. Once those ratios are chosen, it works until something physically breaks like the cable snaps or a tooth breaks off a gear. It's all or nothing.
There is no calibration drift in the odometer.
However, the speed reading part of the speedometer is another animal. I'm not an expert but to me it seems that the rotation of the speedo cable is somehow coupled, maybe magnetically? to a spring loaded needle/pointer which gives, at best, an approximation of speed. That is a pretty fickle readout which can fall out of calibration especially after 40+ years.
This is the reason that at one time there were places called 'Speedometer Shops' dedicated to calibrating this part of the speedometer. I doubt there are many speedo shops still open for business. Maybe one or two in California if I had to bet.
On my GMC, there are parts of the speedo range where it is pretty much correct, and other parts where it is 10mph off. Now that we have GPS on our cell phones, this is easy to observe. Back in the 70s no one would have known.
When I'm doing 70, the speedo says 60 but my odometer is recording miles spot on. The correct fix would be to have my speedometer calibrated at a speedo shop, if one still exists.
The incorrect fix would be to change my speedo cable gearing to make the odometer read incorrectly but my speedometer read correctly. Does that make sense? I've probably just muddled it up further, sorry.
Long story short: If you get the gearing right so that the odometer reads correctly, then your speedometer _should_ also read correctly. If it doesn't, then the speedo could be sent off to a speedo shop for calibration.
Todd Snyder, Buffalo NY
1976 Eleganza II
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