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Transmission shifting [message #83236]

Wed, 05 May 2010 17:30

psakw

Messages: 61
Registered: February 2010

Karma: 0

Member

My trans seems to shift very early, 5mph out of first and 15 or 20mph out of second.
My first question is there any adjustment?
Secondly, I have been told not to shift manually because when you do it uses a second gear band instead of clutches, is that right?

Paul A
73 Sequoia
Key west, Florida

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Re: [GMCnet] Transmission shifting [message #83240 is a reply to message #83236]

Wed, 05 May 2010 17:54

Steven Ferguson

Messages: 3447
Registered: May 2006

Karma: 0

Senior Member

You need to check the vacuum line going from the engine to the
modulator on the trans. If it is good, no kinks or pinches, chances
are the modulator is bad. Cheap fix, only one bolt too.

On Wed, May 5, 2010 at 3:30 PM, paul array <pumppal1@aol.com> wrote:
>
>
> My trans seems to shift very early, 5mph out of first and 15 or 20mph out of second.
> My first question is there any adjustment?
> Secondly, I have been told not to shift manually because when you do it uses a second gear band instead of clutches, is that right?
>
> Paul A
> 73 Sequoia
> Key west, Florida
> _______________________________________________
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Transmission shifting [message #83249 is a reply to message #83240]

Wed, 05 May 2010 18:16

psakw

Messages: 61
Registered: February 2010

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Hello Steven
Is the modulator adjustable?

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Re: Transmission shifting [message #83257 is a reply to message #83236]

Wed, 05 May 2010 19:43

Larry

Messages: 2875
Registered: January 2004
Location: Menomonie, WI

Karma: 10

Senior Member

I had exactly the same trouble with my Manny tranny. After jumping through all kinds of hoops with modulator...droping the pan to check things...etc...etc, I finally reasoned that this is a trans speed issue. I pulled a governor out of a spare trans that I had, installed it and the problem went away. If all else fails, or maybe as a first step, swap out the governor. It's a relatively easy thing to do. Just what I'd do...

Larry

Smile

78 Royale w/500 Caddy
Menomonie, WI.

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Re: Transmission shifting [message #83269 is a reply to message #83236]

Wed, 05 May 2010 21:48

fred v

Messages: 999
Registered: April 2006
Location: pensacola, fl.

Karma: 0

Senior Member

i pulled this reply from a previous thread on the subject:

""Not all of the modulators are adjustable but many of them are. If
there is no screw inside then you don't have an adjustable one.
However, if you used to shift properly and it just started not to --
then check the vacuum line to make sure that it is tight and not
leaking. You might find it disconnected from the modulator. If so,
just push it back on and see if everything works. If not then you
should get a vacuum pump and test the modulator to make sure that the
diaphragm is not cracked. You can also put on a hose and suck on it
to see it you get a vacuum.""

Fred V
'77 Royale RB 455
P'cola, Fl

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Re: [GMCnet] Transmission shifting [message #83289 is a reply to message #83236]

Wed, 05 May 2010 23:59

mannystrans

Messages: 209
Registered: June 2006

Karma: 1

Senior Member

Early shifts are mostly because of great engine vacuum. The spring in
the modulator can be adjusted. turning the screw clockwise increases
the tension (higher speed shifting). Turning the screw
counter-clockwise decreases the spring tension (sooner shifts).
Turning the the screw wither clockwise or counter-clockwise doesn't
give you a liner affect. Sometimes the spring, springs back.
I suggest turning in 1/2 turn or 3/4 turn increments until you get the
desired shifting speed you want.

--
Manny Trovao
mannystrans@hughes.net
Manny's Trans / Power Drive
San Jose, California
408-937-1583
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Re: [GMCnet] Transmission shifting [message #83301 is a reply to message #83249]

Thu, 06 May 2010 03:38

Steven Ferguson

Messages: 3447
Registered: May 2006

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Yes,
But there's not enough adjustment for the increase in range you are
wanting. Larry is probably right about the governor,but it is only a
few bucks to install a new adj. modulator. Governors are fairly
precious as you must have a donor transmission. None left.

On Wed, May 5, 2010 at 4:16 PM, paul array <pumppal1@aol.com> wrote:
>
>
> Hello Steven
> Is the modulator adjustable?
>
>
> _______________________________________________
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>

--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: Transmission shifting [message #83357 is a reply to message #83257]

Thu, 06 May 2010 14:29

Surbo

Messages: 213
Registered: February 2004

Karma: 0

Senior Member

Larry wrote on Wed, 05 May 2010 19:43

I had exactly the same trouble with my Manny tranny. After jumping through all kinds of hoops with modulator...droping the pan to check things...etc...etc, I finally reasoned that this is a trans speed issue. I pulled a governor out of a spare trans that I had, installed it and the problem went away. If all else fails, or maybe as a first step, swap out the governor. It's a relatively easy thing to do. Just what I'd do...

Larry;

The shift points can be changed to a higher speed by drilling a hole in the governor weights so that they are lighter. This will delay the shift to a higher mph as it takes more centrifugal speed of the governor shaft to extend the weights and change the valve position.

The OEM build sheet for the governors are interesting to look at, not a lot of changes in Olds, Cad's & the MH. If I recall, the only difference was one spring.

Bob Drewes in SESD

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Re: [GMCnet] Transmission shifting [message #83383 is a reply to message #83289]

Thu, 06 May 2010 18:32

psakw

Messages: 61
Registered: February 2010

Karma: 0

Member

Manny:
Thank you, I looked at the modulator today and I guess you mean on the outside of it there is a nut with a screw inside it. Is that the screw I should adjust? (1/2 turn in at a time and try it)

Can you answer the second question? I have been manually shifting the GMC because the trans shifts so early. People have said " Not to do that" because supposedly when it shifts by itself it uses clutches but when you shift manually it uses a small band to stop the drum. Your thoughts please.
Personally I thought it was a turbo 350 which I dont believe has bands, only three clutch packs.

Paul A

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Re: [GMCnet] Transmission shifting [message #83422 is a reply to message #83383]

Thu, 06 May 2010 22:30

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

Manny's in Fresno,CA.
He told us not to bother him.
He will get back to you Friday.

On Thu, May 6, 2010 at 4:32 PM, paul array <pumppal1@aol.com> wrote:
>
>
> Manny:
> Thank you, I looked at the modulator today and I guess you mean on the outside of it there is a nut with a screw inside it. Is that the screw I should adjust? (1/2 turn in at a time and try it)
>
> Can you answer the second question? I have been manually shifting the GMC because the trans shifts so early. People have said " Not to do that" because supposedly when it shifts by itself it uses clutches but when you shift manually it uses a small band to stop the drum. Your thoughts please.
> Personally I thought it was a turbo 350 which I dont believe has bands, only three clutch packs.
>
> Paul A
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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www.appliedgmc.com
1-800-752-7502

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Re: [GMCnet] Transmission shifting [message #83437 is a reply to message #83383]

Fri, 07 May 2010 07:26

Steven Ferguson

Messages: 3447
Registered: May 2006

Karma: 0

Senior Member

Paul,
The adjustment screw is inside of the modulator. If you remove the
vacuum line, slip a small screwdriver in the hole, you can feel the
slot in the head of the adjustment. This adjustment if for fine
tuning and has a very limited effect on shifting rpm. I think you're
going to find your problem is the governor.

On Thu, May 6, 2010 at 4:32 PM, paul array <pumppal1@aol.com> wrote:
>
>
> Manny:
> Thank you, I looked at the modulator today and I guess you mean on the outside of it there is a nut with a screw inside it. Is that the screw I should adjust? �(1/2 turn in at a time and try it)
>
> Can you answer the second question? I have been manually shifting the GMC because the trans shifts so early. People have said " Not to do that" because supposedly when it shifts by itself it uses clutches but when you shift manually it uses a small band to stop the drum. Your thoughts please.
> Personally I thought it was a turbo 350 which I dont believe has bands, only three clutch packs.
>
> Paul A
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>

--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Transmission shifting [message #83492 is a reply to message #83437]

Fri, 07 May 2010 13:36

psakw

Messages: 61
Registered: February 2010

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Steve:
Thank you, that vacuum line is pretty small so it must be a little screw, by the way, what is the big screw on the outside?

Paul A
Key West Florida

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Re: [GMCnet] Transmission shifting [message #83513 is a reply to message #83492]

Fri, 07 May 2010 16:20

Steven Ferguson

Messages: 3447
Registered: May 2006

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Senior Member

If it is the hex head you're referring to, it's the mounting bolt.

On Fri, May 7, 2010 at 11:36 AM, paul array <pumppal1@aol.com> wrote:
>
>
> Steve:
> Thank you, that vacuum line is pretty small so it must be a little screw, by the way, what is the big screw on the outside?
>
> Paul A
> Key West Florida
> _______________________________________________
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Transmission shifting [message #83520 is a reply to message #83513]

Fri, 07 May 2010 17:02

psakw

Messages: 61
Registered: February 2010

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Member

Steve:
The hex nut that bolts to the tranny I know about, that is on a steel tab that holds the modulator in. This is a screw (straight head) with what looks like a lock nut around it located on the end of the modulator in the center.

Paul A
Key West Florida

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Re: [GMCnet] Transmission shifting [message #83534 is a reply to message #83520]

Fri, 07 May 2010 17:28

Steven Ferguson

Messages: 3447
Registered: May 2006

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I don't know.

On Fri, May 7, 2010 at 3:02 PM, paul array <pumppal1@aol.com> wrote:
>
>
> Steve:
> The hex nut that bolts to the tranny I know about, that is on a steel tab that holds the modulator in. This is a screw (straight head) with what looks like a lock nut around it located on the end of the modulator in the center.
>
> Paul A
> Key West Florida
> _______________________________________________
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Transmission shifting [message #83600 is a reply to message #83534]

Sat, 08 May 2010 06:43

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

There are several different styles / brands of modulators. A picture would be helpful.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Re: [GMCnet] Transmission shifting [message #83610 is a reply to message #83600]

Sat, 08 May 2010 07:17

Surbo

Messages: 213
Registered: February 2004

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Senior Member

Ken Burton wrote on Sat, 08 May 2010 06:43

There are several different styles / brands of modulators. A picture would be helpful.

Paul is talking about the OEM 'big can style' modulator, there is a locking jam nut for the adjustment screw.

Bob Drewes in SESD

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Re: [GMCnet] Transmission shifting [message #83620 is a reply to message #83610]

Sat, 08 May 2010 07:56

psakw

Messages: 61
Registered: February 2010

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Member

Hi Bob:
I presume that on the big can type the adjustment screw for the spring is the one I am talking about in the center of the can? (with the jam nut) That is the one I turn in 1/2 turn ?

Paul A
Key West, Florida

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Re: [GMCnet] Transmission shifting [message #83629 is a reply to message #83620]

Sat, 08 May 2010 08:49

WD0AFQ

Messages: 7111
Registered: November 2004
Location: Dexter, Mo.

Karma: 207

Senior Member

Paul, at least you can move into the gears. Could be like mine, a mind of it's own. Shifting when it wants, back to 2nd, at 55-60 mph.
Hope everything else is good with you two.

What about sending your knuckles to Dave Linzey, for complete repairs?
Dan

3 In Stainless Exhaust Headers One Ton All Discs/Reaction Arm 355 FD/Quad Bag/Alum Radiator Manny Tran/New eng. Holley EFI/10 Tire Air Monitoring System Solarized Coach/Upgraded Windows Satelite TV/On Demand Hot Water/3Way Refer

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Re: [GMCnet] Transmission shifting [message #83644 is a reply to message #83629]

Sat, 08 May 2010 11:31

Kingsley Coach

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Registered: March 2009
Location: Nova Scotia Canada

Karma: -34

Senior Member

Dan

Did you ever get your tranny working correctly?

Mike in NS

On Sat, May 8, 2010 at 10:49 AM, Dan Gregg <gregg_dan@hotmail.com> wrote:

>
>
> Paul, at least you can move into the gears. Could be like mine, a mind of
> it's own. Shifting when it wants, back to 2nd, at 55-60 mph.
> Hope everything else is good with you two.
>
> What about sending your knuckles to Dave Linzey, for complete repairs?
> Dan
> --
> Dan & Teri Gregg
>
> danandteri.blogspot.com
>
>
>
> ///Halon Automatic Fire Extinguishers
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1977 Kingsley 26-11
1977 Eleganza II 26-3
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