Home » Public Forums » GMCnet » Final Drive Suckiness...
| Final Drive Suckiness... [message #79829] |
Thu, 08 April 2010 22:52  |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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Anyone had the LH side of their Final Drive Leak? It appears to be leaking at the shaft seal. The seals are new, but I was a bit worried about the wear on the shaft from the seal. It appears that is what is causing my leak. After several outings around the block tonight, with complete wipe down in between, this is the only place It can be coming from. The little vent with the wire hook is clean every time. Unless it spurts a few inches away? It drips a lot just after I stop, then the dripping subsides. Nice little dots up the driveway about an inch in diameter and a foot apart, however...
I originally filled it to the bottom of the fill hole, as I have always done with differentials. 
Ideas?
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: Final Drive Suckiness... [message #79835 is a reply to message #79829] |
Thu, 08 April 2010 23:21  |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Chris,
What I've done on new seals and used shafts, remove the lip seal tension spring, unscrew it apart and cut off 1/8" to 1/4" to give the lip more tension.
Be careful not to cut the end that screws inside the other end.
The amount to remove is a judgment call on the seal diameter and wear on the shaft.
It has worked for me.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: [GMCnet] Final Drive Suckiness... [message #79868 is a reply to message #79829] |
Fri, 09 April 2010 09:22 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Adrien,
Your thinking or the Rt side?
On Thu, Apr 8, 2010 at 8:52 PM, Chris Choffat <cchoffataz@yahoo.com> wrote:
>
>
> Anyone had the LH side of their Final Drive Leak? It appears to be leaking at the shaft seal. The seals are new, but I was a bit worried about the wear on the shaft from the seal. It appears that is what is causing my leak. After several outings around the block tonight, with complete wipe down in between, this is the only place It can be coming from. The little vent with the wire hook is clean every time. Unless it spurts a few inches away? It drips a lot just after I stop, then the dripping subsides. Nice little dots up the driveway about an inch in diameter and a foot apart, however...
>
> I originally filled it to the bottom of the fill hole, as I have always done with differentials. :x
>
>
> Ideas?
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD U S S Kobiashi Maru: The Engineer's Motorhome
> S T I L L - U N D E R - C O N S T R U C T I O N
> Scottsdale, AZ
> Photosite: Chrisc "It has Begun"
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.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] Final Drive Suckiness... [message #79869 is a reply to message #79835] |
Fri, 09 April 2010 09:21 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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The left side seal is sensitive as the output shaft has a slight
wobble when there is no load on the unit. It is also a baffled and
vented seal that is not readily available because of the vent and
babble.
Since we sell final drives with various ratio we stock the seals. Not cheap.
On Thu, Apr 8, 2010 at 9:21 PM, Adrien Genesoto <fixman54@syix.com> wrote:
>
>
> Chris,
> What I've done on new seals and used shafts, remove the lip seal tension spring, unscrew it apart and cut off 1/8" to 1/4" to give the lip more tension.
>
> Be careful not to cut the end that screws inside the other end.
>
> The amount to remove is a judgment call on the seal diameter and wear on the shaft.
>
> It has worked for me.
> --
> Adrien
> 75 Glenbrook
> Yuba City,Ca.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Final Drive Suckiness... [message #79871 is a reply to message #79829] |
Fri, 09 April 2010 09:31 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Chris,
When you put the final drive cover gasket on did you use it as it
came out of the box? They are a 2 piece gasket that is stapled
together. The reason that I ask is that a large number of them are
incorrectly assembled. Everyone that I have installed in the last few
years was not assemble so that the vent would work. You have to take
the staple out flip the gasket pieces and reassemble. Check the vent
path. I will go out to the shop and see if I have one on the shelf
and take pictures to show the difference. Without the drive venting
correctly then it come out the seals.
J.R. Wright
TZE Zone Restorations
GMC GreatLaker
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
On Apr 8, 2010, at 11:52 PM, Chris Choffat wrote:
>
>
> Anyone had the LH side of their Final Drive Leak? It appears to be
> leaking at the shaft seal. The seals are new, but I was a bit
> worried about the wear on the shaft from the seal. It appears that
> is what is causing my leak. After several outings around the block
> tonight, with complete wipe down in between, this is the only place
> It can be coming from. The little vent with the wire hook is clean
> every time. Unless it spurts a few inches away? It drips a lot just
> after I stop, then the dripping subsides. Nice little dots up the
> driveway about an inch in diameter and a foot apart, however...
>
> I originally filled it to the bottom of the fill hole, as I have
> always done with differentials. :x
>
>
> Ideas?
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD U S S Kobiashi Maru: The
> Engineer's Motorhome
> S T I L L - U N D E R - C O N S T R U C T I O N
> Scottsdale, AZ
> Photosite: Chrisc "It has Begun"
> _____________________________________
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Final Drive Suckiness... [message #79894 is a reply to message #79871] |
Fri, 09 April 2010 11:42 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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This was a 3.21, so i had to make a gasket. I have determined after several round the block, wipe, look, repeat, that the leak is not the cover, which I was hoping for. It most likely is the worn LH shaft at the seal. The RH has a pressed on ring thanks to Manny, so that one is nice and smooth. I'm hoping Manny may have a fix for the LH, perhaps, machining it and pressing on a ring and using a different seal or something. Otherwise, all I can do is tighten the oil seal like Adrien stated.
The worst part, is to get the LH flange off, I have to take the RH all apart to get to the bolt.
| powerjon wrote on Fri, 09 April 2010 07:31 |
Chris,
When you put the final drive cover gasket on did you use it as it
came out of the box? They are a 2 piece gasket that is stapled
together. The reason that I ask is that a large number of them are
incorrectly assembled. Everyone that I have installed in the last few
years was not assemble so that the vent would work. You have to take
the staple out flip the gasket pieces and reassemble. Check the vent
path. I will go out to the shop and see if I have one on the shelf
and take pictures to show the difference. Without the drive venting
correctly then it come out the seals.
J.R. Wright
TZE Zone Restorations
GMC GreatLaker
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
On Apr 8, 2010, at 11:52 PM, Chris Choffat wrote:
>
>
> Anyone had the LH side of their Final Drive Leak? It appears to be
> leaking at the shaft seal. The seals are new, but I was a bit
> worried about the wear on the shaft from the seal. It appears that
> is what is causing my leak. After several outings around the block
> tonight, with complete wipe down in between, this is the only place
> It can be coming from. The little vent with the wire hook is clean
> every time. Unless it spurts a few inches away? It drips a lot just
> after I stop, then the dripping subsides. Nice little dots up the
> driveway about an inch in diameter and a foot apart, however...
>
> I originally filled it to the bottom of the fill hole, as I have
> always done with differentials.
>
>
> Ideas?
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD U S S Kobiashi Maru: The
> Engineer's Motorhome
> S T I L L - U N D E R - C O N S T R U C T I O N
> Scottsdale, AZ
> Photosite: Chrisc "It has Begun"
> _____________________________________
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Final Drive Suckiness... [message #79951 is a reply to message #79894] |
Fri, 09 April 2010 21:14 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Chris;
It's been a long time since I ran the 3:21 gears. I know the 3:21 gears don't have the vent hole in the cover like the 3:08 gears do.I am now running Jim K's 3:70 gears. When I installed my 3:21 gears I installed a 1/4" copper vent line to vent the case on Fritz Slama's suggestion. It took me 2 trys to get the tubing positioned right in the case. The tubing is located to the top right side of the case(at the highest point )then it extends into the cover (tight to the cover)down a few inches and terminates above the oil level. It will be close to the ring gear
but you will Silver braze to the back side of the cover when you install it . Think about how the oil is being thrown off the ring gear when installing it so you position it properly. Connect length of 1/4" plastic tubing to the exposed end of the 1/4" pipe and run it high up into the wheel well and turn it down. This will vent the final drive nicely and it will not pressurize , mine did not leak a drop. Trust me it works.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Final Drive Suckiness... [message #79989 is a reply to message #79894] |
Sat, 10 April 2010 08:01 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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| Chr$ wrote on Fri, 09 April 2010 11:42 |
This was a 3.21, so i had to make a gasket. I have determined after several round the block, wipe, look, repeat, that the leak is not the cover, which I was hoping for. It most likely is the worn LH shaft at the seal. The RH has a pressed on ring thanks to Manny, so that one is nice and smooth. I'm hoping Manny may have a fix for the LH, perhaps, machining it and pressing on a ring and using a different seal or something. Otherwise, all I can do is tighten the oil seal like Adrien stated.
The worst part, is to get the LH flange off, I have to take the RH all apart to get to the bolt.
|
Ah...the 3.21, that changes things. So... you know then that the venting for the 3.21 is different?
See these:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=16033&cat=4399
and
http://www.gmcmhphotos.com/photos/showphoto.php?photo=16034&cat=4399
Maybe not seal, maybe coming out the vent?
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Final Drive Suckiness... [message #80064 is a reply to message #79989] |
Sat, 10 April 2010 21:12 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Larry:
I checked my old 3:21 to see if it had a vent in the output shaft like your picture suggested. Not in the one I have and it came off a 66 Toro. Mine has a pipe plug and it looks original mabye it was a problem and the later ones had a plug. I got it in 1988 off a car that looked like it hadden't been messed with.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Final Drive Suckiness... [message #80143 is a reply to message #80138] |
Sun, 11 April 2010 11:10 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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Manny. I didn't notice the pin holes. I will have to pull it and see. My Brass check valve is in place. What do you recommend plugging the pin holes with? I did use a seal tool to insert it flush and level. I took care to do so since there is no lip there.
Also, this FD has a vent near the tranny dipstick, it has a little metal tang sticking out of it. Could I have an oddball here or is that something else?
Wondering why an oil seal would have a pinhole or two in it. Seems counter intuitive.
I drove the coach yesterday, no leaks. I'm sure there is still plenty of oil in it, need to get under there and check.
Chris "Thinking about putting the 3.07 back in since with the Power drive, the rev's seem a bit high for my liking at highway speeds" Choffat.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] Final Drive Suckiness... [message #80148 is a reply to message #80143] |
Sun, 11 April 2010 11:32 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Cris,
There is a baffle to isolate the oil from the area where the vent
holes are. This is why it works.
When I ran a 3.21 back in 1983, we had a small vent installed at top
of the cover and ran a 3/8 rubber fuel hose up to the gas filler hose
area to vent.Also it helps to fill it only about 3/4 below the
original fill level.
This was a problem for the cars back then also.
On Sun, Apr 11, 2010 at 9:10 AM, Chris Choffat <cchoffataz@yahoo.com> wrote:
>
>
> Manny. I didn't notice the pin holes. I will have to pull it and see. My Brass check valve is in place. What do you recommend plugging the pin holes with? I did use a seal tool to insert it flush and level. I took care to do so since there is no lip there.
>
> Also, this FD has a vent near the tranny dipstick, it has a little metal tang sticking out of it. Could I have an oddball here or is that something else?
>
> Wondering why an oil seal would have a pinhole or two in it. Seems counter intuitive.
>
> I drove the coach yesterday, no leaks. I'm sure there is still plenty of oil in it, need to get under there and check.
>
> Chris "Thinking about putting the 3.07 back in since with the Power drive, the rev's seem a bit high for my liking at highway speeds" Choffat.
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD U S S Kobiashi Maru (with leaky Warp Drive Nacelle): The Engineer's Motorhome
> Scottsdale, AZ
> Photosite: Chrisc "It has Begun"
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Final Drive Suckiness... [message #80149 is a reply to message #80143] |
Sun, 11 April 2010 11:34 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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We stock these baffled vents as all our final drive unit sold are done this way.
On Sun, Apr 11, 2010 at 9:10 AM, Chris Choffat <cchoffataz@yahoo.com> wrote:
>
>
> Manny. I didn't notice the pin holes. I will have to pull it and see. My Brass check valve is in place. What do you recommend plugging the pin holes with? I did use a seal tool to insert it flush and level. I took care to do so since there is no lip there.
>
> Also, this FD has a vent near the tranny dipstick, it has a little metal tang sticking out of it. Could I have an oddball here or is that something else?
>
> Wondering why an oil seal would have a pinhole or two in it. Seems counter intuitive.
>
> I drove the coach yesterday, no leaks. I'm sure there is still plenty of oil in it, need to get under there and check.
>
> Chris "Thinking about putting the 3.07 back in since with the Power drive, the rev's seem a bit high for my liking at highway speeds" Choffat.
> --
> -Chr$: Perpetual SmartAss
> 77 Ex-Kingsley 455, Power Drive, 3:21 FD U S S Kobiashi Maru (with leaky Warp Drive Nacelle): The Engineer's Motorhome
> Scottsdale, AZ
> Photosite: Chrisc "It has Begun"
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Final Drive Suckiness... [message #80258 is a reply to message #80138] |
Sun, 11 April 2010 20:42 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Manny
I don't dispute what you say about a check valve in the Axel stub but my 3:21 definitely had a pipe plug in it. In 1988 when I removed it from the car it had all the mounting bolts in it and it didn't look like it had been out, the plug is even the same color green as the housing but I guess its possible it had been changed. As far as an external vent in the housing cover if it is positioned properly and extended into the case correctly it does not leak out the vent pipe. That is the way Fritz Slama and others in his group did it back in the day. I put around 20,000 miles on mine and it never leaked except when I just added the vent and didn't extend it properly. I can remember calling Fritz to tell him it leaked and he explained how to extend the pipe into the case.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Sun, 11 April 2010 20:43] Report message to a moderator |
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