Keeping an eye on your final drive.

[Bob Dunahugh]

The NEWES GMC is now 40 years old. And the final drive is certainly the mo=
st under maintained, important part of our coaches. Change that gear lube =
for two important reasons. 1 It was designed for a 4000lbs car. Not a 12,0=
00lbs motorhome. It's overloaded. And only for the fact that GM over design=
ed parts back then. The FD has done well for us. Get some fresh lube in the=
re. And get the contaminates out. ( Note. Make sure you DO NOT plug the LIT=
TLE vent hole in the cover. Talk to members here about that. And some cove=
r gaskets are made wrong. ) 2 Examine the thicker material at the bottom =
of the cover, and case. The slightly gray material is normal ware. If you =
find shiny material. If that's the case. Further inspection, and remplacem=
ent may be required. I just change my lube. Had about 30,000 miles on the =
lube. Found some material in there that concerned me. So I pulled the FD to=
look at the pinion bearing race. As that's the bearing that seems to fail =
first. Race wasn't perfect. But good enough to keep running. So now the FD =
is back in for the trip to Tucson. And thank you to John Biwersi for loani=
ng me his tool to get the FD seal back in without damage. So if your intere=
sted in a 3:21 FD. Or repair. John's the pro on the 3:21. Bob Dunahugh

 

[Rdenney]

The main dimension to check, and it’s easy to do if the FD is off the
transmission, is axial play. Grab the input split and pull it, push it,
pull it, etc., rapidly. If you can feel or hear any play as you do that,
the FD needs replacing. The play is supposed to be 0.008”—too little to
feel. Manny tells me that looseness in this direction damages
transmissions.

Most GMC final drives with the usual 100k miles will be loose. Most
Toronado or Eldorado final drives will not. But the Toro final drives are
2.56 gears—too tall for our use. Time to bite the bullet and get a new one
from the usual sources.

Rick “whose 3.07 failed this test with 103K miles on one of the lightest
coaches in the fleet” Denney

> The NEWES GMC is now 40 years old. And the final drive is certainly the
> most under maintained, important part of our coaches. Change that gear
> lube for two important reasons. 1 It was designed for a 4000lbs car. Not a
> 12,000lbs motorhome. It's overloaded. And only for the fact that GM over
> designed parts back then. The FD has done well for us. Get some fresh lube
> in there. And get the contaminates out. ( Note. Make sure you DO NOT plug
> the LITTLE vent hole in the cover. Talk to members here about that. And
> some cover gaskets are made wrong. ) 2 Examine the thicker material at
> the bottom of the cover, and case. The slightly gray material is normal
> ware. If you find shiny material. If that's the case. Further inspection,
> and remplacement may be required. I just change my lube. Had about 30,000
> miles on the lube. Found some material in there that concerned me. So I
> pulled the FD to look at the pinion bearing race. As that's the bearing
> that seems to fail first. Race wasn't perfect. But good enough to keep
> running. So now the FD is back in for the trip to Tucson. And thank you to
> John Biwersi for loaning me his tool to get the FD seal back in without
> damage. So if your interested in a 3:21 FD. Or repair. John's the pro on
> the 3:21. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[jim kanomata1]

> The main dimension to check, and it’s easy to do if the FD is off the
> transmission, is axial play. Grab the input split and pull it, push it,
> pull it, etc., rapidly. If you can feel or hear any play as you do that,
> the FD needs replacing. The play is supposed to be 0.008”—too little to
> feel. Manny tells me that looseness in this direction damages
> transmissions.
>
> Most GMC final drives with the usual 100k miles will be loose. Most
> Toronado or Eldorado final drives will not. But the Toro final drives are
> 2.56 gears—too tall for our use. Time to bite the bullet and get a new one
> from the usual sources.
>
> Rick “whose 3.07 failed this test with 103K miles on one of the lightest
> coaches in the fleet” Denney
>

>
> > The NEWES GMC is now 40 years old. And the final drive is certainly the
> > most under maintained, important part of our coaches. Change that gear
> > lube for two important reasons. 1 It was designed for a 4000lbs car.
> Not a
> > 12,000lbs motorhome. It's overloaded. And only for the fact that GM over
> > designed parts back then. The FD has done well for us. Get some fresh
> lube
> > in there. And get the contaminates out. ( Note. Make sure you DO NOT plug
> > the LITTLE vent hole in the cover. Talk to members here about that. And
> > some cover gaskets are made wrong. ) 2 Examine the thicker material at
> > the bottom of the cover, and case. The slightly gray material is normal
> > ware. If you find shiny material. If that's the case. Further inspection,
> > and remplacement may be required. I just change my lube. Had about 30,000
> > miles on the lube. Found some material in there that concerned me. So I
> > pulled the FD to look at the pinion bearing race. As that's the bearing
> > that seems to fail first. Race wasn't perfect. But good enough to keep
> > running. So now the FD is back in for the trip to Tucson. And thank you
> to
> > John Biwersi for loaning me his tool to get the FD seal back in without
> > damage. So if your interested in a 3:21 FD. Or repair. John's the pro on
> > the 3:21. Bob Dunahugh
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> 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
http://www.appliedgmc.com
1-800-752-7502

 

[jim kanomata1]

The play you need to check is at the pinion.
One cannot determin it if mounted to the transmission.
As far as the play at the output shaft on the Driver side, they will have
play there as that plate slides into a spider gear which is rather sloppy.
So don't get excited as the will not knock ot the trans.
Just the pinion will knock out the transmission.

>
>
> On Fri, Mar 23, 2018 at 5:18 AM, Richard Denney

>
>> The main dimension to check, and it’s easy to do if the FD is off the
>> transmission, is axial play. Grab the input split and pull it, push it,
>> pull it, etc., rapidly. If you can feel or hear any play as you do that,
>> the FD needs replacing. The play is supposed to be 0.008”—too little to
>> feel. Manny tells me that looseness in this direction damages
>> transmissions.
>>
>> Most GMC final drives with the usual 100k miles will be loose. Most
>> Toronado or Eldorado final drives will not. But the Toro final drives are
>> 2.56 gears—too tall for our use. Time to bite the bullet and get a new one
>> from the usual sources.
>>
>> Rick “whose 3.07 failed this test with 103K miles on one of the lightest
>> coaches in the fleet” Denney
>>
>> On Thu, Mar 22, 2018 at 9:49 PM Bob Dunahugh

>>
>> > The NEWES GMC is now 40 years old. And the final drive is certainly the
>> > most under maintained, important part of our coaches. Change that gear
>> > lube for two important reasons. 1 It was designed for a 4000lbs car.
>> Not a
>> > 12,000lbs motorhome. It's overloaded. And only for the fact that GM over
>> > designed parts back then. The FD has done well for us. Get some fresh
>> lube
>> > in there. And get the contaminates out. ( Note. Make sure you DO NOT
>> plug
>> > the LITTLE vent hole in the cover. Talk to members here about that. And
>> > some cover gaskets are made wrong. ) 2 Examine the thicker material at
>> > the bottom of the cover, and case. The slightly gray material is normal
>> > ware. If you find shiny material. If that's the case. Further
>> inspection,
>> > and remplacement may be required. I just change my lube. Had about
>> 30,000
>> > miles on the lube. Found some material in there that concerned me. So I
>> > pulled the FD to look at the pinion bearing race. As that's the bearing
>> > that seems to fail first. Race wasn't perfect. But good enough to keep
>> > running. So now the FD is back in for the trip to Tucson. And thank
>> you to
>> > John Biwersi for loaning me his tool to get the FD seal back in without
>> > damage. So if your interested in a 3:21 FD. Or repair. John's the pro
>> on
>> > the 3:21. Bob Dunahugh
>> > _______________________________________________
>> > GMCnet mailing list
>> > Unsubscribe or Change List Options:
>> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>> >
>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> 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
> http://www.appliedgmc.com
> 1-800-752-7502
>

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

 

[robert mueller]

Rick,

IIRC the OEM Toronado FD was 3.21 (planetary gear) 1966 & 1967 then 3.07 (spider gear). Eldorados had a 2.73 to 1, however, I've never heard of a 2.65
to 1.
--
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426

 

[LarryW]

> Rick,
>
> IIRC the OEM Toronado FD was 3.21 (planetary gear) 1966 & 1967 then 3.07 (spider gear). Eldorados had a 2.73 to 1, however, I've never heard of a
> 2.65 to 1.

And IIRC the 67' Eldo also had the 3.21. So, 66 & 67 Toro and 67 Eldo had the 3.21. Just what I remember. See this to tell visual difference in
identifying the 3.21 from the 3.07/2.73.

http://www.gmcmhphotos.com/photos/g4399-fd-visual-differences307-vs-321.html
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.

 

[kosier]

Rob,

The 3.07 went from '68 to '72. Then they used a 2.73 as standard with the
3.07 as a towing option.

Gary Kosier
77PB w/500Cad
Newark, Ohio

--------------------------------------------------
From: "Robert Mueller"
Sent: Saturday, March 24, 2018 7:49 AM
To:
Subject: Re: [GMCnet] Keeping an eye on your final drive.

> Rick,
>
> IIRC the OEM Toronado FD was 3.21 (planetary gear) 1966 & 1967 then 3.07
> (spider gear). Eldorados had a 2.73 to 1, however, I've never heard of a
> 2.65
> to 1.
> --
> Regards,
> Rob M. (USAussie)
> The Pedantic Mechanic
> Sydney, Australia
> '75 Avion - AUS - The Blue Streak TZE365V100428
> '75 Avion - USA - Double Trouble TZE365V100426
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org