Final Drive

S

steven d. ferguson

New member
Aug 1, 1999
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Steve,
I too have a 3.21 final drive but I have yet to install it. One thing
has been troubling me and that is something I read in an old volume of
the Cinnabar news letter. The output shaft of the 3.21 ('66-'67 Toro)
is considered too small to hold up in the GMC. This was written by a
reader and the reply to the question didn't mention if it was true or
not. Damned if I can find out anything more on this subject. I'd
really like to get on with the project but don't want to create more
problems later on. Any light you could shine on this subject?
Steve Ferguson
 
Steve, there are a great many 3.21 final drives running around out there on
GMC motorhomes and have been for many years. I think if there was any problem at
all with the size of the output shaft and failure of same, that you would hear
about it immediately on this list. I have yet to hear of a problem in this area.
So install and enjoy.
My $.02
Pat 77 Birch

> Steve,
> I too have a 3.21 final drive but I have yet to install it. One thing
> has been troubling me and that is something I read in an old volume of
> the Cinnabar news letter. The output shaft of the 3.21 ('66-'67 Toro)
> is considered too small to hold up in the GMC. This was written by a
> reader and the reply to the question didn't mention if it was true or
> not. Damned if I can find out anything more on this subject. I'd
> really like to get on with the project but don't want to create more
> problems later on. Any light you could shine on this subject?
> Steve Ferguson
 
Chuck, FWIW, I have just received all the seals for a 3.21 final drive I am
rebuilding. Got them from Cinnebar.
can't remember what they cost (senior moment?), but remember they were very
reasonable. Have fun.
Pat && Birch

> Steve and Emery et al:
>
> What I have been told:
>
> The shaft from the final drive that goes under the engine is smaller in dia
> on a 3.21 than the 3.07.
>
> I was told this by John Bieruski (sp) another GMCer and 3Mer who rebuilds
> them. He cannot find seals for the smaller diameter shaft there fore metal
> sprays them and builds up the diameter so he can use a 3.07 seal. He says
> that Caspro puts on a sleeve to accomplish the same thing.
>
> Since I have both laying on my garage floor, I may borrow a micrometer from
> work and go measure them.
>
> In the next few weeks going over to John to rebuild the 3.21 and will have
> more first hand knowledge.
>
> Chuck D
> 78 Royale
> Stillwater Mn
> Crisp winter day +20 and sunny.
 
This may sound funny but I think I want to be lied to.
I was installing my freshly rebuilt axle shaft on the
drivers side tonight. Yes it is cold here in CT but I
am nuts and leaving for FL in a week and a couple of
days. I noticed as I was tightening the bolts on the
inner end of the shaft that as I pull on the wrench
the whole assembly moves. In other words the shaft
comming out of the diff wiggles say about 1/16 of an
inch maybe an 1/8 th. I am perfectly happy with the
stock final drive ratio! I do not want to replace the
final drive. Here is where I want to be lied to,
someone tell me this is OK and normal. Ok just a
little lie, tell me that it will probably make to Fl
and back. If you won't lie to me, has anybody out
there upgraded and have an origional in good condition
for sale, cheap?
__________________________________________________
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Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
 
Alan,
I've been told before that the play you describe in the output flange on
the driver's side of the final drive is normal. And I suppose that's
true because my "new" 3.42 final drive has had that amount of play for
close to 20,000 miles now with no signs of trouble so far. HTH but wait
for our Net's experts to confirm or refute this. Good luck and try to
stay warm.
Phil Stewart
'76 Transmode,TN

> This may sound funny but I think I want to be lied to.
> I was installing my freshly rebuilt axle shaft on the
> drivers side tonight. Yes it is cold here in CT but I
> am nuts and leaving for FL in a week and a couple of
> days. I noticed as I was tightening the bolts on the
> inner end of the shaft that as I pull on the wrench
> the whole assembly moves. In other words the shaft
> comming out of the diff wiggles say about 1/16 of an
> inch maybe an 1/8 th. I am perfectly happy with the
> stock final drive ratio! I do not want to replace the
> final drive. Here is where I want to be lied to,
> someone tell me this is OK and normal. Ok just a
> little lie, tell me that it will probably make to Fl
> and back. If you won't lie to me, has anybody out
> there upgraded and have an origional in good condition
> for sale, cheap?
> __________________________________________________
> Do You Yahoo!?
> Talk to your friends online with Yahoo! Messenger.
> http://im.yahoo.com
 
Alan,

Relax, it's normal. IIRC, Cinnabar's GMC Motorhome News a couple years back
had a letter in it asking the same question. Your final drive is fine.

Patrick

>
> I noticed as I was tightening the bolts on the
> inner end of the shaft that as I pull on the wrench
> the whole assembly moves. In other words the shaft
> comming out of the diff wiggles say about 1/16 of an
> inch maybe an 1/8 th.
 
Just to be sure I am clear this is not radial play by
wiggling front to back or up and down. If there is a
gear on the other end of this shaft in the Diff and it
engages with another gear it seems that this play
would change the clearances between the gears?

Date: Wed, 02 Feb 2000 21:44:12 -0500
From: plstewrt
Subject: Re: GMC: Final drive

Alan,
I've been told before that the play you describe in
the output flange
on
the driver's side of the final drive is normal. And I
suppose that's
true because my "new" 3.42 final drive has had that
amount of play for
close to 20,000 miles now with no signs of trouble so
far. HTH but
wait
for our Net's experts to confirm or refute this. Good
luck and try to
stay warm.
Phil Stewart
'76 Transmode,TN

> This may sound funny but I think I want to be lied
to.
> I was installing my freshly rebuilt axle shaft on
the
> drivers side tonight. Yes it is cold here in CT but
I
> am nuts and leaving for FL in a week and a couple of
> days. I noticed as I was tightening the bolts on the
> inner end of the shaft that as I pull on the wrench
> the whole assembly moves. In other words the shaft
> comming out of the diff wiggles say about 1/16 of an
> inch maybe an 1/8 th. I am perfectly happy with the
> stock final drive ratio! I do not want to replace
the
> final drive. Here is where I want to be lied to,
> someone tell me this is OK and normal. Ok just a
> little lie, tell me that it will probably make to Fl
> and back. If you won't lie to me, has anybody out
> there upgraded and have an origional in good
condition
> for sale, cheap?

__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
 
Yep - axial play in line with the output shaft. If no one elses finds it
before tonight, I'll look up the GMCMN issue with the letter in it.

Patrick

>
> Just to be sure I am clear this is not radial play by
> wiggling front to back or up and down. If there is a
> gear on the other end of this shaft in the Diff and it
> engages with another gear it seems that this play
> would change the clearances between the gears?
>
> Date: Wed, 02 Feb 2000 21:44:12 -0500
> From: plstewrt
> Subject: Re: GMC: Final drive
>
> Alan,
> I've been told before that the play you describe in
> the output flange on the driver's side of the final
> drive is normal.
 
From GMCMN Sept. 96
====================================================
Output Shaft Slop
I was underneath my (GMC Motorhome looking for a noise that has developed.
When I pushed on the final-drive output flange on the left side, I
discovered some slop. The flange moves up and down, but there is no
lubricant leaking from the seal on the left side of the final drive.
What causes this slop? Can you tell me how to correct it?

The slop is normal, Peter. You aren't the first to discover it, and you
won't be the last. A few years back, Bill Forcum of Chicago Park,
California, called from rural Utah. He had been on the road all day and
heard a noise. When he discovered the slop, he thought his final drive was
not long for this world. We assured him that the condition was normal as
long as the seal on the left side was not leaking. Bill continued his trip,
and his motorhome is still running today with that same final drive.
The left output shaft on the GMC Motorhome final drive is somewhat
unique. The shaft bolts to one of the side gears that basically floats
inside the final drive. There are no bushings or bearings to support it. As
a result, it can move more than one would expect. However, when everything
is assembled and the motorhome is going down the road, you won't see any
slop or wobble.
================================================
hth
bdub

>Just to be sure I am clear this is not radial play by
>wiggling front to back or up and down. If there is a
>gear on the other end of this shaft in the Diff and it
>engages with another gear it seems that this play
>would change the clearances between the gears?
>
>Date: Wed, 02 Feb 2000 21:44:12 -0500
>From: plstewrt
>Subject: Re: GMC: Final drive
>
>Alan,
>I've been told before that the play you describe in
>the output flange
>on
>the driver's side of the final drive is normal. And I
>suppose that's
>true because my "new" 3.42 final drive has had that
>amount of play for
>close to 20,000 miles now with no signs of trouble so
>far. HTH but
>wait
>for our Net's experts to confirm or refute this. Good
>luck and try to
>stay warm.
>Phil Stewart
>'76 Transmode,TN
>

>
> > This may sound funny but I think I want to be lied
>to.
> > I was installing my freshly rebuilt axle shaft on
>the
> > drivers side tonight. Yes it is cold here in CT but
>I
> > am nuts and leaving for FL in a week and a couple of
> > days. I noticed as I was tightening the bolts on the
> > inner end of the shaft that as I pull on the wrench
> > the whole assembly moves. In other words the shaft
> > comming out of the diff wiggles say about 1/16 of an
> > inch maybe an 1/8 th. I am perfectly happy with the
> > stock final drive ratio! I do not want to replace
>the
> > final drive. Here is where I want to be lied to,
> > someone tell me this is OK and normal. Ok just a
> > little lie, tell me that it will probably make to Fl
> > and back. If you won't lie to me, has anybody out
> > there upgraded and have an origional in good
>condition
> > for sale, cheap?
>
>__________________________________________________
>Do You Yahoo!?
>Talk to your friends online with Yahoo! Messenger.
>http://im.yahoo.com
 
GMCers,
For what it's worth, in my search to find an alternate search for final
drive gears I located a new, in the crate, final drive. If you want it
($450.00 was the quoted price) call J&S Gear @ (714)841-4545. The owner
bought 4 of them from a GMC dealership years ago.
Steve F.
 
On Mon, 21 Feb 2000 05:20:15 -0800 "Steven D. Ferguson"

> GMCers,
> For what it's worth, in my search to find an alternate search for
final drive gears I located a new, in the crate, final drive. If you
want
> it ($450.00 was the quoted price) call J&S Gear @ (714)841-4545. The
owner bought 4 of them from a GMC dealership years ago.
> Steve F.

Very interesting, Steve.
While we are on this topic I thought it might be interesting to relate
the pricing from some original color brochures I have from George Byers
and Sons, Ohio GM Truck dealers in the 70's and Consolidated Int'l, both
of whom were offering up to 1,361 transmissions at $375 and up to 597
final drives at $225 or both tranny and final drive in a package for
$495!

They bought up GM Truck and Coach's inventory in early 1979. Initially
they offered the trannys at $475 but a year later they had dropped the
price to $295! All prices were FOB Columbus, OH. What a deal, eh?

David Lee Greenberg
GMC Motorhome Registry
Dedicated To The Preservation Of The GMC Classic!
www.gmcss.com/registry.htm
 
Scott Wrote:
I don't think the ring gear is the problem. I believe it is the pinion
because it is different than rear wheel drive.
Thanks Scott,
Learning as we go on this.
Steve
 
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