3.42 Final Drive

M

mr.c

New member
Jul 11, 1998
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The shop that took my transmission apart suggested the 3.42. When I called
Wes, that is the only one he recommends. The last expert, Bob Lamy convinced
me I was right. He said that the 3.42 at the end of the transmission in the
final drive put less stress on the transmission. That's why I did it. I do
not have any experience in doing it, but Bob Lamy could probably give you some
hints.

Emery - Just for you to prepare for Oct, I have 138 coaches and 260 people
coming. Hope I live through it.

al

> I guess that I'm just going to bite the bullet on cost and replace the 2.73
> that was installed by the transmission shop with a 3.42 from Cinnabar.. I
> should be able to save some by putting in it myself in my driveway. My only
> concern is aligning the shaft into the tranny.
>
> Anyone been there and want to share info on the installation?
>
> Before I order it I would also welcome comments on the pros and cons of the
> 3.42 versus the other ratios on the market. I don't want to pull the
> transmission and replace gears on it so I am looking for info only on the
> final drive modifications available.
>
> Thanks
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
Emery,
I have the 3.55 final in our coach. I got it from Buskirk's and the
price was a little less than Cinnabar. You will need a good floor jack
and make yourself a holder to guide the final. Just take care and
everything will line up. There is a bolt that holds the short shaft in
the final drive. Be sure to reinstall it when you put the shaft back in.
You don't want to forget to put it in. I respect Wes, but there are
several different ratio's out there that work equally as well. Would
you think that he would recommend someone else's unit when he has all
that money tied up in his 3.42 gear assy?? I have a 403 and I can run
with most 455's out there.

J.R. Wright
GMC GreatLaker
77 Eleganza
Michigan

>
> I guess that I'm just going to bite the bullet on cost and replace the 2.73
> that was installed by the transmission shop with a 3.42 from Cinnabar.. I
> should be able to save some by putting in it myself in my driveway. My only
> concern is aligning the shaft into the tranny.
>
> Anyone been there and want to share info on the installation?
>
> Before I order it I would also welcome comments on the pros and cons of the
> 3.42 versus the other ratios on the market. I don't want to pull the
> transmission and replace gears on it so I am looking for info only on the
> final drive modifications available.
>
> Thanks
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
Emery,
I too installed the 3.42 final drive while my Transmode was parked in the
driveway. No special tools were needed. I did use a rolling shop jack (floor
jack) when lowering the old 3.07 drive out and then raising the new final drive
into place. I had the coach up on jack stands so I could use a creeper to slide
in and out from under the coach.

I remember that because of the tight clearances involved between the front of
the final drive's cover pan and the front suspension cross member, the new drive
went back in much easier when I removed the pan first. It had come sealed on
with a new gasket and RTV from Cinnabar. You might want to ask them to ship you
the final drive without the RTV sealant in place so you can remove the cover and
replace it more easily. Of course you take off the cover to drain the oil from
the old drive before taking it out.

I don't recall any problems with aligning the transmission shaft with the drive
( or was it the drive's input shaft with the transmission?)-- just go slow and
carefully. In my case my wife operated the floor jack while I maneuvered the
final drive into place.

Be sure to check the torque on the retainer bolt on the left side output
flange. Mine was too loose. Over all in my opinion this change out is a
project you can do if you're willing to spend all day at it and have some help.

I think you will be happy with the increased "pep" your coach will have on some
of those New Mexico hills once you've done the work.

My 3.42 has been in for about 15,000 miles so far with no problems. Good luck
and let us know how your project turns out.
Phil Stewart
'76 Transmode, TN
 
Emery:

I have heard the "stress" idea espoused many times by individuals, about the
Caspro Power Drive system. I've yet to hear of anyone who had a
transmission problem with it installed. I've therefore concluded that it's
pure speculation. If anyone would, it should be Leigh Harrison. He put in
a new engine and has developed port fuel injection which he installed.
Bobby Moore drove his coach on a test drive during the GMCMI Marion NC
convention last October, which included about eight other individuals along
for the ride. He told me that they were going up a fairly steep mountain
road and Leigh told him to floor it. When he did, the acceleration I'm told
caused the others to fall to the rear of the coach.

I've been corresponding with an individual from the Toronado mailinglist who
is deep into switch pitch transmissions, and also designed, builds, and
furnishes the fuzzy logic control box to Caspro for the switch pitch
transmission. He is high on using the Caspro Power Drive system because of
the new parts (i. e. bearings, gears, chain, etc.) you get with it. In
fact, he sometimes reverses the input and output gears to get an overdrive
effect. You may recall a few months back I contributed a half dozen items
on the Toro/switch pitch transmission from the Toro mailinglist, here.

Have you considered the 3.67:1 unit? If not and you're interested, I can
give you names of several individuals I know who have been running them, to
contact. Sure wish that was available when I installed the 3.42 unit.

Paul Bartz

From: mr.c [mailto:mr.c]
Sent: Friday, February 26, 1999 1:37 AM
Subject: Re: GMC: 3.42 Final Drive

The shop that took my transmission apart suggested the 3.42. When I called
Wes, that is the only one he recommends. The last expert, Bob Lamy
convinced me I was right. He said that the 3.42 at the end of the
transmission in the final drive put less stress on the transmission. That's
why I did it. I do not have any experience in doing it, but Bob Lamy could
probably give you some hints.

I guess that I'm just going to bite the bullet on cost and replace the 2.73
that was installed by the transmission shop with a 3.42 from Cinnabar.. I
should be able to save some by putting in it myself in my driveway. My only
concern is aligning the shaft into the tranny.
Anyone been there and want to share info on the installation?
Before I order it I would also welcome comments on the pros and cons of the
3.42 versus the other ratios on the market. I don't want to pull the
transmission and replace gears on it so I am looking for info only on the
final drive modifications available.
 
Scott---
Tell us more about Henderson's 3.42. Why would you want to use his conversion
when Caspro has so much experience and success with theirs??? What is
Henderson's price??
Gary
North Bend, Oregon Coast -- another "postcard" day

> Hi Emery!
>
> I'm having Henderson's Drive Line Inc. come up with a price on installing
> 3.42 gears in our final drive. I told him to come up with a price that
> included all new bearing and seals. Hendersons have built a very good
> following. Their shop is impecable, just like their work. I told him to
> figure on at least 10. I talked to him on Monday. I plan on calling him
> Friday if I don't hear from him before. I recall you have been pulling a
> wagoneer behind your coach and it had a 307. Seems like you did Ok with it.
> A 3.42 probably would do you well.
>
> Scott NEHODA'S
> BACK YARD
 
Thanks, Scott.
When you get a price keep us posted --- also what the price includes. I will be
changing over but I doubt if there is enough time between now and Albuquerque --
still trying to complete the Harrison brake conversions.
Gary
North Bend, Oregon

> In a message dated 8/26/99 11:46:47 AM Eastern Daylight Time,

>
> > Tell us more about Henderson's 3.42. Why would you want to use his
> > conversion
> > when Caspro has so much experience and success with theirs??? What is
> > Henderson's price??
> Hi Gary!
>
> Henderson's has built itself a good reputation. They advertise in lots of
> auto and truck magazines, maybe Zak has seen their ads. Not that ads mean
> anything! I have never seen a Caspro, nor their shop. Does Caspro actually
> do the work themselves or have it done? Anybody been to their shop? I
> don't think there would be any difference in the quality of the work! I have
> not gotten a price yet from Henderson's. Price would be my objective! If
> Henderson comes up with a less expensive 3.42, I would go with them for I
> don't think qualiy would suffer one bit!
> As for going to other gear ratios 3.50,3.55, 3.66 or 3.73, if gears are
> available at a similar price as the 3.42, maybe they could do them too! I
> will be calling them tomorrow to see about a price. Just trying to get a
> handle on what a "fair" price is, and not nesessarily a GMC motorhome
> "specialist" price!
>
> Scott NEHODA'S BACK
> YARD
 
Scott:

You can't get there in the manner your talking, if going with either the
Cinnabar or 3.67 units. That's because they're only sold as an assembly, in
the case, unit. You either change it out or pay someone else to do so.
With some of the other choices, you only pay for the gears (except the
Caspro Power Drive unit, which includes a multitude of parts), then you have
to find someone to build it up.

Also, Caspro is strictly a mail order parts operation. They have no shop
that I'm aware of.

Paul Bartz

From: Adohen [mailto:Adohen]
Sent: Thursday, August 26, 1999 12:40 PM
Subject: Re: GMC: 3.42 Final Drive

In a message dated 8/26/99 11:46:47 AM Eastern Daylight Time,

Tell us more about Henderson's 3.42. Why would you want to use his
conversion when Caspro has so much experience and success with theirs???
What is Henderson's price??

Hi Gary!
Henderson's has built itself a good reputation. They advertise in lots of
auto and truck magazines, maybe Zak has seen their ads. Not that ads mean
anything! I have never seen a Caspro, nor their shop. Does Caspro actually
do the work themselves or have it done? Anybody been to their shop? I
don't think there would be any difference in the quality of the work! I
have not gotten a price yet from Henderson's. Price would be my objective!
If Henderson comes up with a less expensive 3.42, I would go with them for I
don't think quality would suffer one bit!
As for going to other gear ratios 3.50,3.55, 3.66 or 3.73, if gears are
available at a similar price as the 3.42, maybe they could do them too! I
will be calling them tomorrow to see about a price. Just trying to get a
handle on what a "fair" price is, and not nesessarily a GMC motorhome
"specialist" price!
 
Paul...
You have just said the magic words that will drive Scott crazy....
Gary
North Bend, Oregon Coast

> Scott:
>
> You can't get there in the manner your talking, if going with either the
> Cinnabar or 3.67 units. (clip)
>
> Paul Bartz
>
 
Go Scott Go. Rah Rah Rah!!! Scott, Scott He's our man, If he can't do it,
Somebody else should at least try. If they can do a 3.73 Yahoo. I'm in. This is
one of the upgrades I was going to try to do in NM in October. Waiting patiently
on news of the final drive. Darren

> In a message dated 8/26/99 11:46:47 AM Eastern Daylight Time,

>
> > Tell us more about Henderson's 3.42. Why would you want to use his
> > conversion
> > when Caspro has so much experience and success with theirs??? What is
> > Henderson's price??
> Hi Gary!
>
> Henderson's has built itself a good reputation. They advertise in lots of
> auto and truck magazines, maybe Zak has seen their ads. Not that ads mean
> anything! I have never seen a Caspro, nor their shop. Does Caspro actually
> do the work themselves or have it done? Anybody been to their shop? I
> don't think there would be any difference in the quality of the work! I have
> not gotten a price yet from Henderson's. Price would be my objective! If
> Henderson comes up with a less expensive 3.42, I would go with them for I
> don't think qualiy would suffer one bit!
> As for going to other gear ratios 3.50,3.55, 3.66 or 3.73, if gears are
> available at a similar price as the 3.42, maybe they could do them too! I
> will be calling them tomorrow to see about a price. Just trying to get a
> handle on what a "fair" price is, and not nesessarily a GMC motorhome
> "specialist" price!
>
> Scott NEHODA'S BACK
> YARD

- --
Darren Paget
76 Experimental
Another Fab Day
paget
 
Scott:

When you receive the 3.42:1 ring and pinion gear article I mailed, you'll
see that the 3.07:1 has a 14 tooth pinion and a 43 tooth ring gear. A
3.42:1 is 12 and 41, respectively. Otherwise they're physically the same
size. If yours is apart, you can measure. Recall my e-mail a few days back
on the various sizes and ratios available in the Summit catalog. The
article says the gears are manufactured by Ohio-Richmond Gear, and Summit
carries Richmond???

Paul Bartz

From: Adohen [mailto:Adohen]
Sent: Thursday, August 26, 1999 3:58 PM
To: gmcmotorhome
Subject: Re: GMC: 3.42 Final Drive

In a message dated 8/26/99 2:38:31 PM Eastern Daylight Time,

> Paul...
> You have just said the magic words that will drive Scott crazy....
> Gary
> North Bend, Oregon Coast
>

Thanks Gary!
I needed that, ,just took 4 Prozac, feel much better. There seems to be such

a mystery to our final drives. Emery is driving around with a 2.73, Paul in

a 3.42. Scott not driving around however with a 3.07. My pursuit is to
find
out simply if it is a matter of replacing our ring and pinion with a 3.42.
ring and pinion. I doubt that Cinnabar has these specially made. And if
that is the case though, I'm going to let Henderson's find that out for me,
that is their job. Paul, you very well be right, but I'm going to find out
for myself. ( Paul ,maybe we could take both of ours apart and see what the

difference really is?:).)

Scott NEHODA'S
BACK YARD
 
Scott:

I said that only because I assumed you were using Cinnabar, etc., as your
source. Going to a different source is still to be determined and that's
what I see you doing. Good!

Paul

From: Adohen [mailto:Adohen]
Sent: Thursday, August 26, 1999 4:28 PM
Subject: Re: GMC: 3.42 Final Drive

In a message dated 8/26/99 4:07:00 PM Eastern Daylight Time,

> When you receive the 3.42:1 ring and pinion gear article I mailed, you'll
> see that the 3.07:1 has a 14 tooth pinion and a 43 tooth ring gear. A
> 3.42:1 is 12 and 41, respectively.
Ok Paul!

I guess we are still on the same page. From your message before you said:
"You can't get there in the manner your talking, if going with either the
Cinnabar or 3.67 units. That's because they're only sold as an assembly, in

the case, unit. You either change it out or pay someone else to do so."
This is exactly how I phrased my question to Henderson's. " I want to change

my 3.07 final in my GMC Motorhome to a 3.42, can it be done? and if it can
be
done, I want all new bearings and seals. If it can be done, give me a price

on one and what you would charge for 10 of them after you got "good at doing

mine"."
Maybe after I get the article I will be more intelligent.

Scott NEHODA'S
BACK YARD
 
Emery:

I don't believe there is a need to pull the transmission for Caspro's Power
Drive installation, so it's still a viable option for you.

Paul Bartz

From: EMERYSTORA [mailto:EMERYSTORA]
Sent: Wednesday, August 25, 1999 7:01 PM
Subject: GMC: 3.42 Final Drive

I guess that I'm just going to bite the bullet on cost and replace the 2.73
that was installed by the transmission shop with a 3.42 from Cinnabar.. I
should be able to save some by putting in it myself in my driveway. My only

concern is aligning the shaft into the tranny.

Anyone been there and want to share info on the installation?

Before I order it I would also welcome comments on the pros and cons of the
3.42 versus the other ratios on the market. I don't want to pull the
transmission and replace gears on it so I am looking for info only on the
final drive modifications available.
 
Paul, be aware that the final drive and tranny have to be removed to
install the Caspro power drive as per there instruction sheet. You
don't have to disassemble the transmission just the chain case.

J.R. Wright

>
> Emery:
>
> I don't believe there is a need to pull the transmission for Caspro's Power
> Drive installation, so it's still a viable option for you.
>
> Paul Bartz
>
> From: EMERYSTORA [mailto:EMERYSTORA]
> Sent: Wednesday, August 25, 1999 7:01 PM
> Subject: GMC: 3.42 Final Drive
>
> I guess that I'm just going to bite the bullet on cost and replace the 2.73
> that was installed by the transmission shop with a 3.42 from Cinnabar.. I
> should be able to save some by putting in it myself in my driveway. My only
>
> concern is aligning the shaft into the tranny.
>
> Anyone been there and want to share info on the installation?
>
> Before I order it I would also welcome comments on the pros and cons of the
> 3.42 versus the other ratios on the market. I don't want to pull the
> transmission and replace gears on it so I am looking for info only on the
> final drive modifications available.
 
Emery:

Guess I stand corrected. I thought that I had heard Chuck Stoddard say at
one of his GMCMI convention seminar's that removal wasn't necessary. I just
called him and he confirmed that you do in fact, need to remove. Said it
goes back 1" and then 21" of clearance is needed to get it out from under
the coach.

Paul Bartz

From: EMERYSTORA [mailto:EMERYSTORA]
Sent: Thursday, August 26, 1999 5:57 PM
Subject: Re: GMC: 3.42 Final Drive

In a message dated 8/26/99 4:49:33 PM Eastern Daylight Time,

 
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