3.70 Transmission Gear Set
- Thread starter the hamiltons
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We are on the same page on this one. Darren
> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
> > I thought the final drive change was best now I am not sure. I want to
> > do one of them but not both. Darren
> >
> Darren
>
> Here is my thinking---nothing more. I honestly have no idea which is best.
> I wanted to take the load off the tranny and chain. So my thoughts ran
> to doing the final drive. Thats why I did not like the Caspro system. Now
> I dont know. Hope others speak up.
>
> Take Care
> Arch
- --
Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
> > I thought the final drive change was best now I am not sure. I want to
> > do one of them but not both. Darren
> >
> Darren
>
> Here is my thinking---nothing more. I honestly have no idea which is best.
> I wanted to take the load off the tranny and chain. So my thoughts ran
> to doing the final drive. Thats why I did not like the Caspro system. Now
> I dont know. Hope others speak up.
>
> Take Care
> Arch
- --
Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
I recently ordered a 3.70 final drive from Jim K. Should be here within the
next week. I did this rather than the sprockets on the strength of the opinion
of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions only,
in White S.D. and a few of us "Greater Midwest Classics" have had our
transmissions done there. I am very well satisfied with mine. Just a few words
to inform of his qualifications. Any how, I have a 3.21 final drive that I was
going to install with the 3.50 sprockets from Chuck Stoddard for a final ratio
of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
final because as he explained, it's better to have a happy engine(more rpm's)
and a happy transmission (more rpm's, more internal pressure). When onlyu the
sprockets are utilized, only the engine is speeded up. The cost to me was just
about a wash, so that's what I decided to do and why. Works for me, maybe not
for you.
Pat 77 Birch
> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
> > I thought the final drive change was best now I am not sure. I want to
> > do one of them but not both. Darren
> >
> Darren
>
> Here is my thinking---nothing more. I honestly have no idea which is best.
> I wanted to take the load off the tranny and chain. So my thoughts ran
> to doing the final drive. Thats why I did not like the Caspro system. Now
> I dont know. Hope others speak up.
>
> Take Care
> Arch
next week. I did this rather than the sprockets on the strength of the opinion
of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions only,
in White S.D. and a few of us "Greater Midwest Classics" have had our
transmissions done there. I am very well satisfied with mine. Just a few words
to inform of his qualifications. Any how, I have a 3.21 final drive that I was
going to install with the 3.50 sprockets from Chuck Stoddard for a final ratio
of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
final because as he explained, it's better to have a happy engine(more rpm's)
and a happy transmission (more rpm's, more internal pressure). When onlyu the
sprockets are utilized, only the engine is speeded up. The cost to me was just
about a wash, so that's what I decided to do and why. Works for me, maybe not
for you.
Pat 77 Birch
> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
> > I thought the final drive change was best now I am not sure. I want to
> > do one of them but not both. Darren
> >
> Darren
>
> Here is my thinking---nothing more. I honestly have no idea which is best.
> I wanted to take the load off the tranny and chain. So my thoughts ran
> to doing the final drive. Thats why I did not like the Caspro system. Now
> I dont know. Hope others speak up.
>
> Take Care
> Arch
Isnt there a structural problem with these numerically high final drives.
there is only so much room for gears. If the ring gear is increased and the
pinion is decreased in size seems like we would be sacrificing steangth of
the pinion gear. Any comments?
> I recently ordered a 3.70 final drive from Jim K. Should be here within the
>next week. I did this rather than the sprockets on the strength of the opinion
>of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions only,
>in White S.D. and a few of us "Greater Midwest Classics" have had our
>transmissions done there. I am very well satisfied with mine. Just a few words
>to inform of his qualifications. Any how, I have a 3.21 final drive that I was
>going to install with the 3.50 sprockets from Chuck Stoddard for a final ratio
>of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
>final because as he explained, it's better to have a happy engine(more rpm's)
>and a happy transmission (more rpm's, more internal pressure). When onlyu the
>sprockets are utilized, only the engine is speeded up. The cost to me was just
>about a wash, so that's what I decided to do and why. Works for me, maybe not
>for you.
> Pat 77 Birch
>
>
>> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>>
>> > I thought the final drive change was best now I am not sure. I want to
>> > do one of them but not both. Darren
>> >
>> Darren
>>
>> Here is my thinking---nothing more. I honestly have no idea which is best.
>> I wanted to take the load off the tranny and chain. So my thoughts ran
>> to doing the final drive. Thats why I did not like the Caspro system. Now
>> I dont know. Hope others speak up.
>>
>> Take Care
>> Arch
>
>
>
there is only so much room for gears. If the ring gear is increased and the
pinion is decreased in size seems like we would be sacrificing steangth of
the pinion gear. Any comments?
> I recently ordered a 3.70 final drive from Jim K. Should be here within the
>next week. I did this rather than the sprockets on the strength of the opinion
>of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions only,
>in White S.D. and a few of us "Greater Midwest Classics" have had our
>transmissions done there. I am very well satisfied with mine. Just a few words
>to inform of his qualifications. Any how, I have a 3.21 final drive that I was
>going to install with the 3.50 sprockets from Chuck Stoddard for a final ratio
>of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
>final because as he explained, it's better to have a happy engine(more rpm's)
>and a happy transmission (more rpm's, more internal pressure). When onlyu the
>sprockets are utilized, only the engine is speeded up. The cost to me was just
>about a wash, so that's what I decided to do and why. Works for me, maybe not
>for you.
> Pat 77 Birch
>
>
>> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>>
>> > I thought the final drive change was best now I am not sure. I want to
>> > do one of them but not both. Darren
>> >
>> Darren
>>
>> Here is my thinking---nothing more. I honestly have no idea which is best.
>> I wanted to take the load off the tranny and chain. So my thoughts ran
>> to doing the final drive. Thats why I did not like the Caspro system. Now
>> I dont know. Hope others speak up.
>>
>> Take Care
>> Arch
>
>
>
As I understand it, there is no change in the physical size among the
various gears, therefore no fitment problems. What is different among the
various gear sets is the number of teeth on both the ring and pinion gears,
which results in the various ratios available. Caspro's literature would
have you believe that there are practical limitations on the number of gear
teeth to optimize strength. Not sure that current experience shows that is
any limitation, though
Paul Bartz
From: Tom Warner [mailto:warner]
Sent: Tuesday, January 18, 2000 11:08 AM
Isnt there a structural problem with these numerically high final drives.
there is only so much room for gears. If the ring gear is increased and the
pinion is decreased in size seems like we would be sacrificing steangth of
the pinion gear. Any comments?
> I recently ordered a 3.70 final drive from Jim K. Should be here within
the
>next week. I did this rather than the sprockets on the strength of the
opinion
>of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions
only,
>in White S.D. and a few of us "Greater Midwest Classics" have had our
>transmissions done there. I am very well satisfied with mine. Just a few
words
>to inform of his qualifications. Any how, I have a 3.21 final drive that I
was
>going to install with the 3.50 sprockets from Chuck Stoddard for a final
ratio
>of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
>final because as he explained, it's better to have a happy engine(more
rpm's)
>and a happy transmission (more rpm's, more internal pressure). When onlyu
the
>sprockets are utilized, only the engine is speeded up. The cost to me was
just
>about a wash, so that's what I decided to do and why. Works for me, maybe
not
>for you.
> Pat 77 Birch
>
>
>> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>>
>> > I thought the final drive change was best now I am not sure. I want to
>> > do one of them but not both. Darren
>> >
>> Darren
>>
>> Here is my thinking---nothing more. I honestly have no idea which is
best.
>> I wanted to take the load off the tranny and chain. So my thoughts ran
>> to doing the final drive. Thats why I did not like the Caspro system. Now
>> I dont know. Hope others speak up.
>>
>> Take Care
>> Arch
>
>
>
various gears, therefore no fitment problems. What is different among the
various gear sets is the number of teeth on both the ring and pinion gears,
which results in the various ratios available. Caspro's literature would
have you believe that there are practical limitations on the number of gear
teeth to optimize strength. Not sure that current experience shows that is
any limitation, though
Paul Bartz
From: Tom Warner [mailto:warner]
Sent: Tuesday, January 18, 2000 11:08 AM
Isnt there a structural problem with these numerically high final drives.
there is only so much room for gears. If the ring gear is increased and the
pinion is decreased in size seems like we would be sacrificing steangth of
the pinion gear. Any comments?
> I recently ordered a 3.70 final drive from Jim K. Should be here within
the
>next week. I did this rather than the sprockets on the strength of the
opinion
>of Kent Cooper of "Transmissions by KC". He is a rebuilder, transmissions
only,
>in White S.D. and a few of us "Greater Midwest Classics" have had our
>transmissions done there. I am very well satisfied with mine. Just a few
words
>to inform of his qualifications. Any how, I have a 3.21 final drive that I
was
>going to install with the 3.50 sprockets from Chuck Stoddard for a final
ratio
>of 3.66 at the road. After talking with Kent, I decided to go with the 3.70
>final because as he explained, it's better to have a happy engine(more
rpm's)
>and a happy transmission (more rpm's, more internal pressure). When onlyu
the
>sprockets are utilized, only the engine is speeded up. The cost to me was
just
>about a wash, so that's what I decided to do and why. Works for me, maybe
not
>for you.
> Pat 77 Birch
>
>
>> In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>>
>> > I thought the final drive change was best now I am not sure. I want to
>> > do one of them but not both. Darren
>> >
>> Darren
>>
>> Here is my thinking---nothing more. I honestly have no idea which is
best.
>> I wanted to take the load off the tranny and chain. So my thoughts ran
>> to doing the final drive. Thats why I did not like the Caspro system. Now
>> I dont know. Hope others speak up.
>>
>> Take Care
>> Arch
>
>
>
When I talked to Jim K. I asked him why he thought going the differential
route was better. He told me that the differential will make your tranny and
engine both spin faster and that should help lubrication for the tranny and
even cooling while giving you more torque from the engine (which is my main
goal). He said the drawback is the speedo must be converted with a change in
gearing. He supplies the speedo gearing with his diff. He mentioned that the
other guys change the ratio which makes the tranny spin slower than the
engine. This can lead to heat buildup (his thoughts here so don't attack me
on this guys).
When I got the box yesterday I was surprised how heavy but also how small
the box was. Wooden crate about 18" square that weighs a ton! Thought it
would be bigger for some reason. He gives you both gaskets and I purchased
synthetic oil he recommended as well.
I'll be taking "The Sweat Lodge" in tomorrow for surgery so keep your
fingers crossed!
Nate 75GB (Please don't snow... please)Omaha
>
Date: Mon, 17 Jan 2000 15:11:56 EST
From: Gcbr
Subject: Re: GMC: 3.70 Transmission Gear Set
In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
> I thought the final drive change was best now I am not sure. I want to
> do one of them but not both. Darren
>
Darren
Here is my thinking---nothing more. I honestly have no idea which is best.
I wanted to take the load off the tranny and chain. So my thoughts ran
to doing the final drive. Thats why I did not like the Caspro system. Now
I dont know. Hope others speak up.
Take Care
Arch
route was better. He told me that the differential will make your tranny and
engine both spin faster and that should help lubrication for the tranny and
even cooling while giving you more torque from the engine (which is my main
goal). He said the drawback is the speedo must be converted with a change in
gearing. He supplies the speedo gearing with his diff. He mentioned that the
other guys change the ratio which makes the tranny spin slower than the
engine. This can lead to heat buildup (his thoughts here so don't attack me
on this guys).
When I got the box yesterday I was surprised how heavy but also how small
the box was. Wooden crate about 18" square that weighs a ton! Thought it
would be bigger for some reason. He gives you both gaskets and I purchased
synthetic oil he recommended as well.
I'll be taking "The Sweat Lodge" in tomorrow for surgery so keep your
fingers crossed!
Nate 75GB (Please don't snow... please)Omaha
>
Date: Mon, 17 Jan 2000 15:11:56 EST
From: Gcbr
Subject: Re: GMC: 3.70 Transmission Gear Set
In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
> I thought the final drive change was best now I am not sure. I want to
> do one of them but not both. Darren
>
Darren
Here is my thinking---nothing more. I honestly have no idea which is best.
I wanted to take the load off the tranny and chain. So my thoughts ran
to doing the final drive. Thats why I did not like the Caspro system. Now
I dont know. Hope others speak up.
Take Care
Arch
Just a thought! If the ratio is 3.70 the engine will turn over the same RPM
no matter which gears you change to achieve it, back of the engine/tranny or
final drive.
> When I talked to Jim K. I asked him why he thought going the differential
>route was better. He told me that the differential will make your tranny and
>engine both spin faster and that should help lubrication for the tranny and
>even cooling while giving you more torque from the engine (which is my main
>goal). He said the drawback is the speedo must be converted with a change in
>gearing. He supplies the speedo gearing with his diff. He mentioned that the
>other guys change the ratio which makes the tranny spin slower than the
>engine. This can lead to heat buildup (his thoughts here so don't attack me
>on this guys).
> When I got the box yesterday I was surprised how heavy but also how small
>the box was. Wooden crate about 18" square that weighs a ton! Thought it
>would be bigger for some reason. He gives you both gaskets and I purchased
>synthetic oil he recommended as well.
> I'll be taking "The Sweat Lodge" in tomorrow for surgery so keep your
>fingers crossed!
>
>Nate 75GB (Please don't snow... please)Omaha
>
>>
>Date: Mon, 17 Jan 2000 15:11:56 EST
>From: Gcbr
>Subject: Re: GMC: 3.70 Transmission Gear Set
>
>In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
>> I thought the final drive change was best now I am not sure. I want to
>> do one of them but not both. Darren
>>
>Darren
>
>Here is my thinking---nothing more. I honestly have no idea which is best.
>I wanted to take the load off the tranny and chain. So my thoughts ran
>to doing the final drive. Thats why I did not like the Caspro system. Now
>I dont know. Hope others speak up.
>
>Take Care
>Arch
>
>
>
no matter which gears you change to achieve it, back of the engine/tranny or
final drive.
> When I talked to Jim K. I asked him why he thought going the differential
>route was better. He told me that the differential will make your tranny and
>engine both spin faster and that should help lubrication for the tranny and
>even cooling while giving you more torque from the engine (which is my main
>goal). He said the drawback is the speedo must be converted with a change in
>gearing. He supplies the speedo gearing with his diff. He mentioned that the
>other guys change the ratio which makes the tranny spin slower than the
>engine. This can lead to heat buildup (his thoughts here so don't attack me
>on this guys).
> When I got the box yesterday I was surprised how heavy but also how small
>the box was. Wooden crate about 18" square that weighs a ton! Thought it
>would be bigger for some reason. He gives you both gaskets and I purchased
>synthetic oil he recommended as well.
> I'll be taking "The Sweat Lodge" in tomorrow for surgery so keep your
>fingers crossed!
>
>Nate 75GB (Please don't snow... please)Omaha
>
>>
>Date: Mon, 17 Jan 2000 15:11:56 EST
>From: Gcbr
>Subject: Re: GMC: 3.70 Transmission Gear Set
>
>In a message dated 01/17/2000 1:48:00 PM Central Standard Time,
>
>> I thought the final drive change was best now I am not sure. I want to
>> do one of them but not both. Darren
>>
>Darren
>
>Here is my thinking---nothing more. I honestly have no idea which is best.
>I wanted to take the load off the tranny and chain. So my thoughts ran
>to doing the final drive. Thats why I did not like the Caspro system. Now
>I dont know. Hope others speak up.
>
>Take Care
>Arch
>
>
>
Emery:
Again, as I understand it, the controversy that Caspro's literature points
out from their perspective, is a big concern over the number, size, and
shape of the teeth on the gears. Since I don't recall any discussion in his
literature about differences among the various combinations, it's still my
understanding that there is no difference in their diameters.
Paul Bartz
From: EMERYSTORA [mailto:EMERYSTORA]
Sent: Tuesday, January 18, 2000 1:13 PM
In a message dated 1/18/00 10:08:16 AM, s9d3452
Again, as I understand it, the controversy that Caspro's literature points
out from their perspective, is a big concern over the number, size, and
shape of the teeth on the gears. Since I don't recall any discussion in his
literature about differences among the various combinations, it's still my
understanding that there is no difference in their diameters.
Paul Bartz
From: EMERYSTORA [mailto:EMERYSTORA]
Sent: Tuesday, January 18, 2000 1:13 PM
In a message dated 1/18/00 10:08:16 AM, s9d3452
Emery,
Sorry, but the ring gear is fixed in it's dimensions. The I.D. can't get
any
larger as it is the centering location for the ring. The O.D. is pretty
well
maxed out in the housing and if it gets bigger, then it won't hit the pinion
which is constrained,sizewise, by the location of it's bearing. so if you
add more teeth, they must all stand a little closer together and be a little
smaller. The gear also gets a little thicker. The problem is in the pinion
gear which has to have smaller teeth to mesh with the ring gear and at
the same time less of them in order to have a gear reduction.
If the smaller, fewer teeth are to reach all the way around the pinion,
then the pinion must get smaller in diameter. Therein lies the weakness.
Smaller diameter, smaller teeth, and less of them means less strength.
Chuck Stoddard is dead right on THAT one.
That's all I know.
Gary Kosier
Sorry, but the ring gear is fixed in it's dimensions. The I.D. can't get
any
larger as it is the centering location for the ring. The O.D. is pretty
well
maxed out in the housing and if it gets bigger, then it won't hit the pinion
which is constrained,sizewise, by the location of it's bearing. so if you
add more teeth, they must all stand a little closer together and be a little
smaller. The gear also gets a little thicker. The problem is in the pinion
gear which has to have smaller teeth to mesh with the ring gear and at
the same time less of them in order to have a gear reduction.
If the smaller, fewer teeth are to reach all the way around the pinion,
then the pinion must get smaller in diameter. Therein lies the weakness.
Smaller diameter, smaller teeth, and less of them means less strength.
Chuck Stoddard is dead right on THAT one.
That's all I know.
Gary Kosier
Just something to add I thought interesting. Was looking through my GMC
Motorhome News last night looking for any info on installing the suburban
furnace when I came across March 1966 issue. Question by Zeb Zehnacker
about gear change kit versus final drive. Wes Cauglan says "The
transmission kit changes one of the chain sprokets in the back of the
transmission, Zak and it is not easy to install. While this increases the
overall drive-train ratio numerically, it also multiplies torque on the
passenger car pinion which is the weak link in the original 3.07 final drive
when it is used in the motorohome. Than he goes on to say that Cinnabar
routinely changes the final drive in three shop hours.
Any comments?
>In a message dated 01/18/2000 9:42:56 PM Central Standard Time,
>
>> A low-ratio (numerically high) final drive
>> increases torque AFTER the transmission, so the tranny only has to
>withstand
>> stock torque loads.
>
>Rick
>
>Thank you very much. That was my original take on all of this. From
>some of the surveys we have done it seems like the tranny is more of
>a problem than the front wheel bearings ever were. So back to my
>original thoughts---lighten the tranny load. Thanks.
>
>Take Care
>Arch
>
>
Motorhome News last night looking for any info on installing the suburban
furnace when I came across March 1966 issue. Question by Zeb Zehnacker
about gear change kit versus final drive. Wes Cauglan says "The
transmission kit changes one of the chain sprokets in the back of the
transmission, Zak and it is not easy to install. While this increases the
overall drive-train ratio numerically, it also multiplies torque on the
passenger car pinion which is the weak link in the original 3.07 final drive
when it is used in the motorohome. Than he goes on to say that Cinnabar
routinely changes the final drive in three shop hours.
Any comments?
>In a message dated 01/18/2000 9:42:56 PM Central Standard Time,
>
>> A low-ratio (numerically high) final drive
>> increases torque AFTER the transmission, so the tranny only has to
>withstand
>> stock torque loads.
>
>Rick
>
>Thank you very much. That was my original take on all of this. From
>some of the surveys we have done it seems like the tranny is more of
>a problem than the front wheel bearings ever were. So back to my
>original thoughts---lighten the tranny load. Thanks.
>
>Take Care
>Arch
>
>
I guess I missed something. I didn't realize that there was a
"March 1966" issue of GMC Motorhome News. Does that
mean there were GMC Motorhomes in 1966? ;-)
Just wondering...
> Just something to add I thought interesting. Was looking through my GMC
> Motorhome News last night looking for any info on installing the suburban
> furnace when I came across March 1966 issue. Question by Zeb Zehnacker
> about gear change kit versus final drive.
"March 1966" issue of GMC Motorhome News. Does that
mean there were GMC Motorhomes in 1966? ;-)
Just wondering...
> Just something to add I thought interesting. Was looking through my GMC
> Motorhome News last night looking for any info on installing the suburban
> furnace when I came across March 1966 issue. Question by Zeb Zehnacker
> about gear change kit versus final drive.
Al:
Just so that I understand correctly, when you say transmission gears, =
are
you referring to the sprockets that the chain wraps around??
No differential gear change from the original 3.07:1 gears, right??
Paul Bartz
From: Al Hamilton
Sent: 1/17/00 11:05 AM
I spoke to the owner of Lambke Machine & Rebuild in Cambridge, Ontario
(519-653-1041) and he will be making more transmission gear sets this
winter - the first since 1997. Both rear transmission gears are =
replaced
resulting in a 20% increase in engine rpm and an equivalent of a 3.70
final drive ratio. That results in 2800 rpm at 60 mph with 8.75 x 16=BD
tires and about 2700 with 9.50 x 16=BD tires. The original chain is =
used
and a modified cover is also used. Only 20 sets will be made so if you
have any interest call him soon.
I am not involved in the company so can only provide information on my
use of the gears in the last two years and 10,000 miles and will do so
if there are other questions.
Al Hamilton
76 Eleganza II
Kingston, Ont
Just so that I understand correctly, when you say transmission gears, =
are
you referring to the sprockets that the chain wraps around??
No differential gear change from the original 3.07:1 gears, right??
Paul Bartz
From: Al Hamilton
Sent: 1/17/00 11:05 AM
I spoke to the owner of Lambke Machine & Rebuild in Cambridge, Ontario
(519-653-1041) and he will be making more transmission gear sets this
winter - the first since 1997. Both rear transmission gears are =
replaced
resulting in a 20% increase in engine rpm and an equivalent of a 3.70
final drive ratio. That results in 2800 rpm at 60 mph with 8.75 x 16=BD
tires and about 2700 with 9.50 x 16=BD tires. The original chain is =
used
and a modified cover is also used. Only 20 sets will be made so if you
have any interest call him soon.
I am not involved in the company so can only provide information on my
use of the gears in the last two years and 10,000 miles and will do so
if there are other questions.
Al Hamilton
76 Eleganza II
Kingston, Ont
Paul,
I changed both gears or sprockets at the back of the transmission that
the High Velocity (I think that's what it's called) chain travels on. I
still have the original 3.07 differential.
Al Hamilton
I changed both gears or sprockets at the back of the transmission that
the High Velocity (I think that's what it's called) chain travels on. I
still have the original 3.07 differential.
Al Hamilton
