Horse power....e

[jim kanomata1]

I’ll put it this way,
I was few years behind when the lower gears emerged in 1988.
3.42 was not sufficient and even our 3:55 was not there.
Marvin Peck GearMaster convinced me to develope a 3.70.
Since he was lot more experienced than any ratio .
If you know about the engine torque and why the gear ratio is instrumental
to gain advantage.
Even the trans ratio of 3.50 and a 3,21 final to produce 3.67
Also a good mechanical distributor advance is very important. This can make
a big difference when climbing.
We get tremendous amount of feed back from 3,000 owners of 3.70
Miguel of MGM GMC is a big proponent of 3.70 and 403.
Several are running the 4.10 with 403 and know 4.10 on a car wheel differs
than the coach.
Thinking one can install a turbo system is dreaming.
I did it back in 1991 and learned much during the first two years.
I still use that coach, but I need to rebuild the Cad with the new Turbos
, oh I use the 3.70 LSD final drive.
Again knowing the torque courve of the Cad 540 , 3.70 does best.

On Tue, Oct 1, 2019 at 9:36 PM Richard Denney via Gmclist <

> No, everyone buys a final drive as a complete unit.
>
> Another option is the well-regarded planetary final drive used by Cadillac,
> with a 3.21 ratio. I have one, but my coach is even lighter than Matt’s. It
> climbs well enough but it is not geared for drag racing.
>
> Manny sells a kit that used to be a Caspro product, as I dimly recall. It’s
> called power-drive, I think, and it uses a smaller engine sprocket on the
> chain drive, with a shortened chain. By itself, it is the equivalent of a
> 3.5:1 final drive, when used with the stock 3.07 differential. When coupled
> with the 3.21, you get the equivalent of a 3.67:1 ratio.
>
> Rick “who doesn’t tow but who does drive up and down lots of hills” Denney
>
> On Tue, Oct 1, 2019 at 5:27 PM tonka6cuda6--- via Gmclist <

>
> > So did everyone do a crown gear and pinion swap or did they change the
> > gears and chain?
> > --
> > Rich Mondor,
> >
> > Brockville, ON
> >
> > 77 Hughes 2600
> >
> > _______________________________________________
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> >
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
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>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[powwerjon]

We got our first coach in late 1998 and it was a bone stock 403 with a 3.07=
final drive. In the flat lands is was just OK, but needed some help with =
any hills. Added a 3.55 final and it really woke up the engine. It was lu=
gging along at 2250-2300 at 65 mph and had no punch. The 403 is a big bore=
/short stroke motor and likes RPM. With the 3.55 I could climb most grade=
s in super and keep it right at 50/55 mph and stay with most 455 units. Th=
e sweet spot was right about 2850/2900 RPM. You guys with the 3.07 final d=
rive the motor doesn=E2=80=99t get up on the cam till about 75 MPH and then=
it really likes the RPM. When we got the Buskirk stretch in 2011 is w=
as set up with a 3.21 final and a 3.50 chain drive making it a 3.67 final d=
rive ratio. The coach is heavier than a 26=E2=80=99, when we travel for th=
e winter the coach weights close to 18000# and that includes 14300# for the=
coach and almost 4000# for the towed that also is a trailer, but it pulls =
most of the mountains grades out west without problems. The longest grade =
that we typically did was the grade out of White Sands over the hill into L=
as Cruces, NM on US70 and it does drag us down to 35 mph on the last part n=
ear the top of the grade. If we were to do a lot of mountain driving all t=
he time I would consider the 3.55 or 3.70 final drives, with the 3.55 final=
drive and the 3.50 chain the effective drive ratio is just a smig over 4.1=
1. With the 3.70 final drive and 3.50 chain the effective ratio is 4.47. =
I also do use the stock 225/75R/16 size tire. If you have installed a lowe=
r final drive ration (3.55 or higher) you lose more than 4% of the drive ra=
tio each tire size you go larger than stock sizes. You are defeating the p=
urpose of adding the final drive in the first place. The engine in the str=
etch is a 461CI Jasper BB Olds (Built when Jasper was building great RV mot=
ors), with MPFI, custom ignition, headers and a 3=E2=80=9D exhaust system, =
2.5=E2=80=9D before the mufflers and transition to 3=E2=80=9D just after th=
e SS Flowmaster mufflers. Except for the 3=E2=80=9D long pipe going down t=
he side of the coach it is all SS including the tail piece. My persona=
l experience, yours may differ. J.R. Wright GMC Great Laker MHC GM=
CGL Tech Editor GMC Eastern States Charter Member GMCMI 78 GMC Buskir=
k 29.5=E2=80=99 Stretch 75 GMC Avion (Under Reconstruction) Michigan =
> On Oct 2, 2019, at 3:04 AM, Jim Kanomata via Gmclist wrote: > > I=E2=80=99ll put it this way, > I was few yea=
rs behind when the lower gears emerged in 1988. > 3.42 was not sufficient=
and even our 3:55 was not there. > Marvin Peck GearMaster convinced me t=
o develope a 3.70. > Since he was lot more experienced than any ratio .=
> If you know about the engine torque and why the gear ratio is instrume=
ntal > to gain advantage. > Even the trans ratio of 3.50 and a 3,21 fin=
al to produce 3.67 > Also a good mechanical distributor advance is very i=
mportant. This can make > a big difference when climbing. > We get trem=
endous amount of feed back from 3,000 owners of 3.70 > Miguel of MGM GMC =
is a big proponent of 3.70 and 403. > Several are running the 4.10 with 4=
03 and know 4.10 on a car wheel differs > than the coach. > Thinking on=
e can install a turbo system is dreaming. > I did it back in 1991 and lea=
rned much during the first two years. > I still use that coach, but I nee=
d to rebuild the Cad with the new Turbos > , oh I use the 3.70 LSD final=
drive. > Again knowing the torque courve of the Cad 540 , 3.70 does best=
. > > On Tue, Oct 1, 2019 at 9:36 PM Richard Denney via Gmclist < > =
gmclist> wrote: > >> > Jim Kanomata > Applied/GMC=
, Newark,CA > jimk > http://www.appliedgmc.com =
> 1-800-752-7502