[Charles DeGruchy (Thejagu]

I have searched and could not find this question answered yet. I am considering a ' 76 or newer truck 833 4 speed with over drive to put in my 70 Challenger. I do expect to put 600 hp in front of it. I have 2:76 gears that I want to keep. Question is are these OD 833's able to take the power? Iron box ones and aluminum I heard are available. SOem people say this is the best switch-out modification to ever come along. Others say not enough strength. Any experiences out there? Thanks CHAS

[Robbert D 70'Chally (]

I suppose you allready read the Keisler pages (http://www.keislerauto.com/Mopar_new/index.htm) Gerrad Friedline is refering to? Very interesting material, but a lot more expensive than a 833 I presume...2.76:1 behind it would require real torque in overdrive, I would prefer the 0.83 over the 0.68. with a 2.76. And your 2.76 would be like a 3.41 rear in first combined with the Keisler 5 speed. And go for the 650 HP version

[Ted S (Teds)]

why do you need overdrive with 2.76 gears?

[Robbert D 70'Chally (]

You don't _need_ it, the Keisler gearbox' 5th gear is an overdrive per definition, because its forward ratio of 0.68 is a figure smaller than 1.0. ,sorry if that is strange english. (0.68 gives 32% overdrive, and the optional 0.83 gives obviously 17% overdrive).
Why you want it? Well, low RPM when driving on a highway in 5th gear is quieter, lower piston speeds thus less wear, less fuel consumption.
The 32% overdrive combined with a 3.55 rear and 235/60R15 tyres would lead to an rpm of 2500 at 80 mph. This would be a setup for a very torqy engine in my opinion, because I like instant throtle response without shifting back on our very busy Dutch highways.

[Robbert D 70'Chally (]

Charles mailed me privately about this matter, I post it here presuming he does not mind because no real personal matter is discussed. Maybe somebody else has something bright to ad:

"Robert
Thank you very very much, I did not know of the Keisler pages.
I always prefer a higher cost as long as the quality follows right behind it.
Low maintenance, high HP is what I am all about.
a question.
why does not my 2.76:1 play a part in equation?
The Keisler solution gives 5 ratios, I understand that, but how does the rear end you have in the car come into play?
Chas"

Chas, the gearbox, your axle and your tiresize together determine your rpm/carspeed ratio. See Daves Auto Maths Spreadsheet on http://challenger.mpoli.fi/web/maths.htm

Off course the gearbox/axle/tiresize setup has to match your engine setup and rpm range. And what kind of use is the car going to see mainly, bracket racing only, street/strip or a lot of cruisin'?

[Charles DeGruchy (Thejagu]

street strip and cruisin' My wife lieks the street strip, I go for the 65 to 130