Bonneville (as in the salt flats) Transmission

[CTX-SLPR]

Howdy,

I'm starting to build a Bonneville car and while I'm likely to have a TH350C as starting material, the lack of RPM capacity of the production blocks makes me nervous about trusting a 1:1 top gear and trying to crutch it with a tall rear axle.
Problems are a few. I'm starting with an 81 so no frame extension for a TH200-4R. I'm spending an aweful lot of money on safety gear like a bombproof rollcage, fire systems, and a funny car fire suit; so a full on built unit is not in the cards.
Now on the bright side, traction is not great so I'll be rolling into the throttle and boost. Power is only 300hp target at this point. Car will only make 3mi passes and I doubt I drive it on the street under anywhere near full power with a 3.0L destroker and too big of a carb and turbo. I will be manually shifting it on race day.

Think a stock Cadillac unit would work or do I need to step it up to a BQ or BRF unit?

Thanks,

 

[charlief1]

What about going with a stick? A manual overdrive might be more in line for what you're planning.

 

[CTX-SLPR]

I can't drive a stick on the street, much less racing on the salt. Besides I don't want to go through the work of swapping a stick into an 81.

 

[dr_frankenstein]

cant drive a stick? why not?

 

[turbo nasty]

IMO the trans should be hopped up to cover the basics....i.e. a few- Valve body upgrades, pump and psi modded, better frictions, 4th gear clutch piston cut down to add frictions, directs dual fed, billet forward drum, better band, etc. and you should be good.

With that said make sure the builder sets it up so that the higher psi doesnt allow the trans to not shift at WOT to 4th. Sometimes this will happen when the psi is really high.

Ive had great service with Extreme Automatics/Lonnie Diers and also Jason White building transmissions.

 

[CTX-SLPR]

cant drive a stick? why not?

Never owned stick, no one in my family has owned one since the 60's, never needed to learn.

IMO the trans should be hopped up to cover the basics....i.e. a few- Valve body upgrades, pump and psi modded, better frictions, 4th gear clutch piston cut down to add frictions, directs dual fed, billet forward drum, better band, etc. and you should be good.

With that said make sure the builder sets it up so that the higher psi doesnt allow the trans to not shift at WOT to 4th. Sometimes this will happen when the psi is really high.

Ive had great service with Extreme Automatics/Lonnie Diers and also Jason White building transmissions.

Hmm... I'll have to find out the cost and weigh it against the idea of running a taller rear gear with the TH350C. How much do you think this would run?

 

[turbo nasty]

Id say north of a grand for one. The turbo 350 maybe a better choice cost wise but they have weak parts as well like the sprag, etc.

 

[TexasT]

If you don't need the overdrive and can compensate for not having with the rear gear the th350c will probably be 1/2 as much as a 2004r. That said the 2004r can be built on a budget too. Yours wouldn't need the hammering of neck snapping shifts. The additional clutch in the overdrive as mentioned would be a good addition. A 10 vane pump kit with hard rings, and good spring, a .500 boost valve, large rev boost valve, hardened stator support and hardened Sun shell would also be good additions. A stiffer line bias spring to get pressure up and some fooling with the plate holes to the accumulators to get the shifts good. You can dual feed but the billet stuff adds up.

Not sure on the th350. I have been studying up on the 2004r, and this is what I am planning for mine.

 

[SSedan64]

If you decide to go with the 350C. Very simple Trans to build.
http://www.crankshaftcoalition.com/wiki/TH350_rebuild_tech
This is some of Jakes Info & Crosley @Hughes, Cobalt327 compiled.

 

[CTX-SLPR]

Sounds good, I did some math recently and if I can get the engine to make power at 3000rpm and then be able to wing it to 6500rpm reliably I can use the TH350C and a combo of tall tires or rear gears to keep the RPM in that range.