Will my transmission work for Autocross?

[badseed6986]

First I just want to say I hope that I am posting in the correct section. If not, I apologize.

I have a 69 Camaro that is setup for drag racing. Now I want to go the pro-touring route and set it up for autocross.

There is going to be a lot of changes made and I think I know what I need to do except for one area, the trans.

It has a th400 with a reverse manual valve body and a trans brake. Would I be able to use this for autocross, or am I going to have to look into replacing it?

If the th400 wont work, how would a stock th350 hold up?

Thanks in advance for any help.
John

[67cougnut]

what kind of converter are you running?

[badseed6986]

I am not sure of the brand but the stall is really high, so I had already planned on most likely needing to change it.

[SparkyRnD]

The Turbo 400 is a great transmission, but it is a power hog and takes a lot of hp to run it. For an autocross, ideally you want to have the transmission in one or two gears maximum throughout the race, so you don't spend a lot of time shifting. The manual valve body will be good for that as you can pick a gear and it'll stay. Depending on what your shift points are, you also might have a lot of rpm drop between gears, which can really hurt you on the track. Also, your converter will need to be matched to this type of driving, so I'd spend some time talking to the various converter companies about your car, the weight of the car, the engine and type of racing and have them recommend the right converter. Another point to consider is if you are planning on racing on a road course, you will find that there are different requirements for that kind of racing transmission-wise, so a one-size-fits-all solution might not be found in the Turbo 400. We went with a T56 on our build, as the first three gears would be all we need for autocrossing. The rest of the gears will give us better mileage on the highway and for trips to and from shows, and also for use on road courses (just another point to consider)

[71RS/SS396]

Auto transmissions are not the best for auto-x or road racing, it's harder to keep the car in the power band and they generate a lot of heat. I ran events last year with 2 auto cars and killed the trans in both of them. Imho manuals are the only way to go.

[vanzuuk1]

But dont let that stop you from going to an event..

[SparkyRnD]

true, and also the transmission coolers that are integral with the radiator can heat up the engine temperature as well, contributing to overheating in racing conditions. Of course, with a larger aftermarket radiator that can be greatly reduced

[73CPCAMARO]

A properly set up TH400 can work very good for autocross. Set the car to run most autocross courses in one gear and maybe shift to a higher gear on a really fast course. Use the torque converter to help you get off the corner. My Dad ran his 72 and 74 Camaro for years with automatics and won many championships. You will have to have good brakes as you won't have the engine to help you brake.

Here is a video of Darrel Padberg, past National Champ in his Mustang with an automatic. At the end he had an engine issue, but you get the point..he is incredibly fast with an automatic.


http://www.youtube.com/watch?v=F3BcQ7m1TKY

[solarguy09]

A properly set up TH400 can work very good for autocross. Set the car to run most autocross courses in one gear and maybe shift to a higher gear on a really fast course. Use the torque converter to help you get off the corner. My Dad ran his 72 and 74 Camaro for years with automatics and won many championships. You will have to have good brakes as you won't have the engine to help you brake.

Here is a video of Darrel Padberg, past National Champ in his Mustang with an automatic. At the end he had an engine issue, but you get the point..he is incredibly fast with an automatic.


http://www.youtube.com/watch?v=F3BcQ7m1TKY That was great..i have a close ratio 4 speed , but that automatic run was screaming through the course...

[Steve Chryssos]

We'll be glad to set you up with the right converter for your TH400. There are tons of nationally competitive C Preparedcars running automatics. Converter selection, final drive ratio, and tire diameter will be tailored to have you launch in 1st gear then and then run thru the remainder of the course in 2nd. It's all about getting the converter right. The E transmissions work even better, since we can take advantage of the lock up clutch. We are rather nuts these days so don't be afraid to email or pm a phone number and best time to call.

I love that video.... :drive2:
/Steevo

[SparkyRnD]

I feel dizzy after watching that run!

[bret]

I've run LOTS of autocross laps with a manual valve body 700r4 from Bowler. I consider it almost an unfair advantage. The manual valve body is a must, so is a big cooler with a fan on it. If you really want to have an unfair advantage...put a Gearvendors overdrive behind it.
Don't worry about the power consumption of the TH400...whatever power you have now, it's too much for the autocross anyhow.
Have fun!

[badseed6986]

Thank you everyone for the help.

Bret - I think you definitely helped in justifying using this tranny. I would like to use a gearvendors overdrive, but I cant see spending that much money for it. If I were to spend that amount of money, I would just buy a different trans.

And as far as the power goes, that is gonna have to change. The car currently has a small block 434 with 14:1 compression. I have a 5.3 LS series motor out of a truck that I was thinking of using, it just needs to be rebuilt. I also have a stock 350 that I could rebuild and use. So I figure power is gonna be around 300 crank. Hopefully that is enough.

[Steve Chryssos]

With a 26" tire, run a 3.25 or so gear, then just swap the final drive ratio when you add overdrive. But get the converter right. That's the hard part because everyone wants to sell you a WOT only drag race converter. They have no idea what do if you're womping that throttle On/Off/On/Off/On.

[SparkyRnD]

Something to consider about the GV overdrive, you say it is a lot of money to spend; but if you take the cost of a manual transmission, GOOD clutch kit & flywheel, hydraulics kit and pedals / assembly, you are easily spending the same or more potentially than a GV unit would cost. If the TH400 is built well and works and you trust it, then a GV unit might be the easiest, least expensive / least labor intensive way to go.

[Randy67]

Thank you everyone for the help.

And as far as the power goes, that is gonna have to change. The car currently has a small block 434 with 14:1 compression. I have a 5.3 LS series motor out of a truck that I was thinking of using, it just needs to be rebuilt. I also have a stock 350 that I could rebuild and use. So I figure power is gonna be around 300 crank. Hopefully that is enough.

Your 434 engine sounds alot like several of the CP engines, so it could be used as is, may take a bit of different tuning to optimize it. This is coming from someone running a high-strung 377 with a Z28 crossram that works very well in autocross. So you don't have to change it, but it may be a bit much at first until you get used to it and autocrossing.