Hey guys,

Just curious I upgraded the engine to 600HP, still have the original 350 turbo with now a 3,000 stall. And the tranny has been rebuilt with all HD clutches and a stage 1 shift kit. Do you think I should upgrade the the tranny? If so brand, makes, models or perhaps something I can do to the TH350? What about the rearend take it from the 3.07 to the 3.73 ?

Thanks again guys....

-Louis


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-LOUIE

Louis, I took mine from 3.07 to 3.70 ratio I also changed out the Eaton Posi unit with the newer style with cabon fiber clutches, I also had the gears REM coated. here is a link:    http://www.duntovmotors.com/Differentials_63-79.htm For the transmission I went with TCI Super Street Fighter........It's supposed to be handle 750HP.......it a model between the Street Fighter and the full out race transmission. Here is a link:    http://store.summitracing.com/partdetail.asp?autofilter=1&part=TCI%2D211005&

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I also used a B&M 2800-3200 Stall converter. It has the anti-ballooning plate for nitrous Link to:    http://store.summitracing.com/partdetail.asp?autofilter=1&part=BMM%2D20481&N

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Hey Larry,

Thanks for the help... Thats a TH400 4SPD model correct? I heard that those tailshafts are a bit longer and fellers got to replace the cross member with like a C4 version for our cars and also change out the drive line from a  C4...
did you have to do that?


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-LOUIE

The THM400 is a 3 speed.  The THM700R4 is a 4 speed.  The 700 is a bit longer, and the floor may need to be modified a bit.

You will notice the rpm's a lot with the 3.73. Mine wound out at 3800 at 70mph with the TH-400. I now have a 700r4. There was no problem with the fit.The extra (4th) gear makes a lot of difference .There is also the 4l80e which is basicly a TH-400 with an overdrive gear. Very strong transmission but I dont know about that fit though. Great trans for high hp. I wouldn't go much over 2400 stall converter for the street. 2600-2800 max. Anything over is great for the strip but hard on the street due to searching for the hookup below the stall speed.

I don't want to have to modify anything with this trans swap. I have an extreme budget to finish the paint, engine, and interior. I just want a decent transmission that will handle 600HP and over 500LB ft that will slide right in without a special cross member or drive line  or modifying the floor for that matter. I know the engine is a beast now, I've spent too many years begin picky, I have to let go and let it ride now. I'm heading into 6 years now. I'll be dead before its done and out of money. I'm trying to also buy a house soon.

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-LOUIE

The problem I deduce is the old money and time thing. Hmmm where have I heard that before. The main thing is you have an abundance of power and you will need a stout transmission and rearend.You did consider strengthening the rear also didn't you. As long as you dont beat on the car with your hp you can live with the 350 and 3.08. You can always change/build it up it later. If the trans is out by all means consider a swap/strengthen now
The rest of the this reply is FYI only.
If you leave the rear gears at 3.08 you can live with a three speed trans.A 700r4 (4 speed)has a very steep first gear and will help the grunt off the line plus the top end will be in strickly haul ass mode. By going to 3.73 (with a three speed) the car will be winding out quite a bit at highway speed. With the HP you will be making the 3.08 will sufice. If you want a car to drive at any length (cruise in) the comfort level will be better with the lower ratio gears (3.08) let alone the wear and tear on the motor plus the fuel savings. Unless you need all the possible output you can get I would stay with the 3.08's. You will be much happier. The 700 swap is not that hard to do with no problem with the fit .It dropped right in. I did it in my garage most of it by myself. If you want to go to 3" exhaust the you will need the Bowtie crossmember. The stock crossmember will only allow a 2 1/2" because it goes through it vs under for the Bowtie. It is up to you but you will be spending money on a trans to hold up to your HP anyhow so a built 700r4 with 3.73's will do wonders for you (or a th-400(strong)/th350 (suspect) with 3.08) You will have to shorten and rebalance the driveshaft with the 700 but all this is not hard to have done. You can have the swap done in a weekend or so even taking your time. I did and I am happy. I am not a rich guy by any means but it was somthing I wanted to do. Needless to say I am biased to the 700. A th-400/th-350 with 3.73 will be a real screamer for around town but will be at 3-4000 rpms most of the time. A 700 will also be a tire shreader but you will be able to cruise 2-3000 rpms. For now strenghten the 350 and put some time into strengthening the rearend. You will be on the road sooner/cheaper. Futher mods can be done later

I didn't want to come off as a snooty kid, or worried about time. I got nothin but time. Saving for a house at my age is rough. My life isn't really like a 20yr old's. I basically have a family, and I need to finish my car and get it out of the way so I can save to $30K I need to get my own house. Its gonna take me like 7 Months or so because I'm living with mom and dad. Where can I get a cheap 700R4? Who would be able to shorten and balance the drive shaft? How much should it be taken down? I think 2 inches... the tailshaft of a TH400 and TH350 is like 4" and a 700R4 is like a 6" I believe I saw one that was 8". The rear I plan to go up either way. I have a built TH350 but I don't think it can withstand that power.



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-LOUIE

Try a built up TH-400. Very strong trans to start with. Upgrade to a stouter sprag. It is the one main weak link. Most everything else (in the transmission)can be just the normal performance build up stuff. Us a 2400-2800 stall converterfor the street. You will be much happier than a 3000+ stall keep the 3.08's and strengthen the rear.