Well I'm at the point where I think it’s time to make the swap. I've had the 700R4 rebuilt once by a local transmission shop, that guy thought he knew what he was doing (what a joke), then had an outfit in Chicago that builds race transmissions rebuild it twice, I can say the outfit in Chicago put quality parts in it, burnt the carbon band (band that controls 1-2 shift)-1st time which lasted the longest, then switched to red alto bands (burnt the band that controls 2-3shift) the 2nd time. The outfit in Chicago warned me that transmission will probably hold 600hp to 650hp for a limited amount of time anything over that would be pushing my luck. I think I've got to the point where I've ran out of luck. After burning the transmission up for the 2nd time I brought to a different outfit for 2nd opinion, which I was told a guy could build the 700R4 to withstand 700hp to 800hp, but it would cost a small fortune, they recommended going with a TH400.

So now I'm going to have a TH400 built by the other outfit in Chicago (which builds some transmissions for guys running in the NMCA ranks).

Looking to put a trans break in it, any suggestions on what to go with? This is my first venture into the trans break world so I'm learning. Having a transbreak in a street car (no roll cage) is probably over kill, but what the hell. I still take to the track everyonce in a while.

I have read on different threads that you need to have a vacuum source going to the modulator on a TH400? What does a guy do on a supercharger/turbo set up with having boost or does it matter? Will I be able to use my stock shifter in my car? If not, what have others done.

Cross member-looks like the spohn cross member and torque arm are the way to go as far as trying to make a clean conversion.

Any suggestions as far as stall converters go? I would prefer the car to have good street manners. Dont need anything crazy like a 5000 stall.

In doing all of this I have decide to get rid of the 10-bolt and go with a strange s-60 rear end. Which means I need to get a diff. drive shaft as well.

Anyone that has been down this road is welcome to give any suggestions/ideas. thanks.

 

http://ls1tech.com/forums/forced-ind...solutions.html

Or solve all your problems with a full manual valve body

 

Couple of questions...

I got a turbo 400 and wondering if its possible to get my stock shifter cable to work. I really dont want to put a aftermarket shifter in the car. I did some measuring of the bolt patterns on both the 700r4 and turbo 400, there is a 3/4" difference on the both center to center dimensions to get the shifter cable bracket to bolt up. Also I'm concerned about the location of the shifter cable bracket with respect to gear bracket that the shifter cable bolts up to. From the face shifter cable bracket to the center of the gear bracket is 6", I would think that the "throw" would still be same from a 700R4 to turbo400, obviously losing one gear, going from a 4speed to a 3 speed.

Also when using a transbrake does a guy have to switch over to a reverse manual valve body? I would like to keep the forward shift pattern if possible.

Thanks in advance.

 

Any one?

 

Another issue that I need to get resolved is the speedometer cable conversion from 700R4 (electronic plugin) to back to the tail shaft housing for turbo 400.

I think I found the part "Speed Sensor and Rotor (speedometer VSS) for the TH400 transmission".

Any thoughts?

 

First off....I'd install an aftermarket console or floor shifter, to prevent missing a shift. IIRC, only manual VB are available with a trans brake.

Secondly, I believe Summit makes a th400 crossmember for the third gen.

Thirdly, there are a few companies that make a cable speedo conversion....such as Dakota Digital.

The th400 is a great trans, even in stock form. Have your builder remove the end shaft thrust bearing and replace it with a th350 pump/direct drum bearing and pump shims (to set end play). This will save you rebuilds down the road because with a TB, the load it placed into the thrust bearing and there will be wear that ensues. Using the th350 bearing will alleviate failures in the future.

Good luck!

 

I've got a B&M ratchet shifter from a buddy (new in box) that I can use, but I want to try and keep the center console looking as stock as possible. I'm hoping the ratchet shifter can be installed under my stock center console w/o doing any cutting on the console.

Not sure what IIRC means?

With manual VB required for transbreak I'm assuming the shift pattern will be 1,2,D (what I would call reverse manual VB) instead of D,2,1 normal foward pattern.

As far as the crossmember and torque arm go this is what I'm planning on getting.

http://www.spohn.net/shop/1982-1992-...nsmission.html


This is the company that I'm going to have do the transmission rebuild on my TH400, which is a truck transmission (has the heavy duty housing).

http://proformanceracingtransmissions.com/site/

 

If I Recall Correctly

 

Oh

 

Only thing I don't like about a reverse shift pattern is if you have engine problems at the strip , you have no fast way
of getting back to N to save your engine
You either have to slow down in gear ( too late ) or down shift ( higher revs ) which could make your problems worse

 

 

I totally agree, but if he wants a TB VB.....that's all there is.

The other option is the TransGo 1,2,3 kit. It allows for three different options of kits.....actually like 9 different options total. This kit allows a TON of options and needs to be installed with the pump removed, to up the line pressure.

Hope this helps.

Good luck!

Btw. I like that cross member!

 

Just wondering how you made out....

 

That is actually a truck VSS set up. However, it will work if you add in a DRAC buffer box. The DRAC box is strap programmable, so it can be adjusted for various tires and rear gear ratios. This is likely the best way to go.

The DRAC will replace the current 4-out buffer box that is currently in the car.

RBob.

 

I made a hurst V-matic fit under the console, It wasn't easy, but it wasn't extremely hard. The worst part is you have to cut the plate the the stock shifter bolts to out. its spot welded to the trans tunnel. Then I had to smash the trans tunnel down about 2" so the Hurst would sit low enough to go under the stock plate. If you don't want to mod the trans tunnel the only direct replacement is a B&M megashifter, it comes with a new console plate. See here:https://www.thirdgen.org/forums/afte...questions.html

 

Thanks for the reply and link. That will def. help. Trans is at the shop now being built so it will probably be a couple of weeks before I try and tackle putting in the trans. Its going to get a transbrake and be built to withstand 900hp.

 

if yo can, try to get the shifter sorted out before the tranny goes in. I did the tranny first and it was a PITA to get the bolts for the shifter worked out, lol the trans was in the way. Good luck, and show us what you come up with.

 

thanks for the advice! I'm going to try and tackle this shifter this weekend.

 

Here's the new 12-bolt S-60 from strange.

 

fyi, if any one else wants to use the stock shifter with a th400, it does. its just tough to get 2nd until you get use to it. wanted the sleeper look myself. i got a bolt in DS trans and got the trans and driveshaft modified to be slip. i made my own trans/ torque arm mounts after a while because the one i bought took up too much room for the long tube headers/duals i have. i use a cheap gps for speed, they are cheap as heck these days and dont care about gears, or tires or any of that crap

as far as the torque converter i had the perf trans shop build me one, they just asked all my specs and made a custom one

 

Size does matter.

 

Rbob, need some more info from you...the current current "4-out buffer box" that is currently in the car needs to be replaced? I guess knowing what I'm currently trying to do with regard to getting my current speedometer to work with my new th400, what is best route to go? What parts would I need for the transmission in order to be able to plug in my exisitng wiring harness to the transmission so that I will be able to use my speedometer as I did in past with my 700R4? Thanks for the help.

 

Just talked to Dakota Digital, seems like they have a pretty simple set up for a not a whole lot of money ($115). They told me I need the 8k pulse generator and the adaptor cable set up (SEN-1-01) for GM transmissions with cable drive speed output.


http://www.dakotadigital.com/index.c...rod/prd109.htm

 

im going to be doing the th400 swap soon....how did your speedo work after you did all this?

 

Works great...have the unit in the car so I could adjust the speedometer as I was going down the road with my GPS.