I'm planning a TH400 conversion on my '02 SS A4, but I have some questions:

1. Is there any preferred donor vehicle for the trans? I have a 1970 Chevelle TH400 - is that acceptable, or does it need to be electronically controlled (rather than vacuum)?

2. How is the transmission and torque arm mounted?

3. Can the factory speedo (and odometer) be adapted to work with the TH400? If so, what is needed?

4. Who produces an SFI approved flexplate for this swap, and is there a sponsor that sells it?

5. What length driveshaft is required? Can the factory shaft be modified, or will a new unit be needed?

6. Are there any quirks with the install...such as the need to add clearance or modify anything on the body?

Any insight would be greatly appreciated

 

You can have a TH400 setup with a manual valve body, which is what most people do. Therefore any donor would probably be sufficient.

For the torque arm you will need to use something that relocates it off the tailshaft. Spohn, Madman, BMR all make one that will work. The transmission mounts right up to a M6 trans mount. Just need to slip a 1.25 to 1.50" spacer between the trans mount and the tranny.

The factory speedo can be maintained. You need to get the exciter ring, sensor and wire from GM. It does require you to tear the tranny down to install the exciter ring into the housing. The part numbers for this are as follows: 8655291, 8655315 and 12085498.

Madman and TCI both carry SFI flexplates. Madman also makes the dipstick tube that you'll need.

The driveshaft is signficantly longer than stock. You'll need a new one.

If you use a JW Ultra Bell you MUST clearance the upper portion of the bellhousing to clear four bolts on the rear cover. If you don't you will do some serious damage to your flexplate and torque converter. There are pics on my website under http://www.derty.org/install/th400.

You will also want to get a good tranny cooler. I use a Derale 16 pass cooler with a 10" fan. I also bought the Derale 180 degree inline thremostat. Works great. You'll have to figure out how to run your lines. I just use two -6 lines (about 7' each) with two 45deg fittings on the tranny and one 45 and one straight -6 into the cooler. Not all coolers use AN fittings so check accordingly. You'll also want to tap the pan and install a transmission temp sensor. Get a good shifter for it and you'll be all set. As you'll see the Cheetah shifter takes some work to get it to fit. A ratchet shifter might fit easier.

Good luck.

 

That is exactly what I was looking for - thank you!!

 

Lokar also makes a dipstick that will work mounted inside the vehicle.

 

Derty pretty much summed it up, but I'll throw a few more options at you.
Get the MADMAN dipstick. It mounts like the stock one. The Lokar is a POS that is too short.
If you have the A4 tranny crossmember, it will work too. Just weld a plate on it that sets the mount pad backwards 3". I have pics of mine if you want. If you have a GW tq arm, you can retain the mount point on the stock crossmember. Otherwise, get the MADMAN unit there as well. DO NOT buy the Yank tranny tricker. Not needed. Also, you don't need the Yank adapter plate either. Waste of $$ IMO. Making the speedo work is simple. Use the GM part #'s listed above. The only part of the tranny that needs to come off is the tail shaft. It is simple to make it work.

Tim

 

And now my 2 cents on the subject! Derty hit it square between the eyes.

Talk to Madman Racing about thier tranny kit. I paid $2580 for his best setup with shipping.

Email me if you want a complete rundown on what you get, and will need for your car.

jay.mik@***.net

 

Damn Derty....you left no stone unturned on that post

Just want to add this. I know of a few, and I will be one, using a modified stock A4 shifter with a manual TH400 tranny. It just takes a little grinding and such to make it work. Just another option.

I bought an off the shelf TH400, so I won't be using my speedo for the time being. Just gonna mount the tach and use that.

 

humanoidZ06,

I can't help you out, but I live in Cypress
(you've probably seen me sometime);

looks like you got all the info now from all the nice people;

I am interested to see how your conversion turns out.

 

Yeah about the shifter, if you have a forward manual valve body, the shifter will work with NO modifications. The only thing I had to do is drill a hole dead center between the 2 holes on the bracket that hold the cable to the tranny. It falls right on a bolt on the tranny. No problems.

Tim

 

The shifter will also work with a reverse manual. Mike Brown (twin turbo CE T/A) has been using the setup for a few months. He just cut a little, welded a little, and notched a little. Works like a champ. He even got new decals made for the little window so it looks totally factory.

 

I should add that you may need to tweak your speedo after you get it all installed. It seems that the exciter rings will send a different pulse rate depending on if you went from a M6 to a TH400 or a A4 to a TH400. Just estimate what speed you should be going at a given RPM. If yours doesn't match just adjust it by increasing or decreasing the tire size using LS1 edit or a hypertech until you get it to match up. Right now I have a different ring and I have to use about 53" of tire in the computer to compensate for that. I'm still a little off on the final setting though.

 

If you go from an M6, your speedo will be ~2.5 times off. If you go from an A4, you will be dead on, unless you have changed tire sizes.

 

IMO I wouldn't use the stock shifter. When you put it side by side to a pro ratchet etc. it looks like a weak plastic & tin POS. compared to something that it made to be hammered on.
Oh and I didn't have any problems with the lockar dipstick, its not too short if you know what to do with it.-wait that sounds like my-never mind...

 

Why do you need to 'hammer' on the shifter? A simple 'bump' and you change gears.
I also prefer to check my tranny oil OUTSIDE of the the vehicle.

 

No ****? really?
I said the shifter was well made, I didn't say you needed to hammer on it to shift...If you like that POS use it, I dont give a ****. My dipstick is out of the way now, not cluttering up my engine compartment or my interior.

 

FYI guys. You can get custom length lokar dipsticks. It's like an extra $10/ft. My new one will be in the engine bay like stock. I wouldn't want to use the stock shifter. I would hate to give it TWO bumps coming down from a wheels up launch or something. That is the whole point of a "ratchet" shifter. You can't miss.