[poison heart]

I think that's what the ST400 is, switch pitch. It's a 3 speed but has some sort of variable pitch

Maybe it was just a Buick thing. I know Buick used them from 64+?? I know until at least 66.

I did a search on here with no results, I guess Pontiac never used them

So, were the slim jim and hydramatic the only autos Pontiac had for 64?

[Keith Seymore]

Originally Posted by MOJO Catalina

As far as the TH400, if I end up going that way (the wife says she'd like the better automatic-go figure) is the short tail or long tail better for the GP and if so, why?

Long tail, because it more closely approximates the overall length of the Slim Jim. You could use a short tail (maybe - if the drive shaft would clear the crossmember) but you'd have a really long driveshaft.

BTW - I would love to have a four speed in my car, but the automatic really suits its character better (its a "low and slow" luxo cruiser). Plus hanging a clutch and redoing the back of the motor was more than I wanted to get into.

Originally Posted by MOJO Catalina

Is the adapter only necessary when using a CHevy trans or is it necessary on the BOP version as well becuase of the possible starter situation (still haven't been under to look, lousy weather here.)

The adapter is necessary when using a '63 or earlier block that does not have provisions to mount the starter. In other words, you could simply put a newer BOP trans on the BOP block but you'd have to put a hand crank on the front of the engine (...lol). Hence, my BOP/BOP adapter plate was only 1/4" thick, just enough to provide a spot to mount the starter (horizontally , just like originally). The attaching bolts pass right through the trans bellhousing, through the starter plate and then into the block.

The BOP/Chevy adapter is much thicker, because you have fasteners going in one direction to attach the trans to the plate, and then fasteners going the other direction to fasten the plate to the block. Because it is thicker you can't mount the original starter and therefore have to buy a new mini starter where the bolts go vertically up into the adapter plate.

[Keith Seymore]

Originally Posted by poison heart

But a fresh TH400 for $75 is not typical. I think $600-750 range for a fresh Th400 is a good deal.

Just shows what you can do if you are patient, and in the right place at the right time.



I also had two other Chevy TH400s available but did not want to use either of them for this.

K

[MOJO Catalina]

Thanks Keith, I appreciate you taking the time to advise me on the TH400 swap. I enjoyed reading about your history.

And thanks to all you other fellas for checking in daily. It's nice to know I'm not alone out here...

Well, I suppose I'll be looking for a long tail TH400 and, if my block doesn't have the necessary holes, I'll be in the market for an adapter plate too.

What was the issue with the drive shaft? I assume the original ends up being too long.
Cut it down some? How much? Different yolk? # of splines?

Is it best to get the original driveshaft cut or should I try to get the shaft that went with the trans if it's available?

I don't know whether any have the long tailshaft, but there are at least a few TH400's within driving distance of Charlotte NC. Atlanta/Richmond/Columbia... I'll be checking into those.

[poison heart]

a 400 is a bigger output shaft than the slim jim isn't it?

[stevep]

Originally Posted by poison heart

a 400 is a bigger output shaft than the slim jim isn't it?

Yes.

A ST-400 was a 64-67 Buick, Olds, Caddy thing. Pontiac and Chevy never used them.

[MOJO Catalina]

Any of you fellers out there live close to Charlotte NC?

Once I get all the goods together I could use some help dropping out old Jim and putting the new trans in.

My wife is a good cook and the heating and AC in the house works great.
We even have a "snore proof" room here.

[stevep]

Originally Posted by MOJO Catalina

Any of you fellers out there live close to Charlotte NC?

Once I get all the goods together I could use some help dropping out old Jim and putting the new trans in.

My wife is a good cook and the heating and AC in the house works great.
We even have a "snore proof" room here.

You don't really need much help to do that swap.

[poison heart]

No, but it's nice to have some help.

[MOJO Catalina]

It would be nice to have someone close by that understands machanical language.
Someone who can be on their feet while I'm under the car and who'll be ready to hand a tool over.... or dial 911!

[stevep]

I wish that I was closer. If you brought the car down on Saturday @ 10:00, we could swap the trans and drive the car to get lunch at noontime.

[poison heart]

Remove and replace a tranny in 2 hours?

[stevep]

On that car, at my shop, yes.

[MOJO Catalina]

I believe it. Air tools, trans jack and confident know-how...

Steve, I appreciate your generosity even if I can't take you up on it.

[mike nixon]

Originally Posted by poison heart

Remove and replace a tranny in 2 hours?

For 2 experienced people,on a lift, that's not out of line.

Another tech and myself could change a th350 in mid 70's fullsize gm car in less than an hr with the replacement laying there. A 4x4 Automatic in a GM truck was 2 hrs from rolling in the door to rolling back out if the replacement was ready to install.


Keep in mind this is by two experienced people with the right tools and a ready to go trans that work well together.

Mike

[hurryinhoosier62]

Mojo,

I"crunched" the numbers a couple of years ago...the TH400 conversion is the most cost-
effective. By the time you invest the money needed to upgrade the 700R4 or TH200R4,
you will have paid for the TH400 swap TWICE. I know a lot of guys here will debate the
issue, but the TH400 swap has the fewest problems.

[MOJO Catalina]

Originally Posted by hurryinhoosier62

the TH400 swap has the fewest problems.

I'm getting that vibe from most on here.
The long shaft TH400s seem to be available and there a several guys who have done it with great results.

More questions though:

Any problem with speedo accuracy?
Will console linkage work as is?
I know the selector will have to be relabelled but no big deal there.

And then there's the rear gear situation.
This car has a 3:42 one legger in it now but I have a 2:56 from an economy '63 Catalina, a 3:08 from a 60 Ventura and a 2:69 from a '63 Bonneville to chose from.
Which would be best with the TH400?

[Deadhead]

3.08 would be best IMO.

You will have to have a driveshaft made. The yokes are different and cutting & splicing is not worth it. Likely cost the same as having one made that is all balanced & ready to go.

I think you will be able to find a TH400 for a reasonable price. They are everywhere & not expensive to have rebuilt.

[hurryinhoosier62]

Mojo,

Contact Jeff (Pittsburgh64) on the console issues. My '64 Cat doesn't have a console.
As far as speedo calibration, GM used to sell color-coded gears to correct your speedo.
Hook up the cable. Record your odometer reading. Drive the vehicle over a 5 mile course. Recheck your odometer. If it reads less than 5 miles, multiply the difference by
2(4.7miles=6mph off). Install the appropriate gear to correct. I owned a '76 GP that was
18mph off!! As far as gearing, I'd stay with the 3.42 unless you're running a 455.

[Keith Seymore]

As far as the console linkage, here's a link to the thread where I described what I did:

http://forums.maxperformanceinc.com/...d.php?t=585381

That's a John Deere "steering tie rod" that I used which worked great.

For the speedo, I did a similar error calculation as described above, but used an external adapter (.8, I believe, which I just happened to have laying on the workbench).

I believe my rear axle is a 3.23.

K