Transmission Crossmember Pics
 

I'd like to see pictures of transmission crossmember arrangement with short shaft 400 turbo trans. I'd like to see where it sits on your frame. I have a '64 A-body. Not sure if they changed the frame where the crossmember lands over the year. Thanks!

64 Roto HM and the bigger 4sp HM were both the same overall length and I think the mount to the frame was at the same location. You didn't say which transmission you had but I don't think it makes much difference if it is changed to a 400. The 400 mount should be about 1 inch forward from the original location on the cross member.

My car was originally a 3-speed stick '64 GTO. Had a 4-speed Muncie when I bought it. Currently has a TH400. I spin the crossmember around opposite and it works for both. Length is almost identical. My crossmember lands at the rear of the "step" in the frame where the crossmember bolts up. I have 1/2" spacers under the rear of the mounts. Thus this inquiry. I want to know how the original cars were with TH400's. Did the change the frame or something? Surely they didn't have spacers.

I think the mount on the Muncie mount is farther forward and the crossmember bolts up on the flat raised part of the frame.

Mount is farther back by about 2.5" ROUGHLY, on the 67 Turbo 400 cars vs the 4 speed cars on a 64 GTO.

I assume it is a roof car. The convertible mounts had to have a "extension welded on the frame toward the rear of the frame mount to be able to use the rear bolt on the mount.

The "C" frame hardtop and coupe cars have the open frame but now the Transmission
Mount becomes more critical for driveshaft angle.

So I will leave the Mods for the Open Frame guys to them.

There were a few Coupe and Hardtop cars ordered with the 'Heavy Duty' Convertible Frame.

Tom V.

I had one in my ‘64 Tempest. You move the crossmember back a full 6” and drill new holes.

I was using the factory rubber insulators, the depression in the frame rail where they originally sat caused the insulators to sit not quite flat in their new position but everything worked fine.

If you just want to bolt it to the frame without the rubber insulators you can just drill the ends of the crossmember and corresponding holes in the frame. My ‘64 GTO bracket car also had a short tail TH400 (with a transbrake) that used this method to mount the crossmember.

Both ways work fine.

Thanks for the actual stock dimension Bart with the the factory rubber insulators.
(just shifted rearward).

I assumed that when the crossmember was flipped around the distance the mount moved would be shorter.

As posted before I like the Rubber isolators and that mount system.

Tom V.

Good reference information.

As I said, the crossmember clears one direction for the Muncie. Which is also quite a bit farther forward. It clears the 400 if flipped around. I'm using what I believe to be the most rearward hole in the frame for the front hole in the bracket. I have another hole added for the rear bracket bolt (Which is on the stepped down part of the frame).

I cleaned up my factory crossmember and painted it. Bought some new, nice, clean, plated, brackets for the rubber booties. This will suffice until I get a Chevy crossmember at a decent price.

It looks like I will have to shim the rear of the trans up quite a bit. Also get adjustable upper rear control arms for the rear. This is to get acceptable angles with the LS engine with 400 trans.

I'll add some pics when I get a chance (Worth a thousand words).

Please refrain from attempting to turn this into a design debate.

Thanks!

Not sure if they changed things at all, but if you're interested, I have a photo of my '66 GTO frame that shows the measured distance & placement of the trans crossmember. My car had a short-tail TH400 in it. Let me know if you think it would be comparable and I'll post the photo.

Absolutely! My intent is to learn about how TH400 equipped cars crossmembers were set up. Even good examples of modded crossmember configurations would be helpful.

I never flipped the crossmember around on any of my installations, simply slid it back.

No kidding? I haven't had the 4-speed in it for many years. Maybe I'm mistaken. I thought that it hit the 400 in one direction and Muncie in the other direction. Because there's a lip on one side and not the other (If that makes sense). Maybe I had analysis paralysis! :)Now I'll have to drag my Muncie off of the shelf and look.

Here ya go. On my car, the center of the trans mount bolt holes was about 7-3/8" when measuring from the forward edge of the body mount hole located under the door. See photos for reference.

https://i.imgur.com/J4rwxyDh.jpg
https://i.imgur.com/p8U5Pfwh.jpg

Great Measurements on a Bare Frame makes easy visualizations.

Tom V.

Thanks! I'll see if I can measure mine with the body in the way.

Here's how mine lands on the frame.

Since you are using a 64 M/T or Auto Trans Crossmember, and you shifted the cross-member back as far as you did with the Turbo 400 trans, it is apparent to me that the Doug Nash 5 speed trans falls somewhere in-between those two positions..

Based on the picture of your 64 frame, it would be interesting to see a picture of a 1967 turbo 400 A-Body frame and where the mount locations are.

Tom V.

36 years ago I swapped the 4-speed for a 400 turbo in my 65 GTO. I did not use any of the original 4 holes nor did I space up the crossmember.

LS swap.

Engine position isn’t the same as a Pontiac V8 so to correct the driveline angle he’s having to make some adjustments.

I was comparing your work to mine. Nothing more.