I've got a '66 convertible LeMans - the prior owner swapped out the powerglide for a TH400. The transcrossmember is a modified crossmember from another car. Can I use a stock corssmember in a '66 convertible for the TH400 transmission - or is it a different setup??

Thanks
-dan

I've got a '66 convertible LeMans - the prior owner swapped out the powerglide for a TH400. The transcrossmember is a modified crossmember from another car. Can I use a stock corssmember in a '66 convertible for the TH400 transmission - or is it a different setup??

Thanks
-dan

[b-man]

The tranny crossmember on converts are different from the rest of the other body styles. They are shorter in length and mount on brackets welded to the inside of the boxed frame rails, instead of resting on top of the frame inside on the lower part of the 'C-section' frame rails on non-converts.

To use the convertible crossmember with a TH400 you'll need to cut the welds holding the mounting brackets and move them back and re-weld them in the proper location.

If the modified crossmember you now have is in good shape and in the proper place I would leave it there. Or you can swap in a TH350, then the stock crossmember will work with no mods to anything on the frame.

------------------------------
My wife says I never listen to her, at least that's what I think she said.

[Tom Vaught]

Car was actually not built with a powerglide BUT:

The Pontiac 2 speed trans, a turbo 350, and the 3
and 4 speed transmissions all located the mount for the transmission and the cross-member in a certain location on the frame.

When Pontiac installed the Turbo 400 (with the short tailstock housing) the mount moved to the rear a few inches so all turbo 400 trans cars after 1966 use a different frame (convertibles) or a more rearward mounting hole arrangement in the open channel (roof car) frames but basically the same as the 4-speed frame.

You did not post if the other person put a short tailstock trans or a "big car" (long tail stock)
turbo 400 in your car.

Please provide this info too.

Then we can help you out further.

Tom V.

Okay - the $64 question - how do I determine what type of transmission (long v short)? Also, it looks as though the prior owner used a crossmember from a hardtop - and simple drilled holes in the frame and bolted it on. The plates for the convertible crossmember are there - just not being used. Is it okay as is? I'll try to take some pics and post.

Thanks.
-dan

[b-man]

Pretty easy to tell long tailhousing from short. The short is about 4-1/4", the long one measures about 9-3/4".

If your crossmember was just bolted up to the bottom of the frame it might cause the trans to sit too low at the rear mount. This tilts the whole engine and trans downward at the back, and will possibly cause the fan to interfere with the fan shroud since the engine will sit a tad higher up front.

Easily fixed by putting a spacer (about 1/2" or so) under the trans mount. Just take a close look, it might be fine as-is.

------------------------------
My wife says I never listen to her, at least that's what I think she said.