Trans cross member help needed, 66 Lemans/Tempest convertible - Pontiac GTO Forum
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post #1 of 4 (permalink) Old 11-17-2016, 01:41 PM Thread Starter
 
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Trans cross member help needed, 66 Lemans/Tempest convertible

I'm changing the engine and trans in a 66 Lemans/Tempest convertible.
I can't see how to get the trans cross member out of the frame rails.
Look at these pictures. Everything is painted black under the car and that makes it hard to take a good picture.
The cross member goes into the frame on both sides and seems trapped. There are vertical bolts that go through the frame but no way to put a wrench on the nuts.
It appears like this was a frame off resto and my thinking is someone boxed the frame after the cross member was in, then lowered the body onto the frame.
Please tell me I'm wrong.
Thanks
Danford1

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post #2 of 4 (permalink) Old 11-17-2016, 02:06 PM
 
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Welcome to the forum. Originally, a convert frame was stepped in the boxed inner area. That stepped section to give access for the crossmember & gives the center section rigidity. The contraptioneer who pitched the convert frame, replaced it with a std open channel frame, then boxed it with steel plate didn't understand the whys of the shape of the boxed inserts. Unfortunately, he also did not provide a provision to bolt the trans crossmember.

The easiest thing to do would be take an air saw or sawsall to the crossmember flush at the frame, then weld a tab on each side for the modified remainder of the crossmember to lay on. Can either do it like Pontiac engineers did with a rubber insulator on each side inside a small stamped steel "cage", bolted to the new frame tab, or like other GM divisions did where the trans crossmember bolts directly to the frame.
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post #3 of 4 (permalink) Old 11-17-2016, 06:46 PM
 
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PH is right as the frame you have is not a convertible frame with the factory boxing. You have a channel frame that appears that the previous owner simply left the transmission crossmember bolted up to the frame rails, notched a section to go over the top of the crossmember, then secured it in place and welded it up.

The problem is of course you can't get access to the nuts on the other side of the bolts UNLESS the guy was smart enough to have welded the nuts in place on the metal plate holding the rubber mount that the flat end of the crossmember slides into. I would try to unbolt it first to see if the previous owner/fabricator used any forethought in his construction.

You could use a sawsall as PH suggested and cut the crossmember flush with the side of the boxed frame. Then you will have to fashion a bracket that will go underneath the crossmember end, which will have to be welded to the frame.

I don't know if you will have enough material at the end of the crossmember to use that factory type mount/rubber isolator. If not, then I would drill holes through the bracket/crossmember because you will be cutting off the flat tab/ends found on the crossmember. I would find a round rubber mount ( or cut up the factory isolator and use a portion of it) that will be about the same thickness, and place it between the mount and crossmember end, run a bolt through, and use a lock nut to tighten it down, but not to the point you crush the rubber mount and it has no absorbing properties.

Just an idea.

The attachments are for example only and show the mount like yours found on an open/non-boxed frame and the other shows a boxed frame with mount for the crossmember welded to it.
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Name:	Boxed frame mount.jpg
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ID:	83274  
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post #4 of 4 (permalink) Old 11-17-2016, 11:45 PM Thread Starter
 
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I had another car guy come over and look at this and give me his opinion.
He agreed it must have been a frame off resto and they boxed a normal frame to make it a convertible frame. If I was to lift the body off the frame I could get to the nuts but we both just laughed at that suggestion :-)
Upon further inspection even lifting the body off the frame wouldn't work as there wasn't any access hole on top either. The genius that did this wasn't thinking in the future someone would have to remove the cross member. He just welded the plates on and trapped it.
I ended up cutting the slot wider so I could get a wrench on the nuts. No, he didn't weld the nuts to the metal retainer. They were just spinning inside the frame.
I haven't tried to get the cross member out yet. I ran out of time today. I'll see if it will come out tomorrow.

Thanks for the help thus far.

Danford1
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Undercarriage, Frame, Transmission and Differential Discussions.

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