52 Chevy Tranny swap

[wildfifty2]

I am converting the 52 1/2 ton over to a 700R4 transmission and Chevy 12 bolt rear end out of a 68 Camaro. The transmission will be mounted up to the 235 CI with an adapter. I am assuming that I will need to cut out the cross member that supports the bell housing mounts for the original four speed. Just curious if most people cut this cross member off removing the center section or attack the rivets that hold it to the frame and remove the whole piece? Thanks

[mr48chev]

Depends on if you want to save the crossmember or just don't much care and want the easier way to get it out.
From experience and it wasn't good you have to reinforce the frame either by boxing or coming up with a fabbed crossmember if you pull that unit out. If you don't do something the weight of the cab will push down on the front cab mounts until the frame twists and the cab settles to the top of the frame rails. The reason you see a lot of stock frame trucks that have a V8 and automatic in them that look bent at the cowl.

One thing with the stock front mounts on that six you need some sort of motor mount at the bellhousing area or you will end up with front seal problems in the trans and possibly a cracked trans bellhousing. I don't know what the kit has but it needs support there to limit the flexing.

If you are running side mounts on the 235 it isn't an issue.

[wildfifty2]

Thanks for the info... I do plan to install side engine mounts on the 235. I purchased some from Chassis Engineering but like most projects they will require some modification to make them work.. I was under the truck last night and it looks like I will also be rerouting the brake line as well as it is attached to the cross member that needs to be removed..

Originally Posted by mr48chev

Depends on if you want to save the crossmember or just don't much care and want the easier way to get it out.
From experience and it wasn't good you have to reinforce the frame either by boxing or coming up with a fabbed crossmember if you pull that unit out. If you don't do something the weight of the cab will push down on the front cab mounts until the frame twists and the cab settles to the top of the frame rails. The reason you see a lot of stock frame trucks that have a V8 and automatic in them that look bent at the cowl.

One thing with the stock front mounts on that six you need some sort of motor mount at the bellhousing area or you will end up with front seal problems in the trans and possibly a cracked trans bellhousing. I don't know what the kit has but it needs support there to limit the flexing.

If you are running side mounts on the 235 it isn't an issue.

[whitedog76]

Most folks cut the crossmember out due to the fact they share rivets with the cab mounts.

I have a similar dilemma with my 54. I'm going to grind out the rivets and fab a removable crossmember.

[dwcsr]

Keep in mind that the cross member is not just a transmission support. It also keeps that area stable from flex with the cab mount on top and the rear attachment point of the front springs. It does a lot and you should try to modify it so it stays in place

[wildfifty2]

Thanks for the info..

Originally Posted by dwcsr

Keep in mind that the cross member is not just a transmission support. It also keeps that area stable from flex with the cab mount on top and the rear attachment point of the front springs. It does a lot and you should try to modify it so it stays in place

[Jesse Z]

Edited for content.