crossmember location

[muscle]

Ok, recaping..

1984 Jimmy

removed th350/208 and am replacing with th400/208. tranny and t-case is now married and looks good.

flat crossmember to "W" shaped crossmember requires new mounting holes in the frame. th400 is longer tranny and will require new mounting holes anyways?

Question:

Should I drop the engine in first, then bolt up the tranny to the engine and locate the crossmember location that way?

here is pic of tranny/tcase ready to raise into position.

 

[sweetk30]

bolt it all to gether and lift crossmember to frame and drill holes then bolt.

 

[muscle]

ok thanks.

I read alot of post on the subject of the bolt spacers on the crossmember. After drilling the frame is there a proper way to use the spacers to keep the frame from cracking? what is the OEM use of these spacers?

 

[sweetk30]

hard core offroad and catching somthing on the member is what kills the frame or member. the bolt goes threw the frame from top then member then spacer and nut.

 

[mouse]

Also, people using the stock spacers to lower the t-case cause the frame to crack... I personnally would have the engine bolted in and then lift the transmission/t-case up. Don't drill any unnecessary holes!!

 

[dyeager535]

Yes, the flat and "W" shaped crossmembers require different bolt holes...you can see in your picture where the flat crossmember was, and on the new one, you can see how close the bolt holes are together. (IIRC, even the "single hump" later crossmember uses a different bolt pattern than the flat crossmember. It is wider than the "W" one for sure. Just tech for anyone else that runs across this post)

Anyways, if you have the same problem I ran into, where the bolt holes overlap but don't line up enough to use, I put a factory spacer plus a couple of washers at either the leading or trailing edge of the crossmember. That will allow you to use those bolt holes. I don't like that as much as going with the flat bolt holes, but in my case I didn't have any choice.

 

[muscle]

well my understanding is that i will not be able to use any of these holes. As soon as I drop in the motor i will stab the tranny and be able to drill ne holes. The previous setup was a th350/208 and now is a 400/208. I just dont like drilling more holes in the frame. is there a way to reinforce these holes?

 

[dyeager535]

I couldn't come up with anything practical...weld them shut, you have to grind on the top and bottom and hope you can get them flat. If the tranny/t-case is out, this might work ok. With them in, you can't see to do this.

Only other option my friend came up with was to oblong the frame holes, buy some steel plate, and use it as a giant "washer" on the frame rail. Oblong bolt holes in the frame I have found out do not work well at all, the washer won't seat flush, gets bent and won't allow you to tighten the nut up evenly, so it works loose eventually.

I wouldn't worry about drilling new holes, if you can without hitting any of the old holes, go for it. If I have to do mine again, I'll HAVE to weld to get any more bolt holes in there.

 

[muscle]

ok thanks alot guys ill be completing this weekend ill post to how it came out