47-55.1 Bellhousing Crossmember necessary?

[Dongray]

I have installed a 292 using the side engine mounts and was wondering if the bell housing crossmember was necessary if I used the T5 tranny crossmember. This just buys me more clearance for brake booster, clutch mc and exhaust. It doesn't sound like the best approach but just wondering.

[nvrdone]

OK, do you have a straight axle or an IFS?
Either way you need the cross member at the bell housing. It mounts to the frame right at the rear spring mounts and keeps the frame from spreading, causing problems with the front cab mounts. Remember that these frames flex a lot as part of the suspension. If the cross member causes interference problems you could fab a new one.

[mr48chev]

Nvrdone nailed it spot on. If you remove that crossmember the frame needs to be reinfoced = boxed or there needs to be sufficiant support to keep the weight of the cab from pushing the cab mount brackets down and letting the cab settle until it finally lays on the frame rails.

This is the most common cause of "I have done everything that I can think of and can't get my hood adjusted right" syndrome on AD trucks. If you stand back and look the cab has sagged at the front and the lines of the cab are no longer parallel with the lines of the running boards. Get under the truck and there is no clearance between the frame and the cab at the spot you measure at.

This happened to me when I went V8 automatic and cut the crossmember out even with the truck subframed. You can see it on older builds at a lot of gatherings and rod trots where you see a batch of these trucks. Cut the crossmember out without reinforcing the frame and eventually the cab will sag if you drive the truck.

The simple fix when you are setting the truck up is to make and install a pad/block right above the frame rail inboard of the original mount to carry most of the weight. Use the regular cab mount to hold the cab in place and use the pad to carry the weight.

I've got the measurements out of the assembly manual and the hood adustment instructions out of the service manual here. https://photobucket.com/u/mr48chev/a...c-87a31c3a5b15

[leegreen]

Does anyone know if the cab floor is parallel to the top of the frame rail from factory? I've always assumed it should but the dimensions in mr48's links make me question that.

this picture, do you have the original to confirm this dimension reads 1.83" ?


and here is the back dimension for reference: .76


So there is a 1" difference front to back.

I have everything operational but the hood fit only looks good if you squint. Cab-fender relationship is one of the things on my roundtoit list.

[mr48chev]

That may be the difference in where you measure from.

When I figured mine out in the 80's the cab had settled and pinched the park brake rod between it and the frame. I had been fighting that too at the same time.

[mick53]

I'm putting a 292 in my 53 3100 and a Tremec TKO 600. I'm boxing my frame and replacing all the crossmembers with tube except maybe the front. I agree you need support in that area. You will be picking up some on the trans crossmember but that's pretty far back and probably not enough. With the torque monster 292 there is a lot going on in that area. JMHO I'm no expert.

[dsraven]

I have mentioned before that an original crossmember could be sectioned out and dropped making it a bolt in. maybe something like that interestes you? brace the frame, cut out the center of the crossmember, fab up a new aesthetically peasing replacement part, weld flanges on the tips of the parts where they would meet up and bolt it together, then you can remove the bracing since it was just there to ensure the frame didn't spring out of shape when you cut the cross member, it should all fit back to a stock width then.

[dennislbrooks]

Does anyone have real life pics of their modification for examination?

[dsraven]

mine is long gone but I did see one on here someplace. can't remember where, its been awhile since i seen it. the fella cut the crossmember on each side, close to the frame, then welded some flat stock to the frame parts so it hung down. then he did the same on the cross member only those faced upwards and he had done the math so the frame width stayed the same. then he slid the cross member up in place and levelled it etc, marked some spots to drill holes for bolts and did it that way. exess flat bar was trimmed after. looked ok when done and did the job. it could be unbolted to acceess the trans pan or for engine removal later etc.

[dennislbrooks]

Ogre from Motown did it somewhat cleanly on his yellow 57 with the LS and some OD trans. He boxed the frame in that section of the removed bell housing side mount xmember back to his new rear trans mount then his trans mount is top to bottom with exhaust pipe holes.

Page one of his build toward bottom. https://67-72chevytrucks.com/vboard/...d.php?t=501998


I reinforced my 59 4wd with the 700 R4 trans/transfer case mount.
https://www.67-72chevytrucks.com/vbo...d.php?t=830279