Frame question..
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Instructor
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Frame question..
This is going to sound really odd sorry
... Want to see if anyone knows if there is a steel frame under the c4? I would like to build a actual crossmember for the transmission. I put a built 385 and a turbo 400 transmission in and when I put it in gear the transmission drops and hits the exhaust.. If it had a crossmember it shouldn't drop. But right now it just has the c beam..
... Want to see if anyone knows if there is a steel frame under the c4? I would like to build a actual crossmember for the transmission. I put a built 385 and a turbo 400 transmission in and when I put it in gear the transmission drops and hits the exhaust.. If it had a crossmember it shouldn't drop. But right now it just has the c beam..
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My exact thoughts... I was thinking maybe because the turbo 400 is a heavier transmission than the 700r4 is why it drops a bit more.. I don't know. I think I would have to cut some of the floorboard out to get a crossmember in and it looks like there actually are frame rails on the out sides
Team Owner
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From: Park City Utah
THe C4 does have a steel frame and there are frame rails along the outer edge -the rockers.
There is no reason, however, that a properly adapted tailshaft housing, and properly installed C-beam shouldn't very easily handle those loads. The C-beam is strong enough to lift the front of the car off the ground during a hard launch (modified engine, obviously), so the weight of the T-400 is insignificant to the C-beam. I'd get under the car and see what is allowing that movement to occur, then fix it.
There is no reason, however, that a properly adapted tailshaft housing, and properly installed C-beam shouldn't very easily handle those loads. The C-beam is strong enough to lift the front of the car off the ground during a hard launch (modified engine, obviously), so the weight of the T-400 is insignificant to the C-beam. I'd get under the car and see what is allowing that movement to occur, then fix it.
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Double checked the rear bolts and the motor mounts.. All good. I made a bracket from the original transmission mount to the lower c beam bolts and it's all bolted there. Would that cause an issue? I didn't use the top holes on the c beam.
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St. Jude Donor '16
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Also, when you put it in gear, the tq reaction of the diff housing is going to want to lift the tail end of the trans UP....not push it down. Putting it in reverse would want to push the trans down.
Can you out the car up on a lift or jack stands, set the park brake and have someone shift from neutral to gear/reverse while you lay underneath and watch the diff, c-beam, and trans?
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From: Park City Utah
A bit of reading for you: C-Beam Tech
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Ok I totally understand that. Now when I had a buddy make the mount he cut the top corner to clear the tail housing.. Dumb Idea. I agree. So now either I need a new c beam or could I get a solid piece of steel and make a crossmember and leave what's left of the c beam bolted.. Just to strengthen the mess?
Team Owner
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From: Park City Utah
I'd get a new C-beam, if it were me; it's simple clean, effective and light weight.
If you do a x-member for the trans tail, you still need the C-beam to manage the reactive tq of the diff. OR you need to fab another steel x-member to support the nose of the diff. Bear in mind the strength required there; w/a stock engine, you're making ~350 tq, x first gear ratio (2.7:1) x rear ratio (~3:1). 350x2.7x3=2835 lb-ft of torque, that the diff housing is exerting on the frame (or C-beam, if installed). So if you fab an X-member for the diff nose, it''s got to be pretty stout.
If you do a x-member for the trans tail, you still need the C-beam to manage the reactive tq of the diff. OR you need to fab another steel x-member to support the nose of the diff. Bear in mind the strength required there; w/a stock engine, you're making ~350 tq, x first gear ratio (2.7:1) x rear ratio (~3:1). 350x2.7x3=2835 lb-ft of torque, that the diff housing is exerting on the frame (or C-beam, if installed). So if you fab an X-member for the diff nose, it''s got to be pretty stout.
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Yea my new engine is about 550 hp... If I leave the c beam like it is and just add the crossmember basically sandwich the c beam between the crossmember and transmission mount do you think it would work?
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St. Jude Donor '16
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Tom, I was meaning leaving the c beam the way it is how I only have the lower two mounted to the transmission mount and make a crossmember and run it under the c beam and use longer bolts to go through the crossmember and c beam bracket that's mounted to the transmission.. I'm just trying to make sure I'm explaining it correctly. Sorry