Frame question..
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Instructor
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I thought the same thing when I seen the picture after I put it up then I crawled under it again and it's not.. Must be a glare.. Or the hole that was drilled is oval.
Last edited by Chevrolet12; Jun 3, 2015 at 07:20 PM.
Team Owner
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From: Park City Utah
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I just need a tip on how to make a crossmember or make my c beam work which I don't think I can now that the top bolt holes are cut off. If I can get an idea for the crossmember I will get to making one.
Team Owner
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From: Park City Utah
If you support the trans w/a x member, that will solve the trans movement issue. You'll still have the issue of the reaction tq from the diff -the C-beam being a torque arm. Will that bottom lip be enough? IDK. I'd make the x-member, install everything, then stick a GoPro under there to see how much flex and movement you have w/just the 'bottom mount design". If it flexes too much, you'll have to figure out how to tie the bottom of the C-beam to the cut back top, get a new C-beam or make one specifically to be a torque arm...specific to FIT your car, is what I mean. I SUSPECT, that over time, the bottom lip of the C beam would flex, fatigue and fail...but I don't know for sure.
Team Owner
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From: Park City Utah
You said your engine is 550 hp. I'm going to ASSumer that it's 450 tq, trans is known, and I'm going to assume a 3.07 gear.
450x2.48x3.07=3426 ft lbs at the diff. C-beam is about 4' from the pivot point, so 4/3426=864 lbs.
Using those numbers, and not accounting for the "hit" of the converter, you're looking at a peak of ~900 lbs on that lower lip of the C-beam, lifting up on your x-memeber. Will that piece of aluminum hold that much? I think it would for a while....
450x2.48x3.07=3426 ft lbs at the diff. C-beam is about 4' from the pivot point, so 4/3426=864 lbs.
Using those numbers, and not accounting for the "hit" of the converter, you're looking at a peak of ~900 lbs on that lower lip of the C-beam, lifting up on your x-memeber. Will that piece of aluminum hold that much? I think it would for a while....
Last edited by Tom400CFI; Jun 3, 2015 at 07:41 PM.
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From: Park City Utah
If it's flexing from just shifting into gear, there is no way it will hold the forces of full throttle launching.
.
Last edited by Tom400CFI; Jun 3, 2015 at 07:50 PM.
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We are saying about 550 hp at the least.. Haven't got to the dyno yet. He thinks it may be more.. You are correct on 3.07 gear. And I was meaning maybe fabricate a different way to mount the c beam to the crossmember instead of just the lower lip.. I would prefer this to be a little more stout.
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Burning Brakes
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From: That one city...you know that one. Idaho
I think the easiest thing to try would be to remove the rubber mount from the TH400, and mount what is left of the cbeam directly to the transmission.
Team Owner
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From: Park City Utah
I think the easiest thing to try would be to remove the rubber mount from the TH400, and mount what is left of the cbeam directly to the transmission. I didn't think it would hold and that's why I'm asking you for your advice.
I would like to have a crossmember because it just seems stronger to me.
I would like to have a crossmember because it just seems stronger to me.
Second, I don't think the x-member is stronger than a properly mounted C-beam. Remember that a x member will be very long since the frame rails at that point in the car are very wide (rocker to rocker). So unless you seriously cut into the floor/interior to get a tall x member, it's going to be tough to get a strong, stiff x member that will double as a tq arm mount. If you're going to rearrange it so that you can properly bolt the C-beam to the trans, then you don't need the x member.
IF you move forward w/the X member, then I'd fab some kind of vertical element of the member, that would interface w/the C-beam on a vertical plane, where it has it's strength. Then bolt the C-beam, rigidly to that. Does that make sense?
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I am kind of lost on what you mean by that. I think I still have the piece that was cut off the beam. I may get that welded back on and see if I can get it mounted to the transmission. Any ideas on going that route. It seems like the best route for now.
Burning Brakes
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From: That one city...you know that one. Idaho
For my car it would have required modifying the floor pans to make room for the crossmember.
For that I meant to use the cbeam, but remove the rubber mount is currently on the Th400.
Team Owner
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From: Park City Utah
If it were me, I'd fab a steel unit that bolts to the same flange as the trail shaft housing, extends rearward like 1/2 a box, meets and fits inside the C'beam...then bolt the beam to that.
Team Owner
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From: Park City Utah
The trans is strong enough on the vertical plane to handle those loads, and the C-beam is very weak torsionally, so any twisting forces (motor mounts flexing, frame flex, etc) is absorbed in the C-beem.
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If the original C-beam was long enough and could be used if NOT CUT I'd get another and start with a fresh C-beam that's not been whacked on. They're very inexpensive and there are many available everywhere very cheap probably very close to you. You want a D36/A4 C-beam if the older was long enough, if it was really very much to long you might want to get a D44 C-beam BUT they're not inexpensive and a little more difficult to come by. They're only slightly shorter than a D36 part but for an application that uses a D44 and an appropriate transmission it's much easier too use than to try and drill all four holes that are required and keep an appropriate alignment.
