Frame question..
Team Owner
Joined: Aug 2004
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From: Park City Utah
I think I understand what you're saying. I think it would work fine....as long as that lower "lip" of the C-beam has enough meat to support the diff tq at WOT 1st gear.
Could you use original front C-beam bolts, make spacers for the I.D. of the C-beam, and rung the bolts through the cross member, beam/spacer/beam and sandwich that whole assy together? That would give the beam a lot more strength, and not be a lot harder to do, i wouldn't think.
Could you use original front C-beam bolts, make spacers for the I.D. of the C-beam, and rung the bolts through the cross member, beam/spacer/beam and sandwich that whole assy together? That would give the beam a lot more strength, and not be a lot harder to do, i wouldn't think.
Burning Brakes
Joined: Apr 2009
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From: That one city...you know that one. Idaho
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
The torque arm on the fbody does not hold up the transmission. Somewhere in this thread I read something about the OP needing a new c-beam. If that is the case the fbody type parts are much more available.
Thread Starter
Instructor
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The top holes on the c beam have been cut off because it was touching the tail housing.. I only have the lower two holes. If that would be strong enough for the rear axle I could do that and the crossmember would hold the transmission..
Oil Producer
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the car as a whole needs the cbeam to hold the drivetrain together. without the cbeam sandwiching the tailshaft, the drivetrain is going to twist, torque, flex which will be transmitted to the engine on the front and the diff in the back.
if your tailhousing is too fat to fit in the cbeam, then i would think the only possible option would be to get an alumininum welder to basically make the cbeam custom to your tailshaft, make it wider on the tailshaft end so you fit your tailshaft end in. then get longer bolts and bolt from the too of the c beam down through the bolts on your tailshaft (if holes happen to line up, which i doubt. If the holes do not line up, then basically fill in the bottom unused holes on the cbeam, and make new ones with longer bolts.
you gotta have the c beam, modified so your tailshaft fits into it, sandwich the tailshaft and cinch it all up.
sounds like you need to custom fabricate the c beam. if you do this, weld a nut to the top of the cbeam so you only have to push the new, longer bolts up through the holes and start screwing. easier than the stock setup where the bolt is free ontop.
Burning Brakes
Joined: Apr 2009
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From: That one city...you know that one. Idaho
OP if you would post a picture when you can It should help with the confusion about what you mean.
Read this. The car does not need the cbeam.
Oil Producer
Joined: Apr 2014
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thanks for that. always want to learn. i was referring to holding the drivetrain together. not holding the "car" together. without the cbeam installed as good as or better it came from the factory, the torque, twistys, flex whatever generated by the drivetrain is going to blow his drivetrain apart. not the car. i think i did say "the car needs the cbeam" and later said "the drivetrain needs the cbeam". what i meant was "to drive the car you need the drivetrain supported as good or better as the cbeam was installed from the factory".
anyway i agree with u the cbeam is not and was never meant to be working in tandem with the frame. i dont think thag was ever the op's issue. he has drivetrain sag. cause he only has the bottom of the cbeam attached to his drivetrain and its not sandwiched.
look fwd to seeing how the whole thing is resolved to get to the drivetrain supported.
lots of respect for those who custom fabricate. especially when welding aluminum!
anyway i agree with u the cbeam is not and was never meant to be working in tandem with the frame. i dont think thag was ever the op's issue. he has drivetrain sag. cause he only has the bottom of the cbeam attached to his drivetrain and its not sandwiched.
look fwd to seeing how the whole thing is resolved to get to the drivetrain supported.
lots of respect for those who custom fabricate. especially when welding aluminum!
OP if you would post a picture when you can It should help with the confusion about what you mean.
Read this. The car does not need the cbeam.
Read this. The car does not need the cbeam.
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Team Owner
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I don't know "first hand" of any TH400 installs and that's why I mentioned building the trans that was in your car vs. the TH400 you mentioned wanting to do this. There have been C-beam bracket fabrications for nearly every conceivable transmission and you can actually buy the required parts to do a 4L80E in the C4. There are several of those out there.
There's some T56 fabrications done by some that you could look at snapshots and see how it was approached for those transmissions. All of those have extensions with a x-member provisions and worked well in HP applications.
Some years ago there was likely a BB & a TH400 built near Bradford PA, I don't recall the user name but I was originally from the vicinity and the location sticks. I believe that he discussed a conventional x-member.
There's some T56 fabrications done by some that you could look at snapshots and see how it was approached for those transmissions. All of those have extensions with a x-member provisions and worked well in HP applications.
Some years ago there was likely a BB & a TH400 built near Bradford PA, I don't recall the user name but I was originally from the vicinity and the location sticks. I believe that he discussed a conventional x-member.
Last edited by WVZR-1; Jun 3, 2015 at 04:29 PM.
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Here is the Link to the BB-TH400 post 17
Team Owner
Joined: Aug 2004
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From: Park City Utah
The OP's idea can work, and plenty of people on here have eliminated the C-beam on their drag track oriented cars.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
thanks for that. always want to learn. i was referring to holding the drivetrain together. not holding the "car" together. without the cbeam installed as good as or better it came from the factory, the torque, twistys, flex whatever generated by the drivetrain is going to blow his drivetrain apart.
The only thing the OP needs to contend with is holding up the ***-end of the trans, and supporting the reactive tq of the diff.
The bottom line is, will the one, bottom "lip" of the C-beam have enough strength to support the nose of the diff under heavy acceleration? IDK.
Oil Producer
Joined: Apr 2014
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Again, no it will not. The Engine/trans unit is secured torsionally, by the motor mounts. The diff is secured torsionally by it's batwing mounts...same as most any other car with IRS, RWD and front engine.
The only thing the OP needs to contend with is holding up the ***-end of the trans, and supporting the reactive tq of the diff.
The bottom line is, will the one, bottom "lip" of the C-beam have enough strength to support the nose of the diff under heavy acceleration? IDK.
The only thing the OP needs to contend with is holding up the ***-end of the trans, and supporting the reactive tq of the diff.
The bottom line is, will the one, bottom "lip" of the C-beam have enough strength to support the nose of the diff under heavy acceleration? IDK.
ok, obviously im out to lunch. i am REEeeeALLY surprised though. it is astounding to me that the c beam is unnecessary edit: for anything other than holding the tailshaft side up.
Thread Starter
Instructor
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Does anyone have any pictures of the crossmember someone has made for a th400? If I could see that then I think I could adapt something.. As for the c beam couldn't I just bolt that to the crossmember once I get it situated?
Burning Brakes
Joined: Apr 2009
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From: That one city...you know that one. Idaho
It looks like you left the rubber mount on the TH400? That might explain the movement you are talking about.
Thread Starter
Instructor
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Another thing... If the rubber mount isn't there how doesn't it break the case? Wouldn't it be the same concept as using a solid mount? I've heard of people breaking transmission cases if they use a solid mount.
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Burning Brakes
Joined: Apr 2009
Posts: 1,228
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From: That one city...you know that one. Idaho
The cbeam is bolted to the differential that has two rubber bushings (in the batwing) that hold it to the frame unless you replace those bushings for solid mounts it would not be solid mounted.
Last edited by aDigitalPhantom; Jun 3, 2015 at 07:19 PM.