Torque arm fabrication question - 70 mustang

[funcars]

This is a little long...

I have designed and fabricated a torque arm for my 70 Mach I mustang, but it looks like some undercar surgery may be needed. The trans/driveshaft tunnel just isn't wide enough to tuck it up where I want it. It is designed to work with a lower pivot just to the right of the driveshaft and an upper solid rod-end linkage to allow pinion angle adjustment. It is made from thick wall narrow cross-section rectangular tubing.

I don't want to compromise ground clearance (no Griggs type designs) and want to minimize the surgery to the car. I also have a c4 corvette that has an open C channel running from the pumpkin to the trans and it got me to thinking about fabricating something that partially fits around the driveshaft. It would need a different cross section than the c4 design to get the bending strength required, but it can be done.

Now for the fabrication questions: Has anybody else made something similiar to a C channel torque arm? How hard would modifications be to widen the trans tunnel on the pass side? (I'm a little reluctant to go this way). Rear end is cambered full floater.

I'm using susprog3d to model it.

Thanks for any help

[Mean 69]

I attempted the same exact thing you are describing years back on a 65 Mustang. I had the same concerns about ground clearance, and wanted to tuck it up next to the driveshaft. After a few months of part time attempts, I threw in the towel, and designed a three link instead. On the early cars, it was far easier to package, didn't/doesn't compromise ground clearance, and frankly, offers a better solution to some of the things a torque arm can be prone too (in particular, brake hop due to short side view swing arm). Both Grigg's and Maximum Motorsports do the underslung T/A on the late Mustangs for the clearance issues

If you do decide do the setup as you mentioned, I'd recommend strongly that you have someone that can do FEA analyze the torque arm itself. By the very nature of the device, it's got to be pretty long, and is prone to significant bending forces under forward acceleration. It's got to be right, or bad stuff can happen.

Mark

[funcars]

I knew I wasn't the only one...

For the three-link did you cut into the passenger compartment and tie in the top link to your rollcage? I like a three link better for function, but isn't there a lot more modification of the car required? (I thought so).

I agree on the FEA. For the rectangular section part I did stress analysis on paper and felt fairly comfortable, but for a strange cross section I'd do FEA. I run an engineering group and we have solidworks and FEA packages to go with it so no problem.

Thanks for the reply.

[69MACH1]

My car has a torque arm set up that works very well. It is a complete bolt in with no cutting. It is not tucked up like you want and it is the lowest part of the car but it has never been a problem on the pavement. Take a look, it works very well, or should I say, Try it you'll like it!

http://s45.photobucket.com/albums/f79/kikolemus/?action=view&current=69Mach1under04.jpg

[EvolutionMotorsport]

I knew I wasn't the only one...

For the three-link did you cut into the passenger compartment and tie in the top link to your rollcage? I like a three link better for function, but isn't there a lot more modification of the car required? (I thought so).

I agree on the FEA. For the rectangular section part I did stress analysis on paper and felt fairly comfortable, but for a strange cross section I'd do FEA. I run an engineering group and we have solidworks and FEA packages to go with it so no problem.

Thanks for the reply.

We will have a 3 link available at the end of the summer that will not require any cutting....

Thanks...Mike

[funcars]

Thanks for the link to the photos. You have done a nice job. I live in the Santa Cruz mountains and have some very nasty roads so I need lots of ground clearance. I just can't use an under the rear torque arm like that and not leave parts all over the road. I even had to make my own headers to get more clearance for the exhaust (and clear the rack).

I've done some similiar things to my car including fabricating my own coil overs, making my own control arms, using stock car products custom spindles, a splined tubular sway bar, etc.



Thanks again