Aviator857

I know this has been covered somewhere on this site but I can't find it via the search.

What are the benifits between a torque arm mounted to the cross member istead of the transmission. The transmission one would think would extend to force to the engine and then to the K-member. The cross member/body mount would put the torque on the middle of the car that doesn't have alot of structure there. But the cross member is bolted to the transmission so does it just add extra spread of the force? Is it just mounting angle or does the change also add a benfit that I am missing in the way of body torque.

crytical point

I have been wondering the same thing if one is better than the other. My auto X car is still using the original arm and I have been wanting to make a stronger one since I can't buy one.

I H8 WWD

iTrader: (5)

As far as I know the trans mounted arm puts stress on the tail of the trans, possibly ruining it further down the road. Whereas the x-member mount I guess "spreads" the force over a x-member instead of the actual transmission. Its an upgrade for sure.

AlkyIROC

I don't think the factory system is all that abusive to the tranny. The factory torque arm fits into a rubber mount that's bolted to the side of the tranny. During hard acceleration and braking, there will be extra forces pushing up and down on the tranny case. These forces then need to be transferred through the tranny mount to the crossmember and body. That's a lot of rubber or polyurethane to move energy through.

Using an aftermarket torque arm has a few advantages. First of all, it's stronger than a factory arm so it won't flex and it's adjustable. Moving the front mount directly to the crossmember means the lifting force is direct. Anytime you can eliminate unneeded movement, it's easier to transfer power to where it's needed.

Uncontrolled movement from rubber mounts is wasted energy. Polyurethane bushings are better than the factory rubber but are still not the best. Using a shackle or rod end style front mount on the torque arm is considered a solid mount. It's designed to still allow forward and backward movement as the diff rotates through it's arc but the up and down movement of the front mount is solid. This means all the upward forces from a hard launch are directly applied to lifting the body and not compressing a rubber mounts.

The adjustability of an aftermarket torque arm also allows you to fine tune the suspension by changing the pinion angle. A real high end torque arm may even allow you to raise or lower the IC by changing the height of the front mount like ladder bars do.

You'll lose a bit of length by having the arm attached to the crossmember instead of the tranny but the advantages make up for it. Length is where the instant center is located. Ladder bars put the IC around 3' in front of the axle. LCA such as the Traction Action which eliminate the torque arm by using short brackets to the diff put the IC less than 2' in front of the diff. A torque arm puts the IC about 5' in front of the diff.

My car uses a 4-link so I have many different positions as to where to put the IC. For a high HP car, long and low works best. My IC is roughly 5' out so that puts it roughly where a torque arm mount would be however my IC height is only a couple of inches off the ground and I can even adjust it to be below the ground. Something that a torque arm or ladder bars can't do.

Simply moving the torque arm off the tranny and onto the crossmember should drop the IC down to a better height. It may not be much but even 1" in height can be a big change in how the suspension reacts.

Aviator857

Is there any advantage in road driving beyond launches. I know it helps on adjusting angles when you lower the car so it gets the geometry into shape.

I would think under hard cornering it would transfer a twisting action up the torque arm and if it is mounted to the tranny would be transfered up to the bell housing and to the engine to the K-member area, but mounted to the cross member would transfer the twist or torque at the cross member and the transfer would be to the floor pan and sub frame at its weakest location.

Maybe the torque arm isn't as tightly mounted as I am thinking and just acts to prevent rotation of the axel.

This is good info, I need to learn more of the rear suspension of the car, I am pretty well versed in the front.

UMI Sales

Hello
I noticed that you are inquiring about a tunnel or a transmission mounted! If you are going to be using the vehicle for street use and a weekend cruiser and is close to 450 hp. I would suggest going with a 2205 with a torque arm relocation. And if you are going to be racing it and you are not worried about road noise and vibrations and want faster weight transfer. I would recommend going with a tunnel mounted torque arm. Below is a link to show you what all UMI Performance has to offer.

http://www.umiperformance.com/produc...ategory_id=114

http://www.umiperformance.com/produc...ategory_id=171

If you have any other questions feel free to ask and I will be more than glad to help!
Thanks
Brad

I H8 WWD

iTrader: (5)

UMI, thought about going to a rod end on the x-member mount side of the torque arm? I didn't see this offered.

palric

iTrader: (1)

would you expect any sotp experience from putting a tq arm brace into a street/strip sometimes take it to the track weekend cruiser?

thx

squeeezer

i just ordered the 2216
what are people doing with the ic adjustable mounts for the track????
top or bottom???

Jay

iTrader: (2)

Those are NOT tunnel mount torque arms. Those are cross member mount torque arms. Tunnel mounts have a plate that bolts to the underside of the transmission tunnel.. which is where the name comes from. The torque arm is then attached to that. The Jegster torque arm is an example of this.

scamaro355

heres a few options from bmr fabrications, i've had good luck with all the stuff i've gotten from them. http://www.bmrfabrication.com/F3-sus....htm#torquearm

UMI Sales

The 2205 and a relocation cross member would be a good choice. Unless it is a really modified car some times tunnel mounted arms can be over kill for the street.


If you are asking about the holes for the relocation cross member we recommend going with the next to the bottom!

The link the I have shown for a example is a full length with a relocation cross member. UMI Performance also offers a tunnel mounted arm as well depending on the transmission. Below is a link for that!
http://umiperformance.com/products.php?category_id=114
If you have any other questions feel free to ask and I will be more than glad to help!
Thanks
Brad

BMR Sales

Here are a couple of pics of what happens to the tailshaft if you leave the torque arm attached to it. It can happen to a stock hp car or a high hp car.

SCAMARO 355, thanks for the recommendations.

scamaro355

No prob on the recomendation...i dont mind putting my name out there on a quality product..the torque arm setup is the last thing i need to put on the rear suspension to have everything BMR