remltr

iTrader: (4)

Someone had to do it. Anyone use a Skulte T-56 crossmember and fab a shackle type TA mount to it? Any pics? How beefy does the shackle mount have to be in a 500HP+car. I already have a UMI adj.TA with the shackle mount. I told them what I wanted to do and they said I needed a TH400 length TA. Sent me the TA and the shackle mount. Should I just go with a new adj TA and mount to the trans? Don't wanna break my new T-56 Transzilla...WHEN(if ever!) I get the car to hook....

soarestransam

Bmr sells a t56 crossmember that u can relocate the torque arm to the cross member instead of the tailshaft pretty decent price as well

87350IROC

iTrader: (2)

Well lets assume a 400 ft-lb engine and perfect traction. With a T-56 first gear of 2.66 that is 1064 ft-lb on the driveshaft. With a rear gear ratio of 4.10, that is 4362 ft-lb of torque on the wheels. Now force is torque/distance. The torque arm is what, about 3ft long??. So at the shackle the force is around 1500lbs. So yeah, you will want to make sure it is designed for the job.

InfernalVortex

iTrader: (4)

Youre better off getting a torque arm that has its own standalone crossmember. The T56 mount is so far behind the bolts that attach the crossmember to the frame rails that the frame rails themselves are already under a lot of stress. Add a torque arm to it and it's gonna peel the frame rails off the bottom of the car like a can opener.

87350IROC

iTrader: (2)

The torque arm puts a load at least 10x as high on the cross member than the weight of the trans. There are plenty of people running aftermarket torque arms with success with all different kinds of transmissions. I really doubt the trans mount being another 2" further back is going to make much of a difference.

InfernalVortex

iTrader: (4)

It depends, but regardless, the torque arm is mounted farther back from the mounting holes on a t56 or 4th gen 4l60e transmission because the crossmember itself is farther back. With a standard third gen trans, I wouldn't be as worried about it because the torque arm shackle doesnt have much of a lever to torque against the frame rail since it pretty much lines up with the factory crossmember mounting holes.

I probably wouldn't do it anyway, just because the risk, however small, is unacceptable when it results in your frame rails getting destroyed. I personally am unable to repair broken frame rails. Perhaps if I had the ability and tools to do it I wouldn't be so worried about it.

I know you saw the pictures I posted up in the other thread showing the frame rails terribly damaged, but I've seen similar things happen on a local car here with a powerglide trans and a crossmember mounted torque arm. It hasn't broken or seriously damaged the frame rails yet, but you can see where all the torque and stress going through the crossmember is serously distorting the frame rails where the crosmsmember mounts. And this is a car that doesn't get driven much.

Am I saying it will cause a problem? No. Am I saying it's likely to cause a problem? No. I'm saying it would behoove anyone considering a crossmember mounted torque arm to consider an alternative... ESPECIALLY if they're using a crossmember that relocates the TA shackle and the trans mount far away from the factory crossmember mount centerline.

And you've seen this picture, but Id like to make sure everyone else sees it too.



https://www.thirdgen.org/forums/fabr...hn-torque.html

I just want people to be aware. Best case scenario it will force the aftermarket to come up with a better solution.

87350IROC

iTrader: (2)

The torque arm shackle is in exactly the same location for any transmission. At least for Spohn. When I switched from my 700R4 to T56 I reused my Spohn torque arm. Only the crossmember had to be switched. The only difference is where the trans mount is. Probably about 2" further back.

That picture is indeed interesting. However without more information on that car it is hard to draw a conclusion. Kinda looks like a stock crossmember to me???

InfernalVortex

iTrader: (4)

It would probably depend on certain specifics about how they're attached, but generally the force going through the torque arm mount has to travel through the main crossbeam of the crossmember, and then since that is 4 inches aft of the crossmember mounting bolts, it has potential to create problems.

Read the post I linked to about it. 83 crossfire TA mentions a few details about the car. 14 second TPI car with wheel hop issues that he thought could be deep into the 13's but the guy wasnt really a hardcore drag racer. Trying to diagnose some weird issues he was having, he finally found that damage hiding under the crossmember so he did some repairwork to fix it.

And I dont think it's inevitable that this will happen, I just think to ignore the possibility is being naive because it has happened to more than one car. I also think with transmissions that have the mount farther aft of the crossmember mounting bolts, that problems like this would be more likely and/or common.

soarestransam

Jegs sells a torque arm that will mount to the mid section of the trans tunnel like in the middle so u could weld it to the floor pan it self instead of at frame rails Check jegs.com i believe they still sell

87350IROC

iTrader: (2)

Sure the load passes through the crossbeam. But thats not what failed in your picture. As you pointed out it is the frame rail that failed. No body is arguing about the strength of the crossbeam.

Consider this. Car 1 with 700r4 and aftermarket torque arm. Now car 2 with T-56 and aftermarket torque arm. Now the part inducing the load (the front of the torque arm) hasn't changed location from car 1 to car 2. And the bolt holes in the frame rails hasn't changed location from car 1 to car 2. The loads are about the same for both cars. The issues here is any aftermarket torque arm causing damage. Not just on a T56 equip car.


Right so it failed on a slow car that isn't driven hard on street tires. That tells me there was a random fault with the car not overloading the frame rails by launching on slicks with 400 ft lbs. Can you confirm that car is running an OEM cross member? If so, it would be pretty hard to fault an aftermarket torque arm.

UnstableAviator

I have a home brew crossmember for my Spohn TQ Arm too, and because of the posts showng the broken frame I too worry about the durability of my setup. I've done quite a bit of racing with my old Spohn setup with no discernable damage, but that doesn't mean my next trip to the track won't result in damage.

However....this site has literally hundreds of people who have drag raced 3rd Gens with a crossmember mounted TQ arm, and cases of frame damage seem to be quite rare. So I honestly just don't know how much force is applied, and if its a hard braking event thats worse than an acceleration event.