what are the advantages and disadvantages between these two setups.

short tq arm:
http://www.umiperformance.com/2202?category_id=130

vs.

long tq arm:
http://www.umiperformance.com/2209?category_id=131
http://www.umiperformance.com/2205?category_id=130

thanks
ryan

 

A short torque arm is going to be stronger cause the torque acting on it would not be as strong. Means the shorter torque arm will keep the axle planted down better. The difference between those two products, though, looks like one is meant for long tubes and an aftermarket exhuast.

 

one is a full length with a new tranny crossmember that takes the tq arm off the tranny. i had the badass spohn tq arm with the driveshaft loop and the whole nine yards, but i had horrible ground clearance and i could never get rid of the vibration. i put my stock one back on and the vibration is gone and my rearend doesnt whine near as bad. so it sounds like it was putting stress on the rearend. i was just wondering how effective the full length aftermarket ones are.

 

The torque the torque arm has to counteract is defined by the torque applied at the rear wheels. The TA controls the torque through a combination of length and force applied to lift the body. Since torque = force X distance, a shorter TA has to apply a larger force, which lifts the body. A longer torque arm will apply less lift, but further forward on the body.

 

I guess that's what I was thinking, you worded it better

 

so which one equals more traction

 

I've only seen 4th Gens running the "shorter" TA bolted to the stock trans tunnel brace location, and pulling 1.2x-1.3x 60-fts. I have never seen a 4th Gen running a stock length arm bolted to the trans cross-member, so I have no idea if it offers any advantages.

 

Could the reason for the vibration and noise be an incorrectly adjusted pinion angle? Or at least one that is much different than the stock one gives?

I'm getting ready to swap that same torque arm into my car, even though my stock one seems to plant the tires pretty well.

 

i adjusted the pinion angle every way i could. i called spohn and did just as they said and it never changed. i think the vibration is my driveshaft so i will be running an ls1 driveshaft. but i do know that my gears now are almost totally silent with the stock torque arm. i guess i might try the shortened one again, i just hate the loss of ground clearance and i hope that it wasnt my cause of a vibration. i will call umi and ask them their opinion before i get one.

ryan

 

If you don't mind me asking, where did you lose the most ground clearance? Under the arm itself, or under the front mount for the arm?

My car is at stock height, so I hope to be OK, but I am curious about where yours lacked clearance.

Thanks.

 

Also, with a short torque arm sometimes you will experience wheel hop under very hard braking.

 

i lost ground clearance under the cross brace. i had the one that dropped down lower to clearance the bigger exhaust. i have 1le springs and i still got stuck on speed bumps.

 

The "dropped" support can be a problem with ground clearance on lowered cars. That was the only time I had any issues with the Spohn TA. I've never had a problem with driveline vibrations.

Is it possible you are feeling the increased transmission of normal drivetrain noise and vibrations that is common to the rod-end floor mounted arms, and eliminating that transmitted noise by using the rubber bushing stock arm with no connection to the body at all?

 

i did not have the rod end. i went with the poly bushing. mine was chromoly with a drive shaft loop but i kept the bushing since it was a daily driver.

 

here is what umi said:

The shorter torque arms do offer better weight transfer then the longer full length torque arms. However on a vehicle making 330 HP I don't think you will notice much of a difference. Our tunnel mounted torque arm will be much less quite and more streetable then the Spohn unit you had, we have had great luck with them and very minimal complaints on noise issues. However seeing you had trouble in the past with the tunnel mounted set-up I would recommend a full length arm, this one here would be perfect- www.umiperformance.com/2205 I would pass on the relocation kit at this time and look at purchasing it once you are putting down some more power.