I have a body mounted UMI torque arm, my rear has Richmond gears which whine horribly loud. The rear is being replaced with a moser 9 within the next 2 weeks. I'm wondering if there is any way to add some form of insulation to the torque arm to help cut down on it transferring harmonics from the axle directly into the body.

I hope that makes sense, I'm basically trying to reverse the torque arm directly transferring gear noise to the body and thus making it extremely loud. I keep seeing on factory exhaust attend at work where there is a mount for a large rubber cylinder. I'm assuming that is there to absorb any harmonics that are created?

Would something like that work? Or any other suggestions?

 

Unluckily body mount TAs are known for being noisy. If you could find some 1/8"(or so) thick strips of polyurethane to put between the TA mount and the car body that should help the most, along put some sound deadening (at least 1 layer) directly above (and around) where the TA mounts on the floor pans inside the car.

 

I'll try that and see what happens. I considered the whole putting some kind of rubber between the mount and body, but wasn't too sure if it would hinder it's performance. The more that I think of it a very thin strip shouldn't hurt too much.

 

I was going to make a thread in the near future on this. When I was a Air Condtion tech newb I saw the boss wrap a certain part of the system with a very sticky rubber. I have to look into this and get name of what was used so I can post pics.

The idea is to wrap the around parts of the TQ and see if it will dampen some of the vibs and find a tool that show the amount of vibration being generated and see if it works.

 

I know what your talking about!! some real old school stuff! it has the consistency of tar right? Come in a roll?

 

Hello
Like mentioned above what you could do is cut 2 little pieces of rubber and place under the cross member itself for a insulator. But seeing how the bushings are poly and a much firmer material over a rubber they will transfer gear noise. Unfortunately we don't offer rubber replacement bushings either. Sorry for any inconvenience, If you have any other questions feel free to ask.
Thanks
Brad

 

Yea buddy! What is it called?

 

No clue...one of the techs I used to work with had the roll BURIED under everything is his box.. haha

 

I will call around and post up what the name of that **** is.

 

Not sure if it's the same stuff (this is tin backed), but Home Depot and Lowes both sell a tar-based tin-backed roll product with an adhesive side (tin out) that a lot of guys use as budget sound dampening material for car audio. Can't remember what it's called off the top of my head, but it should be in the roofing or ducting section of either store. Not too sure how the adhesive would stand up to road conditions, though...

As a side note, part of my job is testing products for resonance points and nodes. I know it's not really feasible to expect anyone to be able to test a torque arm for natural resonance frequencies and do a modal analysis, but it's possible to take a thick, lower-durometer (i.e. soft) chunk of rubber and mount it at different places on the torque arm (using something like a big worm clamp or some zip-ties) to try and absorb some of that resonance. Might take some playing around with location, but it would be another thing to try. Unfortunately, different temperatures and rpms are going to change the modal response, so one spot may only work for a specific rpm range. I wouldn't expect a whole lot of harmonic damping with that setup, either...you may cut a little of the noise off, but don't be disappointed if it doesn't help much.

 

Man, I am having the same issue with the BMR torque arm. It connects to my Th350 BMR transmission crossmember so it connects straight to the frame like yours does. I have the strange 12 bolt out back and after a few hard launches at the track that sucka really whines!!

 

Thanks for the info. I also thought there would be so many factors that could change the outcome. What can I buy that will help me get a baseline of the resonance frequencies on the TA?

 

Honestly, for that, I couldn't tell you. Most of the stuff we do is lab-based vibrational testing for electronics prototypes, and while I could probably work out a way (eventually) to mount a torque arm up to an electrodynamic shaker to get realistic driving resonances, it would be a cast-iron bitch to do. I'm sure there's a way of doing it with modal analysis in a different manner, but I haven't gotten far enough into the field to be able to say for sure.

A shot-in-the-dark suggestion would be to try and put some damping material in the middle of the span of the torque arm, and adjust it back towards the axle in steps and see what location helps the most. You could try some very-high durometer neoprene padding, as thin as possible (probably 1/16" to 3/32") and put that between the torque arm mounting plates and the diff, which would cut some of the higher-frequency transmitted noise out. The key there would be to run the softest, thickest pad possible without affecting performance by introducing a lot of squish at the torque arm/diff mounting point. I'd personally think that would be more effective than a damper mounted on the torque arm length itself, since you'd be limiting transmitted noise at the source rather than trying to dampen out vibrations along the length of the torque arm. You could also try the same type of high-durometer, thin neoprene strips between the crossmember the torque arm mounts to, and the body.

As long as the neoprene is very high-durometer and thin, I don't think it would introduce any notable deflection between the diff and torque arm, as long as everything was tightened down properly, assuming there's enough space between the plates and the diff to squeeze it in. It'd probably be easier to get a big lump of rubber and play with clamping it around the torque arm, though, and that might reduce harmonics enough to make you happy without even needing to play with the diff mounting.

 

Thanks. I will post up results when I get around to it.