I just installed a T2 rear end and halfshafts with a new aftermarket driveshaft and a MMR solid plastic rear mounts and mazda competion front mount.

Since doing this I get allot of vibration that builds with speed. It feels pretty bad above 100. Wheels are balanaced with new tires. The vibration feels/ sounds like stiff u joints, but the U joints arent stiff.

Is this caused by the MMR mounts?

Can someone else with MMR rear mounts confirm that they had or did not have this vibration?

At this point I am thinking that maybe the driveshaft is out of balance.
Less likley that the pinion angle is off. The Car is a 13bre car and the engine mounts put the motor lower than stock levering the end of the trans up in relation to the ground. The car was also originaly an auto but I welded trans mounts into it. The pinion ange looks ok but the trans sits really high in the tunnel. As I said I think thats mostly because the engine sits lower.

Thanks...

 

How tight were the diff mounts? If they weren't a bitch to get in then they're probably too loose. I've read that other MMR bushings (DTSS) are really loose. This could be the problem.

They are also solid for all intents and purposes, meaning that they'll transmit much more noise and vibration into the car. That could also be your problem.

 

They are tight enough, I don't think it could be vibration from the mounts, it rythmicly increases with speed regardless of load, except that its worst while decelerating.

I think its probably the drive shaft, which sucks because its new.

 

could it just be that your diff is grounded to the chassis better now by the hard mounts and is transfering engine vibration more into the chassis?

 

I think maybe my trans is making contact with the suport in the trans tunnel. I don't think the diff would transmit vibes like this to the car.

 

it could be that your tranny and engine mounts are shot. and now that you have these new parts with a much stiffer attitude they are coming up as vibrations through the chassis.

instead of your tranny/engine mounts it could also be your front differential mount. it could be super shot, and like above, with the semi-solids in it is putting excessive force on the mount causing it to vibrate.


i would higly reccomend completeing the MMR set up with the tranny& subframe mounts. if you hav ethe money get the AWR engine mounts [and even though i LOVE AWR and their products, you can find thier same mount cheaper here http://www.rotorsportsracing.com/per...tor_mounts.htm ] if you cant afford those get the ones from MMR.




it is really hard on older, more mushy bushings, if you replace only one with a solid or semi-solid bushing.

and if it isnt those parts that i listed, who cares because you should have replaced them anyways

 

I have mazda competion engine trans and front diff mounts, I did replace those parts. I don't normally like plastic mounts but for the rear diff mounts I didn't think there would be any negatives.

 

replace your tranny mounts to a comp as well. harder bushings up front and weakl in the middle, i have heard, can be very fatal

 

As I just said I replaced all mounts but the rear diff with mazda comp. I think the trans was making contact with the tunnel support. I made a spacer out of some aluminum to drop the trans down. I will let you know if the problem is solved.

 

The spacers fixed it, dropped the tranny 1/2 an inch I think I put it about where it would be stock. Weird that this didn't happen untill I revamed the rear end, maybee I changed the pinion angle some with the new bushings and the resulting change allowed the top of the tranny to make contact with the tunnel. That is the only thing I can think of I knew that it was really close before. Like a few MM, but I didn't think it would touch.