Acceleration Vibration
 

I have a 92 325i , the normal up grades (intake , exhast , chip) plus I'm using a 90HP Nitrous System (wet) . On take off while using the NOS I have a vibration or beating in the rear of the car . A freind said that it sounded like a diff. mount going bad . It only does this while I'm using the nitrous during hard take offs through 3rd gear . Any ideas on what is going bad ?

driveshaft outa balance
rear diff going bad
flex disc going bad
If its related to bumps also rear shock mounts.

If the drive shaft was out of balance , wouldn't it do it all the time and be happening a a certain RPM ? read diff. going bad , that's what I'm affraid of . what's a flex disc ?

flex disc = guibo which has another name also. The big rubber donut that connects the tranny to the driveshaft. You normally feel that when shifting when it goes bad.

True driveshaft would be constant.

See if your diff leaked the fluid out. One of my gaskets just went out so I'm having to repair my diff.

how will I be able to tell if this is what is bad ?

If you speaking of the flex disc (guibo) jack the car up and look at the rear of the transmission. Big black rubber donut that connects to the driveshaft. If its cracked or worn looking it needs to be replaced. $40 from the dealer I believe.

Thanks , I'll check it