tmoney223

iTrader: (2)

So I got a MWC 9" with 4.30 gears..broke it in and changed the fluids..drove it for about 300miles and now I get a bad vibration at all differnt speeds..most of the time it's past 55mph and it's not a little one either..seen that the jam nuts were loose on the tourqe arm so I made sure the pinion angle was set correctly again..still have the vibration..the U-joint nuts where loose so I tighten those up and still same thing...it does have a stage 4 t-56 but that's brand new...any ideas in what could be going on?..starting to irritate me and in trying to mess with the pinion angle and nothing seems to work..

MidwestChassis

iTrader: (5)

You are sure that your pinion angle is correct? If so you also might want to check that your driveshaft is balanced properly and if it is check your tires also.

tmoney223

iTrader: (2)

I'll double check the pinion angle..would that actually cause the coming and going of the vibration at lower speeds?..if it's correct then I'll take the driveshaft to a shop to have them check the balance of it...thanks and I'll give an update after I do all that.

tmoney223

iTrader: (2)

Also just out of curiosity what weight of gear oil should I be using?

tmoney223

iTrader: (2)

So I checked pinion angle again and it's good put lock right on the U-joint bolts..and got it up to 60-70MpH in 4th gear and wasn't that bad put it in 5-6 and it's pretty bad..wheels are balanced as well..also I can feel in the trans tunnel from inside the car that it might be coming rearend of the trans..

Bob@BruteSpeed

iTrader: (16)

What driveshaft are you using? If it is the stock driveshaft with a conversion u joint, I have run into several cases where this combination has caused vibrations such as you're experiencing, because the driveshaft is one inch too short. Bob

Bob@BruteSpeed

iTrader: (16)

80/90w. Bob

tmoney223

iTrader: (2)

I've got the chrommoly 3" driveshaft..and thanks on the weight.

Bob@BruteSpeed

iTrader: (16)

One inch longer than stock on the driveshaft length? Bob

tmoney223

iTrader: (2)

Correct. I got it with the rearend.

Blackhawk8

I have the same problem. I installed a new S60 and MWC tonnel mount adjustable torque arm and new PST driveshaft and have had a vibration ever since. I've had the pinion angle from one extreme to another and the vibration stays the same, it starts at 90mph until about 100mph goes away and comes back at about 120mph.

tmoney223

iTrader: (2)

Yeah mine is all over the place still..adjusted it extremely one way and then the other..it seems it's better I between but will not go away..putting it on the dyno tomorrow to try and see where it's come in from..the next step will be to get the driveshaft balanced checked, if that doesn't work then the trans then the rearend..

tmoney223

iTrader: (2)

So come to find out my pilot bearing was ceased..hopefully the input shaft is ok and that's what the problem is..

frez777

Pilot bearing was what? ceased? that's crazy, hope you got it fixed

LiT1_up

iTrader: (16)

Tremec has a great app that turns your smart phone into an angle finder. Get the app and follow the instructions, it help solve the issue I had with my 9". Get it for free at the google play store.

tmoney223

iTrader: (2)

The input shaft was still in spec. But 5/6 gear came off by hand but still good. Will need a new viper main shaft down the road...I used the angle finder on my phone and i like it...so I'm thinking from the input shaft moving around is what's causing the vibration..going to reinstall it with new pilot bearing and Aline the drive shaft again and hopefully it'll be gone.