Vibration Like No Other

[=premo=]

Hi people, just finished an engine upgrade and finally got my car on the road. Everything's great until 100km/h. Thought it was wheels so I changed them for new and balanced but it didn't make a difference. I've always had alloy pineapples (solid mounted sub frame) and the 2-way diff didn't have any problems before the engine upgrade, although I had it out and a friend borrowed it. I've got a second hand R33 5-speed box and a new custom one piece tail shaft. The vibration doesn't come through the steering wheel or gear stick but you can feel it in the back of the seat like a monster sub-woofer.

I'm not sure where to or how to start identifying the problem...?

Any suggestions?

Thanks,

Daniel

[djr81]

Hi people, just finished an engine upgrade and finally got my car on the road. Everything's great until 100km/h. Thought it was wheels so I changed them for new and balanced but it didn't make a difference. I've always had alloy pineapples (solid mounted sub frame) and the 2-way diff didn't have any problems before the engine upgrade, although I had it out and a friend borrowed it. I've got a second hand R33 5-speed box and a new custom one piece tail shaft. The vibration doesn't come through the steering wheel or gear stick but you can feel it in the back of the seat like a monster sub-woofer.

I'm not sure where to or how to start identifying the problem...?

Any suggestions?

Thanks,

Daniel

new custom one piece tail shaft is where to start looking.

Edited August 7, 2009 by djr81

[Birds]

I'd start tracing it back through the drivetrain. At 100km/h (or over), does it still make the same noise if you engage the clutch / put the gearbox in neutral? If yes, then you can basically rule out gearbox and start looking at the tailshaft/diff. Try putting the thing up on a hoist and drive the thing past 100km/h. If the sound is gone it's in the wheels / bearings, if it's still there then it's no doubt diff or tailshaft related. Your friend might have lunched your diff for you...

[=premo=]

The tail shaft has been balanced but its always possible someone made a mistake while doing it. Wish I had a hoist haha. Will check neutral but clutch depressed doesn't make a difference. Will try to take a look at it next weekend if I get a chance.

[=premo=]

Had a look at everything today, there was no excessive play anywhere and no abnormal noise. From tail shaft there is only 1mm of twist movement before the wheels move, so I took the tail shaft in for a balance and they found one of the uni joints isn't snug in its housing so its being replaced, will find out tomorrow if it was unbalanced.