Heatmaker

I cant figure this out at all...


My car has bad vibration in all gears after 3K rpms.... I have no idea what to pin point. I have an aluminum drive shaft, 6 month old 4:10's, and SPohn TA, and the LCA brackets... the pinion angle is set at -2 degrees and it has seemed to increase vibrations. But it's killing me trying to figure out if it's the gears or what... The worse part is it's killing my HP. It feels like I'm going no were once I get above 3K rpms... anybody know what I might want to do?

Hawk

you check that all your wheels are balanced??

383ysi

it could be the flywheel
slowly rev the motor in nuetral if theres no vib its in the drivetrain

Heatmaker

all thats been done ... I will say that my shifter vibrates over 70mph

BLinindoll

it has to be before the output of the transmission due to the fact that it doesnt do it at a certain speed, but at a certain rpm. it might be something in the tranny, but just because it doesnt do it in neutral, you cant rule out the flywheel or something before it. it might only happen when under load. could be the crank dampener, flywheel, torque converter, or anything else in the tranny. mine also has a very slight vibration after 2 grand, but its not that bad so im not worried about it, considering im selling it anyway.

Heatmaker

It's an issue in the reared.

It started out vibrating a little... then over time it just got worse... When I adjusted the angle of the pinion to -2 it seemed to become more agressive.

Al I can do is play around with the anlge... but I doubt the vibration will go away.

wicked_95z

Sounds like you have the same problem I do. My car vibrates at 3k and above and also at 65mph and above. My guess would be a balancer causing the engine vibration and the DS causing the driving one. At least thats what causing mine

Demus

Take off the drive shaft and verify it doesn't vibrate over 3k rpm while in gear.

Did you get the driveshaft balanced after you bought it?

Heatmaker

Thanks guys... I appreciate all of your help.


I'm going to get the aluminum driveshaft checked...

right now I'm going to adjust my pinion angle to 0 degrees and see what happens.

Heatmaker

alright I just got done throughly inspecting the car... you knwo the test you can only do late night when the roads are empty.

So far I ruled out that it's not the rear... or the driveshaft. I did have some poping and extra vibes from the shaft... but I adjsuted it to -1 and now it's no longer doing those things... so that is now ruled out.


I ruled out the gears after crusing around in 6th gear under 2K rpms... if it were the gears they would act up severly at that speed...my car didn't start vibrating at all I even reached 70 in 6th with it... and all seemed normal for a car with full racing suspension. I then dropepd the car into 5th and the RPM's kicked up to 2800 still no vibes... I dropped it again onto 4th and went to 3.5K and slowly the vibes started comming.... I pushed the throttle in and held it.., it was a steady vibration that got more annoying the higher the RPM's reached. What I realized is that the Vibrations were transending down into the driveshaft and into the rear... and causing the sensation I was feeling.

I put the car in neutral... and reved it... feeling the vibrations at 5K rpms now. (which was hard to diagnose... since the rumble of the exhaust covered it up)

so it now has to be between the transmission and the engine. My transmission I rule out because I cannot feel any vibrations through the shifter, or hear any tranny related noises, and all gears are smooth under regular acelleration. The vibrating senstations are not comming through the clutch pedal, so the clutch assembly is on track.

I've had the same experience with my old flywheel, and the new flywheel I installed... so the flywheel is not the issue.


So now I'm looking at the balancer... which is a combination of the MArch under drive pulley, and the stock steel flywheel. I rev my car higher now, so maybe the weak links in the car are now showing... although it's taken time for the car to get to this point where the vibrations are calculated and severe.