4.09 GEARS = VIBRATION AT SPEED

[Earlsays]

The final part of my Magnum install was 4.09 gears...car wouldn't get out of it's own way with 3.55 - it also had a dyno tune with the gear install. Previously, there was NO vibration.


I have a vibration which begins at 50MPH, improves at 60, NO VIBRATION AT ALL at 65MPH, and vibration returns at 70-75 - I have not driven any faster than 75.

This is speed related, NOT related to RPM - if I put the car in Neutral, the vibration remains the same.

Drive shaft has been removed and rotated 180 degrees, no change.

NO NOISE from rear axle, gears don't whine or anything like that. Gears/install kit are all FRPP parts.

Car has Tremec Magnum XL/Mcleod RXT clutch/DSS 3" one piece aluminum drive shaft.

Any ideas? Car is otherwise fantastic.

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[RoadCone]

The final part of my Magnum install was 4.09 gears...car wouldn't get out of it's own way with 3.55 - it also had a dyno tune with the gear install. Previously, there was NO vibration.


I have a vibration which begins at 50MPH, improves at 60, NO VIBRATION AT ALL at 65MPH, and vibration returns at 70-75 - I have not driven any faster than 75.

This is speed related, NOT related to RPM - if I put the car in Neutral, the vibration remains the same.

Drive shaft has been removed and rotated 180 degrees, no change.

NO NOISE from rear axle, gears don't whine or anything like that. Gears/install kit are all FRPP parts.

Car has Tremec Magnum XL/Mcleod RXT clutch/DSS 3" one piece aluminum drive shaft.

Any ideas? Car is otherwise fantastic.

I have a vibration that starts at cruising about 85mp and gets worse about 95mph. The shifter handle on the triax goes crazy vibrating and hummmms.....


Clocked it once and it didn't help. Going to see if it's the driveshaft and have it balanced soon.

I have your same setup.
press in the clutch and its still there.

 

[Earlsays]

Which clutch/flywheel do you have?

 

[EFI]

What exactly is vibrating? The car, the shifter, the seats?

So the car was perfectly fine with 3.55 gears, but after only changing the gears themselves and nothing else now there's a vibration somewhere?

 

[Earlsays]

The entire car is vibrating - seats, steering wheel, rear view mirror on windshield...

The car did not vibrate with this exact setup running 3.55 gears, after changing gears to 4.09 the car vibrates. Dyno tune, but no other hardware changes.

 

[RoadCone]

I have the Exedy Stage 4 with their flywheel.

 

[EFI]

The entire car is vibrating - seats, steering wheel, rear view mirror on windshield...

To be honest that sounds alot more like a wheel/tire balance problem rather than one in the drivetrain, especially if you say this occurs in neutral also when you take the load off the shaft and rear end.

 

[RoadCone]

To be honest that sounds alot more like a wheel/tire balance problem rather than one in the drivetrain, especially if you say this occurs in neutral also when you take the load off the shaft and rear end.

I can tell you it is not the case for mine. I have extra set of drag radials, did it with those. Switch to my complete set drag race wheels from the 6G’s... and still did it. That’s 3 sets of rims and it does it all the same.

 

[RoadCone]

Mine you feel it in the car.... but the shifter is where you really see it and feel it.

 

[whatsup62]

I had no issue at all after 4.09 install.....however...I am running the CF driveshaft which may be masking it.

 

[Earlsays]

gonna get a tire rotation, alignment, balance done and see what happens.

 

[wildcatgoal]

My car vibrates starting at 85 with my Shaftmasters aluminum driveshaft. Started ONLY after I replaced the dust boot over the spline joint on it. I re-aligned everything as it came and installed it exactly where it was. It was never perfectly smooth, but all of a sudden after the repair and re-install, it's causing driveline vibs. So... same boat, brother.

 

[Genxer]

Could you try putting the old DS back in to see if the vibration clears up? A fair number of ppl on M6G have mentioned alum driveshafts having more vibration.

 

[Grimace427]

Can you clock the driveshaft 90 degrees instead of 180? I don't recall if the '15+ has 4 bolts or more at the diff.

 

[CNCLester]

I had 4.09 in my 17 gt auto. Mine vibrated before I modded anything. No matter how much I tried, 1 pc shaft, different diff, diff lockout, cradle lockout, I could never completely eliminate it. Everytime I got the balance better, it would come back. I clocked every possible position. Spent way over 1 k trying to get it. Always came back. Different but still there.
Traded that vibrater car off for an 18 pp manual. Smooth as a towncar. Everywhere. Ain't looking back.
Sorry about your issue. Hope you can resolve it.
Lester

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