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Arrgghhh the dreaded driveshaft vibration

I had the DSS driveshaft installed a couple weeks ago and life was good. I just had a Whiteline Watts link installed today and I've picked up the dreaded driveshaft vibration. I'm going to road test with the lead tech tomorrow morning so I can show him what's going on, but would appreciate any insight on potential causes in advance. I have an adjustable UCA and PA was reset to factory specs when the DS was installed. I'm not sure the Watts Link would have changed PA, but maybe it did? You do have to recenter the axle with the adjustable arms but it shouldn't have changed the ride height. I had them install in the lower of the two sets of holes for roll center.
 
The PA should be set to what the ds/flange angle actualy is, which may be slightly out of stock spec, especially since youve had the motor out, etc. Just a suggestion.
 
So there was no vibration before the Watts link install? What speed does it show up? On a private road of course. ;)
 

ArizonaBOSS

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The stiffer bushings in the WL Watts are probably not quelling any vibe that was already there.

I am thinking NewBossowner is right with the pinion angle under load potentially being changed.

If you can't sort it out with pinion angle adjustment, try "clocking" the DS 180* to the current bolt pattern on the pinion flange (or transmission flange, but not both--because then you're right back where you started).
 
ArizonaGT said:
The stiffer bushings in the WL Watts are probably not quelling any vibe that was already there.

I am thinking NewBossowner is right with the pinion angle under load potentially being changed.

If you can't sort it out with pinion angle adjustment, try "clocking" the DS 180* to the current bolt pattern on the pinion flange (or transmission flange, but not both--because then you're right back where you started).
I've been tied up in meetings all day so little drive time. I'm not sure it's DS as it could be just additional NVH through the bushings. Unlike my Griggs, this isn't heim joints but a composite material that's supposed to be less harsh and I'm going from a poly bushing adj panhard bar. The vibration shows up at high RPM more than high speed but I'll try to get over to Mexico quick before dark. Yep we'll obviously recheck PA tomorrow and I've heard of the 180* clocking trick so will try that too if it's not PA. Need to try to dial in the cause more.....
 
OK....made it to Mexico before dark.....in a business suit and tie....heel/toe shifting in wingtips is a unique skill ::)........

It's not as big of an issue as I thought initially. I only got a couple of miles to drive it earlier, and I've just been paranoid of getting that DS vibration back like I had in the GT500. The bulk of the noise is coming from the damn shifter. If I grab it it's almost gone. There's a plastic ring at the top of the MGW shift boot with enough play in it that driveline vibration really makes it buzz. There's more "vibration" at high RPM versus high speed. At track speeds (in Mexico) there wasn't substantial vibration through the car like I had in my GT500....i.e. the entire car is not shaking. It was actually really well planted at speed and if it was the driveshaft I think it would be worse at higher speed versus just higher rpms of the engine. There is noticably more vibration/buzzing under load at higher RPMs in the console/shifter/ebrake area. It's not in the wheel and it's not shaking the chassis. Might just be the cumulative effect of all the additional hard points/removal of all of the soft compliant rubber bushings in the rear end and motor mounts. Honestly if I can just figure out how to quiet this shifter boot down I think it'll be fine. I'm going to let them road test it in the morning and my buddy that runs the dealership has a very similar setup so will have him drive it too just to make sure they don't think there's excessive driveline vibration.

Oh and the rear end does feel better under acceleration with the Watts link, but I won't really know how well until I can get it on the track.

(Did I mention there are pheasants in Mexico and they like to come out near dusk? Not something you want hitting the windshield at track speed so good thing I saw him coming out of the ditch :eek:)



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It's really no worse than my GT500 the more I think about it. I'm guessing I finally just "crossed the line" with suspension/driveline mods :) Oh well it will be warm enough to roll down the windows soon and I won't even hear it then. I think I'm just being paranoid about the DS. The noise doesn't bother me as long as it's not wreaking havoc and causing damge.
 
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So your saying that since the MGW unit is stiffer, your picking up a drive-line vibration which is causing the boot to rattle? Isnt the boot a full rubber peace?

Btw, any ideas how I can mate the MGW shifter to a 13" Shelby exterior alcantara shift boot? I havnt experimented yet but the shelby boot seems to be a lot slimmer at the top when compared to the boss boot, and I dont think the plastic retainer from the boss boot will fit.
 
sadil said:
So your saying that since the MGW unit is stiffer, your picking up a drive-line vibration which is causing the boot to rattle? Isnt the boot a full rubber peace?

Btw, any ideas how I can mate the MGW shifter to a 13" Shelby exterior alcantara shift boot? I havnt experimented yet but the shelby boot seems to be a lot slimmer at the top when compared to the boss boot, and I dont think the plastic retainer from the boss boot will fit.
No the shifter isn't causing anything, just transmitting whatever's coming through the rear end. There's a collar at the top of the shift boot that buzzes noisily as a consequence. I took the tech out for a test drive this morning and he feels it in the seat even, but doesn't think it's driveshaft related. The Watts link is correctly installed per Whiteline so they're going through other things including the exhaust connections to see if they can isolate it.
 
pufferfish said:
An engine rpm dependent vibration is before the driveshaft.
Good call. It was the "dreaded" LT hitting the frame rail, not the driveshaft ;D I should have thought of that sooner since I read so many posts about that issue. With the 1-7/8s LTs there's not much clearance, not to mention the heavy coating on there.
 

steveespo

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cloud9 said:
Good call. It was the "dreaded" LT hitting the frame rail, not the driveshaft ;D I should have thought of that sooner since I read so many posts about that issue. With the 1-7/8s LTs there's not much clearance, not to mention the heavy coating on there.
Told ya to get American Racing. I'll shut up now. glad you found it.
Steve
 
Gary,

I had the same rattle from the shift boot after I installed my Hurst shifter. Solved it with some rubber washers from Lowes...placed between the plastic ring in the shift boot and the shift lever. Once you tighten the shift ball down the shift boot will be snug...no more vibration/buzz.

r/
Eric
 
Eric said:
Gary,

I had the same rattle from the shift boot after I installed my Hurst shifter. Solved it with some rubber washers from Lowes...placed between the plastic ring in the shift boot and the shift lever. Once you tighten the shift ball down the shift boot will be snug...no more vibration/buzz.

r/
Eric
Good idea, I'll give that a shot.
 

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