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503 has a semi-new vibration

turbowop

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Joined
Apr 29, 2001
Messages
11,971
Location
Yakima, WA
Help me brainstorm to figure this out...

Tires and brakes are new, yet this was an issue with the previous set as well. Engine has no balance shafts and the timing belt is perfectly in time.

At any speed while coasting, car has zero vibration. At any engine RPM in first/second gear, car has no vibration. At higher speeds (freeway, 55-75mph or so) and under acceleration, the car suffers from some type of vibration that can be felt throughout the whole car. As soon as I let off the throttle, vibration goes away. Axle boots are all good and I've gotten underneath the car to grab the driveshaft joints and shake them. No visual problems have been found.

Is it logical to think that a front or rear motor mount may be getting soft and allowing too much flex under load at speed, causing this issue due to higher driveshaft angle? They are the stock mounts. Anybody else ever experienced this problem?
 

ktmrider

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Joined
Sep 10, 2007
Messages
3,128
Location
Tempe, AZ
Good assumption it's in the DS. I've had to remove the DS to diagnose bad u-joints too.

Also look into the carrier bearing bushings ( CB to body ). They wear out fairly easily and allow the CB to squirm quite a bit. May not hurt to try the sillycone boot fill either.

Last have the balance checked if all else looks good.
 

Brianawd

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Joined
Apr 18, 2005
Messages
2,117
Location
Portland OR,
Ujoints. 439 did the same thing tell I replaced the ujoints.
 

U-joints or quite possibly a pinion bearing. Check the diff fluid for metal.
 

turbowop

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Apr 29, 2001
Messages
11,971
Location
Yakima, WA
I can grab it and shake it and it doesn't move. I guess I'll pick up the recall yoke to replace the front u-joint and see if that fixes it. Thanks, guys.
 

IncorpoRatedX

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May 28, 2003
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5,593
Location
Arizona
problem is similar to what I had going on, it was the U-joints, i was in the same boat as you though...

I chased this problem all over hell, t-case, clutch, rear diff, axles, everywhere, all because the driveshaft seemed tight.

I'll see if i can find a pic of how fucked two of my u-joints actually were, they were tight, but marred up and shifted bad.
 

IncorpoRatedX

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turbowop

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11,971
Location
Yakima, WA
Well I'm glad you guys had the same issue and found the problem. Keeps me from having to chase the issue. I figured it was driveshaft related due to the frequency of the vibration, but you guys pretty much confirm it. /ubbthreads/images/graemlins/smile.gif
 

IncorpoRatedX

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Arizona
I want more than a thank you for the amount of work I did chasing this vibration down. /ubbthreads/images/graemlins/banghead.gif
 

galant344

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Joined
Sep 23, 2006
Messages
357
Location
oakforest il.
ive learned over the years that if it feels like a drive shaft issue and the drive shaft feels ok all hooked up you better just remove it to ensure that the joints are moving freely and not stiff.
 

turbowop

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Apr 29, 2001
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11,971
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Yakima, WA
Yeah, I'll pull it off next weekend and get a feel for all the joints. I just ordered a couple of recall yokes from JNZ and will replace the ones that feel rough.
 

Brianawd

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Apr 18, 2005
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2,117
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Portland OR,
Just rebuild the whole drive shaft and be done with it.
 

turbowop

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Apr 29, 2001
Messages
11,971
Location
Yakima, WA
I'm bringing this back up...

I ended up replacing all three u-joints and the problem is still there. I replaced the saggy front motor mount as well. Then I took brianawd's known good driveshaft off his car that he's parting out and swapped it tonight. Still f***ing vibrates at freeway speeds under load. I checked the front half shaft bearing while i was under the car and it's good and tight.

Could the rear pinion bearing cause this? The flange feels normal back there. /ubbthreads/images/graemlins/dunno.gif I'm getting sick of the paint shaker feeling the car gives when I go to pass somebody on the highway. /ubbthreads/images/graemlins/frown.gif
 

Brunoboy

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Apr 25, 2008
Messages
2,880
Location
San Bruno,CA Home of SFO
this problem just started with 352 a few days ago. I found out one rim was bent in the front and hadnt checked the other. The vibration went partially away after i got rid of that rim in front. I am thinking my other Rim is bent too. Check your rims again and balance.
 

transparentdsm

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Jul 27, 2011
Messages
3,690
Location
Cherry Hill, NJ
^ good call shane. i had the same problem, bought the car two weeks later it got a vibration and i rebuilt the DS to find out it was tires out of balance. dont get me wrong, rebuilding the DS was a great idea. took some vibration away.
 
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