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Help diagnosing driveshaft vibration

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  • cdl723
    replied
    Originally posted by grantmiller1 View Post


    The vibration is more pronounced when I accelerate. When i let off the gas, the vibration is noticeably less.

    I'll see about getting a digital angle measurement tool.

    I have new trans mounts on order. My rear subframe mounts (Garagistic 80A) are only 2 years old, I hope I don't have to replace those!
    I believe mine would vibrate bad under decel, but go away when i pressed the clutch or accelerated. Here is a picture of my subframe bushing when they failed. the 2nd pic is in the car and the room on top of the subframe/bushing.

    Also, these were their raised subframe bushings and the diff was properly spaced down
    Attached Files

    Leave a comment:


  • moatilliatta
    replied
    What are you running for engine mounts? Could the CSB be backwards?

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by ADEN View Post
    When gearbox was out?

    Since you vib. on load and goes with clutch in (unload), A combination of stiff mounts and slightly loose/not aligned engine-transmission bolts might be your issue.

    Thanks, I'll check on those. I have new trans mounts on order. I'll double check my engine mount bolts to make sure they're secure. I re-torqued my trans mount bolts recently with no change.

    Will be checking alignment to the best of my ability.

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by cdl723 View Post
    I had something similar happen with my DS, but it would vibrate when decelerating. I found out it was a combination of my trans mounts (80a thru bolt) being compressed and the rear subframe sagging on the Garagistic 80a mounts. This cause the diff pinion angle and trans angle to be out of alignment by 3-4*. The U-joints on the DS accelerate and decelerate as they spin and the greater the operation angle the greater the angular acceleration. I think the trans and diff angle need to be at equal but opposite angles (-1* and +1*) to cancel these vibrations out.

    When youre at speed does the vibration change when you accelerate vs decelerate?

    The vibration is more pronounced when I accelerate. When i let off the gas, the vibration is noticeably less.

    I'll see about getting a digital angle measurement tool.

    I have new trans mounts on order. My rear subframe mounts (Garagistic 80A) are only 2 years old, I hope I don't have to replace those!

    Leave a comment:


  • ADEN
    replied
    When gearbox was out?

    Since you vib. on load and goes with clutch in (unload), A combination of stiff mounts and slightly loose/not aligned engine-transmission bolts might be your issue.

    Leave a comment:


  • cdl723
    replied
    I had something similar happen with my DS, but it would vibrate when decelerating. I found out it was a combination of my trans mounts (80a thru bolt) being compressed and the rear subframe sagging on the Garagistic 80a mounts. This cause the diff pinion angle and trans angle to be out of alignment by 3-4*. The U-joints on the DS accelerate and decelerate as they spin and the greater the operation angle the greater the angular acceleration. I think the trans and diff angle need to be at equal but opposite angles (-1* and +1*) to cancel these vibrations out.

    When youre at speed does the vibration change when you accelerate vs decelerate?

    Leave a comment:


  • moatilliatta
    replied
    E46/ e36 ones work.
    https://www.bimmerworld.com/Drivelin...EaAjzJEALw_wcB

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by moatilliatta View Post
    I still stand on getting rid of those trans mounts and getting a set of rouge engineering if you want something stiff stiff but compliant.

    I had a car that seemed to vibrate more in 5th. Maybe gearbox?


    I'm not seeing a set of trans mounts from Rouge Engineering for E30's ??

    I have the common getrag rattle, so maybe that's the source of the vibration?

    The trans output is pretty solid, I tried to move the driveshaft up and down near the gumbo and there was no play.

    Leave a comment:


  • moatilliatta
    replied
    I still stand on getting rid of those trans mounts and getting a set of rouge engineering if you want something stiff stiff but compliant.

    I had a car that seemed to vibrate more in 5th. Maybe gearbox?

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by Kelso840 View Post
    Gotcha. Yeah, I bet you're just feeling more vibration with the new driveshaft.

    The rubber isolator would be on the shift lever itself, not the DSSR linkage. The photo I posted is looking up the skirt of a shift lever to show how the lower section that goes into the shifter cup is isolated from the top part your hand holds via rubber. I can't remember if the stock e30 shifter lever is designed like that or not.


    That's the part I'm hung up on. One would think that a new driveshaft that's been balanced, new u-joints, new CSB, new guibo would have less vibration.


    The true test I guess is installing the old driveshaft and it's guibo (was still good) for a comparison.

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by moatilliatta View Post
    When did you get the poly mounts?

    The poly mounts for the transmission were installed Jan 2018, same time I removed the driveshaft vibration damper, converted to a DSSR shifter.

    Leave a comment:


  • moatilliatta
    replied
    When did you get the poly mounts?

    Leave a comment:


  • Kelso840
    replied
    Gotcha. Yeah, I bet you're just feeling more vibration with the new driveshaft.

    The rubber isolator would be on the shift lever itself, not the DSSR linkage. The photo I posted is looking up the skirt of a shift lever to show how the lower section that goes into the shifter cup is isolated from the top part your hand holds via rubber. I can't remember if the stock e30 shifter lever is designed like that or not.

    Leave a comment:


  • grantmiller1
    replied
    Originally posted by Kelso840 View Post
    When you say "vibration through the gearshift" are you talking about the shifter itself wobbling/vibrating? I see you have poly bushings on the trans mount and a DSSR shift linkage. That's at least two points of vibratory isolation you've increased rigidity.

    Without seeing/feeling your specific sensation, you might be feeling drivetrain vibration that was normally dampened by the 2 piece driveshaft, stock trans bushings, and a more forgiving shift selector geometry.

    Does your shifter have a rubber isolator?


    Do you have the old driveshaft and have you swapped it back in to see if the vibration goes away?

    Yes, the vibration through the gearshift is just what I'm feeling when my hand is on it. The gearshift is not wobbling. This is very likely normal, but I mentioned it anyways.

    I installed the DSSR shift kit 4 years ago, so I can't remember if it has the rubber isolator or something else.

    I do still have the old driveshaft. I can see about getting that swapped back in this week or the weekend after E30 picnic.

    Leave a comment:


  • Kelso840
    replied
    When you say "vibration through the gearshift" are you talking about the shifter itself wobbling/vibrating? I see you have poly bushings on the trans mount and a DSSR shift linkage. That's at least two points of vibratory isolation you've increased rigidity.

    Without seeing/feeling your specific sensation, you might be feeling drivetrain vibration that was normally dampened by the 2 piece driveshaft, stock trans bushings, and a more forgiving shift selector geometry.

    Does your shifter have a rubber isolator?


    Do you have the old driveshaft and have you swapped it back in to see if the vibration goes away?

    Leave a comment:

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