Shuddering/shaking accelerating from a stop

[MattL]

My car shakes whenever I take off from a stop in first. It’s only as I transition from clutch to throttle, and it only happens in first. Doesn’t happen if I rev up to 3k or so and ease off the clutch as the revs come down, as long as they don’t drop too low. This has been an issue since I got the car last summer. 

 

Any my thoughts or suggestions would be welcome. Thanks. 

[Conserv]

Worn or slipping clutch?

 

Do you know anything about your clutch’s history, e.g., when it was last replaced?

 

Regards,

 

Steve

 

Edited May 13, 2019 by Conserv

[Mike Self]

Sticking advance weights and/or an inop vacuum advance in your distributor?  

 

It all depends on whether the shuddering/shaking is coming from the engine or the drive-train.  If the former, you might suspect my suggestion; if the latter, look at Steve's.

 

mike

[PaulTWinterton]

12 hours ago, MattL said:

My car shakes whenever I take off from a stop in first. It’s only as I transition from clutch to throttle, and it only happens in first.

 

If it's actually your car shaking and not the engine/transmission, also look at the driveline from the guibo backward.

 

I've had shaking if the guibo is distorted and dying, and it presents as significant vibration at low speed, eventually smoothing out at higher rpm.  Any distortion or cracking...replace it immediately.  

 

Check the rubber transmission mount.  If it's dead, the transmission will sag causing the guibo to distort and vibrate.

 

Inspect your center support bearing on the driveshaft.  The driveshaft should pass through the bearing at approximately the center of the bearing.  If it is sagging significantly it can cause a vibration, especially at low speed.  Also check the mounting bolts to make sure they are tight.

 

 

[MattL]

Thanks for the ideas, guys.

 

Steve: I don't know how recently the clutch was replaced, although I think the throwout bearing is in need of replacement at the very least: there's a tinny rotational rattle at idle with the clutch depressed. There's also some general rotational/rattle noise coming from somewhere in neutral independent of the clutch, but I need to do some more elimination to find that. 

 

Mike: I recently cleaned up the distributor and made sure the vacuum advance is operational, but I didn't disassemble completely enough to check the weights. If it's an engine issue, though, it should happen even when parked, right? 

 

Paul: I took a look at the guibo when I rebuilt the shifter a few months back. Looked pretty fresh to me at that time, but I'll check it again. I'll look at the transmission mount and center support bearing and bolts as well. 

 

One thing I neglected to mention: my mechanic has indicated that a pinion bearing in my open diff is at fault for the grinding sound I hear over 20 MPH. So, I'll be putting in a new-to-me LSD pretty soon, along with the CV axles to match. Could the vibration be related to the diff?

 

Thanks again!

[avoirdupois]

5 hours ago, PaulTWinterton said:

 

If it's actually your car shaking and not the engine/transmission, also look at the driveline from the guibo backward.

 

I've had shaking if the guibo is distorted and dying, and it presents as significant vibration at low speed, eventually smoothing out at higher rpm.  Any distortion or cracking...replace it immediately.  

 

Check the rubber transmission mount.  If it's dead, the transmission will sag causing the guibo to distort and vibrate.

 

Inspect your center support bearing on the driveshaft.  The driveshaft should pass through the bearing at approximately the center of the bearing.  If it is sagging significantly it can cause a vibration, especially at low speed.  Also check the mounting bolts to make sure they are tight.

 

To the bottom of the list I would add one or more failing (soft) motor mounts.

[AceAndrew]

In addition, check the driveshaft u-joints for play while you are under there.  Less of a chance than the center-support, but a worn diff pinion is a slight indicator that the rear driveshaft u-joint has some slop.

[MattL]

Not even 24 hours after my post, and I'm equipped with a hefty list of potential solutions. You guys rock. Love this community. 

[MattL]

For anyone still tuning in, I made some more observations on a drive tonight:

 

1. The shaking happens mainly as the car is just getting moving. In other words, as the clutch starts to disengage and the torque transfers to the wheels.

 

2. If I start off in 2nd gear, there's no shaking at all.

 

Can I assume this narrows the list of suspects down to the engine, clutch, and transmission? Or would the fact that 2nd gear = less torque mean the other possibilities are still...possible?

 

Any further diagnosis from you all? I hope to get the car up on stands at some point this weekend and give it a real good poke-around. 

[Rich]

Matt, I have the same problem occasionally, unless I have the revs up very high I get a similar almost violent shaking in first, I am very interested to look at all these amazing diagnoses to find the problem, good luck with yours

[Mucci]

Either of you ever figure this out? I have the exact same issue - a shudder just as i get going unless I start with the revs higher up. 
 

My guibo, center support bearing and trans mounts are new and didn’t fix it. 
 

I wouldn’t think it was clutch since the problem doesn’t occur if you give it MORE gas at launch... which would be asking more of the clutch. 

[PaulTWinterton]

If the alignment of the guibo is off the driveline will shudder at low rpms in first.  You can tell by rotating the driveshaft.  If the guibo distorts at the 6pm position you can try raising or lowering your center support bearing.   Saging engine mounts can also cause the distortion.  Lastly a member here (  @TobyB) enlightened me that the driveline should be assembled from the engine to the diff.  Meaning that the diff should be adjusted last so that the guibo is not distorted when all is tightened up. 

 

Edit: the CSB can also be adjusted right and left.  Poor adjustment could cause the guibo to distort at the 3pm and 9pm positions. 

Edited January 28, 2021 by PaulTWinterton

[MattL]

Thanks for the nudge to come back and update. In my case, it ended up being the clutch. Replaced it and the problem disappeared. 

[Mucci]

3 hours ago, MattL said:

Thanks for the nudge to come back and update. In my case, it ended up being the clutch. Replaced it and the problem disappeared. 

Did it slip on other occasions?

[MattL]

Not that I noticed, no.