Hey guys, I've got a vibration coming from the front end.

The car is doing it only under two conditions:
- While turning left at slow speeds (5-25mph) in reverse or drive.
- While braking in a straight line to slow from reversing.

Details about when I hear it:
- The vibration only happens with my foot off of the accelerator. Applying some accelerator stops the vibration.
- The vibration does not happen when the car is still and at idle.
- The vibration does not happen when the car is moving straight at any speed in either direction.
- The vibration does not happen when the car is moving and turning to the right.
- The vibration does not happen while turning at higher speeds while coasting or accelerating.
- The vibration is unaffected by brake application.
- The vibration does seem to get louder (not more rapid) at the top end of the speed range in which I it is happening.

Thoughts? I have done no troubleshooting so far apart from make a comprehensive list of when the car exhibits the symptom.

Check your motor mounts.

I've already been through the motor mounts. This is not the same kind of vibration as bad mounts. This sounds almost like someone is using a jackhammer on my firewall.

If the vibration is steering related, you will want to check suspension components. How many miles since ball joints, guide rod mounts, tie rods? Does car follow road crown? These cars steer pretty when all is as designed.

Junkman, I'm at 262k right now and I've had it for 20k. No suspension parts replaced during my ownership.

When I had the wheels off, I did look at the upper and lower ball joints, and those at either end of the tie rods. All of them had flat, but not torn, boots. None of them wiggled by hand, though, nor did they respond to my very scientific analysis of tapping them with a rubber mallet while listening for metal-metal contact.

HOWEVER. The car absolutely does follow the road crown. Badly. On the interstate, I've usually got 10-15 degrees of steering dialed in just to continue straight.

I never looked into it because I thought this was just how recirculating ball steering behaved, having only owned R&P cars previously.

So what're my most likely culprits, and how do I tell that they're bad enough to cause the racket? I have seen a lot of posts about the idler arm bushings and drag link causing slop, but none of them described a noise like I'm hearing.

Another noise that I wasn't sure was related (but now I wonder if it might be) is a barely-audible clunk when slowing to a stop. It happens below 5mph, around the time (but not at the same time) the trans does its last downshift.

Check the flex disc. Mine did the same thing and the disc were falling apart.

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Von
Fairport, NY
1973 Unimog 416 Doka
1980 Unimog 416 Doka
1981 Unimog 416 Doka
1984 Euro 280CE w/diesel conversion
1985 300TD Estate wagon
(I really need to stop buying these things!)
http://vonsmog.com

I have always read that the flex disc causes vibration under load, not when coasting or under engine braking.

Is that not the case?

I can't speak to likely culprits. Mine were old and I wanted things fixed the 1st time. Parts were $500-600. It barely follows the crown now. Very fun to drive.

Maybe? I'd check.

Cheers!


snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

Check your motor mounts again...I had similar symptoms and it was because my passenger side mount was collapsed to the point where the mount arm was making sporadic contact with the top of the metal "cup" of the mount. Caused an intermittent, violent jackhammer as you describe.

Very buttery after a new set of mounts

I'll be getting the car up on jackstands at a friend's house this weekend (all I have is a driveway, he's got a garage) to poke things and see what jiggles that ought not jiggle, what metal-metal contact is being made that shouldn't be, and so forth. I think I've got a great list of what to look for from you guys, and it sounds like there are probably some parts I should be replacing regardless of whether they're the source of the racket, like all of my balljointed steering rods, since I've got so much damned slack at the helm. I have a ball joint fork I accidentally stolebought from O'Reilly tool rental for just such an occasion (if you forget to return a rented tool for a long time, they'll just buy a new one and the rented tool becomes yours -- found that out the hard way).

We had rain this morning around here during commute time, which really highlighted my need for new tires . I've got tread, but they are ooooold and hard. Every corner was an opportunity for oversteer with just a bit extra throttle. Every pull away from a stop light was wheel spinning affair, and for a moment on an uphill I was afraid I wouldn't be able to move forward at until the upshift to second reduced torque and gave me a bit of traction.

I have been putting off new tires until I find the source of this racket, in case it's a devastatingly worn suspension bit that will ruin the new set of tires in a few thousand miles with uneven wear.

If you remove the spring, replace upper & lower ball joints and guide rod mounts. Buy 1 each of the bolts that go through the control arms holding them to the body. You don't want to hold the project up. Cut them out if the bolt is stuck. Just put a sawzall with new metal cutting blade on the bushing cap and pull the trigger. Removing when stuck is difficult or futile. Cutting is fast and easy. I only needed 1 bolt on each of 2 SDs.

Certainly do tie rods if needed but they can be done without removing the spring. You'll need an alignment. I have lifetime Firestone alignments which has it's own problems but the use of machine is free so I change parts and align with impunity.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

If I remove the spring, I'm also hacking out a coil so my front and rear will sit the same instead of the assheavy reverse rake I've got now with my saggy rear coils.

But I don't currently have access to the milspec coil compressor this thing requires, and I doubt any local parts place rents a compressor that's tough enough.

You can buy and need a spring compressor. Sell it when you're sure you won't need it again or keep it in the tool box for your children or the yard sale vultures that will pile on when you're dead.

There are different thicknesses of spring pads. I think "2 nub" is the thinnest. Fix your back, don't hack the front.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Oh, but I wanna go low, you see. The springs aren't progressive rate, so I'm not losing anything but that traverses-the-savannah ride height.