Hi all,

I've had a small driveline vibration develop around the 70mph mark which seems to ramp up with increased speed...

Having read some of the other posts on here, I've gone ahead and:
- replaced uni joints (twice with a better quality part each time),
- gotten the whole prop shaft rebalanced in a driveline shop,
- wheel alignment and balance
- rotated prop shaft 180* and tested (turned out to be in the right position initially)
- replaced shock absorbers all round
- replaced engine and transmission mounts
- altered tire pressures
- rebuilt transmission (this was a couple a years ago just for the hell of it, and the vibration developed only in the last couple months, but figured I'd mention that here)

My next step is to replace the transmission mount with a double-bolt mount instead of the original single bolt type, as it seems the nut on the mount has threaded (whoops). After that, bushes and the like in the rear end (front end was done shortly before buying it).

But, should that not solve the problem, do any of you have a driveline vibration checklist to run through to nail these sorts of things? I know the problem by nature could be anything, so suggestions are very much welcome.

I've been told the prop shaft alignment being out a couple degrees can cause this too, so I'll be diving under today to check that out. I've also been told it's possible for the rear brake drums to need re-balancing but you'd think it wouldnt wait until now to speak up if they were off...

Did you lower the car or make changes to the rear suspension at all? That will change the driveline angles and can produce a vibe.

Lou

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Home of Slant6-powered fun machines since 1988

Your steering wheel is on the wrong side of the car!
-Do you feel the vibration through the steering wheel or through the whole body? You mentioned wheel alignment, but are all the ball joints and tie-rods in good shape? Put it on a lift and check for play.
-What model and year car is it?

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1964 Dart GT

Lou, no changes to ride hide at any point, and I don't think the leaf springs are sagging or anything, but I'll double check to be sure. If I remember right the first appearance was when the wheels were switched around to keep tire wear even. First highway drive after that, there it was.

I'd had them rebalanced and an alighment during the switch, and I'd even switched them back and forward a couple times with balancing to be sure...no effect it seems.

Dan, I'd love to have it LHD haha..means not having to get out towards the traffic, which seems to consist of drivers on their phones and/or soccer mums getting their snowflake to piano lessons.

The cars a 1968 Valiant VE, the Aus equivalent of a Dart if I remember right..The vibration is through the steering wheel and the body, but I can't place the location of the vibe off the top of my head (front/rear/middle...I'm inclined to say all round)

Thank you for the tip about the tie rod ends and ball joints - I'll chase that up asap and let you know what comes of it!

"-Do you feel the vibration through the steering wheel or through the whole body?"
Probably won't help, but true story 'bout that: Bought a 1975 Valient Brougham. While driving it home , the steering WHEEL began a slight side-to-side shimmy at 50 mph especially in a slight turn. Lots of troubleshooting and new parts, alignment. Short answer- changed both universal joints and the trouble disappeared. Chalk it up to harmonics travelling through the vehicle and the high node at the top of the steering column, the steering wheel.

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

Check for broken cord or out balance, or out of round tire.

Check wheel baring's by removing, degreasing, looking for discoloration and or non smooth rotation on race when held in hand & rotated by hand; replace as needed.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Hi guys,

After checking leaf springs, replacing all the wheel bearings for giggles, and a few other steps, I decided to start tooling around with my tire pressures to see if that made any difference.

Funnily enough, it did! Raising everything by 2-4PSI all around entirely eliminated the vibration.

It may have been that the slightly more inflated tires affected the ride height/suspension in such a way that it has either eliminated, or overlapped and compensated for the cause/s that were bringing this about.

OR there's something wrong with a/the tires and more pressure has done roughly the same thing.

I'll keep faffing about and come back with findings here in case it ever helps anyone...next step is to throw on my other set of wheels/tires and see what comes about.

Thanks for your help again, all.

Wow, amazing that simply adding a few psi to the tires would eliminate a vibration like that. Sounds like a broken chord or something, could the extra pressure mask a still existing problem with the tires?

brian

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https://tinyurl.com/yynpj4v2

I would check to see if your castle nut on the wheel bearings is tight. I replaced my wheel bearings and after a few hundred miles I got a vibration. Its like the new bearings finally got seated in and were sloppy. I pulled the carter ping and only had to tighten it one slot to the right and put the ping back in. Just a place to check but I would check anything that spins. Breaks, bearings, wheels, hubs, rotors, ect.....

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~Nic

I once had a 70''s era c-body start to shimmy the wheel and I couldn't find the problem until the u joint let go. I was surprised that was my problem, because of feeling it in the steering wheel.
The other thing that comes to mind is the tire rotation. Did you swap radials side to side. That can cause the belts to let go. One more thing, we had a wobble in the mini van steering wheel. Not sure what caused it but the inside of the tire was wore so bad the belts were exposed. Couldn't see it till it got so bad the belts were showing. This was on the inside of the tire so I drove around thinking I was going to have to rebuild the front end. The mini van died before summer and when we replaced it I swapped our good 2 year old tires. That's when I found the bad tire.