Help Rid Me of the Shimmy and Shake

Guys I need a little help.

I am having no luck getting rid of a high speed shake in my wagon.

It's a '63 Galaxie that I've lowered with 3" lower coils in front and blocks in rear.

Original 14" wheels, new tires, spin-balanced twice on two different machines.

Front end aligned and all ball joints and tie rod ends checked.

Low speed is no problem, but around 60 or 70 mph I get a shake in it. Can't really feel it at the wheel, but definitely by the seat of the pants.

I've checked the run out on the wheels with a dial indicator which didn't show anything obvious.

Any help or direction GREATLY appreciated.

- RBR

 

Check drive shaft balance and U-joints. Drive train vibration will increase as speed increases. Hope this helps!

 

Have you checked your front wheel bearings? I've had more than one car where the wheel bearings were just slightly too loose and caused exactly what you are describing. Worth a check.

 

All of the above plus you might need a steering dampner.

 

I failed to add in my previous post that, with your lowering your may have the pinion angle too far out of tolerance. Just something you might check if nothing else solves it.

 

common high speed woes that you indicate can be caused by: improper toe in setting, camber angle too low, loose wheel bearing(s) and it is possible but rare that the 3" ride height change would cause a pinion misalignment but more likely the rubber bushings in the rear springs could be shot OR if you left in the isolator pads between the axle and springs they are allowing the axle to rotate under the high speed load. Also check the conditon of your transmission mounts.

 

Check the steering system as a whole too. Excessive play in the system will become more evident as speed increases.

 

Just wanted to say a quick thanks to those that responded so far.

I'll check to make sure the pinion angle is in phase.

The isolator pads are still in place.

One more note, the shaking comes on slowly, almost like a resonance. It's not during hard acceleration.

Yeah, like I can accelerate hard in this boat

It has the old Ford remote power steering system, so free play can be measured on a yard-stick.

The changes I've made so far have definitely inproved the condition, but it's still there and it makes me nervous about long road trips in her.

Again, thanks all.

Looking forward to more suggestions.

RBR

 

My opinion: Check driveline for less than 5 degrees of included angle. If this is ok maybe balance entire wheel/tire/brake/hub together as one with an old strobe balancer on the car. If this works, then make index mark on a stud and on the wheel so you can put it on the same way every time. Good luck

 

You mentioned the tie rod ends, but have you checked the idler arm bushings? That should show up more as steering wheel shake, but worth a look.
Ditto the above comments on driveline and pinion angle. Very likely if it's not in the front end. Does it shake at all when you free rev it in N?

 

IMHO if you are feeling it in the seat of your pants,it is most certainly coming from the drive train or rear tires. are the tires out of round? if they are out even slightly it can cause shaking,but it doesnt usually get worse as speed increases. has the driveshaft been cut or altered? I would try to find an old shop that can spin the rear wheels and balance them with a strobe balancer.We have solved shaking problems on a few hot rods at our shop by balancing wheels on the car.

 

Let us know what the problem was, once found.

 

Hate to ask. Are you running bias or radials? I have a set of both 15" radials on steelies and 16" bias on 35 wires. I have checked both sets of rims for runout and straightness, all OK. When I run the radials I have none of the shimmy shakes. When I put on the bias for local shows, first off at low (5-10 MPH) speeds the car lurches up and down like a circus car. Then levels off and runs smooth until 60-65MPH when a bad shake starts in the front end, steering wheel is smooth, no shakes in the wheel. Back off to 55 or so levels off again. somethng in bias ply tire construction that causes a shimmy shake. Everyone that I have spoken with that run bias reports the same shimmy shake. Result, I am ordering new bias to put on the 35 wires. Spent way too much time to have some tire shake my car to pieces!!!

 

I'm really glad this subject has come up.

I seem to have the same "seat of pants" shimmy at speed. I always suspected it as the dreaded Ford front end shimmy but there was no sign of it in the front end or steering.

It felt like it was coming from the back of car. Interesting thing about that and reading the above is that its had a quickchange fitted and fitted badly.

It destroyed itself after being on the road for a week. Its coming out so we'll see whats going with it as having the "shimmy" is the pits and just ruins the fun of driving the car.

 

I feel like a proud papa.

This is my first thread to illicit so much good information.

Here are a few more details:

1. There is NO shake revving the car up in neutral.

2. I am running radials NOT bias ply.

3. No alteration to the driveshaft other than an angle change due to lowering.

4. Still trying to find a local shop that can balance the rears on the car.

5. Not check on the idler arm bushings. I am almost certain that the shake is coming from the rear. Definitely a side to side shake. Not so much an up and down shake. If that makes sense.

Thanks again for all of the input.

RBR

 

As said sounds like a driveshaft bent,out of round ,and or out of balance.,

 

Sounds like it could also be a tire with a busted cord. Had a BFG tire do that to me. Looked good, but had a distinct high speed hop.

Try moving the tires front to rear and see if the problem shifts to the front. Better yet, borrow a set of wheels and tires from another car. If the problem persists, you've eliminated the tires as the source.