Projects shimmy on ft wheel Death Wobble --GONE:)

Need some help. My 31 a roadster is on the road. Problem about 30/35 mph the left ft wheel starts to shimmy. it has 25lbs of air press, 1/8 '' toe in, spindle nut tight , new king pins and bushings. It won't stop till I am almost stopped. The tire is not balanced. this will be taken care of tomorrow. when it's not shaking the tire and wheel run true. Has vega cross steer, no shocks,new heim joints.want to put some more miles over 30 mph. thanks, jim.

 

Put a dozen 3/16" ball bearing or some lead shot in there.

 

That will likely fix it.

"On the car balance" is best for our old wheels and drums, but nobody has the equipment anymore.

 

Balance the tires and check toe in. And shocks.

 

Why would you run with no shocks.....................

 

In your post it said "no shocks", was this a misprint? You could swap the fronts side to side and see if the problem transfers to the p*** side. F&J is probably correct.

 

Car is being built and that is the last thing to do before I blow it apart. under 30 its great, over not so great. thanks for all the replies.look on my profile and there is a video. too blury to see anything.it has buick drums also.

 

I have No shocks and no balance .... Why does my car shimmy?
Well......

 

The rt ft is not balanced either. no shimmy. This is my first time with a trad ft axle. will see tomorrow.not a up and down bounce.

 

Without a COMPLETED suspension you're never going to get good results. That's like saying you have a cooling problem, but haven't installed a top hose yet.

 

Tie rods, caster, drag link, spring shackle.
With missing components and balance its kind of like chasing the wind

 

well thanks vicky, will try to get a hand it tomorrow. all the other components are good

 

you can half *** balance a wheel on the car by loosening up the wheel bearing till the wheel spins free enough to rotate back and forth. where ever it stops the bottom is heavy, add a weight to the top, turn it a little, if it "stays" where ever you turn it it's balanced.

 

If all (meaning every other part) is truly good, then it must be what's missing, right?
Well not necessarily, but there is no other logical way to look at anything.

 

How much Caster are you running ?
1/8" Toe sounds excessive.


Search here for Death Wobble.

 

Thats true . did the loose axle nut and it won't take more than a half ounce.

 

Had a bit less and it was the same , increased it and its still the same, maybe at a slower speed.caster is about 7 degrees.When I had a FED it had almost 25 degrees. If you backed up fast it went into a death wobble.

 

Use a panhard bar with cross-steer [ the same length and angle as the drag link ]

 

That's actually about right. Mines at 1/8" and a 1/16 more or less is wobble city.

 

Ditto.....

 

The right front is possibly close enough to being balanced that it isn't wanting to vibrate so that you notice it.

I'd try to find a shop that could balance the tires on the car if possible. With the Buick drums it's quite possible that the drum and the hub aren't in balance.

You will probably have to ask around a bit but the results are well worth the hunt.

On a front wheel like that you can pretty well tell if you have a serious balance problem by jacking up the tire and seeing if it wants to turn to one spot on it's own. If the brake shoes are tight it might not do it but I've seen a lot of them that will turn from where you set them to so that the heavy spot always goes to the bottom.

Also check the run out in the tire when you have it jacked up. set something so the top of it is close to the front center of the tread and turn the tire and watch to see if the distance stays the same or you can see the tire look like it gets closer and then further away from the reference item. If it is out some, break the tire down and turn it 180 degrees on the rim and air it up and check it again.

As for the shocks or lack of them. The car absolutely has to have shocks and the better they work the happier you will be with the car. By that I mean that they have to be the correct shocks for the car that are rated for the weight of the car and set up so they actually work.

I spent a number of years chasing vibrations for very picky Pontiac owners at a dealership in Texas if you want to know where my suggestions got their origination.

 

left ft is a bit out of balance, run out is good,as well as wheel run out.I have cked for an on vehicle balancer,but there isn't on in town. Tires will be balanced this am, shocks on this afternoon. Thanks for all the advice and tips.

 

Everyone above is talking about balance, nobody told you to check for the tire being round. On some tires they need to grind a quarter inch off one side to make it round.
If its a bias ply tire, 1/16 to 1/8 toe. If its a radial. .030 to 1/16 works good.

 

Well, The tires were more out of balance than I thought. 4.5 on the left, and 3.5 on the rt. Moved tire and got them down to 2.5 ,and 3.0. The tires and wheels are as good as you could get. the left is near perfect, and the rt is about .060. Bad news it is still there. Moved up in mph to about 32/33. Looks like the shocks will be on hold till Sunday. Thanks for all the suggestions and help.This is all on a smooth road with radials. Ran out of gas 500 ft from home. Needed my walk.

 

i just replaced a vega cross steer box because of tire shake,the pittman shaft bushing was shot,new flaming river box with neddle bearings did the trick

 

Even with new kigpins and bushing, make sure that you don't need to tighten up clearance between the axle/thrust bearing/spindle. I can't remember how much clearance is allowable, but it helped on my A when I put it together a looong time ago.

 

I understand it is the left tire but I thought I would throw a picture in that might help someone. I put a new pitman arm on steering box and tightened it up but felt like it tightened to quick, put a thick larger inner diameter washer and tightened it more as picture shows. A buddy had the same thing happen to his vega and had to use a thick washer also.

Vergil

 

unfortunately its tight. Sunday ,shocks will be mounted. hopefully that will be the end.

 

I have been slowly following this post to see what has transpired, lack of shocks is not good but on a smooth road should not have much effect on the issue. Question, is this action wheel shimmy, like the tires are fighting each other or is this wheel tramp where one tire appears to be bouncing?

If you have balanced the tire and still have this issue what happened when you switched tires side to side? This checks for balance and a defective tire.

If you switched and the vibration continued on the same side then there are two options to check. First is the balance of the brake drum ***embly Buick brakes are noted for being out of balance and from the factory they have external balance weight added. These weights are usually removed when drums are modified for different hubs. Remove the offending side tire and static balance the hub and drum ***embly similar to what was suggested in static balancing the tire. Put a mark on the drum and spin it if the mark continually stops in the same place then the drum is mounted off center or out of balance. If you can see no runout or wobble in the spinning drum and it stops in random spots then the ***embly is close to being good.

The next step is to square the ch***is to insure that the front axle is square to the rear axle , square to the frame and the tires are square to the axle ***embly. If you have never done this it is important for correct tracking and wheel alignment. There are a number of posts on doing this if you search "death wobble".

Await your reply

 

put shocks on it, and increase tire pressure to what is recommended by mfg. on side of tire.