the shimmys

[John Martines]

Has anyone figured out what causes the shimmy at the front wheels?If I hit my brakes hard or hit a bump just right it starts. I've heard it my be the drag link or warped rotors or bad front U-joints. I don't really want to put a stabalizer on just to make it go away if the problem is still there. (kinda like suger coating a turd) I just want to fix it right.

 

[Philip]

The list of things that could be wrong can get pretty long.



Bad tires



Loose wheel bearings



The coupling at the steering box.



You have a 4X4 have you looked at you steering box mounting plate. It has a known problem of cracking.



The upper ball joints in our axles are a plastic cone. It might be time to replace them.



You can hope it isn't the lower ball joints. These little suckers are not cheap or easy to replace.



A bent rear end housing. If the drive angle is off between the front to rear axle. It will cause a wobble in the front end during braking. The wobble is worse the more the axle is bent. A rear axle with 1 3/16th" of bent can make for a very bad wobble.



On the same thoughts of a bent axle housing. A frame out of square could cause it also.



This list should get you started on the road to knowing your truck better.

 

[midwestdually]

i got the same problem... but will soon hope to fix it... . i got U joints that are shot in the front and a left wheel bearing as well... . hopefully that will fix it!

 

[JFitzgerald]

John, I had the same symptoms you describe. Turned out to be the drag link had one end worn out and loose. I replaced the drag link and the problem is gone.

 

[Madurski]

I am following this thread with great interest :-(



I have had a shimmy for awhile now. Here are the observations on my particular truck with regard to these problem areas.



Bad tires



Not a source of the problem for me. It does it with new tires or old tires, BUT, it does cause my front to wear unevenly. They don't "cup" but they get a sawtooth pattern on the edges.



Loose wheel bearings



Not a problem. I maintain these regularly and have replaced them in the recent past.



The coupling at the steering box.



I looked at this last night and couldn't see any problems. What happens to this?



You have a 4X4 have you looked at you steering box mounting plate. It has a known problem of cracking.



I looked at this last night and couldn't see any problems. What happens to this? Where does the crack occur?



The upper ball joints in our axles are a plastic cone. It might be time to replace them.



Shudder...



You can hope it isn't the lower ball joints. These little suckers are not cheap or easy to replace.



Bigger shudder ... .



A bent rear end housing. If the drive angle is off between the front to rear axle. It will cause a wobble in the front end during braking. The wobble is worse the more the axle is bent. A rear axle with 1 3/16th" of bent can make for a very bad wobble.



I looked at this also. I don't see any obvious alignment problems with the axle itself, but I did notice that one of the spring shackles (front right on the rear spring) was very close to the inside of the bracket. All of the others seemed to be centered pretty well. Wouldn't this also cause problems doing a 4 wheel alignment?



On the same thoughts of a bent axle housing. A frame out of square could cause it also.



I may go to a frame shop and have this checked out.



This list should get you started on the road to knowing your truck better.



Any other problems to look out for?



Thanks,



Ron Madurski

 

[Philip]

I am going to try this one more time. I have written out this post twice and both times the server wouldn't take it.



When the coupling at the steering box get loose it allows the truck to wonder around at road speed. It will also give you a rattle in the steering column when you are running on a rough road. If your box is a little loose then this slop will allow the front end to wobble to some extent.



The steering box mounting plate cracks around the mounting holes where it bolts to the frame. It has been noted that some frames have cracked at this pointy also.





The bent rear axle you won't see by lookiing at it. Do not bet on a frame shop finding it. My truck went threw a shop they missed the bent axle. It was found on a 4 wheel alightment rack. To check for one your self. You would need to make a jig up or drop the carrier out to use a long straight edge on it.

Any other problems to look out for?

Just the normal items. Bent drag links, bent pitman arm, bent cross link, bent rims, and so on.



Here is a pic of my bent axle.



https://www.turbodieselregister.com/forums/showthread.php?threadid=56738&highlight=bent+rear+axle

 

[Madurski]

>The steering box mounting plate cracks around the mounting

>holes where it bolts to the frame. It has been noted that some

>frames have cracked at this pointy also.





I didn't see any cracking around the bolt holes but I think I am going to remove the steering box to get a better look. I noticed the other day that on left hand turns the truck is not as responsive as it is on right hand turns. This tells me that something is loose but I sure can't find it.



Another problem I have is that the tires rub on my mud flap on some turns. I have a 2 deg caster shim on the front and that kicks the wheel back a bit so I may go back to a 1 deg shim or no shim at all to stop the rubbing.



>The bent rear axle you won't see by lookiing at it. Do not bet on

>a frame shop finding it. My truck went threw a shop they missed

>the bent axle. It was found on a 4 wheel alightment rack. To

>check for one your self. You would need to make a jig up or drop

>the carrier out to use a long straight edge on it.



I've had a couple of 4 wheel alignments done in the last year and the only anomaly is a 1deg negative camber on the right front. I am planning on replacing both spindles when I rebuild the front this summer.



One of the messages indicated that bad front u-joints would cause this but I don't see how since they shouldn't be spinning if not locked in??? If it can cause the problem it would explain it for me. The U-joints on the front of my truck are SHOT.



Thanks for the reply.



Ron Madurski

 

[John Martines]

I don't see how a bent rear axle can make the front shimmy when you hit a bump!Mine has a slight shimmy when I drive . More noticable at 50 or so and only sometimes when I brake. I discounted the u-joints since they don't spin unlocked. Kingpin bushing possible!I don't see any cracks and I have a custom steering joint so it's not that. Worn draglink or tierod end might be the cause. Wheel bearings have been checked. I'm going to figure it out somehow.

 

[cdrider]

This same problem drove me nuts for about a year. It varied from a shimmy to a death wobble.

I checked and double checked all the logical components---bearings,tie rods, draglink, u-joints, ball joints etc, etc. I had it checked out and aligned by 2 different shops. I turned the front rotors twice and this seemed to help for a few weeks and then the shimmy/wobble would gradually return.

The solution for me came when I R&R'd the rear brakes. I turned the drums and did the 3" upgrade and proper adjustment. I manually adjust the rear brakes at about 5000 miles and have had no problem since.

I think the front brakes were doing too much work and warping the rotors.



K.

 

[Madurski]

I may have figured out at least part of my problem.



I think I mentioned that I have a 2 degree caster shim on the front axle. Well, I think that this may be causing a misalignment of the whole front axle. There is a pin on the axle that is supposed to fit into a hole in the spring perch for proper alignment. I started thinking about this and I think the shim is preventing the pin from completely engaging the hole ( I think it is a tapered pin) and the front axle is "cockeyed". I am going to remove the shims this weekend and see if it helps any.



Any thoughts?



Thanks,



Ron Madurski

 

[JFitzgerald]

My thoughts - makes sense that could be it. Are you talking about the bolt that goes through the middle of the stack of leaf springs? The head of the bolt is round like a pin, and goes into the spring perch. Sound right?

 

[Madurski]

Yup, that's the one. I never looked at it that closely. I guess it could be a bolt head. Weather was too lousy to work on it this weekend So I don't know anything new yet.



Thanks,



Ron Madurski

 

[Madurski]

Took out my caster shims

So far so good.



As a recap, I had installed 2deg shims to put some caster in the front end. It developed a shimmy (bounce?) at around 45-50 and around 70 it shimmied pretty constantly.



I was thinking that maybe the locating pin wasn't contacting the locating hole properly and causing my problems.



This may have been the case. After removing them I no longer have as severe a shimmy as I did before at 45-50 and the 70 mph shimmy is significantly reduced.



I want to rotate my tires now to see if that helps any. I have been getting some cupping on the edges.



I also have a -1 deg camber problem on the right side that I need to deal with soon.



Later,



Ron Madurski

 

[bighorn]

shimmy

Driving straight axle vehicles for years-I've also experienced the wheel shimmy. Just finished repairing the problem on my '93 dually by changing front springs back to original. As the springs weeken, the axle- tips, also allowing the caster/camber to be effected. Wedges can be inserted at the axle perches to tip the axle back -but I feel this is a bandaid repair and only temporary. I have used the wedges on other vehicles and they do work although. Don't overlook centering your wheels on the hubs, and consider bent wheels also...