Little help guys. My 51 has a 82 Monte Car****o under the front and it has a violent shimmy when slowing under 30-35 mph with light brakes. Front end shop is scratching their head. No parts are worn and the front end align seems ok. So now I am down to asking the real pros. I know someone is going to say that the 'girly motor' just can't hold the front end down.


Bill

 

Is their any chance that the front rotors warped or the front wheels bent?

 

No that is what the front end shop said until they experienced the shimmy.

Bill

 

The only two things I can remember causing a violent shimmy at specific speeds were a bad ball joint and tires. The bad ball joint speaks for itself. The tires would balance fine (about 3 times) but had a defect in the steel belts that would cause a really bad vibration at about 48 MPH and no other speed.

 

George

this is way to violent to be a tire. this shakes so bad that you think something is going to fly off...

 

Can explain the shimmy? Did it do this the whole time or did it just start. The big thing a few years ago was to put a complete late model front end under these trucks. A lot were not done so well. I have looked at a few of these and a lot of them are cracking were the sub frame is welded to the original. Also some of the cross members were cut to fit the engins and weekened the front end. I would give it a good look. It may explain the shimmy but I could be way off.

 

Sounds more and more like a suspension component.

The ball joint I had got so bad that the stud and ball eventually wore through the side of the casing!!! Lucky I was in a parking lot at the tiem. Even with the car jacked up, I couldn't find the bad ball joint because the springs forced the stud and ball against one side of the socket very hard. I have a fair amount of mass (as you may recall from our dinner at PF) and I couldn't get the worn joint to reveal itself no matter how hard I shook the tires. Hope you find the problem.

 

57 thanks. have not seen a crack but i will have the shop look it over again. i am on the road and the truck is in the shop. they said they wanted to put a steering dampner on it. i think they are guessing.


bill

 

George

this is way to violent to be a tire. this shakes so bad that you think something is going to fly off...

Jet Jock

Humor us and rotate the front tires to the rear. You would be amazed how bad a tire can shake if a belt slips. A shimmy at a specific speed is a tire 9 times out of ten if the steering isn't ridiculoously loose somewhere. What year Monte are we talking?

 

George, The best way to check a ball joint is to jack up the front end under the lower A arm closer to the ball joint. This will take the load off the ball joints. With a pry bar between the ground and the tire pulling up you can feel any movement.

 

'fenders

I will have them try the tire rotation. Actually I will have the just put on two new ones. The right side tire was a little out of round maybe that was enough to start this shimmy. The Monte was an 82.


Thanks

Bill

 

Bill

I'll work on my reading comprehension. I see you mentioned already it was an 82. A little tough when I can't see it but here are a few random thoughts.

Your comment that perhaps the tire is "starting the shimmy" is probably the key. The Monte has no steering damper to help the IFS recover once it starts. I have seen this happen to pickup trucks. Tires that are "almost" good get it started. The shimmy then accelerates into a death shake.

Your IFS is on the edge of it's capabilities in the first place as 82 Montes and Malibus are light cars. (They were girly-fied starting in 1979) It will probably need to be perfectly tight and you may have to tweak the alignment specs too. Your alignment man will have to know what he is doing.

I am guessing you are running 15" tires, larger than the stock 14" ? All the more reason the tires have to be good. Your tires may weigh 50% more than stock. The steering damper may not be the worst solution in the world, but it's a band-aid and I would do that after the problem is cured, or at least is a very rare occurence.

Keep us posted.

 

'fenders

tires are going on now. if this doesn't work what do you think about heavier coils???

bill

 

Bill

You may very well need heavier coils. I don't see that as the likely cause of your current problem. Unless the over compression of the springs is not allowing correct front end alignment. You expressed concern with your shop. If they aren't competent, now would be a good time to find an experienced alignment man. Find a technician that wasn't driving a Big Wheel when the donor Monte was new. BTW, not that it matters but Montes were downsized in 78, not 79.

I would double check all steering comonents for tightness once I knew I had good tires. Then get an alignment from someone qualified to make custom adjustments from stock Monte settings.

Can you describe the shimmy in more detail? Anything in particular seem to trigger it? Is it shaking the heck out of the sheetmetal? Does it go away at a higher speed or only after you slow way down. Does the shimmy accelerate from mild to violent like it's building up momentum uncontrollably?

 

'fenders

The shop has the the right people and I have a good head looking at it know. Have not heard yet about the tire swap. The shimmy seems to start about 30 when slowing down. Oncew under braking and a slight right turn down an exit ramp. Next time about 20 I kicked it hard and then let about 30 ( checking carb setting) when the front end went back down it started. The shimmy shakes the whole truck so hard that if it were to continue parts would be coming off. It will shake anything sitting in the seat into the floor. The only way it stops is to continue to stop the truck. I have seen this before a long time ago on a heavier truck, but for the life of me I can not remember the cause or the cure.

Back to the coils if tires does not do the trick, I am thinking of 800 or 1000 lb coils. They can be cut down so not to effect height of vehicle. Speaking of height this truck is not that low.

Bill