Wobble returns...

Lugnut · Post by **Lugnut** » Tue Aug 29, 2006 7:52 pm

Hey yall! After two new front tires, adjusting the toe-in, inspecting and greasing the front bearings, and tightning the steering, the good ole front shimming has returned. I drove her about 30 miles on a Saturday, and when I took a friend for a ride the next day (about 40 miles), I could not go above 30 mph with out violent shimmy. I am taking her to a truck tire place Friday to have the wheels balanced. The guy at the tire place said those bias tires get a flat space on them from sitting to long and they will always wobble! Any truth to this? Any tips to correct this problem would be greatly appreciated. Thanks.

John V Cliche · Post by **John V Cliche** » Tue Aug 29, 2006 8:16 pm

Hi Lugnut
Yes the flat spot thing is true but it isn't the same as shimmy.
The shimmy comes from uncontrolled movement in a part or between parts.
You said you cheched bearings, steering, tires.
But you need to check EVERY SINGLE joint .
Did you check the trunnions they may need to be adjusted probably by removing shims.
The steering box bushings at the pitman shaft may also be worn and loose
Check all the joints and make sure the movement is only in the axis that it is supposed to be .
MVM has had tech articles on just this issue in the past, with loads of good info. I will try to post which issue.
Hope this helps.
John

42cckw · Post by **42cckw** » Tue Aug 29, 2006 8:23 pm

Hi lugnut
There is some truth to the idea of flatsided tires ,after sitting on a flat hard surface for long periods of time the tire can develope a flat spot which is made easier if you don't maintain the correct tire pressure at all times (55psi) . Before you take your truck down the road check for correct pressure and add if needed, once you start down the road and the tires get warmed up after a mile or two it should go away.I have driven brand new vehicles of a new car lot that had been sitting for a long time and had this happen ,but I didn't have shimming just thumping noise from the tires which went away after a few miles down the road. My 353 sits on a cement floor for long periods of time and this has never happened to my truck ,but I always maintain 55 psi because another side effect with lower tire pressure sitting on a flat hard surface for a long time can cause cracking in the side walls.
I hope this helps

JIM 42CCKW

John V Cliche · Post by **John V Cliche** » Wed Aug 30, 2006 3:44 pm

Hi Lugnut,
The MVM tech article on shimmy problems is in issue # 91
Let me know if you don't have it.
Hope this helps
John

Lugnut · Post by **Lugnut** » Wed Aug 30, 2006 7:29 pm

Thanks Gents. John, no I dont have that issue. Can you e-mail it to me?

John V Cliche · Post by **John V Cliche** » Wed Aug 30, 2006 8:57 pm

Hi Lugnut ,
I don't have a scanner so I can't e-Mail them to you .
But I can copy and snail mail them if you want to send me your info via PM or E-Mail.
Or we could discuss the testing procedure here its not difficult but you have to be thorough , a helper on the steering wheel sure speeds things up.
Please let me know

Regards
John

dr deuce · Post by **dr deuce** » Thu Aug 31, 2006 5:38 am

Banjo axled trucks can collect water in the upper trunion bearing race. It will eventually hurt the bearing and cause a shimmy.

I have had 2 trucks like this. I now drill a small hole in the plate under the race to let the water back into the knuckle area.

New knuckle seal kits also help dampen the a shimmy on a banjo front end.

John V Cliche · Post by **John V Cliche** » Mon Sep 18, 2006 8:17 pm

Hey Lugnut,
How are you doing with your wobble problem ?
Haven't seen any posts , hope your'e rolling smoothly

Regards
John

Lugnut · Post by **Lugnut** » Thu Sep 21, 2006 5:55 pm

Hi John, The wobble is still there. The guy at the tire place checked the front tires and one was 1/150 thousands out of round, The other was 1/85 thousands out. He said the front end seems to be tight. So I guess the problem is the tires, and they are new. Also the odometer just turned over 9000 miles.

dr deuce · Post by **dr deuce** » Thu Sep 21, 2006 6:04 pm

Is this banjo or split?

Check the tierod ends. They tend to become loose in the clevis at the end of the tierod.

Are the front spring sagged a lot? That will change the caster.

dr deuce · Post by **dr deuce** » Thu Sep 21, 2006 6:05 pm

Is this banjo or split?

Check the tierod ends. They tend to become loose in the clevis at the end of the tierod.

Are the front spring sagged a lot? That will change the caster.

Lugnut · Post by **Lugnut** » Thu Sep 21, 2006 6:47 pm

Doc, They are split axles. The tie rod ends seem ok. But I will inspect them and the springs.

Chappers · Post by **Chappers** » Mon Oct 02, 2006 2:02 pm

Check your springs,I've had a jeep just come to mine with a real bad shimmy when you go over a drain or pot hole.We checked every thing and all appered to be fine apart from the springs were loose around the spring leaf clamps causing the springs to move,and causing a wobble.We also substituted the front wheels and tyres off another jeep and the problem has dissapeared.It may have been the wheels but worth checking the springs
Just a thought incase it's a similar problem.

regards

Steve

John V Cliche · Post by **John V Cliche** » Mon Oct 02, 2006 6:08 pm

Hi Lugnut,
Sorry to hear you still got the shakes.
Here is how I have found the problems in the past.
Park the truck on a flat surface if possible.
Get someone to help by sitting behind the wheel and turn the wheel back and forth easily , just enough to take up any slack start at the steering wheel and note if the wheel climbs up or down before begining its rotation movement here will require steering box adj. or replacement next look at the pitman shaft and make sure it starts to turn clockwise or counterclockwise and NOT move up or down slightly before turning if it does replace the shaft bushings. Move down the line to drag link first the joint closest to pitman arm and then the other end again make sure the movement is only in the forward or back direction and not in twisting or up and down motion that would indicate wear or adjustment . Keep moving down the line first the tie rod end on the left then the right make sure that the steering knucle and the tie rod move with no play whatsoever between them If you have any play here you will need to either replace the bolt or the bushing or both.
Remember even the slightest amount of play could be the culprit to you "wobble"
Next Jack up the the front one side at a time under the spring U bolt just enough for the tire to rotate freely using a pinch bar between the ground and the tire try to lift the tire and check for even the slightest play in the wheel bearings and the trunnions (the pivot points between the steering knucle and the axle end ) Do the same on the other side. Any play in the bearings adj accord. to the manual for the trunnions you will most likely have to replace shims with thinner ones.
Jack up the front of your truck (use jack stands ) under the frame rails high enough to let the entire front axle hang on the springs
Again use a bar between the frame and shackles , and between the shackles and spring eyes to check for play in the spring pins or bushings
You could remove the bolts one at a time and check for wear, replace as needed. Also check the U bolts and pads as stated in previous posts. With the weight off the front axle it is easier to detect movement or play.
The culprit for the "wobbles" in my experience has always been located this way
Hope this helps
John

Lugnut · Post by **Lugnut** » Thu Oct 05, 2006 5:29 pm

Thanks! I will try all of the above and see what happens.

KEVINABR · Post by **KEVINABR** » Sat Dec 23, 2006 6:26 am

Hi a friend has just changed 2 fronts and he to had the same problem ....could not go over 30 mph and then violent shakes and i mean violent.... check with a tyre dealer they might be able to help... you can get them to insert a gel / beads that always move with centrifugal force acting like a balancer... hope this helps ...his has no problems at any speed now

Lugnut · Post by **Lugnut** » Sat Dec 23, 2006 11:53 am

Thank you. I havent had time to do much on the old truck lately, bad weather, and other stuff im working on. But I will try the tire thing. The last time I drove her was the Veterans Day parade up to Indy. It was cold! I noticed on the way home I could reach about 40 MPH and the wobble would stop. Buy when I backed down to 35, it started again. Go figure??

KEVINABR · Post by **KEVINABR** » Tue Jan 02, 2007 5:02 pm

Hi LUGNUT MY MATE COULD NOT EVEN GET OVER 25MPH WITHOUT THE SHAKES BUT AFTER SORTIN THE TYRES WITH THE TYRE GUY ..THEY INSTALLED A GEL OF SOMESORT... HE CAN NOW GET HER ROLLING WITHOUT LOSING CONTROL AND PURR ALONG TO MAX SPEED

dr deuce · Post by **dr deuce** » Tue Jan 02, 2007 6:25 pm

BE CAREFUL !!!!!!!!!!!!!!!!!!!!!!!

Sometimes you will 'think' you have solved the problem only to find when you hit a big bump or bridge expansion joint it will go into oscillations again but this time at a higher speed.....

KEVINABR · Post by **KEVINABR** » Wed Jan 03, 2007 2:05 pm

YES I KNOW WHAT YOU MEAN DOC MY TRUCK RIDES VERY NICE VERY STRIAGHT ETC... BUT .....POTHOLES???????????

BEWARE

The GMC CCKW

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