Shimmy-N-Shake

[79Chevy kid]

Hello,
I have a 1979 2wd 3/4 ton with a 350, auto. I have had a real bad shimmy in the front end for a while, and it gets a lot worse when I get on the brakes lightly. I know it is not the rotors or the brakes, they are good, it is somewhere in the suspension. I crawled under it and pulled on the tie rods and the steering components. Everything seemed nice and tight. Yet when I had my dad along side me on the road and I put on the brakes to make it do the shake, he said my front tires where like leaves in the wind, just moving all over the place. What do you guys think it is? I am thinking ball joints now, what is the best way to check them? Is there something else that anyone else has experienced this with? I really don't want to have something brake and leave me on the side of the road before I figure this out, all suggestions greatly appreciated, Thanks!
Tom

[RegulatorInqInq]

Does it do it all the time or just sometimes?My truck would do something similar after I hit a large bump or especially going over bridges doing 80 on the freeway.It would vibrate really bad like I had a blowout or something until I slowed down to about 30 or so.It turned out I had a bent tie rod.Good luck

[79Chevy kid]

I get the shake around 55mph some times and pretty regularly when slowing down with light pressure on the brakes. This is why my first instinct was to go with the brakes, but they are fine. I watched under the truck as a friend moved the steering wheel and saw no obvious play in any of the joints. This was leading me to some other part of the front suspension, but don't know where to look next.
Thanks,
Tom
(getting tired of doors rattling at every slow down)

[RegulatorInqInq]

I know what you mean about the doors.Haha.Sorry i don't know too much about front ends I could just relate cause I had that problem with my truck.It sounds alot like the problem I had so you might want to check the tierod ends or even the ball joints.i don't know if it's any different with a 2wd but to check them you're just supposed to grab onto the tire and try to move it in and out.If you have a trustworthy repair shop near-by,most of them will do free inspections.good luck

[74c10]

your problem sounds more like the idler arm on your truck. the way to check this is to get someone inside to turn the wheel while the motor is off. you can look at the idler from under the front of truck, if it moves up and down, it needs replaced. hope this helps.  

[The Rev]

I had a truck once that I ended up putting $300 dollars in front end parts and came to find out I had a bent rim. Doh!

I would check to see first if the tires are in balance. Tires that are out of balance usually start shaking at hikgher speeds and it will also affect brakink if the rim is bent.

regards


the Rev

[the rev]

check all the tires to see if they are in balance. It was my rear rim that was bent and caused the whole truck to shake. Sorry for the bad typing...

the rev

[jaysbeast]

Did you check your u-joints and yoke? Had my rear yoke wear out the u-joint cap would move inside the yoke. Was getting bad vibration at higher speeds. The only fix was to have a new yoke welded on and balance the drive shaft.

[84 silverado]

I don't know how much, if any lift you have on your truck but alot of times you'll get a bad shake under various condition's because the lift(if extreme) causes a real problem with suspension and steering geometry. Your tie-rods, center link, etc, may be at such an extreme angle that it doesn't allow the steering to recover or control the natural shake in your wheels. That's why alot of four wheel guys use some pretty neat pitman arm extensions and other ways to keep steering components in-line. Good luck with it, Bill

[RSBAD454]

jack the truck up in the front.........put one hand under the tire and the other over, try to move tire back and fourth to see if you feel any movement for and aft. could be upper or lower ball joints.

[VileZambonie]

original post was (12/16/01 1:19:26 am)


I hope he fixed it by now  

[77DuallyCowboy]

This is a Quote from the bible for 67-87 Chevy trucks
ahhemm
" 1. Tire or wheel out-of-balance or out-of-round.
2.Loose, or worn wheel bearings.
3.Shock absorbers and/or suspension damaged"
(Added do to experience)
4. Tire treads my be slipped, Place vehicle on jack stands and spin the tire, watch the tread grooves carefully, if straight, procced to next tire, if the groove is wobbly the treads my be slipped. you can also put paint on the tires, then drive like 5 feet forward ON PAVEMENT. then inspect the markings on the ground, pay close attention the the grooves.
5. the rim may be bent.

OR
1. drive the truck and note the RPM at which the vibration is worst. now shift the transmission down to the next gear,and bring the RPMs to the noted RPMs which the vibration was worst as noted.
2. if the vibration occurs at the same RPM regardless of which gear the tranny is in, the driveshaft is not at fault since the driveshaft speed varies.
3. if the vibration decreases or is eliminated when transmission is in a differentgear at the same engine speed, refer the the following probable causes.
4. bent or dented driveshaft, inspect.
5. undercoating or built updirt ect. on the driveshaft
6. worn u-joints remove and inspect.
7. driveshaft and/or companion flange out of balance. check for missing weights on the shaft. rmove the driveshaft and reinstall 180-degrees from original position, then retest. have the driveshaft balancedif the problem persists.
OR
1.check the rear wheel bearings by raising the rear and spinning the wheels by hand, listen for evidence of rough bearings"

Regarding #4 in the first set of probable causes, my mothers cherokee had slipped treads, we spent hundreds of dollars on that thing in balancing alone! finally some guy put paint on the tires, then drive it like 4 or 5 feet, NOT over running the marks from the other tires. and found out one of the treads was slipped.

[Kazz]

I had a 72 GMC 2WD 1/2 ton that kind of did this. It was the bushings for the upper control arms were all but gone. Would shake and bang real bad when the brakes were applied.

Kazz