Never ending "shimmy" battle.... (1 Viewer)

[Cruiserhead05]

Not trying at rehash any old threads by any means. i just had ones question i needed to ask. For awhile now i've been battle a bad shimmy throughout the body of the 80. I initially thought new u-joints would solve the problem. this didnt fix it. The shimmy is bad above 70mph but actually most pronounced at 35-40mph during acceleration, decceleration, and just coasting. I was debating whether or not to go have the wheels balanced by a fancy roadforce tire balancer, i've do two normal balances in the past 8 months but not a hunter machine. Just wanted some opinions on whether or not this was a good idea. Dont want to blow 80-120 if i dont need too.

Thanks

 

[OGBeno]

I would invest in a good balancing. You'd be amazed at the vibrations it gets rid of...especially if you have M/T types tires.

Best.
-onur

 

[IdahoDoug]

Do the "axles on jackstands and set the cruise at 60 in your garage" test. Bet you'll find one or more tires seriously out of round. The balancing machine guys just ignore it when the tread's dancing all around (not my job, man...) and just toss the weights on. The road force is supposed to account for that, but in my experience it cannot. I think it helps, but still leaves a shimmy.

Also, if you've been driving a while with the tires doing this, then they likely have developed corresponding uneven wear which will never go away. Not to rain on your parade, but an out of round or unevenly worn tire is going to be that way for life.

I got into a dispute with an unnamed tire maker over my tires being out of round. It wasn't until I sent a 5 second video clip of each tire to an engineer at their HQ before he agreed with me. They took the tires back and gave me full credit after a year of screwing around. M/T tire and these are often the worst for shimmies as noted.

DougM

 

[MoJ]

Do the "axles on jackstands and set the cruise at 60 in your garage" test.
DougM

Doug you're a brave man. I keep picturing an 80 crashing into the living room.

 

[IdahoDoug]

Actually, IIRC it seemed like a slower speed like 30 was best for seeing the movement. I'd lift them an inch off the pavement and then you can easily see the movement. Some is normal - a sixteenth inch or so - but no tire is perfect. I did it in low range with diffs locked so it would all spin the same. Wouldn't be pretty if it fell down all locked up in low range and cruise at 30. Nope, not pretty at all.....

DougM

Naturally, this is a stupid and dangerous thing to do, so disclaimers apply as to your judgement and ability.

 

[firetruck41]

www.gsp9700.com

Look up one near you, and have them balanced on it, make sure they use the GSP9700, usually they have other regular hunter balancers as well. If your lucky, the shop you bought your tires at, or one of their stores, if it is a chain, will have it and you won't have to pay to have it done.

 

[re_guderian]

www.gsp9700.com

Look up one near you, and have them balanced on it, make sure they use the GSP9700, usually they have other regular hunter balancers as well. If your lucky, the shop you bought your tires at, or one of their stores, if it is a chain, will have it and you won't have to pay to have it done.

This worked for my vibration (say 95% gone now). And it only cost $70 for 4 tires. Give it a shot.

 

[Cruiserhead05]

Alright, sounds good.

Looks like this might be a good place to start.

Idaho,
BTW the tires are maybe 10k miles old so maybe if im lucky they are screwed yet, if this infact my problem

 

[DJForrestA]

Sounds more like u joint\driveshaft to me. Tires tend to be either steering wheel or seat of pants. Steering wheel if its a front and seat of pants if its the rear tire and should be at all speeds. Do you have any lift? IF so maybye DShaft angle or a blown UJoint. Possibly worn shocks or trailing arm bushings.

 

[IdahoDoug]

Anecdotally, I have noted from having owned and driven many 80s that they seem inordinately sensitive to shimmies. It's kind of a moderate body shudder that I feel is easily started and its frequency is well in the range of freeway speed tire rotation. The 97 is less prone to it than our 93. I suspect that adding an ARB front bumper will reduce it as I think it makes a good mass dampener as well as stiffening up the front box a bit. If I were to hazard a guess, I'd say the front springs initial spring rate and the front frame stubs flex rate are too close. A shock tower brace would also help.

DougM

 

[Cruiserhead05]

Dj,

The shimmy is felt through the whole truck but more specifically the seat....
Also, i have replaced all the u-joints, guess i didnt make that clear.
Lastly, as the sig line says...I have 2.5 ome heavies all the way around.

 

[Lars]

I was thinking tire balance issues but your last post has me thinking driveline balance or angle issues.

Do you see the shimmy in your steering wheel? If so, I'd lean back to tires.

You can rotate your rear tires to the front to see if that has any effect.

 

[Cruiserhead05]

well, im scheduled for a "Road Force" balance at 1:30 today. We'll see if it helps.

FWIW, the following are things that could be contributing to this problem.

1. Front rotors are slightly warped, some pulsing during braking.

2. The ome heavies were bought used, dont sag and seem fine but i guess they could have issues.

 

[Cruiserhead05]

Alright,

I just got back home. Only cost 55 bucks so im looking over receipt as im heading home. Receipt says....

"Balanced tires as best as possible tried to check road force machine unable to spin under load. Vehicle has other issues loose steering. ABS problems"

So, ABS problem came about after my birf job. i was extremely careful with the sensor but they still go off at when coming to a stop. The loose steering i get, all the steering components are original...yes, i know, they are probablu due but one thing at a time.

Why he could not spin tires under load is beyond me....shimmy is still there.

 

[IdahoDoug]

Brandon,

You got ripped. The whole point of the road force machine is that it puts downforce on it to help correct for tire variations. I don't mean it's one advantage of the machine, it's the WHOLE POINT. So if they had a problem with their machine and so used it like an everyday balancer but charged you for a road force balance - you got ripped off.

Perhaps the guy used an incorrect adapter, etc?? Strange.

 

[firetruck41]

Was it on a Hunter GSP9700?

It does sound like you got ripped off, and just got a regular/crappy computer balance.

 

[Cruiserhead05]

Yes it was a GSP9700....i made sure it was.

For what its worth though, i think they only charged me for a regular balance. If they charged my 80 + i would have said something.
Now i have to decide if i want to go try again at someother place.

 

[IdahoDoug]

This is just me and how I think. But if I walked in the door and wanted an expensive force balance and the store's machine was broken and they wanted me to pay for a normal balance when they discovered this during work on my truck, here's what I'd kindly say:

"Well, I came to your store for a force balance and I'm going to end up getting one perhaps someplace else. If I pay you for a normal balance and tomorrow I also pay for an expensive force balance then you've made me pay WAY more than I should to get what I came to you for in the first place. In my opinion, you should simply comp me the balance so I can drive away from your store with balanced tires, but you should not charge me for a problem you, your machine or your employee had. It's the fair thing to do - what do you think?"

And for the record, $55 for an ordinary balance is a ripoff, too.

DougM

 

[Bear80]

The whole deal with the tires sounds like a pain. If I where you, I would stand and watch them balance your tires. Most respectable shops have insurance that covers customers in the shop area. The system for the gsp9700 is really simple and you can read and understand it as well as the tech can. I had the kid as discount do the first one of my tires and tell me it was "close enough" that the tire didn't need to be turned to match the light/heavy side. I looked right at him and said that is not what the screen says and told him that matching the light/heavy sides is the WHOLE POINT of the machine and my $80. So bottom line always try and watch the work being done by anyone other than yourself.

Now about your shimmy I would have to say that the steering parts could cause it but it would be noticeable in the wheel and you'd have changed parts by now. Have the aligenment checked, usally its free at most national chains, I know NTB for sure. I'd really guess at castor angles as the cause.

Jack it up and push/pull on the tires at the 9 and 3 o'clock position. It's hard to discribe how much play there should be but you shouldn't really feel any. Have someone help you look at each steering part as you push/pull on the tires to check for play in each component.


I really have to say your problem is tires, tires, tires because of the shimmy at 40ish. It seems to be the magical speed at which Toyota lug centric wheels like to shake when they are balanced with a hub centric adapter.

 

[Cruiserhead05]

Thanks guys. I'm going to keep working on this problem and will try my best to followup on it. I really feel like its the tires and honestly hope it is. Seems like the easiest part to address.