Vibration problem and WTF Is a Road Force Balance?

[marcspaz]

Ok, I have had a problem with my front end vibrating for about a month. It is so bad between 40 - 60 mph that my hand goes numb while driving to/from work.

I waited to work on it because I was getting new wheels and tires. Once the new wheels and tires were installed, it was 100% unchanged. I assumed that there would have to be a steering or suspension problem.

Since it is snowing and or raining every day for the past week and I still have my bikes torn down in the garage, I figured I would take it to the dealer for troubleshooting. Plus, the warranty is still in effect for most of the vehicle, so if I can get it serviced for free...why not.

Well, after telling them there was no way it was the tires because it was the same with both sets, they decided to do a 4 wheel alignment and "road force balance" my tires. The road force balance cost $150! AND after spending a total of $315 the problem is still 100% unchanged.

Well, after doing some complaining, I got a full refund and they said they are going to research the problem some more.

Do you guys have any ideas? I checked the rack, control arms bushings, strut tower mounts, etc... With the exception of regular troubleshooting, have you guys heard of any "known issues" I can look at?

Also, WTF is a "road force balance" and why would the charge me $150 to balance my tires?

Thanks,
Spaz

 

[SoundGuyDave]

"Road Force Balancing" is a way of checking the balance on a tire WHILE the tire is compressed against a roller to simulate being under load on the street. The theory is that the balance will also account for any variation in tire deflection that would affect balance. It takes specialized kit to do it, but $150 sounds a touch high. Usually you can get a tire balanced for around 20-25 a piece, if you didn't buy it at that shop, so 80-100 for the set. An extra $50 for the road-force doesn't sound all that far out of line, given you got it done at the Stealership...

 

[88_Stanga]

have you checked the wheel bearings? could be a rotor. did you happen to get a printout of the force balace? each tire should show what the road force came out to. The lower the number the better. i think 30lbs is the limit. but even in the high 20's you can get a shake. i got a shake with my pirelli's. but thats cause they are a shit tire. I balanced them at work and within 2k miles the shake was back.

 

[marcspaz]

Both with the wheel still mounted and off the car, I tested play on the wheel hub bearings with a digital dial gauge. There was less then 0.003" at any given point in the rotation. The range was about 0.003 - 0.0018.

I somewhat ruled out the tires because both the stockers and the replacements wheels/tires have the exact same problem.

 

[cekim]

Both with the wheel still mounted and off the car, I tested play on the wheel hub bearings with a digital dial gauge. There was less then 0.003" at any given point in the rotation. The range was about 0.003 - 0.0018.

I somewhat ruled out the tires because both the stockers and the replacements wheels/tires have the exact same problem.

What is your toe? They usually give you a sheet showing the spec vs actual pre and post adjustment. I don't recall the correct value, but I am sure we can dig it up if you tell us yours...

Other than an out-of-spec toe with a wider tire - the struts can cause vibration if they have failed...

I don't remember/know what your strut setup is - aftermarket?

 

[marcspaz]

They didn't give me any specific values. They said my cam was ok but cast was out of spec. The sheet they gave me is worthless.

I have Ford Racing struts. 3 pos inverted dampeners. About 14,000 miles on them. The only test I know for them is gen damping. How can I tell if they are the problem?

 

[donnyonee]

did you take the retaining clips/locks off the wheel studs before you installed the new rims?
the wheel wont be sitting flat and vibrating.

 

[88_Stanga]

yea did you get new lug nuts with the new wheels?

 

[marcspaz]

Still have old lugs. DAMN, I did not take the retaining clips for the rotors off.

I am going to replace the lugs and pull those clips...later, cause the feels-like temp is 7 and the act is 10...

 

[KIMMER]

If it has only done it with aftermarket wheels, then it is probably the clips. If it does it with the stock wheels, then it isn't the clips.

 

[cekim]

They didn't give me any specific values. They said my cam was ok but cast was out of spec. The sheet they gave me is worthless.

I have Ford Racing struts. 3 pos inverted dampeners. About 14,000 miles on them. The only test I know for them is gen damping. How can I tell if they are the problem?

Camber/Caster are less likely to cause vibration than toe (out/in) as that is how much the tires point out or in relative to eachother. If they are too far it can cause vibration and "tracking" issues (car pulls to one side or the other).

As for the struts - I think you need to rule out the easier stuff (clips, alignment) and then without a shock tester, the only way I know if is:
1. look for leaks
2. check for play/slop in the motion with them unloaded
3. replace them and see if it goes away

Bad struts are a pain to diagnose unless someone knows a better way, that's the approach I have taken - rule everything else out then replace...

Also if you had the same shop do the alignment both times, they could be "precise" but not "accurate" (i.e. made the same mistake 2x). Try another shop for the balance and alignment if you don't see any leaks/play in the struts...

 

[marcspaz]

If it has only done it with aftermarket wheels, then it is probably the clips. If it does it with the stock wheels, then it isn't the clips.

good point, but I am going to try this anyway. It could be that the stock wheel/tire setup had it's own problems and now the clip/lugs are causing a new problem with the same end result. I am going to ask Saleen if it is ok to use the stock lugs too. there may be a taper size/shape issue with the stock lugs.

Camber/Caster are less likely to cause vibration than toe (out/in) as that is how much the tires point out or in relative to eachother. If they are too far it can cause vibration and "tracking" issues (car pulls to one side or the other).

As for the struts - I think you need to rule out the easier stuff (clips, alignment) and then without a shock tester, the only way I know if is:
1. look for leaks
2. check for play/slop in the motion with them unloaded
3. replace them and see if it goes away

Bad struts are a pain to diagnose unless someone knows a better way, that's the approach I have taken - rule everything else out then replace...

Also if you had the same shop do the alignment both times, they could be "precise" but not "accurate" (i.e. made the same mistake 2x). Try another shop for the balance and alignment if you don't see any leaks/play in the struts...

Sorry, cast/cam was fine. He said the front of the tires were toed too far apparts. It tracked ok before the alignment though. Not sure how far off it was.

I wonder if the bearings at the top of the strut mount are ok. I am going to check those too.

I am going to wait for it to warm up a bit (and/or try to find time to finish the bikes) so I am not freezing my ass of while trying to work on it.

Thanks for the feed back guys! I'll let you know what I find (if anything) in a couple of days. In the mean time, if you have any other suggestions to add to the list while I have it in the air, I'll be checking in...

Spaz

 

[Rangersfan]

It was said once here, but did you check the rotors? I warped my front ones, and I had a noticeable shake in my wheel from it.

 

[scramblr]

Rotors are my guess as well. Same problem on my wife's Stratus R/T, replaced the rotors and all was well.

 

[donnyonee]

and was i right?

 

[Kevin@PMP]

I'm just curious how they did a 4 wheel alignment since there is ZERO adjustment on the rear as far as caster, camber and toe. And I highly doubt they would be picking up lateral movement on the rear to adjust the panhard bar and they wouldn't be checking the rear for pinion angle.

I love it when places charge for 4 wheel alignments and only have 2 to align.

 

[PenguinGT]

WTF are you guys talking about with the "clips?"

Sorry if it is a stupid question, but I'm trying to figure out what you are referring to.

 

[Kevin@PMP]

WTF are you guys talking about with the "clips?"

Sorry if it is a stupid question, but I'm trying to figure out what you are referring to.

There are clips on the wheel studs at all 4 corners behind the wheels, these are used to hold the rotors on during assembly. They aren't needed, they just keep the rotors from falling off until the calipers and wheels are bolted on at the factory.

 

[PenguinGT]

There are clips on the wheel studs at all 4 corners behind the wheels, these are used to hold the rotors on during assembly. They aren't needed, they just keep the rotors from falling off until the calipers and wheels are bolted on at the factory.

Wow, I had no idea! Are they easily visible? I never thought to even check for this kind of thing.

 

[Kevin@PMP]

Wow, I had no idea! Are they easily visible? I never thought to even check for this kind of thing.

Pull the wheels off and if you can't see them you are blind. They are on the studs up against the rotor hat. They cause problems because most aftermarket wheels don't have a recess there so they hit the clips and the wheels sit crooked on the hubs. Stock wheels all have a recess there at each stud hole so it doesn't matter.