I had been having this on going problem with my SVT wheels, they shake pretty harshly going over 60 miles an hour. between 60 and 75 its absolutel horrible, you can even see the dash itself shaking... But once you hit 80 it calms down to a tolerable point. As goes the same below 60 miles an hour, it never really shakes at all. I took the car to discount tire when I first learned of this, and paid them to balance all of the rims, this was at the time when I was changing my winter rims out with the SVT ones in early march... I KNOW it has to be the wheels because when I had the steel ones on, the car drove smooth as butter at any speed... The wheels are now Balanced and shaking between 60 and 75 MPH. I looked the wheels and I saw a new weight or two on a few of them, but other then that I guess they were balanced... Anybody have any insight or should I go back to discount tire and raise hell again... Speaking of which, when I went back a week after I had the rims balanced they said the reason I had the shaking problems was becuase I needed new tires, which is true, I need two new tires in the back... But that wouldnt explain why the shaking is coming from the front on tires with over 50% tread left...
I have the same problem. Mine's not as severe as yours sounds, but my shaking starts right around 65 and tapers off after 80, with the worst being right at 70-75. I've got LOTS of tread left on mine, so I know that's not it. I'm not missing any weights on the wheels either. Could it be some sort of alignment problem?
thats the strange part... I put my old steelies back on, and it was smooth again...
So see what happens if you put the steelies on the rear. If the shake is still there, try the steelies on the front.
It is a balance related problem which can include the tires as well as the wheels.
A still better bit of advise is to fix what you find and go from there. If you know there are junk tires on it, get them off and see what happens next.
Have the wheels rebalanced. Insist that they clean the wheel before reinstalling weights.
They're most likely using clip on weights on the svt wheel, cleaning the wheel unless its covered in mud won't really do anything.
Could be the tires, or they may not be balancing them correctly.
im having the same problem..I spent a lot of money on getting my whole car alligned and balanced and yesterday going 65-75 the car was shaking violently to the point where I had to pull over to inspect wtf was going on!!
Im taking it back to the place though to make sure they fix it..now i just gotta take my lip off..blah!
I'd bet it's just the balance. You'd be amazed at the amount of shops that don't properly balance wheels. And properly balancing doesn't take any longer than to do it improperly and it's not hard at all. The only excuse they could have would be the machine isn't calibrated, but they should realize it and fix it. Maybe try another shop, possibly one recommended by others you know with aftermarket wheels and whatnot.
I thought I had a balance problem. Had a vibration problem between 60 and 70. Put the wheels on my daughters car & it was smooth as silk. My car, with the narrower stock tires was slightly smoother, but still had a detectable vibration.
The problem was worn LCA bushings AND a slightly off alignment. Replaced the old LCAs, much better. Got an alignment & all is right with the world.
Mine did the same with steelies and just a tiny bit at about 70 with the new 18s and new rubber.
I think its some old worn "front end" parts (80,000 miles)you know things are "loose"................ Maybe the rack or end links/bushings?
If any one completely redoes the front with all new parts, we will get an answer...........
Ask them to check the balance and the TIRE RUNOUT - sometimes the tire radial belt starts to separate and the tire goes out of round, so even if it balnces right it's vibrate like a MOFO, just ask Starjammir.
I just got back from Town Fair, they aligned and balanced mine last time so I went back and told them to take a look at it, they said the right fron was off so they fixed that..on the drive home on the highway, it was shaking again!! WTF! I have brand new tires and just replaced my LCA's like a week ago! I dont know whats goin on here!!
See above ^^^^^^^^^^^^^^^^
Also, are you SURE you have the hubcentric rings installed on all 4 wheels??
Originally posted by Stazi:
Ask them to check the balance and the TIRE RUNOUT - sometimes the tire radial belt starts to separate and the tire goes out of round, so even if it balnces right it's vibrate like a MOFO, just ask Starjammir.
Thanks Stazi, I again say im sorry...it wasnt your fault 
its always his fault you didn't know that?
You don't have crap-tastically old struts do you? Totally wasted struts will make your car prone to highway 'bounce'. Very dangerous too.
Originally posted by Stazi:
See above ^^^^^^^^^^^^^^^^
Also, are you SURE you have the hubcentric rings installed on all 4 wheels??
yes sir, I put them in myself..i guess im gonna hafta go back again and make sure to ask them about the the runout..
If it isn't any of the above look at replacing axles. They seem to be going bad quite a bit these days by causing an imbalance that shows up as a shake as described above. The more modified the car or higher the torque loads the more common it is. Anyway, you can spend all kinds of time and money chasing a balance problem on these cars and not find out until the end that it is worn axles throwing the car out of balance under load or under higher speeds.
Originally posted by warmonger:
If it isn't any of the above look at replacing axles. They seem to be going bad quite a bit these days by causing an imbalance that shows up as a shake as described above. The more modified the car or higher the torque loads the more common it is. Anyway, you can spend all kinds of time and money chasing a balance problem on these cars and not find out until the end that it is worn axles throwing the car out of balance under load or under higher speeds.
well a similar problem did happen while doing the LCA's, the passenger side axle was extended all the way where the boot was fully extended because we had the knuckle jacked up seperatly to get it outa the way of the LCA's, and jacking that area only brought it out but it did all the way, you think have it flexed all the way out might of damaged it?
Possibly, it could have damaged either joint. It may not be the problem, but considering the NEW GCK axles from Autozone are like OEM quality and were able to hold up pretty good on Demons car and on mine, and you can replace both for $240, I'd replace them. CV joints wear out over time anyway, even if the boot doesn't tear just from bearing movement. Esp with higher miles or as I said above on high torque vehicles even with low miles.
Anyway, when you think of the money you've already spent and how much repeated alignments and balances are, it may be money well spent.
Originally posted by warmonger:
Possibly, it could have damaged either joint. It may not be the problem, but considering the NEW GCK axles from Autozone are like OEM quality and were able to hold up pretty good on Demons car and on mine, and you can replace both for $240, I'd replace them. CV joints wear out over time anyway, even if the boot doesn't tear just from bearing movement. Esp with higher miles or as I said above on high torque vehicles even with low miles.
Anyway, when you think of the money you've already spent and how much repeated alignments and balances are, it may be money well spent.
it was only one allignment, they are doing the rest for free because of their garuntee, my ball joints are like brand new, not even 2 weeks wold..how do I confirm its my axles however?
Good point on the axles Tom, an old CEG'er ran into the same inssue and when we piulled the pass side axle the CV was in pieces inside the boot.
Gonz you can check by hoisitng up the car and rotatin ght wheel back and force - there should be no noticeable lash in the joint, only in the tranny. It may help to have someone hold the inner CV stilll while you rotate back and forth to eliminate the lash in the trans and thus avoid any uncertainty of where any slop may be coming from.
Alright I am having a very similar problem. I have a slight vibration at 65 to 75, I have FSVT wheels with brand new tires, a reliable friend of mine balanced them for me so I know the tires are balanced. I have one new tie rod end on the passenger side and a new ball joint on that side also. I also have one new cv shaft on the passenger side. I'm just throwing this out there because my brake rotors are original with 100k on them. Could a badly worn brake rotor cause slight vibration? I don't know if this is possible, But if the rotor has deteriorated badly enough in the vented part on the edge it could become out of balance right? I don't know, just an idea, let me know how far off track I am.
Originally posted by Stazi:
Gonz you can check by hoisitng up the car and rotatin ght wheel back and force - there should be no noticeable lash in the joint, only in the tranny. It may help to have someone hold the inner CV stilll while you rotate back and forth to eliminate the lash in the trans and thus avoid any uncertainty of where any slop may be coming from.
Stazi, this is weird cause we did all that listed above when we thought we might of damaged the axle and everything was fine, my friend was holding the inner CV while i rotated the axle and the other was checking for damage..everything seemed fine..I will try to check again once this rain is gone..
Do you have you stock wheels still? If so throw those on to determine whether the new wheels are the problem or if it is something else. i.e. if, when putting the originals back on the noise/vibrationstill exists, then it's either the suspension or driveline. IIRC you also have new LCA's right? If so then it's probably not those and is a good chance it's the drive shafts.
If the noise is gone with the old wheels and tires, then of course it's the new wheels. You said balance is OK, but you have not check for tire runout or wheel runout. The can check both, independantly (or at least I know the Discount Tire I went to once was able to first check the wheel runout and then the tire runout spearately).
will do..the LCA's are new..I'll throw in the stocker rims tommorow..
Keep in mind that I have both of my old blown axles still in the garage and they look like new still!
The vibration had gotten so bad under acceleration that the mirror and passenger seat started to shake going uphill. I let it go a while before they got that bad and as I said the problem first began to manifest itself as a vibration in the 60-75mph range that was slight and annoying at first, unable to be "balanced" away; gradually getting worse up to the excessive case I stated above. The rims, rotors, LCAs, all were new or replaced. One new hub was put on too and always I had that vibration until I put in new axles.
So take this story for what its worth.