Vibration on Newly Purchased G8 GT

[FCNFST]

You just need to hold the rotor snug against the hub, not real tight.

Harbor Freight has cheapy dial indicators. Less than $20. You just need to read change in the runout.

Okay, that what I thought, but just wanted to verify it didn't have to be three for some reason. I had one of the machinist at work bring me dial indicator so I'll knock it out this weekend.

I know you've already thought of this, but make sure the mounting surfaces between the hub and back of rotor are clean. Crusty isn't good.
Also, don't over-torque the lugs when you put the wheels back on. Not good either.

I'll check everything out to be sure

when you first described the vibration you said the steering wheel shook side to side at speed, this usually indicates an issue in the front wheels of the car - there are 3 main causes, out of balance wheel/tire, out of round wheel /tire (high runout), or out of round rotor/hub. there is a 4th cause being the hub bearing - but that almost always brings along other symptoms like noises - jerkiness, but if rolling down smooth highway at a speed, and the steering wheel is rocking back and forth on a sports car - these are the top 3 culprits.

when bad enough you can feel it in the seats - but it always shakes the steering wheel.

other issue tend to only shake the seats, floorboard.



basically what he said.

you can find various runout tools for cheap - I got one for around 60, fundamentally it's something to hold a dial indicator that has a ball plunger tip - you place it to ride the outside edge of the rotor - I typically use the inner edge but whatever. mount rotors with 3 lugs - even pressure - run then down finger tight - on clean hub faces - I often also put a small coat of anti-sieze on there.

with one lug marked (and there is one marked from the factory) - spin rotor - read dial - if the sweep of the needle stays below 0.006 or so, then you are good. I often check all 5 locations just to see how low I can get it but I'm odd that way.

rinse repeat until you get your happy zone - finish brake install

on torquing wheels - these cars (and many others like it) are sensitive to how the lugs are run down. Its often recommended that with the car up - mount wheel, run in lugs to around 50 ft lbs (I have to brace the tire often) - this centers the wheel and the lugs nuts freely (notice they are coned on the end) - and then lower the car and torque to the 120-125 value

Thanks for the rundown. I'll let ya know what I figure out this weekend.

[FCNFST]

So I attempted to clock the rotors this weekend but fell short due to the nuts not being able to tighten down on the rotor with the wheel off. I had my girl grab some washers, but the ID was just too small to slip over the bolts. So I attempted to use what I had laying around, which were some small cylinder sand wheels. This sort of worked, but I was unable to fully tighten the nuts down without busting the sanding wheels(spacers). I couldn't find a good mounting location for the mag base on the dial indicator, so I firmly held the base to the ground and proceeded with my runout testing. Runout seemed to be within spec, but I need to recheck my footage. I will post the video I recording showing what I described above later tonight.



From what I can tell these wheels are OEM hub-centric, but please verify:




As you can see, the mounting surfaces were caked up with "high-temp" paint. I sanded everything down with a light grit paper, resprayed with an industrial strength paint called "Steel-It"(this stuff is the bee's knees) and placed the wheels back on, being very mindful of torquing everything down in a correct manner. I took the car for a test drive and noticed a good reduction in the steering wheel vibration. I still felt the vibration in the seat at 80-90 though.

With all of this being said, I feel I have found the main cause of the steering wheel vibration. Front passenger wheel is bent. I was watching the mechanic perform the Road Force balancing yesterday and saw it. I can't decide if I want to spend the money on a new OEM wheel or not, or just let the tire wear conform to the bent wheel(old tires didn't seem to conform too well...).

Overall, after the install of the new, Road Force balanced tires, most of the vibration has been eliminated, but there is still the 80-90mph "seat" vibration and some slight steering vibration, most likely due to the bent front passenger wheel.

[G8eraid]

So I attempted to clock the rotors this weekend but fell short due to the nuts not being able to tighten down on the rotor with the wheel off. I had my girl grab some washers, but the ID was just too small to slip over the bolts. So I attempted to use what I had laying around, which were some small cylinder sand wheels. This sort of worked, but I was unable to fully tighten the nuts down without busting the sanding wheels(spacers). I couldn't find a good mounting location for the mag base on the dial indicator, so I firmly held the base to the ground and proceeded with my runout testing. Runout seemed to be within spec, but I need to recheck my footage. I will post the video I recording showing what I described above later tonight.



From what I can tell these wheels are OEM hub-centric, but please verify:




As you can see, the mounting surfaces were caked up with "high-temp" paint. I sanded everything down with a light grit paper, resprayed with an industrial strength paint called "Steel-It"(this stuff is the bee's knees) and placed the wheels back on, being very mindful of torquing everything down in a correct manner. I took the car for a test drive and noticed a good reduction in the steering wheel vibration. I still felt the vibration in the seat at 80-90 though.

With all of this being said, I feel I have found the main cause of the steering wheel vibration. Front passenger wheel is bent. I was watching the mechanic perform the Road Force balancing yesterday and saw it. I can't decide if I want to spend the money on a new OEM wheel or not, or just let the tire wear conform to the bent wheel(old tires didn't seem to conform too well...).

Overall, after the install of the new, Road Force balanced tires, most of the vibration has been eliminated, but there is still the 80-90mph "seat" vibration and some slight steering vibration, most likely due to the bent front passenger wheel.

Why not just get the wheel fixed, if its not cracked it should be less then $80.
Or I have been able to get some pretty nasty bends out of wheels with a combo of rubber mallets, small sledge Hammer, several bricks(to lay the wheel/tire down properly), thick cardboard, towels or a piece of wood or two for protection ... Just need to make sure you have the wheel laying properly not to damage the opposite side, start with rubber mallet first. Also taking the air out of the tires helps as there will be less pressure on the sidewall. Most bends are on the inside of the barrel, but I've even done some on the exterior just need to take your time.

[FCNFST]

I didn't even think about that being an option....GRRRR8 IDEA!!!

[Seattle09GT]

Place right by my house in Kirkland WA does wheel refinish and straightening.

[Napalm]

there are a few places around that will do wheel straightening, ask the people that you took it too for the balancing and alignment - they might know of a local shop.

usually the wheels are spun with a tension wheel on the inside of it to help push it back in shape - more or less

or

OEM wheels - should be able to find one easily enough - might be worth while to buy 2 of em

or go up and get some camaro 20's

[FCNFST]

I found a mobile vendor to straighten the wheel via the reference from the shop. After checking the runout, the wheel was bent in three places: one being out 200+ microns, 140 in another and 100 in another, all of which have been brought down to <85 microns. I have since had the the wheel and tire re-balanced. There is still some slight vibration in the wheel but nowhere near what it was.

[Napalm]

also you need to get you some open end lug nuts - so that you can index your rotors one day. I'm sure there is someone with some spare stockers laying around.

i'm still using all of mine or I'd send you 3 of them.