kfriedenberger

As I'm waiting on ACG to get back to me (and I'm in Chicago so I can't stop in), thought I'd check with this group.

Just installed my new 19" Forgestar CF5s with hub centric rings, straight from the manufacturer through ACG for mount/balance. 8.5" wide front, 10" back. Tires are Hankook v12 245/35 front, 275/30 rear. OEM suspension. Lug bolts are conical to match the wheels and torqued to 100lbs each. Test drove after install and noticed a good bit of steering wheel vibration going on after 80 mph. Definitely didn't exist when I was running OEM wheels on blizzak 235/40/18 at all four corners.

1) So I'm thinking wheel balance? I checked out the wheel weights and none seem to be missing from shipping. Front wheels have 2-3 1/4 oz weights, rear right has 5 1/4 oz weights (balanced between inside and outside of the rim) and the fourth (rear left) has 9 weights on the outside and 3 on the inside. I know ACG has a hunter machine so this seems a bit out of the ordinary? Could this cause vibration at high speeds...odd that it would be in the steering wheel though?

2) Bent wheel? Anyone ever seen a wheel bent from shipping??

3) Bad / warped tire?

4) Alignment? (low probability)

How would you suggest I diagnose this issue? Clearly I'm going to wait on ACG to get back to me but many times I've seen some of these detailed issues have a very simple answer...

Ezec63

I bought 19 inch Forgestar CF10's from ACG last year mounted by them on Nitto NT05's. The vibration was horrible and dangerous at anything over 100 mph vibrating the car violently especially getting on the brakes hard. Took it to a regular tire shop got it re-balanced got much better but still had an annoying vibration. Found a shop with a hunter road force balancer and the car is smooth as glass up to 180mph when I went to mexico

If they have a hunter machine they sure dont know how to use it find a good shop with it and get rebalanced !

jvanbrecht

You have an 09, unless you have had an alignment in the last year or 2, it is probably that, especially when you take into account crappy quality roads.

kfriedenberger

Ezec63, what tire pressures are you running?

kfriedenberger

jvanbrecht, i've heard alignment is rarely the primary cause for vibration, it usually will just eat the hell out of your tires? but yes, i'll check that as well.

MaroonC63

Hmm. I'd go back to ACG first, maybe they can diagnose your problem.

MB torques to 113 btw, M3's are 103. So why 100?

abcut973

Get your wheels balanced properly. That would be my first step.
Then check for bent wheel. At the same get a good alignment it never hurts

jvanbrecht

Yeah, do not torque your nuts to 113 lb ft. MB Torques the wheel nuts to 130 Nm per AR40.10-P-4050CW (Wheel Lug Bolts), that equates to 95 lb ft, 113 is enough to do some damage.

What is slightly interesting is that many tire centers have a memo that says to torque them to 86 lb ft using thin wall yellow lug nut adapters for the air torque drivers.

Critter

Definitely recheck the balance of all wheels especially the fourth with the 9 weights on it. Performance tires should require little weight to balance, with the set up you have and the number of weights needed to balance it does not show good quality control for either the rim manufacturer if the rims are checked without rubber mounted and show signs of imbalance or the tires themselves. On the fourth(9) weights remove the tire and just try the balance on the rim, some shops will mark the position of the tire, check rim then remount in a different spot to reduce balance issues, either way it will be balance, also over torque of wheel bolts is not added security but could lead to stud failure or rotor issues. IMO

Girard@ACGautomotive

Sent you a PM in reply.

Sorry for the delay, with all of us being out at Shift-S3ctor over the weekend we gave everyone Monday off.

Let me know if my suggestions help out or not

Rafiki

Dealing with same issue with my CLS 63, bought 20" rims directly from XO , and vibration at 80-85 mph, getting road force balance on sat, will report back on outcome

Tinbucket

You have wheel and tire problem. Hopefully it is just balance. Many many shops have their machines set with too wide tolerance for balance or ans just say good enough and want to get you out and another customer in.
They don't sell "seconds" however some Distributors sell returned tires a second time or third.
They could be out of round or lumpy and all the balance weights, in the world, won't make them ride right.
Usually the car Dealer will have the first picks but don't count on it.
Take it back until they balance perfect not a quarter of half ounce off.
Road Force Balancers can get many tires to ride smooth.
The wheels, you have, I'm not familiar with.
When you have them rebalanced watch them spin.
The Dealer, that sold you the tires wants satisfied Customers , hopefully.
He should want to find the problems for you.

roadtalontsi

lol 113lb ft enough to cause damge? haha get real. factory wheel bolts can take 300+ with no ill side effects. Alignments dont cause vibrations. They can cause tire wear which cuases vibrations. It's clearly a wheel/tire issue. I wouldnt say hankooks are all that great of tire so it's quite likely they are bad tires, are they really noisey too?

SROC276

Same thing I had on several occasions. There is a very high probability that the tires/wheels are not balanced properly. You need to have them check and if possible load balanced if at all possible. Last time there was too much weight on one side. Bring it to a wheel shop to check but I am almost sure it's the tire balance.

RawBenz

Quick heads up guys.
When you buy new wheels and they are already balanced... they need to be rebalanced to your own tyres. Or rebalanced to the tyres you're going to put on the car.

So once your wheels arrive, you need to take them to a tyre shop, get them to mount the tyres onto the wheels then balance them.

Also if the wheels are aftermarket they must use hub rings. Mercedes is usually 73.1 - 66.6 and if they are mercedes replica wheels you will not need hub rings.

Hope this helps

Diabolis

Hold on a sec... are the Forgestars NOT hub-centric? If you have to use the crappy centering rings, that would explain the problem right there. Been there done that.

MaroonC63

They are not hub centric, not the f14's i had atleast. I had to order my own rings as mine didnt come with them. Op said he put the rings on.

Diabolis

That would explain the vibration at high speeds. Even with the centering rings there's still too much play when it comes to properly centering the wheel on the hub, so they are a crude measure at best.

Unless you go to a machine shop that can make you an exact set of rings / sleeves machined from aluminum and (permanently) pressed in the hub bore of the wheels, your only option at this point is to keep taking the wheels off and putting them back on until you hopefully end up centering them somewhat better than the first time.

Girard@ACGautomotive

They only forgestars that are happen to be the CF10's they make specifically for the C63.

Everything else is a generic center bore so they supply the rings per application.

Agree with you that it's not optimal, but it's how they offer the product at this price unfortunately.

Kirk, can you verify you cleaned the hubs as well before putting the wheels on?

Keep me posted.

kfriedenberger

Thanks for all of the posts. I just had a road force rebalance done; minor tweaks but the RR needed a bunch of weight added (1.5oz). They didn't take the step to remount the tires to reduce the weights required on the rears (they're both in the 2-3 oz range now). I drove into the city today and still feel some vibration but it seems to be a bit improved. The only other thoughts i have at this point:

1. Check the hubs to make sure they're clean as Tal suggests. I'm going to pull off the wheels and wire brush them; I didn't do that when I mounted them originally.

2. Recheck that the rings are the right size; I didn't check the stamps on them, but would assume I would've seen the misaligned lug holes in the rotor / wheel.

3. Get an alignment; am I just noticing the toe-in drag more with more surface contact and wider tires? It also felt this morning like the vibration may have been less or gone when taking a sweeping left turn. Maybe a slight pull to the left as well?

Diabolis

IMHO it's NOT a wheel balance issue, it's centering the wheel properly on the hub. Better (aluminum) centering rings might help, but you're still at a disadvantage as the entire weight of the car is now also supported by the bolts alone instead of the hub (it's the same argument I've made before about using hub-centric wheel spacers). The only proper way to deal with it is to find out what is the inner bore of the wheels and have spacers/rings/sleeves made to properly fill the gap. BBS does this with some of their wheels like the RS-GT.

Diabolis

You would need something like this that fits the Forgestars:





There are a number of pre-made rings that you can buy from http://www.1010tires.com/store/0mm.-...-4)-60632.aspx. Inner bore that you'll need is 66.56 mm - and maybe someone else (Tal?) can chime in with the center bore size of the Forgestars.

amdeutsch

That does not seem right. Way too much weight. Get it checked.

kfriedenberger

I pulled the wheels off again last night and scrubbed the hubs with a wire brush then wiped them off. Mostly grease, and quite a bit of it...drove to the city today and it seems to have fixed the rest of the problem completely.

Hub before photo:


Hub after photo:


Should I have the rear tires rotated, e.g. 90 or 180, on the wheel and road force balanced to remove some of the weight? Each has about 2-3 ozs of weights now.

Critter

Just being ****, but the PSS I had installed on factory rims, one rim/tire took 1 ounce and that was the highest weight value, the rest were 1/4 ounce-1/2 ounce range. Performance tires should not require a 2-3 ounce weight IMO, That weight is usually reserved for light truck tires. The other issue I would have is with that amount of weight when or if some falls off you are back to searching "Why" does the car shake. That one rear tire on your car should be checked again and possibly rotated for better results. Also check to make sure you have proper amount of thread contact, in the pictures it does not look very deep. Hopefully it is just the pics.