Hello Lads:

Just installed C-5 wheels (17x8.5) with 245/45/17's (Khumo Ecsta's). Used to have 15 x 7's.

What a difference! Totally transforming change in performance; however, Bird now vibrates at freeway speed and the steering wheel vibrates quite a bit. this didn't happen when i had the smaller wheels and narrower/bigger profile tires.

any clues?

 

Did you have them balanced? Are your wheel spacers tight? Did you use old tires?

 

How did you get vette wheels on? Many people put them on via adapters and they are only lug centric. By not being hub centric, mounting must be done correctly, or you may get vibration.

 

we need pics

 

its prob careless installers at a tire shop that put your tires on and balanced them. I work at a tire shop right now and see alotta people just kinda fling on whatever wheel weights they want. They just dont care if its .75 off or whatever they just wanna be done. so id go complain to them

 

You are so right about tire shops. Many places dont care, as long as it as on the rim. I have seen tires that cant not even be balanced on a rim at all on a hunter GSP9700. One tire maker has even given us a new tire due to that problem.

 

i a toyo proxie that the actual tire was defective as well.

 

Thanks for the responses. Here are some answers:

I used 2" wheel spacers that i got on line and the tire shop was not familiar with such a set up. the spacers were put on with the lug nuts that came with the spacers with the usual power tool. Is there a particular way that the spacers should have been installed?

Both the wheels and tires are new and, I went back to the tire shop to have the front tires re-balanced. I had asked that the tires be balanced without weights on the front side of the wheels. was this a mistake?

 

They can balance them without weights on the front. They use stick on weights that they stick to the inside of the rim for the outer balance. Then they can use regular wieghts on the inside. They may not have done an outer balance.

 

Actually, they did use stick on weights on the outer part of the rim. so, i think they are balanced and the problem must be the installation of the spacers (or something else in the front end that has been revealed because of the new set up?).

 

i had this same problem with my bmw when i stuck the rims on it at about 80kmh to 100 the stearing wheels shook like mad then leveled out my dad manages a tire shop and we made double sure everything was correct altho still has the problem and still haven't figured it out i am running no spacers on that car

 

I hate to say it but..... Bent Rim Did you buy them new or "slightly wrecked?

 

bought them new. you think i should switch the fronts to rear to see if it makes a diff?

 

Still could be a adapter problem as well.

 

Is the tread design on the tires a directional style? Sometimes certain tread designs only go on the right or left side of the car because they are designed to run in ONE direction. Could be an adapter issue too?? Check the smaller easier fix items first then go to others like bent rim, poorly machined adapter etc etc DOUBLE CHECK everything, like lugnuts for tightness even if you think you got em good... I hate 2nd guessing myself but I'm not perfect

 

I have the EXACT same problem. Which is, the spacers have no means of centering the wheel on them; so the wheels can easily be as much as 1/16" off-center. It's impossible to just stick the wheels on and have them go on right. The only solution for right now, is to use 2 flat nuts and 2 washers to initially hold the wheel on; eyeball them very carefully as I put them on, by spinning them and watching at the center to make sure the center hole of the wheel runs true with the center hole of the spacer; and once I get it as true as I can with the 2 flat nuts, put on 3 lug nuts, and replace the flat ones with lug nuts.

Mine are Vette Brakes spacers, BTW; I doubt it makes much difference though.

I have the wide-spoke C5 wheels, silver painted. My car is silver. The wheels match the car's bright silver ground effects almost perfectly. The car & wheels look most excellent together.

I'm in the process of attempting to create a solution. I'll have it in hand in a couple of weeks. If it works, I may consider offering it for sale, if I can find enough people who need it, to offset setup costs. It looks like the per-piece cost would come out somewhere in the $35-40 sort of range, 4 per car. Like anything, the price would go down as the quantity goes up.

We'll see how it does.

 

thanks for the info!

 

Are those C-5 wheels lug centric?

 

When on spacers, yes; since the spacers have no hub. However, the wheels appear to be hub-centric when on a C5.

 

Are the adapters lug centric?

 

the adapters are indeed lug centric.

 

Yes, unfortunately; however they only lack about .015" of being hub-centric. You can easily center them with feeler gauges. It's a little tougher with the wheels, since there's no hub AT ALL to center them on.

Seems kind of stupid to make an adapter for a specific purpose like that, and make it that far wrong in diameter, yet that close to being right. Oh well. But who am I to talk about "stupid", anyway?

 

can you explain to me how a lug centric adapter does not center itself properly? and how the rim does not either? I own 2" skulte adapters which are lug-centric and 17" formula wheels which are also lug-centric, and have zero problems with them.

 

there are two common types of tire/wheel vibration....if they vibrate at a certain speed and the vibration goes away at a higher speed, it's usually a balance problem....if it vibrates at that certain speed, and it gets worse at a higher speed, the wheel and/or tire are out of round or defective....HTH

 

First, you don't have "Skulte" adapters; Andris simply re-sells the Vette Brakes ones (AFAIK ... I suppose it's possible he might have changed suppliers, but I don't think so). So yours would be identical to mine.

Second, I have Vette wheels, not Formula wheels; maybe those do better at cenetering themselves on the lugs than the Vette ones do. I have no idea about that. I don't find that there's much to explain about how they don't center. They simply ..... don't. You put them on, and there's nothing that holds the wheel exactly in the center. On my car, like I said, if you just walk up to the car and slap a tire on like you would in a hub-centric system, it will end up a good 1/16" off-center, maybe more. If you spin it you can see it wobble. You can mark the high spot with a Sharpie or something and loosen the lug nuts and let the wheel fall some other way, and now it will be 1/16" off-center in some other direction, with some completely other high spot.

This issue has nothing to do with defective or out-of-balance wheels or tires. It's inadequate design, pure and simple. You can balance tires from now till Doomsday, and you'll still have vibes, if they don't go on the car centered.

 

if the wheel or adapter is 1/16" off, i would consider that to be an "out of round" condition (re-read my post)....what i mentioned is a great rule of thumb in general...it helps people diagnose tire/wheel related vibrations....personally, i wouldn't trust any adapter even if i was paid to take it...

 

They're not out of round; they simply don't have any feature (like a hub for example) that centers them when bolting them up.

Round = a circle

Out of round = not a circle

Pretty simple stuff here. Just the facts. No need for an argument.

 

I might be mistaken? but don't the tapered lug nuts center the chamfered (adapter or wheel) mounting holes to the studs? In ohter words, puts each stud in the exact center of each mounting hole, therefore centering the entire assembly.

 

RB83L69,
We do not use Vette Brakes adapters. When we first started selling billet wheel adapters is 1997, we used Vette Brakes, but stopped selling them due to quality issues at the time. We've switched machine shops several times to have the best quality adapters made possible, and have not used VB for about 7 years now.

The current (and for the last 7 years) adapters use a conical lugnut, with a matching seat in the billet adapter. If the adapters are gradually torqued on as specified in the instructions with a star pattern and anti-seize (starting with a star pattern round finger tight, then 20 ft-lbs, then full torque), the adapters will center themselves to the hub because the conical seats on the lugnuts and adapter tighten concentrically. It's important to gradually torque them on, not just tightening the 1st one with an impact gun, otherwise the adapter will not move and center itself. Vette Brakes used to use (don't know what they use now) the older style mag and washer style lugnuts, which had some slop, and permitted more run-out than I was comfortable with. With the new (well, since 7 years ago) adapters, I've never had any vibration issues myself road racing the Z28tt, nor have any of my customers called trying to troubleshoot vibration issues.

GM service manual on wheel runout is actually .045", which gives an idea of what GM considers acceptable.

I hope this clarifies a few misconceptions.

 

Good to know...

Mine are the type that uses the conical lug nuts. The adapter itself however, for whatever reason, doesn't fit tight to the hub; it's about .035" larger than the hub. But, it centers up fairly well anyway. The problem I'm seeing isn't how the adapter fits on the hub.

It's how the wheel fits on the adapter. I know about hand tightening etc. etc.; that's what I always do anyway. I don't try to pretend like I'm a NASCAR crewman or anything. Even doing that, I find that I can put the wheel on with 2 hand-tight lug nuts, spin it, and get 1/8" of runout (1/16" off-center); loosen the nuts, and the wheel will fall, and might be 1/8" off again, in some other direction; and I can repeat the process indefinitely. The ONLY WAY to get them on straight, is to support the wheel somehow (usually with a piece of wood as a lever), use 2 flat nuts with washers to "tack" the wheel in place, and check for runout. Then loosen and re-adjust; lather, rinse, repeat. Pretty tiresome. It's much more difficult on the rears. Now I've only been taking off and putting on wheels for 35 years or so, so perhaps I'm still a bit of a novice, and need some of these other people here to tell me all about how I don't have a problem or I'm an idiot or whatever; but just the same, I find it near impossible to get this whole system I've got, to assemble without vibes. It's definitely lacking some critical engineering.

Seems to me, but as I said of course I'm pretty stupid, that it would be smarter to have a hub on the adapter, so that the whole thing centers itself like it's supposed to; but what do I know. I'm just an engineer for a living.

 

We offer machining a wheelcentric lip on the outside face of the adapters, if the customer would like it, but most customers have been happy with the adapters as they are, and have not had vibration issues. In your case, it appears a wheelcentric lip would be helpful. I'm curious what the runout on your tire is, since that's where most of the rounout seems to be, from what I've measured (comparing hub, adapter, rim, and finally tire OD).

The hardest thing is having someone not experienced with precision measuring instruments measure the ID of their wheel accurately, as most folks don't have a set of calipers, let alone good inside mic's.

I've found the inside inside diameters of the various rims folks like to bolt onto their third-gens varies quite a bit (along with the snout of the front rotors or rear hubs), so we'd have to machine the lip to the smallest OD, to ensure it fits all rims, if it's on the standard, off the shelf adapters.

Andris, another living engineer...

 

Yeah I have all those tools too.... don't know what I'd do without them. I can't imagine trying to build anything without such things.

The Vette wheels are 2.775" ID IIRC. The hubs on the axles and front rotors are about 2.770 - 2.772". I have probably a dozen axles and at least twice that many rotors I've checked, and they're all within that range.

The ID of the spacers is 2.810". What's up with that?

The tires are fine. I watch the center of the wheel vs the center of the spacer, for measuring/minimizing runout.