Coats wheel balancer accessory - new stuff
07-03-2010, 04:13 PM
#1
Race Director
Thread Starter
Coats wheel balancer accessory - new stuff
I had 4 710's mounted & balanced at DT yesterday & I always hang around & talk with the guys/manager etc.
A new guy doing my balance took out an adapter that looked like have really big spacer with 5 pins screwed into it .
The pins engage the 5 lug holes (on the wheel) & press the rim to the machine when the locking spinner is screwed on.
This is instead of the tapered adapter that I was more familiar with.
He said it better centers the rim & simulates bolting the wheel up to the hub.
That made sense since our wheels are stud centric not hub centric.
I looked on the Coats site to try & find a pic to post but not all the accessories on their site have pictures.
If you know what I am posting about & have a pic, please post.
I should add, I never had a problem when my tire guys did the balancing using cones in the hub hole. I think the quality of the stock speedline wheels is really excellent, I have 4 sets.
A new guy doing my balance took out an adapter that looked like have really big spacer with 5 pins screwed into it .
The pins engage the 5 lug holes (on the wheel) & press the rim to the machine when the locking spinner is screwed on.
This is instead of the tapered adapter that I was more familiar with.
He said it better centers the rim & simulates bolting the wheel up to the hub.
That made sense since our wheels are stud centric not hub centric.
I looked on the Coats site to try & find a pic to post but not all the accessories on their site have pictures.
If you know what I am posting about & have a pic, please post.
I should add, I never had a problem when my tire guys did the balancing using cones in the hub hole. I think the quality of the stock speedline wheels is really excellent, I have 4 sets.
Last edited by froggy47; 07-03-2010 at 09:19 PM.
07-03-2010, 04:42 PM
#2
Burning Brakes
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07-04-2010, 10:29 AM
#6
Burning Brakes
07-04-2010, 10:41 AM
#7
Melting Slicks
-TJ
07-04-2010, 11:29 AM
#8
Burning Brakes
From an engineering standpoint, the fasteners should be the clamping force, not the locators. This is why dowels exist on various components. Also, only very few race wheels have steel inserts for the lugs, so repeated wheel changes could mean all the lug seats end up deformed, possibly offset a bit.
Dunno... Every car I've ever worked on came with hub-centric wheels from the factory (including my GM cars, the C4 and a '92 F-Body I had). I assumed this meant it was important. I'm just very surprised the C5 wheels are lug-centric. Maybe it's a non-issue.
-michael
edit: are we agreement with the terminology? if you slide a C5 wheel on and seat it flush against the rotor hat, its weight is hanging off the studs and it's slightly offset from being centered until the point that the lug nuts are tightened? on my C4 if i seat the wheel by hand, it's perfectly centered.
Dunno... Every car I've ever worked on came with hub-centric wheels from the factory (including my GM cars, the C4 and a '92 F-Body I had). I assumed this meant it was important. I'm just very surprised the C5 wheels are lug-centric. Maybe it's a non-issue.
-michael
edit: are we agreement with the terminology? if you slide a C5 wheel on and seat it flush against the rotor hat, its weight is hanging off the studs and it's slightly offset from being centered until the point that the lug nuts are tightened? on my C4 if i seat the wheel by hand, it's perfectly centered.
Last edited by MSR; 07-04-2010 at 11:34 AM. Reason: clarification
07-04-2010, 01:53 PM
#9
Race Director
Thread Starter
I don't have my 96 anymore but IIRC it too was lug centric.
The fit of the rim onto the hub bearing LIP (which is where it would center if it were hub centric) is very LOOSE.
Throw a rim up onto the hub and wiggle it around. If it were hub centric it would not have any play/looseness once it were seated past the lip of the hub.
As the lug nuts draw the rim to the hub the taper on the nuts forces the rim to center itself on each of the 5 (reverse if you will) tapers on the holes of the rim.
This taper to taper interface, moves the rim ever so slightly to it's final location rim vs hub.
Hence lug centric.
Think about the guys who put spacers on. The hub lip is only about 1/4 inch, right? You put a 3/8 spacer (and I hope a longer lug) on and then bolt up a rim it is nowhere near that lip any more, so how is it getting centered to the hub? By the tapers of the rim & lug nuts, lug centric. Same on c4, I ran spacers on my 96 LT4 quite often.
A hub centric rim would be like a F1 rim (or I think one of the newest models of Porsche has the option) with ONE center NUT to fasten the whole rim on.
My old 1961 MGA with true knock off wire wheels was like that. One spin on center "nut" that you would hammer with a brass mallet. Splines on the hub held the position of the wheel to hub constant. The spinners (not to be confused with COSMETIC spinners) would loosen once in a while so you kept the brass mallet in the "boot". If you took a swing and lacked hammer control you would miss the spinner & wack one of the wires on the wire wheel. If it broke then you had to take the whole deal off, take the tire and TUBE off and replace the broken wire & then true up the rim (like a bicycle wire wheel) , done that a couple of times (decades ago).
Diden't one of the mid year Vettes have a center knock off spinner nut? That would have been hub centric, yes?
The fit of the rim onto the hub bearing LIP (which is where it would center if it were hub centric) is very LOOSE.
Throw a rim up onto the hub and wiggle it around. If it were hub centric it would not have any play/looseness once it were seated past the lip of the hub.
As the lug nuts draw the rim to the hub the taper on the nuts forces the rim to center itself on each of the 5 (reverse if you will) tapers on the holes of the rim.
This taper to taper interface, moves the rim ever so slightly to it's final location rim vs hub.
Hence lug centric.
Think about the guys who put spacers on. The hub lip is only about 1/4 inch, right? You put a 3/8 spacer (and I hope a longer lug) on and then bolt up a rim it is nowhere near that lip any more, so how is it getting centered to the hub? By the tapers of the rim & lug nuts, lug centric. Same on c4, I ran spacers on my 96 LT4 quite often.
A hub centric rim would be like a F1 rim (or I think one of the newest models of Porsche has the option) with ONE center NUT to fasten the whole rim on.
My old 1961 MGA with true knock off wire wheels was like that. One spin on center "nut" that you would hammer with a brass mallet. Splines on the hub held the position of the wheel to hub constant. The spinners (not to be confused with COSMETIC spinners) would loosen once in a while so you kept the brass mallet in the "boot". If you took a swing and lacked hammer control you would miss the spinner & wack one of the wires on the wire wheel. If it broke then you had to take the whole deal off, take the tire and TUBE off and replace the broken wire & then true up the rim (like a bicycle wire wheel) , done that a couple of times (decades ago).
Diden't one of the mid year Vettes have a center knock off spinner nut? That would have been hub centric, yes?
Last edited by froggy47; 07-04-2010 at 02:14 PM.
07-04-2010, 02:37 PM
#10
Burning Brakes
Yes, that's one of the evils of spacers. If you look closely at the thick spacers, you'll note the good ones are hub-centric to the hub, and have a corresponding lip on the outside face to properly index the wheel. (Check out the H&R Trak spacers, which are TUV-certified, they're machined specifically to remain hubcentric to the fitted vehicle. That said, the pics Pfadt has of their 1/2" spacers do not show an outer lip, which is a pretty strong argument that lug-centricity isn't really that bad.)
Dunno, maybe there's still a disconnect on terminology, or maybe just the degree of rigor. Thinking I could be way off, I just did a google search for "hubcentric wheels." The very first link was to an article for Sports Compact Car Magazine. Cut/paste:
The other element that affects directly whether a wheel can be bolted onto a car is hubcentricity. Long ago, in the deep mists of time, wheels were located by the taper of the lug nuts or bolts. This could lead to all sorts of problems, but they can be summarized by saying centering was liable to be less than perfect, and the sheer stress on wheel bolts or studs could be enormous. I am not aware of any passenger car wheels now made that are not hubcentric. Hubcentric wheels have a hole at their center that fits closely over a round feature on the hub, serving to center the wheel on the axis of the spindle, as well as bear the vertical weight of the vehicle. The wheel bolts or studs then serve simply to hold the wheel onto the hub, and are loaded only in tension, where they are strong. If the studs were required to absorb vertical forces, they would be loaded in single shear, the weakest arrangement for any fastener. Factory wheels are all machined to fit their specific application exactly, and some of the better aftermarket wheels are, too. However, many aftermarket wheels rely on centering rings. This means that, instead of machining wheels specifically for each O.E. centering hole diameter, the wheel manufacturer machines all wheels to one size, and then uses inserts to give a centering surface of the diameter required for each application. This is obviously easier to do, and makes inventorying a complete wheel line much simpler and less costly. If you buy wheels that use centering rings, be sure the rings fit snugly in the wheels. If they are loose enough to fall out, how accurately can they be locating your wheel? Some tire shops automatically remove centering rings to balance a wheel, just to make sure there is no slop to make their balancing inaccurate.
The fact that a wheel physically bolts onto a car doesn't necessarily mean it "fits." The centering surface could be too large, in which case there essentially is no centering. Just as importantly, the offset could be wrong.
GM sells the C5 with lug-centric wheels? Or are we picking nits in how close the tolerances are for the wheel to hub fit? Both my CCWs and my A-molds are pretty dang tight to my hubs. If I slide them on flush with the rotor and have a friend spin on and tighten the lugs, there's no movement of the wheel. In contrast, some Centerline wheels I bought for a Mustang I used to race had no hub indexing at all, they were about as lug-centric as they come. It took lug tightening to get them into position. They never spun true on the car, but did spin true on a balancer machine, so I gave up on them. That was a huge data point to solidify the idea, for me, that hub-centric wheels were a requirement for racing.
I'm willing to concede both that lugcentricity isn't an issue, and that C5s use lug-centric only from the factory, I'm just very surprised by this.
-michael
Dunno, maybe there's still a disconnect on terminology, or maybe just the degree of rigor. Thinking I could be way off, I just did a google search for "hubcentric wheels." The very first link was to an article for Sports Compact Car Magazine. Cut/paste:
The other element that affects directly whether a wheel can be bolted onto a car is hubcentricity. Long ago, in the deep mists of time, wheels were located by the taper of the lug nuts or bolts. This could lead to all sorts of problems, but they can be summarized by saying centering was liable to be less than perfect, and the sheer stress on wheel bolts or studs could be enormous. I am not aware of any passenger car wheels now made that are not hubcentric. Hubcentric wheels have a hole at their center that fits closely over a round feature on the hub, serving to center the wheel on the axis of the spindle, as well as bear the vertical weight of the vehicle. The wheel bolts or studs then serve simply to hold the wheel onto the hub, and are loaded only in tension, where they are strong. If the studs were required to absorb vertical forces, they would be loaded in single shear, the weakest arrangement for any fastener. Factory wheels are all machined to fit their specific application exactly, and some of the better aftermarket wheels are, too. However, many aftermarket wheels rely on centering rings. This means that, instead of machining wheels specifically for each O.E. centering hole diameter, the wheel manufacturer machines all wheels to one size, and then uses inserts to give a centering surface of the diameter required for each application. This is obviously easier to do, and makes inventorying a complete wheel line much simpler and less costly. If you buy wheels that use centering rings, be sure the rings fit snugly in the wheels. If they are loose enough to fall out, how accurately can they be locating your wheel? Some tire shops automatically remove centering rings to balance a wheel, just to make sure there is no slop to make their balancing inaccurate.
The fact that a wheel physically bolts onto a car doesn't necessarily mean it "fits." The centering surface could be too large, in which case there essentially is no centering. Just as importantly, the offset could be wrong.
GM sells the C5 with lug-centric wheels? Or are we picking nits in how close the tolerances are for the wheel to hub fit? Both my CCWs and my A-molds are pretty dang tight to my hubs. If I slide them on flush with the rotor and have a friend spin on and tighten the lugs, there's no movement of the wheel. In contrast, some Centerline wheels I bought for a Mustang I used to race had no hub indexing at all, they were about as lug-centric as they come. It took lug tightening to get them into position. They never spun true on the car, but did spin true on a balancer machine, so I gave up on them. That was a huge data point to solidify the idea, for me, that hub-centric wheels were a requirement for racing.
I'm willing to concede both that lugcentricity isn't an issue, and that C5s use lug-centric only from the factory, I'm just very surprised by this.
-michael
07-04-2010, 06:11 PM
#11
Race Director
Thread Starter
Well, this is a good discussion, thanks for the posts.
I use Wiki a lot too, but it is, after all is said, written by all of us, so I do allow for some "margin of error" in the articles.
Coats sells their set of adapters for tire retailers who do mount and balance for about $10k per tire store according to one of the guys at my DT store.
I wouldn't guess they would fork that out if it wasn't for a good reason.
The 6 sets of rims I have, one Wagon Wheels, one Grand Sport coupe (for sale in another thread) and four c5Z are all oem.
I don't believe the hub lip spec has changed for c4/c5 or c6, but I don't know what that diameter is.
When I throw up a wheel (I do all my own tire shuffling) and run up 5 lug nuts just short of hand tight, I can still move most of those wheels up or down or left or right one or two mm. Then I tighten the lug nuts and it shifts a bit due to the cone/cone centering action.
So yes, it's "almost" hub centric, but not. As you said, the thinner spacers are sold (by good companies) with no lip taking it out of the "centering business" completely.
I think Gary (aero space engineer) did an study one time that looked at whether there was ANY load on that lip, which would be if hub centric, and all the load was on the lugs.
Anyway happy 4th, gotta go bbq & drink some beer.
God Bless (and save) our country, please vote in November.
I use Wiki a lot too, but it is, after all is said, written by all of us, so I do allow for some "margin of error" in the articles.
Coats sells their set of adapters for tire retailers who do mount and balance for about $10k per tire store according to one of the guys at my DT store.
I wouldn't guess they would fork that out if it wasn't for a good reason.
The 6 sets of rims I have, one Wagon Wheels, one Grand Sport coupe (for sale in another thread) and four c5Z are all oem.
I don't believe the hub lip spec has changed for c4/c5 or c6, but I don't know what that diameter is.
When I throw up a wheel (I do all my own tire shuffling) and run up 5 lug nuts just short of hand tight, I can still move most of those wheels up or down or left or right one or two mm. Then I tighten the lug nuts and it shifts a bit due to the cone/cone centering action.
So yes, it's "almost" hub centric, but not. As you said, the thinner spacers are sold (by good companies) with no lip taking it out of the "centering business" completely.
I think Gary (aero space engineer) did an study one time that looked at whether there was ANY load on that lip, which would be if hub centric, and all the load was on the lugs.
Anyway happy 4th, gotta go bbq & drink some beer.
God Bless (and save) our country, please vote in November.
Last edited by froggy47; 07-04-2010 at 06:17 PM.
