Finding rims with the correct offset for the front of an 88 is a PITA.
I read on this forum that subaru impressa WRX rims have the correct offset and bolt pattern.
I have purchased some stock subaru alloy wheels (they say Subaru on the centre cap but that's a minor detail ;-)).

Problem is the hole in the centre of the wheels are 1mm too small to fit on the fiero hubs.

An obvious sollution for this problem is to have the centre-bores of the subaru wheels machined 1mm larger (to 57.1mm).
Has anybody had this done or done it themselves? What tools were used? I was wondering if a brake-cylinder honing tool would be capable of performing this task?

Another sollution that accurred to me is to machine down the circumferance of the circular part of the fiero hubs bij 1mm (the part of the hub that the centre-bore of the subaru wheels ride on). Advantage to this method would be that any subaru impressa aftermarket wheels will fit on the 88 fiero. Plus you can easily sell your un-machined subaru wheels to a subaru owner in the future, should you decide to upgrade and need to get rid of them..
What do you guys think about this method? Any disadvantages I'm overlooking, such as maybe weakening of the fiero hubs?
What tool could be used to machine the "hub- wheel-flanges" down bij 1mm? Would it be possible with the hubs still on the car?

Any input would be appreciated!!
Thanks
Iwan

I know that some Pontiac (Aztek?) wheels were the same way (correct fitment, but the hub opening was a bit too small). I believe the standard "fix" for this was to enlarge the opening (some did it by machining - others with a Dremel).

https://www.fiero.nl/forum/Archives/Archive-000002/HTML/20050818-1-051205.html

I would take a dremmel and very lightly using circular motions just whittle it down. Techinicaly the center bore is supposed to be very precise, but as long as you remove the same amount of material all the way around, it should come out close enough, the lug nuts are "conical seat" so they are going to force the wheel down into a centered seating anyway.

But somehow I doubt that you have the right offsets. The fronts are a staggered offset, that is the rim needs to tuck in farther on the front than the rear. I dont think subaru's have a staggered offset, so your rears are going to tuck in way too far. I have a 17x7 40mm and 18x7 40mm combo and the rears are just set in a little, but it would look fine, the fronts stick out about 1/2 and look a little odd if you look for it.

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DON'T USE A DREMEL! GET THEM PROFESSIONALLY MACHINED!!!!!

My wheels were 56.1 hub bore and they were machined very precisely. If you are off even the slightest bit, the wheel will be off center and will NEVER balance properly. The chances of you screwing up the wheels is high if you try to do it by hand are vary high....and getting 4 perfect is VERY unlikely.

Also, you will probably have too much offset both front and rear with factory subie rims.

[This message has been edited by Bigfieroman (edited 03-09-2006).]

Fieros are hubcentric: the hub is what centers the rim, NOT the lug nuts. You cannot do this by hand, it must be done with precision machining tools.

quote Originally posted by Steven Snyder: Fieros are hubcentric: the hub is what centers the rim, NOT the lug nuts.

For Fiero wheels, yes - this is correct. But for many aftermarket (or non-stock) wheels, maybe such as those in question - that is not the case (hence the need for special lug nuts).

STILL - I wouldn't think to try enlarging something like that by hand anyway

[This message has been edited by MinnGreenGT (edited 03-09-2006).]

Definitely take them to a machine shop. They can take that out in a single pass with a borring head. 1mm = .03937" roughly .020" load. If you mess with them at all, they won't have enough material to fix it without lots of chatter. With a little setup time, you could do it yourself on a drill press, but again, if you screw up, they are junk.

quote Originally posted by MinnGreenGT: For Fiero wheels, yes - this is correct. But for many aftermarket (or non-stock) wheels, maybe such as those in question - that is not the case (hence the need for special lug nuts). STILL - I wouldn't think to try enlarging something like that by hand anyway

You're missing the point. The hub is designed such that the center hub bears some of the load. Without centering rings, the lug nuts must hold up to all of the shear stresses. They are NOT designed to do this.
The aftermarket rims are supposed to come with centering rings. If not you will not center them properly! Even "lugcentric" rims need rings to center them on the hub.
The wheel studs are NOT designed to take shear stresses beyond braking and accelerating, thats what the hub is for! If you hit a pothole you may shear your lug nuts off if the wheel is not supported by the hub!
From one of Tirerack's techs:
"With the exception of a very limited number of older exotic vehicles, the center hub is the load bearing area. Lug studs and bolts have a limited shear strength. All of the wheels that we sell are hub-centric we refuse any application that is not. The basic differnece is that the lug studs are designed to hold the wheel against the hub, not to hold the car up. The issues that can be created by "lug centric" wheels range from minor (vibration) to very major (wheel loss) under different driving conditions. If you plan on driving at all aggressively get a hub-centric wheel. Your factory wheels are hub centric for a reason."
I believe he's incorrect about the rarity of lugcentric applications (MANY old cars were lug centric). However, almost all modern cars (including the Fiero) are hubcentric and do not have adequate wheel studs for lugcentric wheels.

great responses guys. I am not going to do anything with a dremel or so, it doesnt seem wise after reading your ideas.
Does anybody have a view on machining the hubs themselves to leave the wheels intact?

Thanks
Iwan

I Have that setup on my car. Got the centres machined out. Just need to pick up some centre caps.
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Interesting, Iv'e been running for years on a set of aftermarket wheels (Borbet) that have the wrong concentric ring. The wheels were on a chrysler product before I bought them and the bore was larger, Iv'e never had any problems with balance.

quote Originally posted by Steven Snyder: You're missing the point. The hub is designed such that the center hub bears some of the load. Without centering rings, the lug nuts must hold up to all of the shear stresses. They are NOT designed to do this. The aftermarket rims are supposed to come with centering rings. If not you will not center them properly! Even "lugcentric" rims need rings to center them on the hub. The wheel studs are NOT designed to take shear stresses beyond braking and accelerating, thats what the hub is for! If you hit a pothole you may shear your lug nuts off if the wheel is not supported by the hub! From one of Tirerack's techs: "With the exception of a very limited number of older exotic vehicles, the center hub is the load bearing area. Lug studs and bolts have a limited shear strength. All of the wheels that we sell are hub-centric we refuse any application that is not. The basic differnece is that the lug studs are designed to hold the wheel against the hub, not to hold the car up. The issues that can be created by "lug centric" wheels range from minor (vibration) to very major (wheel loss) under different driving conditions. If you plan on driving at all aggressively get a hub-centric wheel. Your factory wheels are hub centric for a reason." I believe he's incorrect about the rarity of lugcentric applications (MANY old cars were lug centric). However, almost all modern cars (including the Fiero) are hubcentric and do not have adequate wheel studs for lugcentric wheels.

Interesting... I'd be curious to see how many people here with aftermarket wheels have ever even thought about this... I know I haven't. I haven't had my aftermarket wheels on for long, but have not had any problems. On the other hand, I had a rear hub separate when I was still using stock wheels! (I understand that this was a problem with some aftermarket replacement hubs).

quote Originally posted by MinnGreenGT: Interesting... I'd be curious to see how many people here with aftermarket wheels have ever even thought about this... I know I haven't. I haven't had my aftermarket wheels on for long, but have not had any problems. On the other hand, I had a rear hub separate when I was still using stock wheels! (I understand that this was a problem with some aftermarket replacement hubs).

I worked as a sales manager in a tire shop for about a year, and the only cars I saw where the rims sat snugly enough so there was no slop between the center bore and the hub were large trucks. If you put flat nuts on a wheel that is designed for a conical seat it will vibrate like a B. This is pretty much every wheel out there thats not on a full size truck. If you look at the lug nuts from a F250 you will see they have flat washers on the bottom of the nut, this is hub centric, if you look at the nut from pretty much any car out there, the bottom has a cone shape that indicates lug centric. When you put the rim on a F250 it sits dead even and has no slop, put one on a car and it moves around. Cars have enough slop that if you do not tighten the lugs properly they can actualy sit far enough off center that they will hang on the walls of the nut-holes (snicker) and will not center the rim.

You only need to machine as far into the rim as the hub protrudes, not all the way, as long as you leave the outer edge intact, it will balance out fine on any spin balancer. Then use a cone pressed into the outside of the center hole, so it doesnt matter what you do to the rear side.

The center hub might help support the rim if the lugs flex enough to allow the rim to contact it, but from the factory they have slop in them. The space is sometimes small enough that corrosion that builds up can lock the rim on the hub, but using a dremmel and only removing what you need should give you resonable results, and im betting you can probably get it closer than stock.

The front wheels have ET55 (offset of 55mm) putting the front wheels in the right location in the wheelwells. Actually 5mm further in than stock which reduces scrubradius a little, a good thing IMO. The rear wheels also have ET55 which will place them 20mm too far in which requires using some good (hubcentric) spacers.
I'm quite allarmed to hear that most aftermarket rims have a centrebore which is too large placing all the stressses on the lugs!!

So nobody has a view on whether machining the hub centres down to fit the subaru rim centre bore is a possibillity?

Thanks far the responses, keep it going!

Iwan

Well look at it this way, you can machine the $100 rims, or the $400 hubs, which would you rather have to replace if you want new rims later? lol

Machine the rims.

The rears are going to need a lot of spacer, and the fronts are going to hit the control arms/swaybar at full lock without a spacer.

Actually after discovering that Subaru Impressa WRX Rims have the correct offset for an 88 Fiero I think that if and when I want different rims I'll go looking for aftermarket rims intended for the Subaru. The sellection range would be the same as the WRX crowd have. So hopefully will remain for a while as it is a fairly common car over here.
I would think I an advantage to convert the car (the front hubs) to the subaru centerbore size.
I would buy spacers intended for the sub and have the back-side machined to fit the rear of the fiero hub.
Now my fiero has basically become a subaru as far as wheel selection goes. (The spacers are a one time investment)

The drawback may be the complexity of machining the front bubs down 1mm. I'm no machinist but I would think it requires removing of the lug studs. Is that correct? Anybody ever replaced the studs? They are pressed in right?
Would machining the hubs create a safely issue, I intend to drive my fiero on a road race track (The Ring in Germany)?

Iwan

bump for any more input

Don't know if this helps at all but many of the aftermarket rims I've been interested in for my Fiero say they're intended for Subarus and have 48mm offsets. This will put the back wheels in 13?mm too far on an 88, and all four wheels in 13mm too far on an '84-'87..