chaadster

Hey Y'all,

Well, I just got my wheels back from the paint shop and went to get new rubber put on at my friendly, neighborhood Discount Tire. However, when they went to install the wheels, they said the fronts didn't fit on the hub center!

The wheels are the Cup II type, with the 993 part number, which seemed to be a very popular application around here for us 928ers. Front and rears are 17s, with ET 55. I'd never heard of this problem, so this is definitely unexpected.

Does anyone know if there is a fix for this? Could it be simply the thickness of the powdercoating? The problem is that piece with the groove cut in it to accomodate a hex key for adjusting the bearings; maybe there is a replacement part that is thinner? The rear wheels fit fine, but neither the designated fronts nor the rear wheels would fit on the front hub center.

I'll go grab the wheel part number and post a pic here shortly. I'll also measure the outside diameter of the hub center and the ID of the wheel, in the hope that it will reveal something.

Thanks in advance.

chaadster

The wheels at issue are PN 993.362.124.00

928drvr86.5

Strange, and they fit before the powdercoat? If so i would just grind off the power coating on the ID of the wheel where it's hanging up, it's not visible anyway, right?

928drvr86.5

When i first put my Fikse Fm10's on my car, i couldn't get the centercaps on because convex part of the grease caps on the front hubs were sticking out too far. I had to knock that convex surface flat to get the cedntercaps on.

Garth S

Although my wheels are a different pattern, they are '993' p/n's, 17x7 fr (9" rear), all ET 55 .... and they fit perfectly on an '88.
It does sound like sandpaper time ... for the grease cap should not be an issue: I too would suspect the hubcentric ring area: chalk it up .... a nice pink ought to do , and try to fit a wheel - the interference area should stand out.

928ntslow

I kinda had this same issue. Grab a medium/fine file and take a good look at the hub nose surface around the bearing and cap. Look for scars or scratches and run the file across a couple of times. I know it sounds weird, but the tolerances are so tight, that this DOES make a difference of the wheel going on or not.

Jim bailey - 928 International

Porsche wheels are hubcentric . the wheel is NOT located by the wheel studs but by the hub as such tolerances are very tight...literally

chaadster

Thanks for the replies, guys!

Ben, I have not had these wheels on the car before, they are new to me.

From what I read, it sounds as though I didn't overlook some crucial measurement in the wheel fitment choice, so I'll just recover the wheels from the shop and get to work sanding the hub a bit when I get home tonight.

I like the chalk tip, Garth. I'll definitely use that to find the interference area. With my luck, though, it'll probably hit all around the circumference! On the brighter side, this sounds like it might be the first time I get to use the Dremel! I just never seem to have a job for that supposedly handy little thing...

928ntslow

Based on what Jim says, locate the painted stud end..set the wheel with the valve stem 180 degrees from the stud...this will tell you if the hubcentric thing is the issue

Fogey1

chaadster wrote:
" ... I'll just recover the wheels from the shop and get to work sanding the hub a bit when I get home tonight.
I like the chalk tip, Garth. I'll definitely use that to find the interference area. With my luck, though, it'll probably hit all around the circumference!"

If hubcentricity is an issue, an even, consistent circumferential interference is a good thing. For the same reason be very careful with any filing/grinding, you don't want a not-round mating flange.

Bill Ball

The red paint on the stud is long gone on my car, and I've never found any issue with how things oriented. Also, I always thought it was valve stem nearest that stud and wheel lock on it, if you had a one. Brian asked me last weekend. He thought like you. Who's right? Does it matter? The only thing I do now is wheel lock near the valve stem. Oh, and crest pointing to the valve stem!

len928

Those wheels don't happen to come with hubcentric rings do they?
I only ask because a friend had this problem and it was due to the rings being inside the wheel opening improperly.
Just a thought, because I don't know if the wheels come with the rings or not.

Mrmerlin

Hi I would also remove the center cap then you can look into the hub area whilst putting on the wheel and possibly see what the hangup is instead of filing the wheel get some acetone and with the wheel facing up tilt it and with a rag gently wipe the powder coated surface the acetone may dissolve the coating but it will take a while, dont use too much solvent it will run all over the the place, Stan

928ntslow

Bill, Wheel lock and valve stem equals out of balance! They should be opposite! Check factory specs

SharkSkin

That applies to the clunky original lock, but with the newer locks it's not necessary.