Mark,

The other night you responded to a question about later offsets on rims with a 55+/- offset vs. the original wheels on our cars (both '86 944s). You wrote that you added two inch spacers in the rear of the car by adding 29mm (to correct the offset deficiency) and 21mm to compensate for the lack of spacers that the earlier cars had. I'm thinking about the same issue here and am wondering if the hubs are somewhat different than the earlier cars. I checked the PET parts CD and I think the hub part numbers are different. Maybe I read that wrong, though. That said, have you ever had any problems with adding the 2" spacers?? I measured my fenderwells and 2" may be a little wide but if you've done it in practice than it must be good. Have you done any other mods, etc? Lowered the rear? I'm considering adding about 32-37 mm in the front.
Thanks in advance for any more advice....

Frank

 

I think that he may have meant to add 2" total of the two spacers, 1" per side. If you were adding 2" spacers per side, then you may be adding 993TT hollow spoke wheels.

 

early cars had the 21mm spacers because the steel arms place the hub flange 21mmm further inward than the aluminum arms. I fyou have an '86 and you are running BOTH 21mm and 29mm spacers in the rear, then you are 42mm TOO WIDE on the rear track! Take off the 21mm spacers.

I run 21mm spacers on the rear of my '86 951 to use late offset wheels. 28mm (or 29mm) would be ideal, but the 21mm spacers are CHEAP, as they are found on any early 944 or 928 in the junkyard.
I've found that the 21mm spacers allow me to run 17x9 in the raer, lowered, without any rubbing problems whatsoever, so I'm happy with the additional clearance.

Seriously, if you are stacking 29mm AND 21mm spacers on an '86 with aluminum arms, you need to remove one or the other.

 

Well, I'm not an expert on the issue, so you may want back-up from someone else . . .

When I purchased my '86 944 back in '97, it came with late-offset 7" phone dials. I'm not sure why a PO did this, but the wheels were deeply recessed into the fenders. The rear wheels sat particularly deep into the fenders. A few months ago I put 1.25" spacers on the rear wheels. I did this mainly for cosmetics, and, in my opinion, this helped the look of the car.

However, it bugs me that all four wheels still sit nearly an inch inside the fenders. Since a 1986 car should have 23 mm offset wheels and mine has 53 mm offset wheels, that means each wheel is off by 29 mm (about 1.25"). In addition, my 1986 car does not have the 21 mm spacers for the rear wheels (I believe this is true of all '86 cars). So, even if I had the proper offset wheels, each rear wheel would sit in the fender about 21 mm deeper than a pre-1986 car. I'm not sure how '87 and later cars addressed the issue of getting the rear wheels spaced out further.

There was a post many months ago where someone with an '86 car added 21 mm spacers and longer studs to get his wheels to fill out the rear. His wheels had the proper offset and he still made use of the 21 mm spacers! He posted pictures before and after, and the before picture had a big gap, while the after picture showed both front and rear wheels filling the fenders.

It seems to me that my rear wheels (which are the wrong offset!) should be spaced out a total of 50 mm to get them to fill out the fenders. So, I ordered a set of 2" spacers from Crow Automotive. I will put these on the rear, and I will move the 1.25" spacers to the front of the car. I believe this will give me the proper spacing at all four corners. (Actually, 1.25" is 32 mm, so my front wheels will each be spaced out an extra 3 mm.)

Even with the 1.25" spacers currently on my rear end, there is a significant gap between the tires and the fenders. I have no doubts that an extra 0.75" will not pose any problems in terms of rubbing. However, I haven't received and installed the 2" spacers yet. Since I'm on vacation next week, I probably won't get them installed until after August 10. I'll post my results at that time.

Cheers,

Mark

 

I just re-read Keith's post, and it may very well be that I am not accounting for any differences caused by the switch from steel control arms to aluminum control arms.

However, I can say with confidence that on an '86 car, if all four wheels are the same size with the same tires, then without using any spacers, the front wheels will fill out the fenders more than the rear wheels. An '86 car with 23 mm 7" phone dials will have a considerable gap between the rear wheels and the rear fenders. Perhaps Porshe did this to facilitate the use of wider wheels on the rear of the turbos???

As I said in my previous post, spacing out my 53 mm offset wheels by 32 mm still leaves a fairly wide gap between the rear wheels and the rear fenders.

 

Mark - make sure you have the front and rear wheels on the proper ends - they are typically different offsets (and usually different widths).
I see a LOT of 944s rolling around with one of the rear (deeper dish) wheels on the front...

 

Keith,

All four of my wheels are the same part number. Also, I occasionally rotate the wheels front to rear and rear to front, and this makes no difference in how the wheels fill out the fenders. My wheels are all the same 15X7, 53 mm offset. Keep in mind that you are running wheels in the back of your car that are 2" inches wider than mine. If our wheels have the same 53 mm offset, then your wheels will stick out an inch farther than mine. With a 21 mm spacer, you are then sticking out about 46 mm farther than my wheels without a spacer. If I add 2" (50 mm) spacers to my rear wheels, then I'm only off of yours by 4 mm. You said that 28 or 29 mm spacers would be ideal for your car, which means that my being off by 4 mm should not be a problem.

On my 1986 944 there is simply more space between the mounting surface for the rear wheel and the rear fender than there is space between the mounting surface for the front wheel and the front fender. I assume this is the case for all stock '86 944s. Since I have four 7" phone dials with the same 53 mm offset, I can use 1.25" spacers up front and 2" spacers in the rear.

The bottom line for Frank is that he has to be careful what he does. What works for my 7" phone dials may not work for him if he uses different wheels. For example, I'm sure that I could NOT use 2" spacers with 9" late-offset wheels. However, if Frank puts 7" wheels with a 53 mm offset on the rear of his car, then he should be able to use 2" spacers.

By the way, my car has not been lowered or otherwise have the suspension modified.

 

Unless the car came with the optional wheels or the turbo wheels, all the 944 n/a had the 15x7 wheels on four corners.

 

Yup, and I'd love to know the story of how my car came to have phone dials with the late offset. Oh well, I guess that's a mystery that I'll never solve. Stupid PO tricks.

 

You know that I was actually looking for a set of late offset wheels? I was going to do a late suspension conversion, but ended up getting a good deal on a spare early offset wheels, as well as a set of 18" supercups. At least if you upgrade your suspension to, say '87+ 951 you have the wheels to start with. I have '86 951 brakes and the 15" phone dials actually clear the calipers. They also have 951 part number.

 

yes, you are correct, Mark. I remember that my old '86 na actually had 951 phones on it.

I'd be concerned about premature bearing wear, possibly, but I guess that is about it...

 

Mark, Keith and All,

Thanks for all of the comments. I have basically come to the same conclusions that you all have expressed. I have wheels from a C2 (I think)and the offsets are around 52-53mm. I take the comments that I need to "add" around 29mm to equal the offsets of the original 15" PDs. I have aluminum arms on mine so the 21mm should not be an issue. Actually, at this point, I have the PDs on one side of the car and the Design 90s on the other. I'm not driving it that way but just making comparisons.

Mark is right about the spacing of the wheels. With my original PDs there is still at least .75 in. left in the rear wheel well that could be "used " to increase the track. What I have done is the following (not very scientific, but..)
I put a straight-edge the the tire and extended it up to the inside of the rear fender(top of the arch). The inside will simply give you an idea of how far it is possible to go so you don't jam the tire into the fender at full bump (if its at all possible to get that situation). I use the tire because that is the outer edge of the entire assembly. I measured about 2.00 in., just what Mark said, on my '86 NA. I'm planning on ordering a 43mm spacer, though, just to leave a little space but to use up some of that area to increase the track (about 14mm ). This follows directly with Mark's measurements or suspicions of far one could go to increase the track without running into problems. Tell me what you think of the 2.00 in. jobs, Mark. I'd be interested how they look!!

My front wheels are another issue since they are a 6 in. wheel with a 52mm or whatever offset. Here I figure I need to add the 29mm to correct the offset plus some to compensate for the fact that the wheels are narrower. Right now I am sitting on the fence about using the 35mm or the 43mm spacers. I put some new springs in this past weekend and it might be a little lower. I'm trying to avoid the full bump issue noted above for the rears so the 43mm spacers might just be a few mills. too wide.

If there is any major fault in my reasoning or understanding of the situation please feel free to comment. I really appreciate all the advice.

Frank

 

My '86 944 has that spacing between the tires and the fenders even with the correct factory wheels on it.

 

I've had 3 sets of aftermarket wheels for my 86 951. The Momo star wheels had a 23mm ofset in the front and about 10mm offset in the rear. It appears that my 2 sets of Gotti wheels are the same. I split up the sets and run the 7" wheels from both sets on the front and back for street use. Then I run the 8" wheels on the front and back for track use with wider tires. The offset for the wider wheels is considerably different than the 7" wheels. I believe it's about 10mm to 15mm. They fill out the fenderwells quite nicely where the 7" wheels are sunk in.

I'm trying to say that the actual offset to fill out the fenderwells is 10mm to 15mm not 23mm. So if you run 2" spacers 2x24.5mm = 50mm. 55mm - 50mm = 5mm offset. You're real close to my guess of 10mm.

I hope this makes sense.

Now to my question. I thought I read somewhere that one of the later cars, a turbo maybe, had wheels with about 15mm offset. Can anyone verify that? It might be a bolt on...

Heres a pict of the wider wheels. Notice Danno's ultra wide wheels. That's another subject!

 

DanD,

If I understand this correctly, the offset is the distance between the centerline of the rim and the mounting surface. If you have a lower offset, like say 10-15 mm, then that is less than the stock (if the stock were around 23mm) so they should be good and should even stick out a little more than stock, depending on the width, of course. Its the wheels with the higher offset, say around 52mm, that pose a problem because more of the rim is tighter into the wheel well looking sort of sunken in.


Frank