16x7 Fuchs wheels w/911 Part Numbers - differences?
 

Hello,

Assuming that all 7x16 Fuchs were created equal, I just mounted a new set of tires to a set of 7x16 Fuchs I had sitting in my garage. When I swapped them on to my car (race car w/non-stock front brakes), I discovered that the inside of the rim interfered with the brake calipers... WTF? I have 2 sets of 7x16 Fuchs that came with the car and they fit fine...

Upon closer inspection, I have 7x16 Fuchs with different part numbers...
The 7x16 Fuchs that fit are PN - 911.362.115
The 7x16 Fuchs that do not fit are PN - 911.361.020 44

The backspace seems to be the same (both measure about 120mm), so either my measuring abilities are not valid or there is something slightly different about the inside diameter of the rim that causes the not-fitting wheels to interfere with the brake calipers.

After a lot of cursing and measuring, I resorted to google... (isn't that where we all end up anyway?)

I found a wheel data chart with some info:

https://members.rennlist.com/911pcars/WheelWts.html

The chart lists (2) 7x16 Fuchs varieties - one marked as 911 and the other marked as 944 - and notes that the 944 version has more clearance for brake calipers! Based on PN, it seems that the wheels I have that fit are the ones marked for 944. The chart indicates that the offset is the same but the the backspace differs between the (2) varieties... how can that be? Also, I measured the backspace to be about 120mm - which does not jive with the numbers in the chart... I'm so confused...

Is there simply a small (undistinguishable by eye) difference in the profile of the inner rim between the 911 and 944 7x16 Fuchs? Or am I really missing the boat on this?

http://forums.pelicanparts.com/uploa...1662338347.jpg

Here is a fuch spec pic... I believe the 944 fuchs are from the turbo variant. The offset are there for the bigger brakes but physically from the front look like 911 spec fuchs.

http://forums.pelicanparts.com/uploa...1662342193.jpg

edit: it seems that your wheel is not on the list.

are you sure you dont have 8x16 951 fuchs in there... they look just like the 7x16 911 fuchs.

Thanks for the posts and chart.

The chart only shows the 7x16 with the 944 PN I think?

Unless they are stamped incorrectly, they are 7x16...

http://forums.pelicanparts.com/uploa...1662343313.jpg

http://forums.pelicanparts.com/uploa...1662343313.jpg

The difference between "911" and "944" 7x16's is neither the backspacing nor the offset. Both are the same. The "944" wheels have a thicker hub section, and place the petals, or spokes, further outboard than the "911" wheels. This is where they gain clearance for bigger brakes. You will notice that the lug nuts seat into counterbored holes on the "944" wheels, and are much deeper into the hub section of the wheel than the "911" wheels.

Bingo!

These 2 are the 944 7x16 Et23.3(951 part#) showing the recessed lugs, These wheels provide just under an 1" of extra lateral clearance for brakes
http://forums.pelicanparts.com/uploa...1662384424.jpg

http://forums.pelicanparts.com/uploa...1662384424.jpg

http://forums.pelicanparts.com/uploa...1662384424.jpg

http://forums.pelicanparts.com/uploa...1662384424.jpg



Here's a set of 7x16 ET23.3 and 8x16 ET10.6 911 wheels w/ the normal shallow lug seats
http://forums.pelicanparts.com/uploa...1662384424.jpg

The only other wheel w/ the recessed lugs is the 9x16 ET15
http://forums.pelicanparts.com/uploa...1662385161.jpg

Jeff & Bill -

Thanks so much for your posts. I appreciate your responses and info.

Interesting to note that my wheels have a 911 PN, not a 951 PN and I don't think the lug nut seats are as remarkably different as the images that Bill posted. None of them look to be that deep...

To recap, I have a bunch of 7x16 Fuchs, with 2 different PNs, both of which start with 911:
The 7x16 Fuchs that fit are PN - 911.362.115
The 7x16 Fuchs that do not fit are PN - 911.361.020 44

I will double check, but I don't think I have any Fuchs w/951 PNs...

Best,
Tom

All Fuchs 7s have ET23.3, doesn't matter if they are 15 or 16

all w/ 911 part #s are the shallow seat / less brake clearance variety, but will accommodate 930 brakes w/ a slight buff to the outer edges of the calipers, again doesn't matter if 15 or 16

al w/ 951 part # are the recess seat larger brake clearance variety and only come in 16

911.362.115.00 or .90 are surely 7x15ET23.3 911 wheels

911.361.020 44 I don't have a listing for, but I'll keep looking , it was superseded by 911-362-115-07 This is also a 7x16ET23,3 oe on '77 Carrera 3.0

I've run up to 964 calipers on 930 rotors w/ the 911 7s, they needed a thin maybe 5mm spacer for clearance, 930s will usually need the outer fins mowed a tad

try the wheels on both sides, maybe the caliper on one side is shimed differently from the other

This is a great suggestion, which I did, but still no joy...

I did some cataloging of my Fuchs sets and I have 7x16 w/2 different PN and 8x16 w/2 different PN. All start w/911 ... It's interesting to look at so many PNs, especially those w/stamped numbers because they are all a little different... Some numbers were even stamped backwards! Interesting too that some of the wheels had the offset stamped under the size and some didn't (noted in my cataloging table).

http://forums.pelicanparts.com/uploa...1662409048.jpg

Here's a photo of where the offending 7x16 wheel rubbed on the front calipers:
http://forums.pelicanparts.com/uploa...1662409677.jpg

Backwards stamp:
http://forums.pelicanparts.com/uploa...1662409048.jpg

With offset stamped:
http://forums.pelicanparts.com/uploa...1662409048.jpg

http://forums.pelicanparts.com/uploa...1662409048.jpg


Without offset stamped:
http://forums.pelicanparts.com/uploa...1662409048.jpg

http://forums.pelicanparts.com/uploa...1662409048.jpg

These are 8x16 ET10.6, not a good fit for the front at all unless you have 930 fenders
http://forums.pelicanparts.com/uploa...1662409048.jpg

http://forums.pelicanparts.com/uploa...1662409048.jpg

Hi Bill,
I should have been more clear... my cataloging was of complete sets. The 8x16 wheels are for rear use only... the 9x16 wheels are just an outlier rear set I picked up a while ago, but do not use.
Thanks,
Tom

According to the OP's link, your two 7's decode to a wheel with the same general specification but with different production dates. This seems to be confirmed by the PET but the PET, especially for older cars, can have errors. For what it's worth - both numbers appear to be for a 911 - neither is for a 944.

That said, there is typically a reason for a part number change. It is quite possible that Fuchs or Porsche engineers changed the forging slightly to meet any number of criteria; strength, clearance, economics.

I have read, anecdotally, that Porsche and/or Fuchs was aware in the mid-80's of the need to strengthen the design of the Fuchs wheel.

That said, I would argue running old Fuchs on a race car is asking for trouble; how many heat and load cycles have they been through.

ok, but I am curious as to why or in what way 'The 7x16 Fuchs that do not fit are PN - 911.361.020 44'

If there is interference where is it? if it's the caliper what caliper and rotor are used?

There are multiple part #s for the exact same wheel because of minor appearance or manufacturing changes over the years, the only change in actual fit was the 951 7x16 wheel

Hi Bill,

You and me both, hence this thread!

In post #9, I posted a photo of the wheel that interfered w/the caliper and the resulting wear ring on the inside of the rim - that shows where the interference was...

I don't know the rotor size off hand... but the calipers are AP Racing, obviously non-stock...

http://forums.pelicanparts.com/uploa...1662494267.JPG

http://forums.pelicanparts.com/uploa...1662494267.JPG

Whew! So I wanted to close the loop on this by posting an image with some wheel profiles that I've created. They show the difference between the 2 different 911 part numbered 16x7 Fuchs I have and also how they compare to the Braid 16x7. I need to give a HUGE shout out to Paul Eddleston at Braid who sent me the Braid profile and also sent me an actual 16x7 Braid wheel to verify fitment. He also was willing to chat on the phone once or twice and email back & forth with me as I compiled the profiles and data etc...

The end result shows that the 2 911 part numbered Fuchs are indeed different. And the difference is enough, in just the right area, to allow one to fit over my brakes and the other to NOT fit over my brakes. The Braid 16x7 has TONS more room than either Fuch in that area.

Here's an image that shows the profiles overlaid over the Braid profile that I received from Paul. The pink circle indicates the area where there is interference with my brake calipers.

I hope this helps someone in the future...

http://forums.pelicanparts.com/uploa...1664469437.jpg

Very nice work!!

Who'd a thunk it

The rotors appear to be roughly stock size ~282x20 or 24

The issue is the caliper, though I've used 964 calipers on larger 930 rotors on 7x16 911 wheels w/o issue, I never recorded the wheel part #s and unfortunately they are long gone, It looks like the 964s are curved a bit more that the AP's

Here's a shot of 930s w/ 7x15 911 Fuchs


http://forums.pelicanparts.com/uploa...1664476726.jpg
http://forums.pelicanparts.com/uploa...1664476911.jpg
http://forums.pelicanparts.com/uploa...1664476911.jpg


Next question if those are stock sized rotors why the AP calipers? Doesn't make any sense to me

Thanks Bill. The car came to me with the current brake set-up. I'm not certain about the rotor size, but can check... if it's the same as stock, I'd agree that the AP calipers don't make a ton of sense - although they are 4 piston, not 2; I bet the brake pad surface area is bigger than stock... regardless, they work great! And now the wheel fitment mystery is solved - I just ordered a set of Braids too...

Thanks,
Tom

I wish your diagram had the 951 on there as well. So I have 993 brakes up front on my SC and sure enough ran into the same problem with the 044 hitting the caliper when snugged down. You and I exchanged messages about the 951's I picked up. I just got them in the mail today and the 944 clearance are just enough. Here is the 944 on the front of my SC with 993 brakes.http://forums.pelicanparts.com/uploa...1664478298.jpg

http://forums.pelicanparts.com/uploa...1664478298.jpg

http://forums.pelicanparts.com/uploa...1664478298.jpg


Side by side SC 044 and 944 951
http://forums.pelicanparts.com/uploa...1664478298.jpg

If you send me one, I'll measure the profile and add it! (and then send it back to you!) My best guess is that it's similar to the 911.362.115 profile.

I'm glad they fit over your brakes!

Best,
Tom