Rear wheel position mystery on 911SC

[octanemaestro]

I have a 911SC Euro in a land far, far away from a plethora of mechanics. The car is pretty new to me and I just noticed that the entire right rear wheel seems a bit too far outward (toward the outside of the fender) and the left rear wheel seems MUCH too far inward toward the center, like by several inches. I don't have the history on why this would be the case. Does anyone have a guess as to what is the likely culprit, maybe that driveshafts are not original from two different cars? Any suggestions about how to fix whatever caused this? What's typical?

I am attaching pictures of the left and right side. I can take additional pictures if it would be useful. Any help would be appreciated...




When I view the pictures on my computer they are oriented properly, but after they are uploaded on Pelican they are 90 degrees off...annoying, sorry about that!

[tdw28210]

Missing a wheel spacer?

[octanemaestro]

It has 7x16 wheels on the front and 8x16 wheels on the rear. Neither side has spacers currently. But should they have spacers? I do have some extra spacers laying around from the aftermarket BBS wheels that came with the car before I put on these Fuchs.

[82 SC]

I think you will have to pull the wheels and measure each side and wheel to see what is up. It does look like a spacer is missing on one side, strange to say the least.

[tdw28210]

Originally Posted by octanemaestro

It has 7x16 wheels on the front and 8x16 wheels on the rear. Neither side has spacers currently. But should they have spacers? I do have some extra spacers laying around from the aftermarket BBS wheels that came with the car before I put on these Fuchs.

I am "wheel offset challenged". : ). Wait for the true experts to weigh in. Has the car had rear flares added to it?

[GeorgeM]

Just about every 911 I've seen has a difference between left and right sides in the rear. The right side is always the one with the wheel further in.

Although, maybe it's the camera angle, but I haven't seen that much of a difference before.

Previous accident damage perhaps?

[Bill Verburg]

Originally Posted by octanemaestro

It has 7x16 wheels on the front and 8x16 wheels on the rear. Neither side has spacers currently. But should they have spacers? I do have some extra spacers laying around from the aftermarket BBS wheels that came with the car before I put on these Fuchs.

there are 2 fundamentally different versions of both 7 & 8 x16 Fuchs

for 7 it's a relatively minor difference between the 911 7 ET23.3 and the 951 7ET23.3, the 951 wheel has more caliper clearance.

for 8 it's a more significant difference. The 911 8x16 has ET 10.6, the 951 8x16 has ET23.3, this means that the 911 8x16 wheel projects 12.7mm more out board than the 951 8x16.

You can see the difference w/o pulling the wheels and reading the backs, the 951 8 has recessed lug nut holes, the 911 wheel has the more usual projecting lugs.

No regular production street 911 ever used spacers w/ stock Fuchs from the factory(exception the 911R, used spacers in back but that wasn't a normal street car), 930 did and some owners have installed spacers to get the wheels closer to the lips w/o purchasing new wider wheels w/ correct ET.

[octanemaestro]

To clarify, these rear wheels are repro Fuchs by Euromeister (ET10.6) which are supposed to emulate '87 911 Fuchs except perfectly fit a stock '81 911SC Euro according to the phone technician.

Someone asked whether flares were added...I don't think so. I don't feel any fiberglass or riveted metal and the fenders don't seem especially wide.

This is really bothering me even more...the left wheel is about 10cm deeper in to the center of the car than the right wheel. The distance from the rotor rub surface to the outside of the center of the wheel is the same so the rotor model or size being different left to right or missing spacers (at least spacers that would against the wheel surface) on one side are not to blame.

I am adding some pictures from underneath..I can hardly get my hand into the left inside tire area because the wheel is so far in. The right side was much easier to get my hand and camera on the inside part of the tire area than the left. Something is definitely very, very wrong.

Below you see a left side measure of about 12cm. The same measurement for the right hand side rear wheel is about 5cm.

[LeftCoastErik]

It's gotta be an offset issue. Pull them and measure them to verify they are the same. Otherwise, the it's going to be bent suspension. But with that much difference I doubt that the car would be alignable

[Chuck.H]

Are you sure it isn't an alignment issue? If you have a little more camber on one side it will push the top of the wheel inward and give this illusion.

Chuck.H
'89 TurboLookTarga, 423k miles

[octanemaestro]

Originally Posted by Chuck.H

Are you sure it isn't an alignment issue? If you have a little more camber on one side it will push the top of the wheel inward and give this illusion.

Chuck.H
'89 TurboLookTarga, 423k miles

I really hope it's an alignment issue but I am pretty sure it's not because the wheel center hub is about 7cm deeper in on the left than it is on the right. I will measure again.

[octanemaestro]

Originally Posted by LeftCoastErik

It's gotta be an offset issue. Pull them and measure them to verify they are the same. Otherwise, the it's going to be bent suspension. But with that much difference I doubt that the car would be alignable

The car drives fine without feeling like it has out of whack alignment.

Do I have to pull the wheels to measure offset? It's so far off shouldn't I be able to measure it roughly while on the car?

[rnln]

I would check the wheel size/offset. Then camber. Then measure the distances between the hub to the vertical/level line of the fender lips.
Yeah, hope it is alignment issue.

Originally Posted by octanemaestro

The car drives fine without feeling like it has out of whack alignment.

Do I have to pull the wheels to measure offset? It's so far off shouldn't I be able to measure it roughly while on the car?

[tdw28210]

Originally Posted by Bill Verburg

there are 2 fundamentally different versions of both 7 & 8 x16 Fuchs

for 7 it's a relatively minor difference between the 911 7 ET23.3 and the 951 7ET23.3, the 951 wheel has more caliper clearance.

for 8 it's a more significant difference. The 911 8x16 has ET 10.6, the 951 8x16 has ET23.3, this means that the 911 8x16 wheel projects 12.7mm more out board than the 951 8x16.

You can see the difference w/o pulling the wheels and reading the backs, the 951 8 has recessed lug nut holes, the 911 wheel has the more usual projecting lugs.

No regular production street 911 ever used spacers w/ stock Fuchs from the factory(exception the 911R, used spacers in back but that wasn't a normal street car), 930 did and some owners have installed spacers to get the wheels closer to the lips w/o purchasing new wider wheels w/ correct ET.

Bill, you were one of the experts I was hoping would chime in here. Thanks.
Q: Didn't the M491's come from the factory with stock Fuchs and spacers? pretty sure my '85 did.

[javadog]

I would put the car on a lift and check for collision damage.

JR

[techweenie]

If the offset and size are the same on both rear wheels, there is likely a chassis tweak.

I had that on a 73 many years ago and discovered the torsion bar tube was bent, despite no visual indication of chassis trauma. That is not an easy issue to tackle, and in my case, it was a low buck track car, so I had my alignment shop bend the spring plate to compensate for the angle of the torsion bar. Worked fine as a 'field expedient' fix.

Anyone who has been around 911s a few decades has run into the differing positions of wheels in the rear - and to some extent in the front. In my experience, it's always related to chassis "history."

[OsoMoore]

My '79 SC is about one half inch off center (comparative difference from wheel to fender is one inch). That's a standard error due to hand manufacturing. This looks significantly larger.

[LeftCoastErik]

Yes. Pull wheels. Straight edge across inside wheel edge. Measure to back pad of wheel.

[Peter Zimmermann]

Take a good picture of the left and right sides of the inside of the engine compartment. It's very possible that your car has been rear-ended, has a damaged frame rail, and when repaired wasn't done correctly. What I need to see is the rubber seal/engine tin area below the spark plug wires... A sure give-away is if you can see the road below one side (between the edge of the rubber seal and the engine tin), and find that the engine tin is tucked in under the frame rail rubber on the other side.

[Bill Verburg]

Originally Posted by tdw28210

Bill, you were one of the experts I was hoping would chime in here. Thanks.
Q: Didn't the M491's come from the factory with stock Fuchs and spacers? pretty sure my '85 did.

yes, but that's a 930 chassis and running gear not 911, both chassis were fitted w/ the same Fuchs

while looking into another separate issue I did find that the '68 911 w/ 5.5x15 Fuchs did use 7mm spacers in back