New 911R Fuchs offset idea

[CamB]

So looking at the pics of Waynes 9x16s has got me thinking AGAIN about 911R offset 7" wheels.

Background info:

I've got an early car with no flares at the back and plenty of power - too much for 205/50R16s on 16x6" wheels. I also have extra crap weight distribution (SC-based engine rather than mag case engine). Despite other people's possible experience, there is no way in hell I am fitting 225s in the back - rolled guards or otherwise - on a 23mm offset 15 or 16x7"wheel. I don't want to add flares.

A solution is 15x7" 911R wheels at something like $1000 apiece. No thanks. 911R wheels have an extra inch of backspacing over the equivalent 15x6" wheel. Regular 15x7" (and 16x7" ) Fuchs have the same backspace as a 6" wheel with greater, errr, "frontspace".

Wayne's wheels go me thinking.

For reference - pics of his wheels are here and here.

They are a 6x16" wheel with a wheel half from a 3 piece wheel stuck on the front. Presumably this involved machining off the outer rim on the 6" wheel and it appears from the photos that the new outer half is held on by cap screws in drilled/tapped holes in the wheel centre.

My questions:

- could this be done on the BACK of a 16x6" wheel to make a 16x7" wheel with an extra inch of backspacing - I don't have a wheel to look at at the moment to see if there would (or could) be a flat mounting surface?
- is the method of mounting the rim half on Wayne's wheels strong enough (drilled and tapped in alloy). Most 3 piece wheels I see have bolts/nuts right through, I think?

The beauty of this mounting method is that by drilling/tapping and attaching by screws (on tha back), there would be no external evidence of widened wheels. In other words, it would still look like a 16x6" wheel (and would match the front), but would be 7" wide and allow the use of a 225 tyre. I realise I would need to check wheel well clearances - spring plates and oil lines in particular, and may need small spacers.

Well, what do you guys reckon?

[Bill Verburg]

here's the relevant section from the data I've been collecting(Still looking for more contributions by the way )
note that both front space and back space are different on the 6and 7R

[Matt Smith]

Sounds good to me Cam. No reason why you can't do the same on the back as the front.
The prob would be the drilling & tapping to ensure strength. How about going the time cert rout if it's looking dodgy going straight into the metal>
Then you'd have to certify it I guess. Arrow Wheels are good blokes from what I hear- give them a bell.

Or splice on some RSR 'glass hips with pop rivets & a spatula sized gob of bondo for good measure.

[mjshira]

never say never, I am running 16x7's on the rear of my non-flared 69 911. The inside lip of the fender at the top needs to be cut away (this does not show unless you have the wheels off) and then some camber work and you'll be good to go

[CamB]

Thanks guys. Any more opinions (especially on the strength)?

I'm still gonna say never. The 205s are about 5mm from the unrolled fender lip - rolling might give me a whole 10mm (and I'd want some clearance!). I am already running around 1.5 deg of camber (from memory).

Then you'd have to certify it I guess.

The joys of New Zealand. I've already done this once. I don't want to pay again. I guess I better give Arrow a call...

[CamB]

I'm gonna bump this. Normally engineering opinions abound around here.

[dvkk]

Why not have the 6x16 widened by welding in a band? It would be stronger and you wouldn't have to worry about air leaks.

[island911]

Yeah, welding in a band could be a good way to go. Maintaining concentricity would be the tough part of that approach.

The approach that was used for Jack Olsens 17's seemed like a winner. (take the centers out of 6's, slip heat-expanded custom size outer rim over, weld in place)

That approach gives a lighter, and cleaner finished product.

Another approach may be to simply have the inside of the rim spun out to the wider dimension. . . . if there is enough meat there to do this. (though there likely isn't) --just a thought.

[CamB]

I reckon getting a band welded in is too expensive as you probably need ANOTHER pair of wheels to sacrifice the band. Fuchs wheels don't grow on trees in New Zealand.

I wondered about the Jack O way. I also wonder if it would work with 16s not 17s? It certainly wouldn't look exactly the same as a 16x6"when it was done.

[Paul Thomas]

Cam,
I'm with you buddy, i think about this ALL the time. How can i fit 225/50 in the back? My 205/55 on 7's fit just fine with rolled lips and no -camber, but i want the extra meat of the 225, especially if i get shorter gears this winter.

I would talk to Lindsey Racing, but i dont want 17's.

Why not just add 1/2 inch to the inside and make it a 7.5 incher? Did the R not use a spacer to clear the spring plate?


Paul

[island911]

Originally posted by P-THOMAS
Cam,
I'm with you buddy, i think about this ALL the time. How can i fit 225/50 in the back? . . .

Ah, more SC envy. MUHAHAhahahah . ..
give in to the siren call of the SC's 3.0 liters of under-stessed displacement. MUHAHAhahahah . ..

cool flairs too.

Anyway, if you were to have a band welded in I doubt that you would need ANOTHER pair of wheels to sacrifice, to get the band.
. . .though you would likely need another pair of wheels to sacrifice for the first two screwed up, by the welder.

edit:
Oh, and I too would suggest you talk to Lindsey Racing . . .that would be a great product opportunity for them.
(read: unlike the ubiquidous, perfectly sane, SC owners, there are lots of nutty early guys)

[CamB]

Why not just add 1/2 inch to the inside and make it a 7.5 incher? Did the R not use a spacer to clear the spring plate?

I'm too lazy to measure up, but since the 7" goes "outwards", this means you can't run 225s and, presumably, you are fractionally worse off with 205s than I am (albeit it fits). I reckon I could fit 205s on a regular 7" wheel too... just. It stands to reason the tyre would be 1/2" further outwards. So... if you gained another 0.5" inside, it would move 1/4" back the other way, but add another inch of tyre with (1/2" each side) and you get (geeez, where am I?).

Err, I'm making drawings now, where is my calculator

OK. I'm starting from scratch.

Bill's info is very useful for this:

- a 911R wheel has 145mm backspacing, of which it appears that 135mm would be optimal (as a 10mm spacer is apparently usually needed)
- it lists all the other stuff necessary

OK. I've decided to go for the black box version of this calculation.

I THINK, based on an 8.4" wide S-03 in 205/55 (or 205/50) and 9.3" wide for 225/50), what you have to contend with is:

- a 911R wheel with a 225 would have 146mm backspacing, plus the tyre is 20m wider than the rim. Total distance from hub to tyre is 166mm. Add 10mm spacer - you have 156mm from tyre to hub mating surface
- a 6" wheel with 205s will have 121mm backspace, plus about 21mm tyre each side. Total only 142mm (ie 1 inch less than 911R, but only about 1/2" less than spaced 911R)
- a regular 7" wheel with 205s is 121mm backspace plus 5mm tyre, gives only 126mm - heaps of room on the inside (must be less on fender side)
- a regular 7" with 0.5" extra backspacing (ie 7.5") is 133mm backspacing, and 20mm of tyre, giving 153mm - close enough to 911R with 10mm spacer.

So yeah, it would probably be good. At least on my piece of paper. Its never that simple, right? Besides, it would LOOK like a 7" wheel (I have a set of 6s, but as an alternative would like a set of 7s, but I think mixing and matching on an early car looks wrong).

This whole thing will probably never happen for me. I need to find some way of getting a 225 up in the wheel well, but I know it is going to be extremely tight, even with the correct offset...

give in to the siren call of the SC's 3.0 liters of under-stessed displacement. MUHAHAhahahah . ..

Hahaha - last I checked both Paul and I had stripped the everything of value from an SC (ie the engine case - me = 3.2 short stroke, Paul = 3.5) nobody mention rust, nobody mention galvanising

[dvkk]

I had 4 Fuchs cut and welded a couple of months ago. Concentricity is not a problem for a shop that does it on a regular basis. They've "learned" on other guys wheels already.

[Bobboloo]

From what I've read. 911R wheels can be made from two deep six wheels by cutting and rewelding to give you the extra inch of positive offset. Then you need the half inch spacer like Paul mentioned to clear the suspension on the inside as was used with 911R wheels.

You could do the same with regular sixes but it wouldn't look like a 911R wheel.

[Cornpanzer]

I have had a local machine shop cut and narrow some aluminum wheels for me several times. They are going to make me a pair of 15x7 R wheels out of some early 6's that I have as soon as aI can find another late 15x7 donor wheel to sacrifice. No big deal at all to cut and weld the wheels if done by a reputable shop

[andyjboy]

I also had a pair of deep dish 6's widened (by welding in a band) to 911R (49mm offset) spec recently :





Andy
'69 911E------->R

[Tspringer]

What is really needed here is referral information for a proven and reputable shop that can do this modification. I have some old wheels to use as donors.... but I dont have anyone I trust to do the mod.

Who can do it, where are they, and how do we contact them? Perhaps a group buy effort?

Why is Pelican not having this done and selling the resulting "R" wheels? There is certainly enough demand!

Terry

[CamB]

OK, so lets assume welding in a band is by far and away the best option. It is also not an option in New Zealand (right now there are probably zero 6x16s for sale, and although I intend to sell a pair of regular 7x16s, I'm not gonna cut them up instead.

I also get the feeling that welding in "something else" is a bad idea.

I might try contacting one of the three piece wheel manufactuers in the US (the on in NZ hasn't replied yet).

[nick-moss]

Andy

Who did the banding?

[Cornpanzer]

Originally posted by Tspringer
What is really needed here is referral information for a proven and reputable shop that can do this modification. I have some old wheels to use as donors.... but I dont have anyone I trust to do the mod.

Who can do it, where are they, and how do we contact them? Perhaps a group buy effort?

Why is Pelican not having this done and selling the resulting "R" wheels? There is certainly enough demand!

Terry

Terry,
I can have my guy do a pair for you when he does mine. I have the donor wheels that I need now.
PM me and we can discuss the details
Dave