Building BBS wheels, advice needed

[jsveb]

Hi guys

I am having fun building some BBS Motorsport wheels for my matte Schwartz 930.

I decided on these, since I really like the bbs look with gold centers, and I think It will look awesome with the looks of the car.

The wheels are E88, I believe.

They are 18"

I have got some pictures to help understand my questions, here goes:

I need new barrels for the rears, now I need advice on how big/wide I should go. The typical thing would be 11" but if some of you have got better ideas, I'll listen.

Remember, I started out emphasizing looks. My Fuchs are really good for handling. These wheels will mainly be for show...however, I expect good handling as well.

What inner and outer barrels would you recommend.

Here are the pictures:





The first is just to give you an idea of what I've got. The second shows the centers. Which will need refinishing, and I'm a still looking for a place that can soda blast these centers. Let me know, if you know anything local to the Monterey area.

The last picture is my notes on the data

The first line shows that ( for these bbs rims) you have to add 7/16" to the labeled width, meaning a 4" rim is actually 4 and 7/16" etc.

The seal ring is 3/16. This will further increase the overall width.

The center is 6/16". This should not affect the width since the rims are laid together on the same side of the center with the sealing ring. Hence this is taken into account when considering offset. Makes sense?

The offset on the center is 12/16 this will reduce the "dish", too bad, but that's the way it is.

With this data at hand, can you help me pick the best barrels for my wheels?

Btw, this is the car in question, it is a 1978 930:

[jsveb]

Anyone?

[JFairman]

Jim Dorociak may be able to help you with the barrel sizing, do a search to find his posts and contact info.

I've restored and rebuilt BBS E50 motorsports wheels and the thicker heavier cast aluminum center BBS RS DOT spec street wheels.
Don't bead or soda blast or strip the finish thats on there now because you'll never get as good a sealed base coat over the magnesium or aluminum centers that BBS puts on there now and it's in pretty good shape with no corrosion I can see right now.
Just clean them good and hand sand the paint thats on them now with 150 to 220grit paper to smooth out any scratches or blemishes and then prime that. Then hand sand the primer smooth without burning through with 320 and then spray on the finish coats.

There is a special primer sealer that self etches into the metal those centers are made of. The motorsports wheels were usually magnesium for the lightest weight and no self etching zinc chromate or whatever primer you can buy at an auto body supply store locally is as good. Some guys say there is but they are full of themselves.

[gumba]

I run 6" inner & 5" outer x 17's w/Fuch centers on our race car, '75 Carrera IROC look. Same as a turbo body. I run some small spaces to move the wheel out. The rims are measured from the inside of the lip. Tires are Hoosier 315's. Same set up with the street tires.

[jsveb]

Gumba, I remember your car, nice!

What is the offset on those Fuchs centers? If I know this, I should be able to figure out, whether I can add back spacing since my centers are offset 1 12/16"

Jim, I don't think doroziak deals in BBS, I think I might have asked him a while back. Thanks for the tips.
How would I rough up the finish - in prep. for paint - without removing the casting structure. I prefer to keep the original finish where it is not just smooth, but a little rough.

BTW, the BBS oem gold color is NLA.

[JFairman]

I have no idea what you mean by not knowing how to hand prep sand a painted wheel center "without removing the casting structure". That makes absolutely no sense.
It's obvious you have no experience in this kind of thing at all so just forget what I said and do as you wish... and there's nothing special about BBS gold paint. No one is ever going to know the difference between it and a generic gold color especially after it has some dirt and brake dust on it.
Gold color paint is sand colored base pigment with gold colored metalic particals mixed in.. but you don't have to believe that either.

Originally Posted by jsveb

Gumba, I remember your car, nice!

What is the offset on those Fuchs centers? If I know this, I should be able to figure out, whether I can add back spacing since my centers are offset 1 12/16"

Jim, I don't think doroziak deals in BBS, I think I might have asked him a while back. Thanks for the tips.
How would I rough up the finish - in prep. for paint - without removing the casting structure. I prefer to keep the original finish where it is not just smooth, but a little rough.

BTW, the BBS oem gold color is NLA.

[jsveb]

Originally Posted by JFairman

I have no idea what you mean by not knowing how to hand prep sand a painted wheel center "without removing the casting structure". That makes absolutely no sense.
It's obvious you have no experience in this kind of thing at all so just forget what I said and do as you wish... and there's nothing special about BBS gold paint. No one is ever going to know the difference between it and a generic gold color especially after it has some dirt and brake dust on it.
Gold color paint is sand colored base pigment with gold colored metalic particals mixed in.. but you don't have to believe that either.

Easy does it!

If all the people on this board new the answers to the questions posted, this place would not exist. So thank you for stating the obvious, yes, I have no experience in this, hence the questions...

What I am trying to say: the BBS centers are not smooth like I.e. A set of RH 3.6 center "spokes", instead I can feel and see the structure in the alloy. In lack of better words, it looks grainy.

If I just sand down the original paint, I will remove some of this, and further smoothen the surface.
So what I should have asked is, is there another form of blasting ( or other ways) where I won't remove the paint, but rather just scuff the surface in prep. For paint?

[gumba]

The Fuchs centers don't have an offset, but they are .375" thick if that helps. The Fuchs sit inside the outer rim, so they don't add any width. I found the BBS rubber gasket too expensive so I bolt the wheels together, then add a bead of silicone sealer.
I would wipe down the BBS centers with mineral spirits or acetone to make sure they're clean, then paint them. No need to scuff them up.

[jsveb]

Originally Posted by gumba

The Fuchs centers don't have an offset, but they are .375" thick if that helps. The Fuchs sit inside the outer rim, so they don't add any width. I found the BBS rubber gasket too expensive so I bolt the wheels together, then add a bead of silicone sealer.
I would wipe down the BBS centers with mineral spirits or acetone to make sure they're clean, then paint them. No need to scuff them up.

Thank you

The silicone bead is what I have heard, except for on BBS Motorsport wheels. I talked to bob woodman Motorsport, that's what they said these wheels required, why I don't know? Just trying to gather information on how to proceed.

[Clay.0]

The e88/e28 wheels have a course finish, the roughness you described. This can be smoothed out with several light coats of a high build primer. Do as JFairman said, just several times and they'll smooth out.

As for color, Eastwood offers this which is very close to the original color. It's inexpensive and one can will do two wheels.

Vintage Racing Wheel Paint Gold & Silver 11 oz.



All of the 3-piece BBS motorsport wheels use the seal rings. These are meant to be taken apart and back together easily as the halves are considered to be "consumables". The seals are re-useable. This allows a damaged wheel to be repaired at the track. 3-piece street wheels typically use a silicone bead because they are not torn down as often. That said, you can use silicone instead of the seal ring. I've done it both ways. Your choice. If you don't use the seal rings the bolts will stick out 3/16" further, so be sure to get the correct length.

For the barrels width, just measure. Mount one center to the rear hub, measure to the swing arm, subtract the 7/16" bead width, and then round down to the next 1/2" to allow for clearance. For example say you measure from the mounting surface on the center to the swing arm 8 3/8" - 7/16" = 7 15/16". Round down to 7.5".

If you plan on running fat tires, subtract another 1/2".

[quattrorunner]

Originally Posted by Clay.0

The e88/e28 wheels have a course finish, the roughness you described. This can be smoothed out with several light coats of a high build primer. Do as JFairman said, just several times and they'll smooth out.

As for color, Eastwood offers this which is very close to the original color. It's inexpensive and one can will do two wheels.

Vintage Racing Wheel Paint Gold & Silver 11 oz.



All of the 3-piece BBS motorsport wheels use the seal rings. These are meant to be taken apart and back together easily as the halves are considered to be "consumables". The seals are re-useable. This allows a damaged wheel to be repaired at the track. 3-piece street wheels typically use a silicone bead because they are not torn down as often. That said, you can use silicone instead of the seal ring. I've done it both ways. Your choice. If you don't use the seal rings the bolts will stick out 3/16" further, so be sure to get the correct length.

For the barrels width, just measure. Mount one center to the rear hub, measure to the swing arm, subtract the 7/16" bead width, and then round down to the next 1/2" to allow for clearance. For example say you measure from the mounting surface on the center to the swing arm 8 3/8" - 7/16" = 7 15/16". Round down to 7.5".

If you plan on running fat tires, subtract another 1/2".

I used it, here is how it looks

[JFairman]

I used to have 3 piece BBS motorsports wheels on an old E21 chassis BMW. They were on the car when I bought it back in '95.
I think they were the E50 series for 15" tires with 4x100 bolt holes. They were the lightest wheels made with magnesium centers and thin gauge spun aluminum barrels. They were made for the track not the street so they were not DOT approved and the barrels or rim halves could bend easily if you hit a pothole.
They had the gold basket style centers and I restored and painted them gold once and then years later I painted the centers gloss black to match the car.

The rim halves were so easy to bend that BBS said to never use a tire mounting machine to mount or dismount tires so I never tried that. Instead you had to assemble the wheel around the tire and dismantle the wheel to remove the tire... a lot of labor to change tires but that's how they were.

They had the aluminum ring in the center that had a big oring in a groove on each side and BBS would not sell that oring unless you bought all new bolts for assembling the wheels at the same time. You were only supposed to tighten and use those 6mm 12 point bolts only once.

They were supposed to be assembled dry but I used blue hylomar sealent on the orings because it worked really well and was easy to clean off with rags soaked with wash laquer thinner when rebuilding the wheels to mount new tires.
That way I could reuse the orings smeared with hylmar and reuse all the bolts and it worked.

I was sick of those wheels and glad when I sold them to another BMW enthusiast that put them on a flared out BMW 2002.

[Clay.0]

The e50 series wheels use the same centers for 15", 16" and 17" wheels. The halves are stepped up to the larger O.D. while using the same I.D. The 15" halves do not "step" at all, they are flat. There is no room to mount a tire with a tire machine, that's why 15" wheel have to be assembled with the seal rings inside of a tire. It isn't physically possible to mount with machine. Larger diameter wheels can have tires mounted after assembly, jsveb shouldn't have any issue with that.

The e88's that jsveb has use different hardware than the e50's. It looks like his use a nut and bolt, and the centers mount from behind, where e50's have press-in nutserts that mount on top of the halves. So he shouldn't have the same hardware issue either.

[65rsr]

Both of these racing tire guys are super helpful and knowledgable have new and used parts, maybe the BBS powder paint also, for the BBS motorsports wheels.

SascoSports Inc is a full-function racecar preparation restoration shop

Sports Car Racing Tires - Performance Track Tires & Vintage Race TireBob Woodman Tires

[Blaine Sellie]

I'm running the same 18" wheels on my 930 using the following-

Front- 6" inner and 2.5" outer
Back- 6.5" inner and 4.5" outer

Bob Woodman Tire most often times has used parts. Last month I bought two outers, they were shipped new from BBS.

[jsveb]

Thank you very much for the advice. I think, even I got it

Originally Posted by Clay.0

The e88/e28 wheels have a course finish, the roughness you described. This can be smoothed out with several light coats of a high build primer. Do as JFairman said, just several times and they'll smooth out.

As for color, Eastwood offers this which is very close to the original color. It's inexpensive and one can will do two wheels.

Vintage Racing Wheel Paint Gold & Silver 11 oz.



All of the 3-piece BBS motorsport wheels use the seal rings. These are meant to be taken apart and back together easily as the halves are considered to be "consumables". The seals are re-useable. This allows a damaged wheel to be repaired at the track. 3-piece street wheels typically use a silicone bead because they are not torn down as often. That said, you can use silicone instead of the seal ring. I've done it both ways. Your choice. If you don't use the seal rings the bolts will stick out 3/16" further, so be sure to get the correct length.

For the barrels width, just measure. Mount one center to the rear hub, measure to the swing arm, subtract the 7/16" bead width, and then round down to the next 1/2" to allow for clearance. For example say you measure from the mounting surface on the center to the swing arm 8 3/8" - 7/16" = 7 15/16". Round down to 7.5".

If you plan on running fat tires, subtract another 1/2".

[jsveb]

65rsr, thank you.

Blaine you've got an awesome car, the wheels look amazing.

You guys have given me enough courage to proceed, i will report when, I have made some progress

[jsveb]

Today I spent some time to try and figure out what I need.

I was actually able to use my 8" inner barrels. With the offset on the centers it translated into a backspacing a little over 6". This leaves about 20mm to the bolt on the trailing arms that is going to be closest to the tire. I could actually go to 8.5" on the inner, but I think 8" is just fine.

The outer is a little more difficult to measure since I can't really confirm my calculations with the car jacked in the air. However, I think I am going to end up with a 3" outer.

Here is a picture of a 4" inch outer. It obviously doesn't work, but it is just to give you an idea. The next photo is with a 2.5" outer.

Tell me what our think. 3" is the safe bet and will give me an 11" inch rear wheels, which seems to be the norm.

I prefer meaty tires over ricer look, since this car is ol' skool with Cibies etc, but let me know what you think.

4" outer


2.5" outer


I actually think I am going to use a silicone bead instead of the sealing rings, simply because of the look with the two barrels on the center, but that's not final yet.

[TimT]

Here is a picture of a 4" inch outer. It obviously doesn't work,

You cant tell what rim half or tire will fit while the suspension is at full droop...You need to jack up the trailing arm using another jack such that the axel is close to where it will be when the car is on the ground... then check clearances

[jsveb]

I did as TimT suggested and jacked up the trailing arm. Here are the pictures, I pretty much think they confirm the preliminary conclusion from the measurements.

With 4" outer, it could work with a stretched tire, not what I am aiming for:

This is with the 2.5" outer. I think a 3" outer would work nicely, what do you think?

Still 2.5" outer:



Yet another one just to show the gap on the 2.5":



Let me know, if my conclusion is off. I am thinking 3" outer and a 8" inner for a total of 11" ( which is what most run) the center is offset, so the backspacing is about 6.25". This leaves about 20mm to the nearest bolt on the trailing arm.

Edit:
Forgot to mention, for paint I'll probably be using this:
http://www.grimmspeed.com/catalog/product_info.php?cPath=89&products_id=144

I have researched online, people say it is a closer match than the Eastwood, which did also receive good reviews.