Super RS question

[lowlydubb3r]

I'm not sure if anyone would know but here goes:
I got a set of BBS Super RS's and had them up-converted from 18" to 19". Originally the wheels are 2-pieces and the face was mounted in the rear of the barrel/lip. With the step up the wheels are now 3-pieces and initially the wheels were assembled sandwich mounted. I am wondering if it would be safe to assemble the wheel with the face front mounted to gain a bit more clearance?

Here's some pictures for reference:

[1badg35]

what does the back of the face look like? The back of the face would need to be machined in order to sit over the lip and barrel in order to properly face mount.. I am pretty sure it isnt machined enough to be able to sit over the thickness of the lip and barrel which is about 4-5mm thick when you add the two pieces up

did whoever converted these wheels machine the back of the face for sandwich mounting? If they did, the face is already thinner than original, so I wouldnt suggest machining any further.


*with all of this said, people face mount improperly all the time, and I have yet to hear of a failure. I wouldnt personally ever do it unless it was machined properly for it, but I know of many people who run faces improperly and drive through manhattan streets without issue.

[lowlydubb3r]

what does the back of the face look like? The back of the face would need to be machined in order to sit over the lip and barrel in order to properly face mount.. I am pretty sure it isnt machined enough to be able to sit over the thickness of the lip and barrel which is about 4-5mm thick when you add the two pieces up

did whoever converted these wheels machine the back of the face for sandwich mounting? If they did, the face is already thinner than original, so I wouldnt suggest machining any further.


*with all of this said, people face mount improperly all the time, and I have yet to hear of a failure. I wouldnt personally ever do it unless it was machined properly for it, but I know of many people who run faces improperly and drive through manhattan streets without issue.

I was hoping you were going to put forth your opinion Vince. So to answer your question the face itself has not been altered around the assembly surface. And the wheels were assembled by a local wheel shop that did the sandwich mounting only did it because that's the way normal RS's are assembled. I was hoping that I could front mount the faces since the original build of the wheels seemed similar to LM's.

So if I wanted to front mount the faces what would you suggest me doing? Are you still bogged down with work from last year?

[1badg35]

post up a picture of the back of the face, and I can look into it. Also take a measurement if you dont mind with the thickness of the bolt shelf on the face (the part of the face that the bolts go through- should be approx 3/8"-1/2" thick).

typically I like to keep a face as close to 1/2" thick at that point on the bolt shelf as possible, as there are many stress points there if it is mounted in an "improper" fashion. If it has this thickness though, the back of the face can be machined down to accept face mounting. Weve done it a few times before on our machines. Pretty straightforward if you have the machinery


side note, I work 60-70 hours as a design director for a large corporate firm, and then run my studio in the off hours, so its always hectic. haha. Everything is good though, lots of new things in the works for 2014. early winter is always a slight bit slower, so it allows me to catch up on decision making for the many wheel builds going on at the studio

[lowlydubb3r]

post up a picture of the back of the face, and I can look into it. Also take a measurement if you dont mind with the thickness of the bolt shelf on the face (the part of the face that the bolts go through- should be approx 3/8"-1/2" thick).

typically I like to keep a face as close to 1/2" thick at that point on the bolt shelf as possible, as there are many stress points there if it is mounted in an "improper" fashion. If it has this thickness though, the back of the face can be machined down to accept face mounting. Weve done it a few times before on our machines. Pretty straightforward if you have the machinery

I'll take a photo later when I get off work. The bolt shelf you speak of is where the assembly bolts go, right? Not where the lugs go?

[1badg35]

yes, where the assembly bolts go through the face. basically the thickness of the outermost diameter of the face

[lowlydubb3r]

Looks like it's 3/8". I took some pics of the surfaces too if that helps any.





I contacted the company to see what they suggest is the assembly too, so we'll see what they advise.

[1badg35]

so, technically those were improperly installed the last time around when they sandwich mounted them.. the way the front of the face has the drop and the rear doesnt means this set was initially intended for the face to be rear mounted. the drop is intended to locate the face physically inside of the barrel/lip so as to lock the two parts together snugly prior to assembling with bolts.

So now what does all of that mean... the face being sandwich mounted at least still had itself locked into the outer lip when being sandwiched. Face mounting would not have it locked into any of the wheel halves, putting stress on the bolts. the bolts are not made for shearing stresses, so I would not recommend to do this to the set. Could be improperly loading stress where it is not needed.

the only way to compare would be someone running a set of wheels with a larger centerbore than the car. The wheel floats loosely around the centerbore and thus putting additional stress on the studs, bolts, or nuts that hold it to the car.




-- now solution or part solution would be to machine the back of the face down to mirror the depression that is on the front of the face. positive and negative here. You are thinning up the "bolt shelf" thus making the wheel less strong, but by machining the groove for sandwich mounting, you are strengthening the wheel as it locks in the face, lip and barrel when sandwiched.

if the face was thicker, I would suggest machining the back of the face down 4 or so mm so you could face mount and have it lock onto the parts when face mounted, but the issue is that the bolt shelf in this scenario is only 10mm or so (3/8"). removing 4-5mm of material would only leave you with 5mm of material, bordering on thin..


with that said, people run things like this all the time without thinking much about it. Just figured I would put all of the info out there so everyone is aware of the implication.


not a horrible idea to sticky this thread for future questions that may pertain to this

[lowlydubb3r]

Well that's bad news for my plans but at least I know my options. I guess I'll figure it out. Thanks for your help.