fill and redrill wheels?

I have a set of old BBS wheels that I want to redrill for my 928. Some googling shows me that having the holes welded up with aircraft aluminum (whatever that is) and redrilled, with steel inserts if needed, is surprisingly affordable. Opinions seem to range on the internet, from "it's totally fine, I have redrilled wheels on my track car and they've been great" to "if you do that your wheels will immediately break, your car will catch on fire, and you will die."

Has anyone had rims redrilled? If so, is there a vendor you'd recommend? I emailed a place about it but haven't heard back yet.

A lot of it depends on the geometry of the wheel, some are much more suitable for redrill than others.

If I had to pick, it would be my 3rd choice after getting the correct wheels or using high quality lug adapters.

How about some bolt pattern hub centric adapters?

Samples

They will cause some slight widening of track, but the 928 could benefit, appearance-wise, of the Wheels pushed out a little. 

Are they safe? We ran a set for the entire 2018 one lap of America...a pretty grueling environment.  No problems.

I've seen bolt patterns changed by redrilling the existing holes and adding different inserts. That only works if there is a minor bolt circle change though. What pattern are you changing to and from?

I'm not sure I'd want to take on that task. Things could be fine, or they could not.

If they're old wheels, it's likely that there's a good amount of contamination in the lug seats/holes. That will have to be very thoroughly cleaned, because welding on dirty aluminum is a losing proposition. Usually what I do when I'm filling and drilling on aluminum is to drill the existing hole oversize (to remove any crap or crud in the hole itself), back the bottom of the hole with a copper pad, and fill it from the inside using 4043 or 5356. Thing is, welding creates a heat-affected zone and will change the temper of the material. Re-drilling is absolutely possible but I would worry that, unless the wheel were re-tempered, you'd have different tempers and therefore additional potential failure points.

On clean new wheels I wouldn't worry as much, but on old wheels with many years of gunk in the lug pockets, impact stresses, and millions of revolutions I'd be a little more trepidatious. Is it possible that filling/redrilling can be done safely and effectively? Absolutely, but it's also not a sure thing.

If it were me I'd prefer adapters such as those that John linked (or just run wheels with the correct bolt pattern to start with, of course). 

From my understanding, Porsche 928s require an offset of around ET55-ET70 up front or else you get tracking and handling issues. John, those spacer/adapters look like a possible solution, but I'd have to measure. I'm afraid they'd push the wheels out too far. There isn't a ton of room on a 928 for things to go out, plenty of room to go in. My current Etoiles up front are ET51 and 16X9 and they stick out about an inch too far, for example. One interesting note: I was told they came off a 930, and when I got them the center was bolted to the front of the barrel instead of behind it. The only picture I have is from the original eBay auction a year ago:

I don't like how that looks and it doesn't feel entirely safe, though. Plus, it mars up the lips. It would certainly fix the backspacing issue, but it feels problematic, looks bad, and I'd still be stuck with 16" tire selections.

So, I have some 17" BBS RC090s I got from a junkyard for $200 a while ago that I pulled apart and refinished. 17X8, BMW bolt pattern. My plan was to get them redrilled and get new barrels and lips for them, which would essentially allow me to custom tailor both my size and offset. The plan would be 17X9 and 17X10, maybe a 17X11 rear for them big ol' meats.

Ultimately, I want a set of 17" BBS wheels for my 928. I can't seem to find any, so this feels like my solution. If anyone else can tell me how to get 17" BBS basketweaves on a 928 for less than $4 grand, I'm all ears. It seems my options are either this, or find a set of original 16s and get step-up barrels to make them 17s. Which, I'd be fine with, but the 16s alone are often 4 grand, and the barrels and lips would be another $1500.

I'd say the person doing the process is probably a bigger concern than the process itself. If they are experienced and have a good track record with doing this sort of thing I don't think you have a lot to lose. I'd keep a close eye on them for the first year of use looking for any cracking just to gain confidence in them.

If we were talking about a set of BBS RS that you just spent a pile of money on I wouldn't take the risk. A set of RC090's though that you snagged for $200, why not? Even though the price of these have gone up a lot there are still lots of them out there.

This is a company on the interwebs that specializes in redrilling. I emailed them and asked, just waiting to hear back from them. If need be, I may yank a wheel off of each car and hold the RC090s onto the Porsche and see how much room there is. If the wheel center is flush with the outer fender, the spacers won't be an option. If there's some wiggle room, I might be able to do it. I'll just have to calculate lip/barrel to get the right backspacing. 

I've been referred to this guy who is semi local to me;

https://satisfiedincorporated.com/

I inquired about redrilling a steelie for my dually awhile ago and he seemed confident and willing.

A lot of the BMW guys run fillndrills. I don't have any experience with them though.

Does the procedure involve redoing the heat treatment on the wheels after welding them?  

If converting from 4 lug to 5 lug, or vice versa, I get the need to fill and redrill. But on a  5 lug to 5 lug it seems like drilling oversize for a pressed insert or drilling a second set of holes would be better than destroying the OEM heat treatment. I'd be rather reluctant to have my aluminum wheels welded on without proper heat treatment... Which also introduces the potential for warping.

If drilling a second set of holes, I believe those already have a smaller second set of just straight-through holes. This creates two minor potential issues. First is that it's not just drilling a new hole pattern, it's milling a new hole pattern. Second is that the new hole might not totally overlap the old hole, but I'd actually be less concerned about a slight hole mismatch than the welding.

The other issue I see here, that is the same for all solutions, is that the widest part (socket counterbore) of the OEM holes are already into the radius structural radius for the face that the 'spokes' are loading into. Moving each hole outward by 5mm will push the widest part of the hole not only deeper into the radius, but potentially into the face itself. I would be much less concerned about a smaller 5 lug pattern breaking into the inner lip, and certainly wouldn't guarantee that breaking into the outer lip couldn't also cause a failure down the road. Perhaps if you could find a specific lug nut set that fits under the center cap and uses a socket requiring a significantly smaller counterbore, and keep the counterbore tigher to the socket, perhaps you could manage to not go deeper into that radius?

In reply to Driven5 :

That's something I've seen, redrilling to the Porsche 5X130 would push the holes out too far. So unless someone knows of some 17" BBS basketweaves that will fit a 928, it looks like I have two options:

1. See if the RC090 centers will fit with a spacer. If they aren't out too far, get custom lips and barrels to get the right offset/width. Cost, around $1500.

2. Splurge for 16" basketweaves, then get step-up lips and barrels. Cost, anywhere from $3-5000 total. 

I really want this to work. I've always loved BBS wheels, my fiance loves them also, and I think they're a perfect match for the 928. I don't want to go up to 18s with Cleveland roads, and 16s have a terrible tire selection.

Ehrlich wheels

I don't know if this is even an option for your situation, but I was looking at redrilling the hubs for a project that I am using some C5 parts on. 
 

Just another option I guess. 
 

https://www.fdfraceshop.com/collections/corvette-c5-c6/products/c5-c6-5x114-3-conversion-plate?variant=39766570991669

In reply to Somebeach (Forum Supporter) :

That is another option, and I appreciate it! I don't have a drill press, and I don't think I have the skill to mess with that.

In reply to Slippery :

Looks like they specialize in BMW wheels. Not much on the 17" front. Thank you, though.

I raised the 928 and pulled the wheel off. My brain was in BMW mode because I just pulled the wheel off the E90, so I was thinking lug bolts, not lug nuts. The 928 has really long studs and aluminum lug nuts, so I wasn't able to put the BBS wheel up against the hub to check for backspacing. I did a very scientific method of holding it in place and using my finger to estimate and I think the hub centric adapters might be an option as long as I get a very shallow lip. I went ahead and ordered a pair of hub centric adapters so I can put the wheels on the front and properly measure things. Fingers crossed this will work. I'll be one of the only 928s around with 17" BBS wheels, which will be cool. Although I do dread separating the faces from the barrels again. That's nightmare material. 

Here's a question: When calculating my offset using spacers, I'll include the spacers in my measurement, right?

In reply to infinitenexus :

Correct. The spacers reduce the effective offset by the thickness of the spacer, so the wheel itself needs to be a the spacer thickness greater offset than desired... If the way I said that makes sense.

45mm wheel offset - 25mm spacer = 20mm effective offset

or

20mm effective offset + 25mm spacer = 45mm wheel offset

And the offset is where the wheel mounts in comparison to the center of the wheel, right? So, assuming I put a 1" lip on there and that fits, I can increase the width of the barrel to essentially get the offset where I want it.  Fingers crossed, this will work. Fortunately, several companies make custom lips and barrels for the RC090 wheel. I can even get a half inch lip if that's what I need (which might well be the case)

(or throw a middle finger to the purists and flare it)

infinitenexus said:

And the offset is where the wheel mounts in comparison to the center of the wheel, right? So, assuming I put a 1" lip on there and that fits, I can increase the width of the barrel to essentially get the offset where I want it. 

You've got it nailed.

I do have a fender roller, so I think I'll put some work on those front arches just to be safe. I have a feeling I'm going to get pretty close to the edge with these, but it'll be worth it.

infinitenexus said:

In reply to Slippery :

Looks like they specialize in BMW wheels. Not much on the 17" front. Thank you, though.

They do exactly what you need and they do it right, fill and re-drill.

Send them a note.

It's interesting that I was just doing a search on plugging and redrilling aluminum wheels last night, and this popped up this morning.

Then another thread on the e-golf after seeing a YT video in my feed.