What variation in weight is normal within a set of Campagnolos?

The relative difference in weight is impressive.
I am surprised however there is absolutely no distinctive feature in the casting of the wheels, mag or alu.
Usually the mag castings are rougher than the alloy castings, and there are often cast markings or specificities on the wheel, especially on the inside. Also thickness differences in e.g. ribs.
Have you thought also of a possible difference in tire weights?

 

Art,

I'd never powder coat an older magnesium alloy wheel. My newer magnesium wheels on my Ghibli Open Cup were simply painted. Those were track only rims. You want to be able to see anything developing and powder might hide that. People who tried to use them on the road version of those cars had lots of crack failures. I ended up getting aluminum 3pc racing wheels custom made for that car so that the originals could be preserved and any track incidents could be easily be repaired. But the weight difference is enormous and you can actually feel the car accelerate better with the mag rims. It's substantial. Refinishing my Espada's Campagnolos was an enormous task. Those are a beautiful design but a terrible casting. The reproductions are all aluminum which is what most restorers use on the Miuras.

That weight difference is quite alarming, something is quite screwy. Dismounting all the tires is a big PITA but I think it's called for. I never have refinished the rims on my Bora and I had one that developed a slow leak so it got sidelined. Sorry but it's in very long term storage at this point so I do not have access. Otherwise I'd weigh it for you. Someone must know the number maybe McGraths?

 

B Shorey here (bs), I'm the guy with the wheels Art mentioned. Some of you might remember me from the days of the old Yahoo Group list.

Anyhow, the wheels are all restored and powder coated, that's done and there's no going back. New tires on all five of them. The weight difference is definitely in the wheel, not the tire, and fwiw it's 6-1/2 lbs. It was the guy at the tire shop who picked up on the weight difference, I grabbed one of each before the tires were mounted and it was significant. At that point I probably should have just gone home with the wheels and perhaps cut them all up for some proper metallurgical analysis and the good of humanity, but I'm hoping to drive my Bora again after 10+ years, so I went ahead and got the tires mounted.

I have chiseled a small chip from the damaged wheel and have sent it off to a metallurgist friend of mine and Arts. So soon we will know the compound of the heavy wheels that were original to my Bora. Then the mystery becomes what the heck is the other wheel made of.

The odd wheel was purchased maybe 15 years ago from EBay. Some of you also might remember that, a bunch of us on the Maserati Yahoo Group who only needed a single wheel each got together and purchased a set of wheels that showed up on EBay, and we each ended up with one. So somewhere, there are 3-4 other Bora owners who might have the same mystery as myself.

The markings are identical on all wheels. I can provide pics if you want. There is zero indication that this odd wheel is anything different from the other five, other than the significant weight difference. If I learn that this lighter wheel is some modern repro, I'd actually be more than happy to buy another four of them and make them the working set of wheels for my Bora.

bs

 

Looking forward to hearing the results Brian. So why not send a small sample of the other one as well?

 

Two reasons. First, I've got no problem taking a chisel to a busted wheel, but I do have a problem taking a chisel to a perfectly good (and expensive) wheel. And second, all but the physically broken one have been powder coated.

bs

 

It has to be that intrusive/destructive?

 

Don't know. But I'd have to scrape through the new powder coating to get any kind of a sample, and I'm not willing to do that. I took a fingernail size sliver from the broken wheel to send to the metallurgist.

In hind sight, I'd have done this before the powder coating. But as nobody picked up on it until after the powder coating, here we are.

bs

 

The hub faces of the wheels surely aren't powder coated right?

Just a thought ...

Hope your car is finally getting close?

 

They are. Given the whole porosity thing, my understanding is that you can't leave any area exposed. Anyhow, a friend out here who does high level restorations on Alfas used a shop that he does business with, between the two of them they've forgotten more about this stuff than I'll ever know. I trust their abilities, they know what needs to go on the face, the hub, the mating surfaces, etc etc.

The car is very close. I moved to Ca 10 years ago, the car has been sitting in New England since I left. I finally gave up on the shop that was supposed to paint it back east and dragged it out here last fall. I've got the calipers off and apart right now, whomever rebuilt them I think didn't use proper LHM rubber bits, so they were all seeping. And of course I've now realized, that even though I have not driven it in a decade, I should probably be replacing/refreshing the accumulators that I replaced and refreshed maybe 12 years ago before I start pouring LHM back into the system. Why not, I just replaced the old tires that probably only had 200 miles on them.. It never ends, does it?

Anyhow, going to pull them off this weekend and send them somewhere, and maybe try to get the calipers back together and put back on the car.

I've owned this car for 20+ years and have probably put less than a thousand miles on it, none in the past decade. Now that it's here in Ca with me, that's going to change.

Whoo hoo!!

bs

 

Well you really do not want powdercoating on any of the surfaces which are used to secure the wheel to the hub as it can fracture under torque tightening and then you'll have quite a problem. I watched a very new Lotus Elise go right off the end of the long straight runway at Lime Rock because the guy had not observed this caution. That includes the lug nut recesses especially.

 

https://www.matsuk12.us/cms/lib/AK01000953/Centricity/domain/3676/Physical%20Science%20Web%20Page/Ch%2013/Story_of_Archimedes.pdf

 

I think Harbor Freight has those for $22.00 now ...

 

Since we've been talking about alloy wheels and how they get properly treated I wondered what people think of this methodology.

Repairing and refinishing alloy wheels for daily drivers is a big deal here in the NE of the USA.
There's a place in Fairfield, NJ that will take your car, put it up on jack stands, remove the wheels, repair and replace the tires all in a one stop two day operation. $160/wheel for 20".

I have need to refinish all 4 wheels on a car I just bought. It needs new tires as well so I find this very appealing.

Upon inquiring I learned that all they do is powder coat. That's OK with me for modern wheels. When I asked if they powder coat inside and out (I'd heard that they do not) he said they do the front and back of the wheels plus about 1/2" into the bead area. I was flabbergasted as to why they don't do the entire rim. I even asked if I could pay more to have that done. He said no and told me that they don't because it's a waste of money.

Something sounds fishy about this. So I'll end up with raw bead blasted alloy inside the tire. How can that not cause problems and why are they really doing it this way?
I've also heard that some American OEM wheels are finished this way?

 

Maybe they don't do the bead area because:
- it's hidden;
- alloy does not oxidise (apart from an ultra thin layer of aluminum oxide) and remains perfectly air-tight; and
- they only refurbish the bead areas in contact with the tire, to avoid leaks.

Mag would be a different story as it may become porous, crack and leak througout the material.
A professional chromate treatment by a specialist is the only valid protection of mag to avoid these issues.

 

They claim they do go into the bead area but how far is open to debate IMHO. They got a bit testy when I began asking these questions.

The lack of corrosion on aluminum rims on the bead area has not been my experience. I have a set of 3 piece Hayashi rims on my 84 Biturbo that I bought new in 1985 and they've worked out great but about 4 years ago it was time had to rebuild them and in the process I developed some slow leaks which my very reputable tire shop suggested was due to improper sealing of the two split rims so I chased that twice and then we looked at the bead area which wasn't perfectly surfaced even after I had tried to clean it up a bit. The spun aluminum rim halves never had any finish just a great polishing on the outside halves. So we then tried some bead sealer and all the slow leaking was gone. That has never seen road salt and only snow in the California Sierra mountains where they don't use salt. It's road salt that causes these rims to be refinished now.

My tire installer of 25 years who is hooked up with all the sports car clubs has a ton of experience and it's he who old me that OEM rims from some of the American car manufacturers were using rims made WO a protective finish on the inside. He also rightly points out that moisture does collect inside of tires over time, hell sealer they use probably is water based.

I find the OEM rims thing hard to beleive but I also can't explain this vendor's methodology and he's the 900 lb Gorilla in this business around here. I think I'll look at some more vendors.

 

I've moved on to another place that actually does the entire rim for the same price. But this approach seems fraught with potential issues. It's a good reminder that it's still very much a caveat emptor world out there.
Homework is tedious and time consuming but typically quite necessary.

I still can't fathom the weight difference in Brian's wheels. Something doesn't add up. Let us keep Hercule Poirot on the case!