Wheel spacer question…

[A930Rocket]

I know the debate/pros and cons of spacers, so let’s set that aside.

If you were going to use a bolt on wheel spacer, would it be preferable to use a steel spacer with thread in race studs and nuts or aluminum spacer with press in studs for the wheel side? Weight is a concern, but safety is priority.

The hub side will be held in with factory lag bolts.

My 330, currently has the thread in studs with Loctite. I currently use MSI studs with about 15 mm of engagement.

For some reason, I always think that a press in stub with a flange, is a stronger system. I have no information to back this up.

Thoughts?




Current set up with no spacer.



Current set up wheel studs with 30 mm spacer.

[asphaltgambler]

I'd be more concerned that the spacer fits hub-centric to the hub and has protruded hub-centric for the wheel. I believe the threaded stud into the spacer would be a better choice.

[Scott Douglas]

I'll see if I can get my brother to take a look at your diagram and give an opinion. He's a pretty sharp mechanical engineer.

He's probably out working on his stuff now so it will more than likely be afternoon before he sees my email.

[David]

I'd go aluminum. I researched this recently and couldn't find any issue.

I could run an FEA model but there are other things I could do that for that are less well known.

[cockerpunk]

i would think aluminium with pressed in studs would be safer. it might not be stronger, but it has less failure modes. ie, the two ended studs make my nervous in a way a pressure fit stud doesnt.

[bleucamaro]

For material, I've only seen aluminum.

I think the bigger issue is stud length and thread engagement.

The only hub spacers I've used are actually hub adapters to fit Porsche wheels on my 190e merc. They bolt to the hub and have their own studs. They're made by H&R so I trust them.

[MMiller]

Aluminum is all I've ever used on multiple Jeeps that were wheeled hard.

I have purchased from this outfit in NV.. USA made

https://www.motorsport-tech.com/

I think they will build you what you need if it is not a stock size they carry

[b2524]

I have a couple questions.
First off how wide is the spacer going to be?
I believe PCA and POC have a limit of 1/2 inch for track use. My mind is fuzzy it could be 1 inch but if you are thinking track use check the rules.
H&R or H&H make spacers in aluminum that are hub centric and use recessed steel wheel open nuts along with the factory studs to hold the spacer on and they use pressed in studs for the wheel. I have a set that are 2 inch and I have a set of 1 inch. I’d need to look at the 1 inch to see if they bolt on the same way. Like I said my mind is fuzzy haven’t looked at my spacers in a couple years.
Regarding press in verses double threaded I would go pressed in as long as you use the correct pilot hole for the stud. I think the factory knows best, you never see wheel studs threaded into aluminum.
I think the reason is wheel studs can be easily over torqued by a grease monkey which could cause the threads to start to pull out in aluminum. Another thing your typical grease monkey might not notice when a threaded stud has started to back out and before you know it only 2 threads are engaged and the stud falls out. Product liability issues.

[A930Rocket]

Thanks, guys

I’d only use aluminum with a press in stud. Steel for thread in stud. With aluminum, the question is the depth of the hole and do I add any of the threaded stud to the standard depth…5-10mm?

MM… motorsport-tech is the company I’m talking to. They can do whatever I require. I’m sure they know the correct depth of the press in stud.

I test fit the wheel and a 35mm spacer will work. My MSI Racing studs are short. I need another 1” of extra threads (or 1.5” to my liking).

Originally Posted by MMiller

Aluminum is all I've ever used on multiple Jeeps that were wheeled hard.

I have purchased from this outfit in NV.. USA made

https://www.motorsport-tech.com/

I think they will build you what you need if it is not a stock size they carry

The spacer is hub centric.

Originally Posted by asphaltgambler

I'd be more concerned that the spacer fits hub-centric to the hub and has protruded hub-centric for the wheel. I believe the threaded stud into the spacer would be a better choice.

[A930Rocket]

b2524… I’ll track the car (DE, etc.), but no racing, etc.

[A930Rocket]

My thoughts as well.

Originally Posted by cockerpunk

i would think aluminium with pressed in studs would be safer. it might not be stronger, but it has less failure modes. ie, the two ended studs make my nervous in a way a pressure fit stud doesnt.

[John Rogers]

When I installed a set of those really famous Carrara dish and caliper adapters and wanted to keep my Center Line 15" aluminum wheels since they and the Goodyear Cantilever slicks are probably the lightest combo you can ever find. My mentor at Black Forest in San Diego who was also the lead technical race inspector for PCA said that wheel studs had to attach to the hub which is, of course, fastened to the spindle with that big ass nut. Porsche Cars America sold longer studs which were VERY EXPENSIVE! I have attached 2 pictures with just the hub and with spacers. Since you said you plan to race the car some, I would strongly suggest contacting the organizations to see if the rules have changed any since my young and wilder days?
John

[A930Rocket]

John, I’m not going to race the car. Only lapping days and DE’s.

I have not found anybody that will make a longer screw in thread than I have now. That said, I think I want to go with the press in studs and ARP makes a 3 1/4 inch from the back of the flange to the tip. It’s the longest I can find in my size.

Custom wheel studs are either unattainable or forever to manufacture.

[John Rogers]

"Racing" is a widely variable term and an autocross, fast laps, driver ed events ALL will put more stress on all parts of any car wither a Mazda or BMW or Porsche. The parts that will face the highest stress all need to be strong.......but you already know that which is why you asked. As I said I would find a "race" shop, no matter the make and listen to what they say about your question. Also, as I suggested, check with the organization that runs things, but you already know that too.

An example of cutting corners was found in a couple "race cars" in the first race I did south of the border in Tijuana MX when the tech inspectors found exhaust tubing had been used to make the roll cages in a pair of VWs! The chief inspector thought the cages looked too good and slightly too large to be real, so he broke out his sonic wall thickness meter and whoa....way too thin! Called the shop that did the fabrication and such and there was a lot of angry Spanish flying, seems that was all the tube he had and Gonzalez Brothers Exhaust Shop in Mexicali MX!
John

[A930Rocket]

You are correct.

And good story!

Originally Posted by John Rogers

"Racing" is a widely variable term and an autocross, fast laps, driver ed events ALL will put more stress on all parts of any car wither a Mazda or BMW or Porsche. The parts that will face the highest stress all need to be strong.......but you already know that which is why you asked. As I said I would find a "race" shop, no matter the make and listen to what they say about your question. Also, as I suggested, check with the organization that runs things, but you already know that too.

An example of cutting corners was found in a couple "race cars" in the first race I did south of the border in Tijuana MX when the tech inspectors found exhaust tubing had been used to make the roll cages in a pair of VWs! The chief inspector thought the cages looked too good and slightly too large to be real, so he broke out his sonic wall thickness meter and whoa....way too thin! Called the shop that did the fabrication and such and there was a lot of angry Spanish flying, seems that was all the tube he had and Gonzalez Brothers Exhaust Shop in Mexicali MX!
John

[A930Rocket]

Update 10/22/22.

I reinstalled the wheels today using a 25 MM spacer. I can stick my fingers between the inner fender and the tire, so I have enough room.

Looking online, ARP has a press in stud that’s a 83mm from the back of the head to the tip, with no cone/bullet vs the MSI at 67mm to the end of the threads.

I’ve ordered new rear wheel bearings (might as well as do them while I’m there) and will get the ARP studs installed if everything measures out correctly.

I thought about doing it myself on my HF drill press, but I think I’ll have a machine shop install them.

Edit: would you replace the hub or use the existing hub? I really don’t see that it’s a wear item. For $140, I can get Febi hubs or $200 for BMW hubs and have the machine shop work on them while I can drive the car/replace the bearings only.




Swapping the 30mm spacer for 25mm, will give me 5mm more.

[Racerbvd]

Remember, Porsche used slip on spacers on 930s, and newer Porsches are also using spacers. This 944 Turbo has been running spacers since 2000.

When the car was built, the team that built it had a wheel sponsorship, but the wheel manufacturer didn't offer 5 on 130 in the size we needed at the time, so hub centric spacers were used.



This has been primarily a track car (but is tagged and insured for the street) since 2000, lots of track time, never an issue with the spacers.

[A930Rocket]

^^^ Thanks, Byron. What size studs are those? They look huge.

I need to pull the wheel and rotor to take some measurements to confirm the ARP press in studs will work.

One concern is the back of the hub, where you can see where it’s tapered. Is there enough material there for the new stud. Is it tapered to clear something? Will the head of the press and stud conflict with something?

If things don’t pan out, I’ll go the route you did.

Edit. After thinking about replacing the wheel hubs, I realized I need to replace the bearings. While I’m in there, I might as will rebuild the axles. Mission creep.