Is anyone using aftermarket wheel studs that are able to deal with the stress / abuse of racing? I need something that fits the stock hub and is the same length or slightly longer than stock.

Does ARP make studs for the car?

Thanks!

-Rob

 

everybody seems to be pleased with the nismo studs.

 

I have heard that the NISMO studs are longer than stock, but are same material and are not any tougher than stock. So I was looking for another alternative.

Do you know if the Nismo studs are hardened in any way?

 

We tried to get a group buy together to get ARP Studs made for our cars, but couldnt get the 80 people needed to get it rolling. They would have cost half what the Nismo's do but been much stronger.

 

I'd be curious on how hardened studs would fare with the fatigue of mounting/dismounting wheels, plus the stress of driving them.

Are you breaking studs often Rob?

 

I was changing wheels every weekend and after about 20 mounts the rear studs would strat to break. Not a problem on the front. I have switched to Nismo studs and find them able to torque consitently every time. I have about 20 remounts now as I drive this car to and from the track and do at least three track dayas plus prep work for each track day over the last five months. I notice that the studs touque up nice and tight were as the standard studs never seemed to be tight. I could feel the stud soften on each torque. By the way a T2 guy out on the west coast told me not to toreque more than 60 lbs due to the differential expansion between the aluminum wheels and the lower thermal eapansion of the steel studs. This seemed to me to make sense.

Any other feelings on torqu setting?

Ray

 

I broke some studs on the track a few weeks ago which caused me to lose the LR wheel. I suspect that the broken studs are a result of not changing the studs after being punted at the runoffs this past fall. Others who are racing the Z have reported problems with the studs, but I don't know of anyone who has settled on a satisfactory solution. I used to run ARP studs on my Camaro, but I am open to other high qualifty studs.

Does anyone know what the GAC teams run? Do they run factory hubs?

I torque the wheels to 80 ft/lbs. In understand the aluminum / steel expansion argument, but I don't really feel safe torquing much less than 80.

-Rob

 

I would call BJ at 350 Evo. He might be able to give you some insight as to what your options are. He has been very helpful for me in the past. Just a suggestion.

 

Rob, I'm using the Nismo studs. I can't vouch for them being hardened, but I can tell you that I was breaking 1-2 studs a weekend prior to installing the Nismos on my car. I haven't broken one since then, over a year and a half ago now.

 

I am using eibach 10mm spacers... they come with longer studs, but haven't tracked them yet.

I wouldn't torque the wheels bellow 80ftlb, not on a car like 350z.. porsche guys torque them 90+ religiously

 

My $0.02: I ran OEM studs for 3 years & over 30 DE's with 70+ wheel changes without an issue. I torque to 85 ft. lbs. Just installed Nismo long studs, as I feel better with total thread engagement. They seem to be of a better quality than OEM, but that's just a gut feeling.

I will caution everyone to make sure the chrome plating on your lug nuts isn't flaking. My OEM nuts were crap. Machining the face of the wheel where the nut mates is NOT a good thing.

 

I've had ~half-dozen nuts fail upon torquing (to only 80ft-lbs), and if you're not extremely careful, they will cross-thread easily. I find the OEM stud metal quality to be exceptionally soft and of substandard quality - I too need to find a safer alternative as well.

 

Hey Rob - so far so good with the NISMO studs, but they are longer. I have broken a few OEM studs in the past as well. The GAC Zs (at least the 2 I've been involved with) use pretty big ARP studs.

Drive on!
Jason

hendersonmotorsports.com

 

IMO, and it may initially seem obvious to many of you, stud failure is due the lack of strength. But, what may not be obvious is why there isn't enough strength from the stud, so bear with me for a minute...

Kolia brought up a great point about fatigue. Although most folks would think that fatigue originates from the loading and unloading of the studs during cornering. The studs are actually prestressed when the lug nuts are tightened. If they are stressed sufficiently, the studs do no experience the repetitive loading cycles from cornering. As long as the wheel mating surface never leaves the hub/rotor hat mating surface the stud maintains at the same stress level, and does not "see" a stress cycle.

Some may argue that changes in temperature causes repetitive loading, but the gradual and relatively slow heating and cooling cycles from track sessions are not enough to cause fatigue issues. When dealing with fatigue, we're usually dealing with 100's of thousands of cycles.

Now, back on the subject of strength. If we tighten the lug nuts per specs (85-90 ft-bls), the stud is stretched within its elastic range. Preferably, it is stretched nowhere near its yield strength. What happens with us minority track folks is that our brakes get hot, our tires get hot, and our wheels get hot. Because aluminum's thermal expansion coefficient is nearly twice that of steel, there is additional expansion of the material between the hub and the lug nut that effectively "tightens" the stud above and beyond what we initially tightened them to. Many of you already know this, I'm just trying to accommodate others who haven't been through problem.

So where am I going with this?

1) Don't overtighten your lug nuts, or you'll be using up the residual strength needed when the stud is further stretched during your track sessions. Use a calibrated torque wrench. If you're using lubrication in the threads and/or lub mating surface, reduce the torque a bit.

2) Don't use thick aluminum wheel spacers. In fact, avoid using spacer if you can. The more aluminum you have between the lug nut and the hub, the more chances you have of stud failure.

3) Spinning, then hitting berms laterally, digging your wheels into hard dirt, or any lateral impact to the wheels may very well overstress your stud. It is probably a good idea to replace them.

I don't quite know what to say about Christoc (1-2 broken studs per weekend). That is just nutty. The heat levels aren't as high in autoX, so I'm puzzled. Are you using spacers? What are you torquing your lugs to?

As for John, Jason, and others who are torquing to specs, but still snap studs frequently, you're probably just heating up your wheel more than the rest of us. About a year ago, I recall seeing posts of brembos baked to the point of being the color of poo. I have the 355mm Stoptechs, and I don't think I put that much heat into them and into the wheel because they are not poo colored yet.

 

well said

The only thing I might add... is RE-check and RE-torque your nuts(lug) after each session!

I am not an hardcore auto-xer or track junkie, but the only case of wheel stud failure I have witnessed was from someone who wasn't torquing back to spec his lugnuts after each session.

 

yes...be sure to re-torque them before each session...but be sure to do so only once they have cooled.

i have seen people come off track, check tire pressures, then go about re-torquing the lug nuts. this definitely brings up the possibility of over stretching and cracking the lugs.

also...for what it is worth...i have taken my wheels off/on at least 50 times with no issues (yet...knocks on wood)

sean

 

I am shocked to hear of all the broken studs.

I must have over 100 4-wheel changes (I have 5 sets of wheels for my car, and I bet I change them at least 2 or 3 times a month, sometimes 2 or 3 times a weekend). I have NEVER had a stud break. I tighten to 95 ft-lbs every time with a quality torque wrench. I still have the stock studs.

I have replaced the stock lug nuts with Gorilla lightweight lug nuts. These have held up very well, are maybe a third the weight of the stock lug nuts. They are chrome plated, but the chrome is holding up perfectly - no flaking at all.

I also use some anti-seize on the threads. Not much, just a little. This makes loosening the lug nuts much easier, perhaps putting less stress on the studs both when tightening or removing the lugs.

Are you guys seeing your stud failures while driving or when tightening or loosening?

 

My stud problems were most likely one of two reasons.

1. using the stock lugs and causing threading issues.
2. using a 4 way bar and spinning them on, most likely not always straight.

When I changed to good studs I also stopped using the bar and went with a socket to run the nuts on completely. That is most likely why I quit breaking studs. I actually still run stock studs in the rear because I've been too lazy to change them out.

I also run a 1/2" spacer up front to fix the offset for the enkie wheels

 

When retorquing your wheels be sure to loosen them first. To add one more "click" and then one more and one more brings up the torque rating much higher than you intend. Take a breaaker bar and take the torque off before setting them at the torque rating you want.

 

Rob,
ARP has them for the 350Z. I am running the STuds that came with the H&R spacers that I am using. They are German TUV approved, and I know the TUV approval process is pretty stringent, with wheels they require they can withstand a huge lateral load without distortion, something like 3000lbs. I figure they probably require a similar type test on wheel studs/spacers (The last thing they want is studs failing on a 5000lbs Mercedes at 160 on the Autobahn). So far so good, the studs seem to be holding up well. In the future I will probably change them to the ARP's with the rounded ends.