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I am thinking of getting some good quality 15mm wheel spacers how safe are they to use on the ISF, ( do they handle track work )has anyone had any problems and are they legal.
I used H&R spaces with built in studs (not extended studs) without any issues on OEM wheels throughout each winter. I checked them from time to time to ensure there was no loosening or anything else, which there never was, but it is always a good idea to keep an eye on them.
If you use the original studs and they are long enough (they must extend into the lug nut at least the diameter of the stud) then they are just ok. If not you must get longer studs. Be sure any new studs are of the correct grade of steel. Larger diameter studs are a good idea especially if you are serious about tracking your car. If you drag race with sticky tires, this goes double.
Never and I mean never use adapters. They are a very bad idea. Saw an accident one time where a pickup truck was overloaded and sheared the studs on the adapter. Several members of the family died.
No short cuts on securing wheels. Be sure to get a good half inch drive torque wrench and check the torque on the nuts. Over tightening is not good either.
The safety issue would be reduced somewhat if the spacer holes were a press fit on the studs (in effect extending the hub), but they're not.
This means that the wheel load exerts a bending moment on the stud where it exits the hub (as if the spacer were absent), and has greater leverage (mechanical advantage) because of the extra length.
Assuming you inspect them frequently and avoid hard cornering loads you should be safe, but other than disassembly I don't know any way to detect stud bending - which is the first step to failure.
Technically the friction fit from the clamping force of hub and wheel is what is taking the load from the bending moment you speak of. You can do some some calculations, and find that the clamping force is enough to hold 3000-3500lb per wheel before slipping. The actual studs shouldn't experience any force unless the lugs are loose. This is why you usually see people with broken studs because their lugs where loose. I would say extend studs with a spacer are safe and I know people who run them on their spec racecars without issue. Adapters are another story and I would only use them for street. They tend to vary in quality and could possible crack.
Some manufactures(like Porsche) use spacers on their production cars. That should tell you how safe spacers can be if used properly. I say don't ever skimp and don't get the cheapest when it comes to spacers. Set it up properly, since it is your life on the line.
An example of going cheap and getting studs from Home Depot.
Extended studs or even the HR integrated studs with spacers should be zero risk if installed properly. They are hub centric, or at least should be otherwise I wouldn't run them. That's merely an extension of the factory hub. There's no "hinging" on the studs as some believe. Clamping force has already been discussed.
Most spacer "horror" stories are from people that bought cheap garbage, didn't torque their damn wheels, or are running those adapters that are ridiculously thick. Only issues of a proper wheel spacer in my opinion is increased bearing wear which is no different than wider low offset wheels.
I use H&R with extended studs for 3 years already 20mm all around. Daily driver and aggressive driver on the weekend, at times i carry 3 adults during long drive. No single problems encountered. Its safe!!!
I've run H&R 15mm spacers w/extended studs at my last 4 track days. I haven't noticed any issues. Of course, I torque my lugs before hitting the track and check them several times throughout the day (after letting them cool a bit). No problems yet. Though, I'll remove them when I start using dedicated track wheels w/stickier rubber.
10-02-16, 12:09 AM
How safe are wheel spacers
Though, I'll remove them when I start using dedicated track wheels w/stickier rubber. 
