Bolt on Spacers for Track - Yes or No

Postby **NitroDann** » Sat Aug 31, 2013 6:45 pm

Your wheel is held in place with friction, not hanging off a stud loaded in single shear.

Same as your tailshaft.

Dann

Postby **beavis** » Sun Sep 01, 2013 12:43 am

I ran 20mm bolt on spacers with 15x8 6UL rims (36mm offset)

This resulted in near flush fit.

I had no issues with this setup, had no loosening bolts.

This was on a track car with semis.

Depending on wheel width and tyre, you can go with around an 8" rim with as little as +16 offset, or a 9" wheel with +25mm offset.

Bolt on spacers are fine, but don't get any smaller than 20mm.

stb · Postby **stb** » Tue Sep 03, 2013 2:28 pm

NitroDann wrote:Your wheel is held in place with friction, not hanging off a stud loaded in single shear.

Same as your tailshaft.

Dann

I think my point has been missed. I agree on the wheel being held in place by friction, the problem is the load is being transferred through the spacer from one set of studs to the other resulting in a bending moment through the spacer. If the spacer is too thin that could be a problem. The OE arrangement does not have this load path/stress, even with slip on spacers.

Postby **NitroDann** » Tue Sep 03, 2013 2:30 pm

There is no bending at all if friction holds the wheel to the spacer and the spacer to the hub, its locked in place just as it is without the spacer.

Dann

sailaholic · Postby **sailaholic** » Tue Sep 03, 2013 2:51 pm

Your not reading it right dann. Slip on yes, bolt ons no.

There is no through clamping force only two separate clapping forces with a stressed member (the spacer) in the middle. The spacer has to transmit the loads from the wheel to the stub.

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Postby **NitroDann** » Tue Sep 03, 2013 3:08 pm

Ah I see, my apologies, so the question is 'is a bolt on spacer strong enough'?

Dann

sailaholic · Postby **sailaholic** » Tue Sep 03, 2013 4:35 pm

All good, I had to think about it twice too.

Close I would think it world need to be. It's a bolt on spacer of X thickness ok?
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fcruz3r · Postby **fcruz3r** » Tue Sep 03, 2013 6:24 pm

ah damn. there i was getting this warm fuzzy feeling that I had the nitrodann seal of approval for bolt on spacers

so what would be the minimum thickness required for bolt ons...25mm ok?

narita · Postby **narita** » Tue Sep 03, 2013 7:29 pm

think about how long your studs are, should be 20-25mm (not sure with these cars)

lets say its 20mm, you would need atleast 20mm spacers so the oem studs can sit flush.

Sage · Postby **Sage** » Wed Feb 04, 2015 11:21 am

reviving this old thread. so hub centric slip ons 20mm or greater with longer studs seems to be the consensus.

Dan · Postby **Dan** » Wed Feb 04, 2015 12:20 pm

^ The width is up to you but using extended studs I think is the safest option and is what I did on my Evo.

Before you install, clean where the spacer will contact the hub with some brake cleaner before putting on the spacers on to get good contact and reduce the chance of any vibration.

Also keep your stock studs in case you change to different offset wheels and don't need spacers anymore.

manga_blue · Postby **manga_blue** » Wed Feb 04, 2015 12:27 pm

As I said right back at the start read the CAMS vehicle regs for your class before you go with slip-ons. They have been banned from some classes. As far as I could find they had no problems with bolt-ons. If you do go with bolt-ons then 25mm are thick enough to clear the wheel face from the inner set of nuts; 20mm is as thin as I'd like to go but you will need some relief in the wheel face for the nuts.

e.g. CAMS RA19-Group-2F-2015-1 - Cams wrote:Track extenders or spacers may be used provided that they are fixed to the hub.

It's pretty pointless canvassing uninformed opinions from a forum if what you're asking about is banned anyway.

project.r.racing · Postby **project.r.racing** » Wed Feb 04, 2015 4:24 pm

bolt on spacers or get correct offset wheels.

Caffeine · Postby **Caffeine** » Wed Feb 04, 2015 6:26 pm

At Wakefield many moons ago someone rocked up with some thick slip on spacers and standard length wheel nuts. There was around 1.5 turns of thread holding the wheels on.

Sure enough, one third of the way round the first lap (in the hands of an experienced instructor) a couple of the wheels fell off. Made a mess of the brake discs!

pezchops · Postby **pezchops** » Wed Feb 04, 2015 6:41 pm

narita wrote:think about how long your studs are, should be 20-25mm (not sure with these cars)

lets say its 20mm, you would need atleast 20mm spacers so the oem studs can sit flush.

if you had a 20mm thick bolt on ring the bolt holes to attach to the hub must be counter bored to take the M12 nut.
c/bored at least 13mm or 14mm so there is only an effective 6 or 7mm thickness of aluminium in 4 place at the bottom of the c/bore to hold the whole lot on.
you would need to cut down the studs so as not to stick out more than the spacer ring thickness.
haveing said that ,in reality im sure it would be strong enough but it would always be on my mind.

Emily is correct in that fitting longer studs to your hubs, and slip on spacer rings is safer.
your slip on rings would need a c/bore on the hub side to fit the hub spigot and a spigot on the wheel side to fit the wheel bore.Like a big hub centric ring.
also with longer studs torque the wheel nuts 2 or 3 times as the longer the stud the more stretch under torque.
whatever way you go you probably need to modify something
In a nutshell its probably cheaper and easier to sell your wheels then buy wheels with your prefered offset.