biggest discs under 15 inch wheels

Sun Nov 27, 2011 8:09 pm

hi all

I have finally lunched the EBC discs on my car after a good season on track. they are the grooved n drilled jobbies. they are matched to wilwood 4 pot calipers

I would like to be able to go up a size but just wondering how big people have gone under 15s?

up to 295mm with spacers?

any advice on good disc choice would be most welcome too.

Thanks, DC

Sun Nov 27, 2011 8:13 pm

280mm Audi discs with dainty 4pots (such as the WMS or Wilwood dynalite units) is the biggest for the 15inch cross spoke. Maybe able to go larger with an aftermarket 15" wheel.

Sun Nov 27, 2011 8:15 pm

i have got raceline RL7s as well as some other aftermarket ones. both ET15 with good clearance.

its just the brackets and fitting I am worried about.

thanks.

Sun Nov 27, 2011 8:27 pm

I think you will struggle to find a caliper that will clear a disc bigger than 180mm under a 15 inch wheel

Sun Nov 27, 2011 8:29 pm

I can supply bigger discs if that helps? Off the top of my head:

290x20
298.5x24
300x26
312x25

....or slightly smaller, custom turned down.

Which Wilwood caliper have you got?

I managed to get a 310x32 kit under the standard TVR Chimaera 15" wheel the other day, but it was CLOSE so I changed the spec to 298.5x32 to hedge my bets!

Sun Nov 27, 2011 8:48 pm

We use 300mm Wilwood discs in 15". We needed to use some Team Dynamics Pro Race 2.0 wheels which are very flat on the inside.

Sun Nov 27, 2011 8:50 pm

thanks Keri.

i was thinking of going up to 300 if I could maybe. I have the 4 stud set up still. the bigger the better really.

pics of the set up:

with the raceline wheels on:

i think there is a bit of room in there still so should be able to go up a little. can you PM me some prices Keri?

Nick

Sun Nov 27, 2011 8:50 pm

Nick - That's the Midilite, a radial mount - you should be able to shim it our further with washers (and get nicer spacers later) to see how much bigger you can go and take it from there....keeping the brackets, but with longer bolts of course.

What discs are those by the way?

Tom - The Team Dynamics Pro Race 1.2 has loads of room too, handy wheels!

Sun Nov 27, 2011 9:01 pm

keri-WMS wrote:Nick - That's the Midilite, a radial mount - you should be able to shim it our further with washers (and get nicer spacers later) to see how much bigger you can go and take it from there....keeping the brackets, but with longer bolts of course.

What discs are those by the way?

Tom - The Team Dynamics Pro Race 1.2 has loads of room too, handy wheels!

Yeah, the 1.2 is a great option as well but we got a great offer when looking for the 2.0.

Sun Nov 27, 2011 9:09 pm

TD wheels are a good price if bought from Rimstock.

Mon Nov 28, 2011 9:45 am

agreed they are cheapo but not great quality or that strong. that is why they are cheapo!

Keri thanks for the prices. the discs on mine are EBC ones i think so not great.

i think i will just got solid disc so no grooves or drilled nonsense. if I can get 300 under there then great but maybe 295 or 298 is good enough.

will be in touch once I know more.
Nick

Mon Nov 28, 2011 12:06 pm

I Use revolution milleniums on the rally car, I had a 325 mm disc under them at one point with a wilwood dynapro caliper. Direct from revolution they cost around 75 quid each and are superstong with steel inserts, downside it that they are a bit on the heavy side.

Those racelines look like they have masses of clearance, I would hazard a guess and say you can probably go up another 40mm on the disc diameter

Tue Nov 29, 2011 4:06 pm

Nick,

I did say when you were asking me about the car, you will need bigger brakes!

Im running 330 under a 16" wheel no problemo.

Tue Nov 29, 2011 8:32 pm

Yeah I know Andrew. I wanted to do suspension first and then kill the 280mm discs that were on there.
I would like to stay on 15s if I can so will look at 300mm or as big as I can go.

Wed Nov 30, 2011 1:31 pm

Thats fair enough.

What have you got on the rear?

I have a nice 282X10mm Disk and sliding M3 Calliper with RS19's setup that i might be tempted to let go

Very good hardly used condition!

Wed Nov 30, 2011 5:30 pm

JFYI for folks in Racing saloons.. I read the regs as you need to be able to refit the OEM wheel over the setup you use. so going for a 15 with more internal diameter doesnt work.

I'll double check as I'm considering an upgrade as well.

Wed Nov 30, 2011 5:57 pm

Is that BPMW or TTRS? I know (think) PBMW brakes have to be std, thought TTRS brakes were free - but the OEM wheel-fit-thing is handy to know if that's the case!

Are (thin) wheel spacers allowed in TTRS?

Wed Nov 30, 2011 7:17 pm

PBMW, defo standard.

Racing Saloons see here.
http://www.pbmwc.co.uk/P8RS/regs/
Read down through the Wheels section below as it refers back to braking systems.

Wed Nov 30, 2011 8:13 pm

Andrew you got PM. NW

Wed Nov 30, 2011 10:35 pm

Black_Potato wrote:http://www.pbmwc.co.uk/P8RS/regs/
Read down through the Wheels section below as it refers back to braking systems.

They are a bit vague, a "wheel of original diameter" could be any 15" wheel! But I think you're right, they seem to want to have an OEM wheel (15" BBS in this case) so they can do spot-checks.

If someone does have a "BBS" with them for this purpose they better make sure it's the BBS or FPS made one, as the Alu one has little "wedges" on the backs of the spokes. It clears the WMS 280x22 setup if the wheel is at it's original offset, 7mm from the hub (G60/280mm discs's 5mm flange plus 2mm spacer) but they might not like that.

Strange rule, maybe it's to make it easier to recover bent cars or to allow wheelss to be bent but clear the brakes still..?

Wed Nov 30, 2011 11:00 pm

Regs often stipulate things in such a fashion so that they can be enforced if need be which is where I expect they are going with the OEM bit. That way no argurment over which brand etc.. The reality is I doubt you would have any issue with any 15" and it would be classed as in the spirit of the regs but there is always that small risk that somebody raises the matter with the MSA and they get disqualified as a result of a hearing. Not quite F1 but but these things do happen in club motorsport.

Thu Dec 01, 2011 6:01 am

keri-WMS wrote:[Strange rule, maybe it's to make it easier to recover bent cars or to allow wheelss to be bent but clear the brakes still..?

It's more about restricting brake size. Trying to write regs around brake sizes would be a minefield, difficult if not impossible, given that the cars are all different makes and models and race in different classes. Easier to prevent monster brakes by having free regs around brakes, but stipulating that an OEM wheel must still be able to fit over them.