Best alloys for track use???

[J-1]

I'm looking to change alloys for my track setup. I'm currently running the 15" 'flat-fives' at the moment but I am thinking about increasing the sizes to allow for a bigger brake kit.

What size would be best for tyre choice, drive quality and lightness? Ideally they'll be light!

[alanmr2turbo]

you don't want to go over 16" for handling

[Marf]

16x7/8 and as light as possible

[rgb]

i had 16s and now iv got 17s and id say 16s are better

[J-1]

What about tyres for 16's - aren't they more expensive?

[Rogue]

There are many, many considerations to take into account, so take the sweeping generalities about 16" rims with a pinch of salt. Unless you start getting into expensive custom made wheels then the odds of you finding the perfect diameter, width and offset are slim. Finding the perfect tyre size to match is even harder. Everything will be a compromise.

On my Roadster I currently run 16x8 at the front and 17x9 at the rear. Offsets have to be made up with substantial bolt on spacers at both ends of the car and I've converted to a 5x114.3 stud pattern at the rear - partly to improve the selection of wheels available.

Since we've installed the supercharger, both the brakes and tyres need upgrading. We need to go six pot at the front and four pot at the rear. The braking force of the car is adequate at the moment, but the longevity of the pads is not - they need to be replaced every five hours or so.

This will necessitate larger diameter wheels at the front so we'll bump up to 17" and almost certainly increase the diameter of the rears to 18". The upshot (for us) is that this in turn improves the selection of tyres available, and probably eases the wheel offset situation as well - it all needs careful consideration.

So my advice would be to start with the things you can't change - such as the minimum diameter required to clear your brakes - and then work out what tyres you want to run. Then see if you can get rims to suit. If you can't, revisit the tyre situation and see what the nearest options are. It's a convoluted process and you won't know if your choices are right until you've made them.

[dantheman]

why do you want bigger brakes?

-Are you unable to lock your wheels if you push the pedal as hard as you can?
-Are you having brake cooling issues in which you think a larger radius disk with bigger alloys is the solution?

If the answer to both of these questions is no then dont touch the brakes, you are wasting time and money in persuit of worse brake performance

[Rogue]

The ability to lock your wheels is not a measure of the ability of your brakes. Quite the opposite in fact.

[dantheman]

Do explain because i rather disagree.

without over complicating things, what you want from your brakes on track is to hold the wheel rotating at a speed which causes the maximum amount of stopping force. This speed requires less pedal pressure than that required to lock the brakes completely. Unless you only have to touch the brakes to lock the wheels (which would give you no degree of control at all), if you can lock your wheels your brakes have excess brake performance and so are perfectly adequate.

Other performance factors include endurance, longevity, initial bite and overall feel etc but none of these are going to improve by simply putting on some bigger brakes as they are mostly affected by brake compound. instead you just mess up the brake distribution.

[Rogue]

You pretty much answered your own question. You should be able to lock up your brakes, but that's not the de-facto requirement. You want as wide a window as possible between zero brake force and full lock up to give you as much braking flexibility as possible. We've had to remove brakes from cars that acted pretty much like an on/off switch.

Also agree that bigger brakes are not necessarily the answer, and often people introduce brake imbalance in this way. Better compounds are always our first port of call. When going bigger, correctly matched brakes are critical (and available for all versions of the MR2).

[J-1]

Thanks for the info regarding the wheels and brakes.

As for the brakes, I had previously thought about the standard discs with Carbotech pads. The WMS setup that I like also saves me 11kg's.

Because I am not chasing huge power figures, I plan on focusing on:

Weight reduction
Braking
Handling

So that was my main reason for upgrading the brakes.

[Keri-WMS]

According to Kongaroo (based on my +/- 1mm printable PDFs, so not 100% confirmed), the 298.5x18 WMS kit fits under his ET43 15x7 Rays TE37...

So there are 15" wheels out there you can get to about 300mm under, sadly not the OEM 15" one. I'll be looking at doing a kit to fit under that soon.

[J-1]

According to Kongaroo (based on my +/- 1mm printable PDFs, so not 100% confirmed), the 298.5x18 WMS kit fits under his ET43 15x7 Rays TE37...

So there are 15" wheels out there you can get to about 300mm under, sadly not the OEM 15" one. I'll be looking at doing a kit to fit under that soon.

How soon?

[Keri-WMS]

I wanted to use the new larger caliper, but it's taking a while to release.

I've been messing about with PDFs just now as you gave me an idea, and I've made some progress. I can do two kits very easily using the existing T20 caliper:

- 280x28 T20, straight fit, no spacer. (EDIT after finding it fits too...)
- 280x22 T20, straight fit, no spacer.

[J-1]

Can you pm me prices please, including Carbotech pads?

[Keri-WMS]

I just added some info in affiliates, I'll send you a PM now.

[hkwc104]

What effects do the offsets of the wheels have on the handling characteristics of the car and is there an ideal offset for handling for a mk2 mr2?

I'm currently have a set of 16x7 (et 32) and 16x8 (et 38 ) wheels which I'm intending to use on the track use am debating whether to get some 3mm spacers to increase the rear track but am unsure if it will make any difference to the handling of the car.

Also, is it safe to use spigot rings on the track as it's often hard to find aftermarket wheels with the correct centre bore?

[dantheman]

The track of the vehicle has an affect on handling. Increasing track across an axle decreases the amount of weight transfer therefore increasing the total grip limit for that axle.

However its a proportional relationship. You are talking in the region of 10mm on an overall track in the region of 1500mm, so the difference is 2/3 of 1%, ie negligible.

And yes spigots are safe for track use, but i would advise aluminium ones as i have heard of plastic ones melting.

[Rosssco]

Also, is it safe to use spigot rings on the track as it's often hard to find aftermarket wheels with the correct centre bore?

Yes I believe so. The only real purpose of spigot rings are to correctly center the wheel onto the hub prior to correctly torquing the wheel nuts / bolts. They don't actually take significant load once the wheel is on (or shouldn't) hence most are made from relatively soft plastic...

Perhaps for heavy track use or racing there may be benefit in using higher grade wheel studs and nuts to allow a higher tignening torque (therefore higher wheel clamping force), but I presume this is on a case by case basis.