Rear wilwood compatibility!

[cdavie2002]

Iv not looked at this for a while, so here goes again.

Iv got wilwoods on front, and im looking to put wilwoods on rear.

I cant remember off top of my head the measurement of the original 323i rear piston area.

The problem is, i cant work out how to compare single pot piston caliper(original), with new wilwoods which are 4 pot (2 opposing pistons.) I need to be able to compare the two so i can match new to old.

Also how do you know what the original front/rear ratio is, is it not a fairly standard 70% front/30% rear setup?

[murran]

cant you just fit a bias adjuster in the brake line to fine tune the brake balance?

[cdavie2002]

Yeah i will, but id like to know the original % ratio to begin, then adjust from there.

[cdavie2002]

I think i have figured it out?

The single piston in the original rear 323i caliper has to move twice as far, as say a piston on a 2-pot system for the brakes to work. The pistons of the 2-pot only have to work half as hard, so the piston area should be half the original size?

Yes / No / Maybe ???

[Jason_323i]

All brake calcs are based on the total pistion area of one side of the caliper, work out the oprginal % front to rear and keep that with the new caliper selection.

the brakes international web site has all the tech info on OEM calipers, and rally design for the wilwood

Jason

[cdavie2002]

323i fronts have a piston diamater of 48mm.

323i rears have a piston diamater of 32.9mm. The rears have a single piston, does that not make it more difficult trying to match it to a caliper with opposing pistons?

[Jason_323i]

It's worked out on the total piston(s) area it does not mater if it is one or six

Jason

[cdavie2002]

Thank Jason

FRONTS
So the original front caliper has 2 pistons at a size of 48mm per piston, so it has a (TPA) total piston area of 3619 mm squared. The group buy wilwood replacement 120-8729, has 4 pistons, each 35.1mm and a TPA of 3870 mm squared.

REAR
The original 323i rear caliper has 1 piston at a size of 32.9mm, so it has a piston area of 850 mm squared. I need a wilwood caliper to match?

[Jason_323i]

You only take one half of the caliper

OEM front 1809.6

OEM rear 850

Front rear split 68/32

Wilwood front 1935

so you need a rear of about 908mm2 which is hard to achieve in a 4 pot caliper but an e30 touring rear calipers are close and bolt with a bit of maching (think I have a set)

Jason

[cdavie2002]

Will they not just be quite similar to the single pot 323i ones?

[Jason_323i]

Touring's have a larger 35mm piston.

Why do want to upgrade, a little more forward basis will not effect things to much as the wilwwod is within 10% of the OEM caliper

Jason

[cdavie2002]

Might just refurb the rear 323i calipers i have.

What i do want to do is upgrade the old rusty linkages and maybe go the route of boosterless and use a pedal box. Can a boosterless pedal box setup be used for normal road use?