floating rotors

[VFR750]

The proportioning valve is for adjusting the rear brake. It increases the bias with heavy brake application.

So if you do the stop tech front, it will not matter. If you keep the carrera rear brake caliper, you still need the proportioning valve

[Bill Verburg]

Originally Posted by VFR750

Stop tech uses 32mm leading and 36mm trailing pistons in the front calipers. Either st42 or st43. That data comes directly from stop tech.

The stock brake bias is unaffected. And the volume is the same, so no change needed to the master cylinder.

St42 and st43 w/o dust seals fit inside 16x6 Fuchs without any spacers. Verified.

St43 with dust filters need a spacer. Less than 10mm but the front hubs can’t run something below 14mm.

I’ll post a table later tonight comparing many options.

Basically the stop tech upgrade is the easiest and has the least impact to the whole system. Cost is a little high, but in reality once you add up all the work it is a reasonable gain. With >2x the pad volume and 28x282 rotor. Full floating front.

Assuming the above Stoptechs are used on 288x28mm rotors w/ an effective diameter of 234mm and that stock 38mm M rear are used on stock rotors. Brake bias is fine at 1.541( stock A/M is 1.491)

If used w/ '84-89 wide M rear bias is 1.261 and the p/v needs to be retained to correct that

[Bill Verburg]

Originally Posted by VFR750

The proportioning valve is for adjusting the rear brake. It increases the bias with heavy brake application.

So if you do the stop tech front, it will not matter. If you keep the carrera rear brake caliper, you still need the proportioning valve

Just a clarification, a p/v can only reduce brake torque on the axle it is used on(hopefully the back) It provides a bent bias curve, w/ lower slope above the knee

This is the effect of a stock 33bar p/v used on '84-89 911. The knee is at 33bar line pressure which is quite low, This is a very aggressive p/v

[VFR750]

This is a high level summary of many weeks of work.

Ground rule: MUST fit inside 16x6 ET36 Fuchs. With or with out spacers.

There are many more options, but these are the "best = most compatible with least modifications" for each grouping.

"red" means this was a show stopper. "yellow" was notable. "green" was meeting the "key requirements". No shading was just more comparative data.



Rebel RSR conversion will fit with 14mm spacer, but you can't cheaply fix the excessive front bias. I verified the fittment with a 16x6 using a 996 front caliper and a simulated rotor attached to a spare hub. brake fluid cross over line needs to be bent slightly to get clearance.

930 brakes use a 21mm spacer to fit 16" wheels. Without the flares, my wheel would have rubbed. And they are way too much $$$$

The wilwood option looked very promising, but even the small rotor and calipers did not fit without a large spacer for the 16x6 Fuchs. Too large it turned out with stock (rolled lip & slightly bulged) fenders.

[Bill Verburg]

930 brakes use a 21mm spacer to fit 16" wheels.

did you mean to say 6x16, ET36 Fuchs? also assuming 6x15

because the fit fine even in 7, 8 & 9 x15 Fuchs

I don't know that i'd be looking for more brake torque w/ 6s, You'd want 7s and hopefully 225 to take advantage of it. Bigger thermal envelope , sure

[VFR750]

For me it’s rim x width

Yes a 6” wide. ET36.

I run my winter/rain tires on my stock 16” rims. I need them to fit. 205/55 f.

7” wide phone dials with 225/45 front R888R track tires.

225/45 fronts lower the nose ~1/2” for track use.

Tire and rims for every condition. 😀

[safe]

Originally Posted by VFR750

930 brakes use a 21mm spacer to fit 16" wheels. Without the flares, my wheel would have rubbed. And they are way too much $$$$

Were did you find that out?
I have 930 brakes on my narrow body car, I use a 5 or 7 mm spacer for the calipers to clear my rims. I run 6 + 7 X 16" Fuchs and 7+7x16" Fuchs.

My take on brake upgrades are that unless you upgrade the size of the rotors, its not much of an upgrade. It could be for lighter calipers but that usually not it.
There is very few upgrades out there other than 930 that upgrade the rotors.

[VFR750]

Running 930 calipers and rotors require a spacer. Not sure how you can run a 5-7mm spacer on the front without defeating the hub centering feature.

What I said was Porsche uses 21mm spacers and that won’t fit sc flares.

Also my table said cost is prohibitive.

Adding rotor size is good. Provided you also increase the rear rotor to keep the bias. That is the 996 option. There is no, easy, rear caliper option to get the bias back to a reasonable level.

I need heat rejection. Thicker rotor, with much better internal vanes will be a good improvement over the Carrera rotors

Full floating rotors also decrease heat flow into the hubs. I am seeing wheel bearing grease leaking due to high temps. The separate hat and disk is an improvement

Pad size and volume will help with pad life and maybe overall temperature.

Modern calipers with stainless pistons will help with heat conduction into the fluid

I concluded that they are a good upgrade for the front, which needs the most heat rejection.

[chrisbalich]

Based on the table and comments since, it appears to me that the Wilwood would be a fine setup for someone with 17s and ample brake clearance, no?
I'm looking to maintain OE feel but with minimized weight. Aluminum calipers and 2pc front rotors seem like they'd be worth the money and effort of fabricating some brackets.

[safe]

Originally Posted by VFR750

Running 930 calipers and rotors require a spacer. Not sure how you can run a 5-7mm spacer on the front without defeating the hub centering feature.

What I said was Porsche uses 21mm spacers and that won’t fit sc flares.

Trust me, they do fit with less than 21 mm. Porsche uses spacers to fil the arches with puny 7" wheels not to clear the calipers...

I cant't argue with the cost perspective, it is a significant bunch of cash nowadays....

On one car I have 928 S4 calipers on the front. I think they could be used with floating rotors, but now I have 993 rotors over the hub, which act as a 5mm spacer, might not be the best. Not sure how much space the calipers would need to clear Fuchs on a narrow body.

[tirwin]

Originally Posted by VFR750

The proportioning valve is for adjusting the rear brake. It increases the bias with heavy brake application.

So if you do the stop tech front, it will not matter. If you keep the carrera rear brake caliper, you still need the proportioning valve

This is great info and exactly what I was thinking/wondering about.

I like the StopTech front/SC rear combo. I already did the Wide A front with M rear and it seems to be doing the trick. If I were to do it over again today I think this would be high on the list.

[Harpo]

Who sells the Mclaren 2 piece floating rotor fasteners?