floating rotors

[r lane]

What are the assets of floating rotors over fixed rotors or vise versa?

[Bill Verburg]

Originally Posted by r lane

What are the assets of floating rotors over fixed rotors or vise versa?

floaters handle thermal stress better

old style 930 floaters rattle more, new style floaters w/ McLaren type clips, not so much

[bkreigsr]

clank, clank, clank, clank, driving down the street will attract attention.

[r lane]

I should have stated, is a track car only

[Iciclehead]

I have floaters for street use and yes, they do clank.

I solved my problem by putting a tiny dab of high temperature silicone on each clip, the rattle mostly went away and I think that they still function as they are supposed to....certainly I have had no problem although I am certain I will need to redo the silicone dab at some point.

Biggest issue I had with those discs is that if you use them gently you get pad build up which leads to a judder on braking. Solution has been to do a couple of sequential hard stops to clean them off...you may not have that problem being a race car and all.

Dennis

[stownsen914]

I've had floating front rotors on 2 different racecars, a 911 (factory style) and 914 (Coleman rotors and hats). I've never noticed / cared about any noise or judder with them.

[Bill Verburg]

Originally Posted by stownsen914

I've had floating front rotors on 2 different racecars, a 911 (factory style) and 914 (Coleman rotors and hats). I've never noticed / cared about any noise or judder with them.

Again it all depends on the fasteners, the floaters on my 993 don't rattle either, it's mostly/only the old style 930 fasteners that have this issue

[Uwon]

I’ve had 79-80 930 floating rotors For 20 years and many, many miles on both roads and track. Never heard a rattle. Fabulous brakes!
Cheers,
Johan

[safe]

I have 930 floating rotors with VCI hats. They did cling, clang a bit, but I think it has gotten better over the years or my hearing more selective....

[panzerfaust]

bunch of advantages... better cooling, less run-out, better axis alignment, more consistent thermo expansion attributes, much lighter and the replacement rotors cheaper after the initial monstrous cost. :-)

can be clanky , less durable and more maintenance prone

[Bill Verburg]

These are the older 930 style, lots of moving parts, lots of noise






these are McLaren style tension clips, no noise





just for fun because I came across the pics, some really neat 993 Cup heat shields, for ABS sensors and tie rod rubber

[tirwin]

I just saw somewhere recently that StopTech is making brake kits for G body cars now. They are using floating rotors and they are wider. I have 28mm in my head but not sure. The calipers were pretty big too. I wondered what the bias is.

Bill V, have you seen this setup?

[75 911s]

Hey Tim

I did a review of the setup I bought and cover the rotors and some basics of the Stoptech kit:



It is 28mm thick front floating rotors btw.

[tirwin]

Duane, thanks! Now I remember where I saw it!

I don’t think I was able to finish it because Mrs. Tim was trying to tell me something REALLY IMPORTANT at the same time. No doubt that funny TikTok dog video was worth every moment.

Do you know what the front/rear bias is with that kit? What’s your impression so far?

[Bill Verburg]

Originally Posted by tirwin

I just saw somewhere recently that StopTech is making brake kits for G body cars now. They are using floating rotors and they are wider. I have 28mm in my head but not sure. The calipers were pretty big too. I wondered what the bias is.

Bill V, have you seen this setup?

Big calipers and lots of pad area are not the thing to look at

there are 3 aspects of brakes that a person might want to improve for one reason or another, not counting looks or counting coup
1) thermal performance in multiple stops: to improve this you need more and better cooling, high temp pads and fluid, bigger rotors(thickness and or diameter)

2) brake torque: stopping distance/time is more usually limited by tire friction but if the tires grip has been significantly upgraded then more brake torque can be utilized. To increase brake torque you use bigger caliper pistons, bigger effective rotor diameter and/or higher friction pads.. You could also add power brakes or up the boost and/or use a smaller m/c but these last have mostly negative influence elsewhere, like on

3) brake feel: here the slave/master ratio, mechanical linkage ratio and friction curves of the pads are the most relevant

[tirwin]

Yea I get all that. Just wondering if you have a row of one of your spreadsheets for the StopTech. It would be interesting to see how it compares technically to other solutions and cost-wise.

[Bill Verburg]

Originally Posted by tirwin

Yea I get all that. Just wondering if you have a row of one of your spreadsheets for the StopTech. It would be interesting to see how it compares technically to other solutions and cost-wise.

Stop tech plays it close to the vest wrt tech details, so no I have almost no info

to calculate bias you need to know all the pistons sizes and the effective rotor diameter, someone that ones one of these setup would need to measure and report

[tirwin]

Gotcha, thanks

[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.

[tirwin]

Nice writeup. Thanks!

As I recall, stock ‘84-‘89 Carreras used a proportioning valve. SCs did not. Right now I’m using the late Carrera front calipers with stock SC rears so no PV required. It’s been a great setup so far. I was curious if this kit would mean an SC with no PV would need one.