Randy V

^^ Brakes have 'power'?

jcorenman

No, they have torque.

jstadter

Mark or Gary - When you get a chance, could you post pics of the brackets you made? Do you recall which Aluminum you used (e.g. 6061 or 7075)?

jcorenman

I am sure that 6061 would be fine. But Mark forgot to mention that you need to grind away on the S4 calipers to make the GTS rotor fit:
https://rennlist.com/forums/928-foru...l#post12355903

It's a personal choice, I would either stick with S4 brakes or do the full upgrade.

stuartbrs

I tracked my S4 today, the circuit is hilly, and there are two big stopping zones, one down a steep hill, and the other at the end of the shortish back straight. After 4 laps there was some noticeable fade, and I was being more than generous with braking distances. However, I believe changing fluid and installing better pads would make all the difference.
The S4 stopped much better than my old S at this circuit, but the S didnt fade noticeably. I put this down to the S4 pads being NRG.. not real good. There was a lot of time I left on the table with the car today, as I just went out to open it up a bit and have some fun.
The sport suspension made the car handle light years better than the S.

FredR

The S4 brakes are probably way superior to what you were previously used to but- more stopping power = more energy to dissipate and thus perhaps more prone to fading especially if the localised air flow is not really up to track work.
On my late S4 I had wider rubber up front [265] and sharper pads [Hawk plus] but I did not fill with a higher boiling point brake fluid and on the Dubai Autodrome went into the bend at the end of the back straight with no brakes- not good! I survived to tell the tale but I advise anyone going to the track run with ATE Blue or something equivalent.

Rgds

Fred

stuartbrs

Good advice there Fred. If I take it again I`ll be changing the fluid and putting better pads in it.

It was fun, but in the back of my mind is the constant fear of binning my daily drive.

Manual S4`s are a wonderful thing.

Gary Knox

Randy V. wrote: "Just noticed that a 928 OC Officer doesn't own a 928?"

Randy, you are a little late to the party. Both when I was asked if I'd accept a nomination, and in the 'candidate biography' on the OC web site, I clearly stated that I did not currently own a 928, although I had owned 6 of them over the previous 17 years. And I clearly understood that some members might desire that an officer also be an owner (although the by-laws do not require it). Therefore, I said I would gladly step aside if someone else wanted, or was nominated for the position of Treasurer. IF that was an issue to you, you probably should have brought it up BEFORE the election!

I also stated to the nominator and in the 'bio' that I have served for 10 years, and this would be my final term IF I were elected. Since there were quite a few new officers on the slate this year, both Marc White and I decided we were willing to serve one more term each, in order to have some continuity. In the 'bio', I also requested that members start thinking about candidates for Treasurer in the next election cycle. So guys - again - start thinking.

By the way Mark and Jim C. - I don't recall having to grind anything off the S4 pads I used with the S4 calipers and GTS rotors on my track car. Been nearly 3 years since I last installed new pads on that car, so the memory may not be totally accurate! I do know the braking on the track was improved [I also put 993 rear calipers on the car (plug and play), which have 22% larger pistons than the OE 928 calipers].

Jim M. The aluminum was just a stock piece 0.40" thick I bought from a local metals shop (I think it was 1" wide). I cut it to length and drilled the necessary 2 holes in it and bolted it and the calipers on with the new (longer) bolts.

mark kibort

braking torque (or force) at a particular speed is power. commonly called BHP

mark kibort

I mentioned that, but also mentioned that i went to C2 turbo calipers (same as s4 but radiused) and was able to go even bigger ..... 330mm.

mark kibort

technique is going to pay big dividends here. but if, you have fade, its going to be the pad compound. get some PFC-11 performance friction pads. (or Pagid black RS14) pure race, but they are fine on the street and can handle the heat (no fade) make sure you have decent racing fluild... the brakes will handle anything you can throw at it.... even more if you are not running slicks or DOT slicks.

mark kibort

Fred, i race World challenge for my first two races with the S brakes. (and raced on DOTs for a couple of years with them as well) sure, a little tough for them to dissipate the heat, but the power is the same...... until fade, then the power wasnt there same power when not overheated, but the larger rotors going from 11" to 12" was a big differerence in heat dissipation. pads were and are critical too..... if the heat goes up do to the power demands and the pads cant handle it, they fade.... larger rotor, more head disipation, lower heat in rotor and pad, more effective braking power

hacker-pschorr

I'm going back on vacation

mark kibort

You can relax to know , brakes have power and torque....... just like a car.
in fact very similar to engine torque vs rear wheel torque, is braking torque and braking force.

braking HP is like engine BHP.... rate of change of KE.... KE start - KE end = power. (for engine or brakes)

why the head banging.. not making sense?

mark kibort

i think it was 6061 almost 90% positive.
the pic is listed below .. just have two 1" round "washers" made to the thickness required... i have the exact dim for GTS rotors or 13" rotors. but you have to use the 10mm longer bolts as was mentioned.


if you want the pads to sit on the GTS rotor just as they did on the S4 rotor, you will need to grind the edges of the calipers... 2mm or so.
you used a .4" spacer , which is part of the reason it might have worked.
.36" is what is needed so maybe that .04 (near 1mm) is what you needed for clearance. however the pad would have been a little over the edge by 1mm... and thats ok i guess.