mark kibort

Are you saying that the ring thickness is really 7mm just to make sure things seat ok?
and the OD is 84.95 , to make sure it goes in the rotor?

interesting about the chamfer too, that without it.... more fitting issues.

mk

xschop

71.60mm ID
84.95mm OD
7.00 thick
0.0625" chamfer (one edge only per ring needed)

mark kibort

Thanks!
Ill get back to you with scots decision with the project. this for sure is needed!
thanks for all the help!!

mk

mark kibort

With the dimemsion changed on the adapters. (thanks to Sean, making the 2mm change) a better fit is found, and much less grinding to the caliper bracket is possible. in fact, it all almost bolts up with out issue. I did the 2nd side in about 30min including the grinding.

So, the net net. 330mm rotors on the S brake old 928s. All that is required is the adapter, a couple of bolts, the needed centering ring, and some minor grinding to the edge of the caliper mounting braket and its bace and a few thou off the spindle mounting casting edge for the mounting bolts.

mark kibort

the caliper bracket and finished product

Ducman82

very good work. me likes!

mark kibort

It turned out perfect. couldnt have done it without the list's help . centering ring, who would have thought?? (among many other input here). Thanks to Sean for the remake of the first adapter that required too much grindig of the caliper. Now, cheap rotors, under 100 bucks each, zimmerman, and they are 330mm!!

thanks guys!

Mark

karl ruiter

Awesome. Once you guys get some track time with this be sure to report back on actual performance. How is the feel changed? How does it compare to the S4 brakes?

pcar928fan

SO, who mentioned that hubcentricity issue...LOL! Yea, that did end up being important huh?

I love the finished product... Will the brackets be made and come with a pair of the rings??? I am ready to make this upgrade! Also will there be DETAILED (and I mean VERY DETAILED with pics...a la Dwayne!) instructions on how, where and how much grinding to do?!

Cost for spacers and rings? Who has the disc's??

I can't wait to put these on EURO85! They will look SO NICE behind those Carrera Light Weight 5 spoke wheels!

mark kibort

it should blow away the S4 brakes, but the feel of the pedal will still be "S", which i never felt was as good. it is a single piston, not that it cant be effective. the M3 racers for years and years used this exact same pad combo and caliper size and would brake very well , as race cars with simiar weight. us using 11" rotors and them using 12s.

yes, there will be discs, brackets and rings needed. the grinding , as you can see after the mods were made to the prototype, barely any. just enough to fit around some casting ridges . the major part of the gridnign was the edge of the caliper structure. you take that part down very slightly and you have a very clean fit. the passenger side was done first and we took way too much material away, due to the adapter being too shallow. now , the mods to the draiwing makes it all perfect.

I figure the entire kit would be as it stands now,
$150 for the adapters, $100 for the rings, and $250 for the rotor pair.

so, $500 for effectively, big brakes with S calipers!

Oh and YES, you were dead on right about the concentricity . i still cant believe i couldnt center it with drilling the centering holes for holding the rotor to the hub face. with the rings on, they are true and straight! nice prediction!

smiffypr

re "the feel of the pedal will still be "S""
When I put S4 brakes on the front of my S, I still had the S feel, but as I had made the fronts more powerful without changing the rears, I decided to by-pass the pressure reduction valves for the rear brakes. After I did that, the pedal feel was much improved. I think that the (two) pressure reduction valves introduce a lot of sponginess to the system.

IcemanG17

great update.....Sean has a set for me too...just need the spacers to make it work (+ rotors)...

I still am a FIRM believer in the S brakes.....

I did a bit of research into why the Estate has such good brakes....I KNOW it has a 55 bar bias which supposedly is only with the 9" booster.....I haven't researched the part # on my booster...but the brakes flat work....kinda like the cars handling....it just works....

Moving on....does this mean Scott will actually RACE his car this year?

pcar928fan

Thanks for the props AND MOSTLY for all the work! This is pretty damn awesome!

I can't wait to put this on my EURO85 car.

BTW, as others have noted I think the changing of the bias bar to a 911 Turbo bar makes the brakes TONS BETTER! My S4 has that and MAN does that car stop and the brake feel is TONS BETTER than ANY of my other cars.

I think EURO85 and the '92 will be the next cars to get that little alteration!

mark kibort

you have to realize that you will get a lot more pedal feel on the brakes now with a massive amount of increased leverage on the front spinning mass. this means for a lot less brake pressure, the same front braking force will be created. BUT, this means you are actually using a lot less rear brakes too.
But, with a lot more tire up front, you can use more brake pressure up front, and this gives more rear pressure. keep in mind, with more front brake pressure , you get more weight transfer, and less weight on the rear tires, so its kind of a self regulating system.

mark kibort

with that estate hp , and the weight and tire you carry, the brakes might work just fine however, the larger rotors can really help for even better braking and control. probably not essential until you grab some more hp or visit laguna!