Girodisc rotors finally installed

Dervish · 02-21-2010, 04:04 PM

Upgraded the front rotors from OEM cross drilled to Girodisc slotted.

The Girodisc are 8% larger (340mm vs 317mm) and fit using the stock caliper with a reduction in weight from 9.0kg to 7.8kg per disc. The increased diameter provides a larger effective radius giving more braking force for the same system pressure. I really didn't want to go down the Brembo BBK route requiring almost a complete new disc/caliper system and pressure/bias changes.

Here you can see the quality...

And here the size comparison with the OEM...

It's a very easy install, the only difference to the usual disc change is the addition of the 12mm spacer to move the caliper further away from the arm. The spacers are included in the kit together with 12mm longer caliper bolts (strangely Porsche part numbered?).

Finished...

Thanks to Craig at rennstore for all the info and help...

Now I just have to see how they compare on track...

ivangene · 02-21-2010, 04:10 PM

SWEET !!

LVDell · 02-21-2010, 05:33 PM

Looking good! And I'll bet you are going to be even more excited to know it's more than 8%. **hint....area of a circle not difference in diameter**

redridge · 02-21-2010, 07:31 PM

Im assuming the longer bolts comes with the kit.... looks great! The spacers are a bit cheesy though.

2K3TTMIA · 02-21-2010, 07:41 PM

Quote:

Originally Posted by redridge

Im assuming the longer bolts comes with the kit.... looks great! The spacers are a bit cheesy though.

+1, maybe an entire single billet piece to cover the caliper contact area.

redridge · 02-21-2010, 08:03 PM

Quote:

Originally Posted by 2000996MIA

+1, maybe an entire single billet piece to cover the caliper contact area.

yup.... that'll be a winner! The way it is... it looks like the caliper will run hotter than the stock setup, just my guess.

ivangene · 02-21-2010, 08:22 PM

anyone interested in having me make a one piece?

redridge · 02-21-2010, 08:28 PM

Ed, you might want to talk to the vendor..... this might be a good option for some. If I was in the market, I will def give you a call.

Shark Attack · 02-21-2010, 10:14 PM

that looks like a mod worth while and easy. I agree on the spacers. I think a nice one peice spacer that looks like it is supposed to be there would be better.

FLY996 · 02-21-2010, 11:12 PM

makes the calipers look to small...

Dervish · 02-22-2010, 02:12 AM

Why would a one piece spacer be any better? It's just added weight, you're not doing it for looks as it's never seen. The spacer design is perfect for the application and has been race tested.

I agree on the caliper size thing hence keeping them black, red would stand out too much, but it's only marginal. Like I mentioned before though if I wanted bigger calipers etc I would have gone down the GT3 6pot route but then you're talking $1000s more...

Barn996 · 02-22-2010, 08:56 AM

Let us know how the new rotors perform compared to OEM without upgrading the calipers. You are probably doing this for the track as opposed to street use? They look great.

2K3TTMIA · 02-22-2010, 11:28 AM

Quote:

Originally Posted by Dervish

Why would a one piece spacer be any better? It's just added weight, you're not doing it for looks as it's never seen. The spacer design is perfect for the application and has been race tested.

...

First and foremost, the rotors look badazz and like quality pieces..I pm'd craig myself and am interested in the upgrade vs cost factor...

I'm not an engineer, but I have been wrenching for 28 years on everything from beaters to hi-performance muscle cars. The single piece spacer for one allows for a solid contact between the caliper and the mounting surface. I haven't witnessed the effects of heavy braking on these items first hand, specifically on P-cars, but I imagine there are some forces involved and alot of heat generated.
I would think you'd want to spread some of those forces and heat uniformly from the caliper, not just thru those two 12mm thick washers. the air moving in that gap is not going to do squat to have a cooling effect.
my other .02...
- and the spacers look cheesy.

LVDell · 02-22-2010, 12:59 PM

Curious why they would not make them as direct replacements to the stock unit and not require the spacer.

Has anybody that purchased these MEASURED the rotor area and compared to the stock units? In other words, measure the width of the rotor that is from that area where the hat ends and the rotor edge ends.

redridge · 02-22-2010, 01:09 PM

just looking at the pics... the stock is def smaller. It will be hard to make a 2 piece the same size as the stock.

the stock is 317mm vs 340mm... so the radius is longer... the advantage with this rotor (aside from heat dissipation?, fade etc? weight) is since the pads are further out, the stopping power is greater (more torque).

02-21-2010, 04:04 PM	#1
Dervish Addict Rennlist Member Join Date: Jan 2008 Location: London Posts: 241	Girodisc rotors finally installed Upgraded the front rotors from OEM cross drilled to Girodisc slotted. The Girodisc are 8% larger (340mm vs 317mm) and fit using the stock caliper with a reduction in weight from 9.0kg to 7.8kg per disc. The increased diameter provides a larger effective radius giving more braking force for the same system pressure. I really didn't want to go down the Brembo BBK route requiring almost a complete new disc/caliper system and pressure/bias changes. Here you can see the quality... And here the size comparison with the OEM... It's a very easy install, the only difference to the usual disc change is the addition of the 12mm spacer to move the caliper further away from the arm. The spacers are included in the kit together with 12mm longer caliper bolts (strangely Porsche part numbered?). Finished... Thanks to Craig at rennstore for all the info and help... Now I just have to see how they compare on track...

02-21-2010, 07:31 PM	#4
redridge Addict Rennlist Member Join Date: Oct 2006 Posts: 6,616	Im assuming the longer bolts comes with the kit.... looks great! The spacers are a bit cheesy though. __________________ Ferdinand

02-21-2010, 08:28 PM	#8
redridge Addict Rennlist Member Join Date: Oct 2006 Posts: 6,616	Ed, you might want to talk to the vendor..... this might be a good option for some. If I was in the market, I will def give you a call. __________________ Ferdinand

02-21-2010, 10:14 PM	#9
Shark Attack Addict Rennlist Member Join Date: Oct 2005 Location: North West PA USA Posts: 10,468	that looks like a mod worth while and easy. I agree on the spacers. I think a nice one peice spacer that looks like it is supposed to be there would be better. __________________ Kyle 99/911 Aerosmith 6 speeder I also have a strong respect for the 928. => another good forum http://reutterwerk.com/forums/forumdisplay.php?f=60

02-21-2010, 11:12 PM	#10
FLY996 Addict Rennlist Member Join Date: Jan 2007 Location: CT Posts: 753	makes the calipers look to small... __________________

02-21-2010, 04:10 PM	#2
ivangene Parts Specialist Rennlist Member Join Date: Aug 2008 Posts: 15,430	SWEET !!

02-21-2010, 05:33 PM	#3
LVDell Addict Rennlist Member Join Date: Oct 2003 Location: Tobacco Road, NC Posts: 3,816	Looking good! And I'll bet you are going to be even more excited to know it's more than 8%. hint....area of a circle not difference in diameter

02-21-2010, 08:22 PM	#7
ivangene Parts Specialist Rennlist Member Join Date: Aug 2008 Posts: 15,430	anyone interested in having me make a one piece?

02-22-2010, 02:12 AM	#11
Dervish Addict Rennlist Member Join Date: Jan 2008 Location: London Posts: 241	Why would a one piece spacer be any better? It's just added weight, you're not doing it for looks as it's never seen. The spacer design is perfect for the application and has been race tested. I agree on the caliper size thing hence keeping them black, red would stand out too much, but it's only marginal. Like I mentioned before though if I wanted bigger calipers etc I would have gone down the GT3 6pot route but then you're talking $1000s more...

02-22-2010, 08:56 AM	#12
Barn996 Addict Rennlist Member Join Date: Sep 2007 Location: Kittery, Maine Posts: 7,244	Let us know how the new rotors perform compared to OEM without upgrading the calipers. You are probably doing this for the track as opposed to street use? They look great. __________________ MY99 996,C2 Coupe,LSD,black/savanna beige, 6 spd., US MO3O suspension,black 3 spoke steering wheel,leather sport seats,TC, rear seat delete,ashtray delete, FisterD exhaust...current miles 59k Barn/Steve 1999 996 C2(current) 2002 Audi TT(history) 1998 Audi A4 " 1979 911 SC " 1986 Saab SPG " 1968 912 " 1960 AH Bugeye "

02-22-2010, 12:59 PM	#14
LVDell Addict Rennlist Member Join Date: Oct 2003 Location: Tobacco Road, NC Posts: 3,816	Curious why they would not make them as direct replacements to the stock unit and not require the spacer. Has anybody that purchased these MEASURED the rotor area and compared to the stock units? In other words, measure the width of the rotor that is from that area where the hat ends and the rotor edge ends.

02-22-2010, 01:09 PM	#15
redridge Addict Rennlist Member Join Date: Oct 2006 Posts: 6,616	just looking at the pics... the stock is def smaller. It will be hard to make a 2 piece the same size as the stock. the stock is 317mm vs 340mm... so the radius is longer... the advantage with this rotor (aside from heat dissipation?, fade etc? weight) is since the pads are further out, the stopping power is greater (more torque). __________________ Ferdinand

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