RS rotors with stock calipers
08-22-2002, 03:32 PM
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RS rotors with stock calipers
I've seen a nice (cheap) halfway to Big Reds conversion using bigger RS discs (rotors) with standard 993 calipers.
Basically to accomadate the 15mm bigger rotors you use 15mm spacers (and longer bolts) between the caliper and it's mounting points to move the caliper out.
Although the brake pad won't sweep the inner 15mm of the rotor, you get the advantage of better cooling due to the larger area and marginally more mechanical advantage.
The car I saw using this mod had 18" Ruf alloys. Although I have 18" Turbo Twists for the road, I use my original 17" Cups at the track which due to the curved spoke design look like they run very close to the caliper in the standard position!
My question is will I need a wheel spacer and if so what size??
Does anyone else have any experience with this mod?
The owner of the car I saw this on said it had a noticeable effect on pedal feel in Track conditions.
Basically to accomadate the 15mm bigger rotors you use 15mm spacers (and longer bolts) between the caliper and it's mounting points to move the caliper out.
Although the brake pad won't sweep the inner 15mm of the rotor, you get the advantage of better cooling due to the larger area and marginally more mechanical advantage.
The car I saw using this mod had 18" Ruf alloys. Although I have 18" Turbo Twists for the road, I use my original 17" Cups at the track which due to the curved spoke design look like they run very close to the caliper in the standard position!
My question is will I need a wheel spacer and if so what size??
Does anyone else have any experience with this mod?
The owner of the car I saw this on said it had a noticeable effect on pedal feel in Track conditions.
08-22-2002, 03:43 PM
#2
It sounds like a great setup. The stock 993 front pad is really only 10mm shorter than the big Red, so you are only giving up 76 sq cm of pad area all together(Big Red is ~151 sq cm/caliper 993 is ~113 sq cm/caliper).
08-22-2002, 05:02 PM
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Jeff,
Yep, massive...
If you do it when you need new rotors anyway (as I do) and you already have and will only use 18" wheels the cost is almost nothing.
Provided you don't need the more expensive bolt on wheel spacers rather than say 7mm wheel shims for 17" wheels it's still very inexpensive.
Yep, massive...
If you do it when you need new rotors anyway (as I do) and you already have and will only use 18" wheels the cost is almost nothing.
Provided you don't need the more expensive bolt on wheel spacers rather than say 7mm wheel shims for 17" wheels it's still very inexpensive.
08-22-2002, 05:13 PM
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[quote]Originally posted by Bill Verburg:
<strong>The stock 993 front pad is really only 10mm shorter than the big Red, so you are only giving up .53 sq cm of pad area all together(4pads).</strong><hr></blockquote>
So what are you saying? How big of differences are there at the rear? Is it worth the money to go to big reds?
I am thinking about the conversion but I am yet convinced of better braking power from the big reds...What do you recommend for a car with some track use? Maybe just a brake cooling kit???
<strong>The stock 993 front pad is really only 10mm shorter than the big Red, so you are only giving up .53 sq cm of pad area all together(4pads).</strong><hr></blockquote>
So what are you saying? How big of differences are there at the rear? Is it worth the money to go to big reds?
I am thinking about the conversion but I am yet convinced of better braking power from the big reds...What do you recommend for a car with some track use? Maybe just a brake cooling kit???
08-22-2002, 05:17 PM
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Hey guys
did you read the car& driver big brake upgrade article. Mentioned Stoptech brakes were excellent. I emailed them yesterday re: big brakes for 96. They mentioned they are doing a 993 set within 2 months!! It will be cheaper than Brembo & according to car& driver, very very good. Just a heads up for you.
did you read the car& driver big brake upgrade article. Mentioned Stoptech brakes were excellent. I emailed them yesterday re: big brakes for 96. They mentioned they are doing a 993 set within 2 months!! It will be cheaper than Brembo & according to car& driver, very very good. Just a heads up for you.
08-22-2002, 05:30 PM
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The article can be read here:
<a href="http://www.caranddriver.com/xp/Caranddriver/features/2002/september/200209_feature_braketest.xml?keywords=stoptech" target="_blank">car & driver brake fade article</a>
<a href="http://www.caranddriver.com/xp/Caranddriver/features/2002/september/200209_feature_braketest.xml?keywords=stoptech" target="_blank">car & driver brake fade article</a>
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08-22-2002, 05:39 PM
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[quote]So what are you saying? How big of differences are there at the rear? Is it worth the money to go to big reds?
I am thinking about the conversion but I am yet convinced of better braking power from the big reds...What do you recommend for a car with some track use? Maybe just a brake cooling kit??? <hr></blockquote>
MarkC only mentioned changeing the front rotors, so there is no change at the rear.
The Big Reds only advantage over the std 993 front fare is the bigger rotor 322x32 vs 304x32 and slightly larger pad area. The larger rotor gives a little bit of mechanical advantage and a lot more heat sink, the larger pad area reduces the mechanical and thermal stresses at each sq cm of pad promoting cooler running and longer life. Hydraulicly the 2 calipers are identical.
So, no you do not get better braking in the sense of shorter stopping distances, you do get greater thermal and mechanical reserves which will allow the brakes to functions optimally under TRACK conditions
Unless you are really frying brakes or rotors or boiling your brake fluid then I would stick w/ the old standards
Marks suggestion is a resonably priced next step and if all else fails buy the full Big Red kit
Yes, StopTech makes nice brakes but they have been promising 911/964/993 stuff for a while. I still havn't seen any of it.
I am thinking about the conversion but I am yet convinced of better braking power from the big reds...What do you recommend for a car with some track use? Maybe just a brake cooling kit??? <hr></blockquote>
MarkC only mentioned changeing the front rotors, so there is no change at the rear.
The Big Reds only advantage over the std 993 front fare is the bigger rotor 322x32 vs 304x32 and slightly larger pad area. The larger rotor gives a little bit of mechanical advantage and a lot more heat sink, the larger pad area reduces the mechanical and thermal stresses at each sq cm of pad promoting cooler running and longer life. Hydraulicly the 2 calipers are identical.
So, no you do not get better braking in the sense of shorter stopping distances, you do get greater thermal and mechanical reserves which will allow the brakes to functions optimally under TRACK conditions
Unless you are really frying brakes or rotors or boiling your brake fluid then I would stick w/ the old standards
- fresh. h/p fluid <a href="http://members.rennlist.com/911pcars/brakefluid.htm" target="_blank">Brake fluid Info</a>
- relatively new or at least not worn out h/p pads <a href="http://www.pagidusa.com/characteri.html" target="_blank">Pads</a>
- cooling <a href="http://www.pcasd.org/tech/tech_apr.shtml" target="_blank">Cooling mods</a>
Marks suggestion is a resonably priced next step and if all else fails buy the full Big Red kit
Yes, StopTech makes nice brakes but they have been promising 911/964/993 stuff for a while. I still havn't seen any of it.
08-22-2002, 05:41 PM
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A quote from the Car & Driver article....
"Caliper size is a small component in fade resistance, as most of the braking heat goes into the rotor."
Which makes a low cost option to fit the bigger rotors very attractive to me.
"Caliper size is a small component in fade resistance, as most of the braking heat goes into the rotor."
Which makes a low cost option to fit the bigger rotors very attractive to me.
08-22-2002, 05:58 PM
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Bill
I'm newer to this than you - you've probably been talking o them for ages about 911/964/993 stuff!!
I e-mailed them yesterday & they said two months....but they may have been saying his for two years???
I'm newer to this than you - you've probably been talking o them for ages about 911/964/993 stuff!!
I e-mailed them yesterday & they said two months....but they may have been saying his for two years???
08-22-2002, 06:21 PM
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[quote]Originally posted by KC993:
<strong>One more question, AJusa Brake Cooling Kit...good? worth it???
</strong><hr></blockquote>
I don't have any personal experience with the AJ kit but I remember a very respected Porsche shop saying that they were very unimpressed with it.
My winter project is to get the kit for the GT2 fitted to my car. It allows a large duct to be directed into the hub. My current set up is pretty crude but I just ran some ducting from the front along the a-arm up towards the rotor. Since going to the Big Reds and rotors I haven't had a problem with fade.
<strong>One more question, AJusa Brake Cooling Kit...good? worth it???
</strong><hr></blockquote>
I don't have any personal experience with the AJ kit but I remember a very respected Porsche shop saying that they were very unimpressed with it.
My winter project is to get the kit for the GT2 fitted to my car. It allows a large duct to be directed into the hub. My current set up is pretty crude but I just ran some ducting from the front along the a-arm up towards the rotor. Since going to the Big Reds and rotors I haven't had a problem with fade.
08-22-2002, 06:52 PM
#13
The only AJ-USA kit I've seen is this one
Its not really for a 993 and I don't like the scoop hanging under the car, they always get torn off and in addition I'm not a fan of the ribbed tubing(though it's a necessary evil in most caes). Pickups in the front spoiler using large diameter, smooth wall tubing, necked down where necessary, ducted to the rotor throat are the way to go(you do want some air flowing up both faces of the rotors w/the bulk through the interior). Something like these pieces
sold by Autometrics
Greg any pic of the GT2 setup? I've never seen on up close.
Its not really for a 993 and I don't like the scoop hanging under the car, they always get torn off and in addition I'm not a fan of the ribbed tubing(though it's a necessary evil in most caes). Pickups in the front spoiler using large diameter, smooth wall tubing, necked down where necessary, ducted to the rotor throat are the way to go(you do want some air flowing up both faces of the rotors w/the bulk through the interior). Something like these pieces
sold by Autometrics
Greg any pic of the GT2 setup? I've never seen on up close.
08-22-2002, 10:19 PM
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[quote]Originally posted by Bill Verburg:
<strong>
Greg any pic of the GT2 setup? I've never seen on up close.</strong><hr></blockquote>
No pics but I will try to describe it. The area around the rotor is totally sealed except for where the 4" duct comes in. It has a piece like what you see in the autometrics pic that flattens so you can still turn your wheels. If you get the chance to look at most professionally done race cars you will catch my drift.
What does autometrics charge for the pieces? Where were going to have a local composite guy do some but it might not be worth the trouble if they are reasonable.
Greg
<strong>
Greg any pic of the GT2 setup? I've never seen on up close.</strong><hr></blockquote>
No pics but I will try to describe it. The area around the rotor is totally sealed except for where the 4" duct comes in. It has a piece like what you see in the autometrics pic that flattens so you can still turn your wheels. If you get the chance to look at most professionally done race cars you will catch my drift.
What does autometrics charge for the pieces? Where were going to have a local composite guy do some but it might not be worth the trouble if they are reasonable.
Greg
08-23-2002, 07:47 AM
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OK,
The concensus seems to be that along with better cooling via additional ducting this is a good cost effective idea.
I will purchase and fit the RS rotors and 15mm spacers and then experiment with wheel shims/spacers to determine the minimum size required to use with 17" Cup wheels.
I won't be able to do this immediately but I'll post the results here when I've finished the job.
In the meantime if anyone has already done this and knows the spacers required I'd appreciate it if they could share the information here.
The concensus seems to be that along with better cooling via additional ducting this is a good cost effective idea.
I will purchase and fit the RS rotors and 15mm spacers and then experiment with wheel shims/spacers to determine the minimum size required to use with 17" Cup wheels.
I won't be able to do this immediately but I'll post the results here when I've finished the job.
In the meantime if anyone has already done this and knows the spacers required I'd appreciate it if they could share the information here.
