Brake questions
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From: Roanoke, VA
Brake questions
I've got a 90 C2 with the 2 piston rear calipers, and soon to replace the fronts with some TT calipers and rotors. 
Anybody know a good place to acquire some rear 993 or RS calipers and rotors. What is a "reasonable" (that's a hoot isn't it?) price to pay for them? Is a dealer like Sunset the best place to look?
Also, having read Adrian's book - I see that if I wish to be able to stop ALL THE TIME - I better change out the brake fluid reservoir (Big Reds going on the front) Can anyone supply a part number for the larger reservoir? Also, if anyone has changed them out - how much is involved in the swap? Any modifications required to make it fit? Watchouts?
I was planning to keep the 964 master cylinder.... at least for now, to avoid the vacumn boost to hydraulic boost issues.
And I keep asking myself - why do I keep doing this? (I know it's cause I love it, but... my accountant is beginning to think I'm out of my mind.
What an addiction right?) He'll be happy if I change the model of the car from 911 to 9$$... but I say, what the heck, you only live once.
Any words of wisdom about doing the mechanical parts of the conversion appreciated.
Marshall McCray
1987 944S
1990 C2 - On Steroids
Anybody know a good place to acquire some rear 993 or RS calipers and rotors. What is a "reasonable" (that's a hoot isn't it?) price to pay for them? Is a dealer like Sunset the best place to look?
Also, having read Adrian's book - I see that if I wish to be able to stop ALL THE TIME - I better change out the brake fluid reservoir (Big Reds going on the front) Can anyone supply a part number for the larger reservoir? Also, if anyone has changed them out - how much is involved in the swap? Any modifications required to make it fit? Watchouts?
I was planning to keep the 964 master cylinder.... at least for now, to avoid the vacumn boost to hydraulic boost issues.
And I keep asking myself - why do I keep doing this? (I know it's cause I love it, but... my accountant is beginning to think I'm out of my mind.
What an addiction right?) He'll be happy if I change the model of the car from 911 to 9$$... but I say, what the heck, you only live once.
Any words of wisdom about doing the mechanical parts of the conversion appreciated.
Marshall McCray
1987 944S
1990 C2 - On Steroids
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From: Santa Rosa, CA
I would not put big reds up front and normal C2 calipers in the rear. I used "big reds" up front (with the bigger rotors) and the 965 set-up in the rear (also bigger rotors). This was the set-up recommended by Race Technologies .
While I respect Adrian's opinions (I also have his book), I do not believe that a bigger reservour is required. You do need to pay attention to fluid leves in it, but changing it is not required. I have not changed mine.
The MC is the biggest issue (in my mind) with the bigger brakes. You will have a relatively soft pedal feel with the stock MC. The problem here is that the MC from a 993 C2 (also vacume boost) is not a plug in replacement, you need an adapter due to the difference in the plumbing. I'm determined to get this change made, it just has not happened yet.
My $0.02: You do need to ask why you are doing it. I see no reason to make this change for a street car. I made the change on my track car primarily for the bigger rotors and pad area to give better cooling, not better stopping. The difference in stopping power/distance is minor with the change. The cooling is significantly helped on tracks that are hard on brakes. You will need at least 17" wheels to fit the big reds and not all aftermarket 17" rims provide adequate clearance (Porsche Cup wheels are fine).
While I respect Adrian's opinions (I also have his book), I do not believe that a bigger reservour is required. You do need to pay attention to fluid leves in it, but changing it is not required. I have not changed mine.
The MC is the biggest issue (in my mind) with the bigger brakes. You will have a relatively soft pedal feel with the stock MC. The problem here is that the MC from a 993 C2 (also vacume boost) is not a plug in replacement, you need an adapter due to the difference in the plumbing. I'm determined to get this change made, it just has not happened yet.
My $0.02: You do need to ask why you are doing it. I see no reason to make this change for a street car. I made the change on my track car primarily for the bigger rotors and pad area to give better cooling, not better stopping. The difference in stopping power/distance is minor with the change. The cooling is significantly helped on tracks that are hard on brakes. You will need at least 17" wheels to fit the big reds and not all aftermarket 17" rims provide adequate clearance (Porsche Cup wheels are fine).
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I got mine from Crescent City Porsche (but I've been told that they've changed their name?) in New Orleans. I had shopped around and they had the best prices. I would ask for John (Porsche parts guy). You might want to try CDOC, I hear they are competitive for pricing.
I've had mine for two years, strictly for DE and club racing, and have never had a soft pedal. The brakes are awesome. Even after one hour of very hard racing, my co-driver in a 90 minute enduro commented about how firm the pedal felt. I never changed my master cylinder.
I've had mine for two years, strictly for DE and club racing, and have never had a soft pedal. The brakes are awesome. Even after one hour of very hard racing, my co-driver in a 90 minute enduro commented about how firm the pedal felt. I never changed my master cylinder.
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As stated the 993tt f will need at least 965 rear for balance. The 964s have a smallish 20.64mm m/c and should use the 23.8mm m/c w/ the 993 or 965 brakes.
All 993s start out w/ at least a 23.8mm m/c and so do not need to worry about this.
A 993 23.8mm power brake setup can be adapted to the 964. Do a search.
All 993s start out w/ at least a 23.8mm m/c and so do not need to worry about this.
A 993 23.8mm power brake setup can be adapted to the 964. Do a search.
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I assume you plan to race competitively, and need some extra margin.
For street use, the stock set up seems more than adequate. The wheels are easily locked even on dry pavement, and the ABS kicks in in case you don't know how to drive. I do some spirited street driving, including some hard braking on a bolt stock 92 C2. I don't see any signs of distress in the stock brake components. I agree with the comment that all you are getting for the big $$$ is some extra thermal mass, and some increased cooling area. Both are important, but more than you can use is of little benefit. Just my $0.02.
For street use, the stock set up seems more than adequate. The wheels are easily locked even on dry pavement, and the ABS kicks in in case you don't know how to drive. I do some spirited street driving, including some hard braking on a bolt stock 92 C2. I don't see any signs of distress in the stock brake components. I agree with the comment that all you are getting for the big $$$ is some extra thermal mass, and some increased cooling area. Both are important, but more than you can use is of little benefit. Just my $0.02.
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A 993 23.8mm power brake setup can be adapted to the 964. Do a search.
I did a search and didn't find the info (probably just botched the search words). The information I'm aware of, is as Tom mentioned, that a 993 MC can be adapted with a set of adaptors for the brake lines (Tony Taylor had this done by 9M to his 964). Unless you fabricate your own, you also need the 993 bracket. So, the parts list is shaping up as:
993.355.910.00 master cylinder
993.355.212.00 MC to vacuum cannister o-ring
993.355.163.03 support
This assumes that the mating to the 964 vacuum cannister is the same as the 993.
Tom, it's a race to see who can get this done first (and then share the connectors!)
As mentioned by Manny and others, many people upgrade to big reds and don't change their brake fluid reservoir or their master cylinder, and are pleased with the results. A Big Red upgrade needs to be front and rear, to keep braking in balance. Oh, and forget about switching to one of the hydraulic-based systems - the complexity and expense, to some, wouldn't be worth it. You're vacuum-based today, and have options with C4, 993, and Big Red components.
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Yes, Tony's car is the one I was thinking of. Again just because you can do something doesn't mean that is best. There is a worlsd of difference when the big calipers are couplesd w/ big masters. 23.8 is the smallest I would want w/ a set of the big piston calipers.
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From: WhippetWorld, .........is it really only this many
Originally Posted by Bill Gregory
Bill,
This assumes that the mating to the 964 vacuum cannister is the same as the 993.
This assumes that the mating to the 964 vacuum cannister is the same as the 993.
Burning Brakes
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From: WhippetWorld, .........is it really only this many
I wrote this at the time
"Re: the 993 MC - I did post on the RS brakes topic but it seems to have been lost in the forum change over.
The 993 MC was a direct bolt on but we had to use the 993 servo as the return spring on the 964 MC was on the MC itself but on the 993 it was integral in the servo - which was also a direct bolt on. ( obviously they managed to fabricate an adapter from the 10mm 993 MC to the 6mm 964 brake pipes). All is now fitted to the car with no problems associated with the change."
"Re: the 993 MC - I did post on the RS brakes topic but it seems to have been lost in the forum change over.
The 993 MC was a direct bolt on but we had to use the 993 servo as the return spring on the 964 MC was on the MC itself but on the 993 it was integral in the servo - which was also a direct bolt on. ( obviously they managed to fabricate an adapter from the 10mm 993 MC to the 6mm 964 brake pipes). All is now fitted to the car with no problems associated with the change."
Burning Brakes
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From: WhippetWorld, .........is it really only this many
Originally Posted by Bill Verburg
Yes, Tony's car is the one I was thinking of. Again just because you can do something doesn't mean that is best. There is a worlsd of difference when the big calipers are couplesd w/ big masters. 23.8 is the smallest I would want w/ a set of the big piston calipers.
"The pedal is much firmer. Braking is much improved since stopping power is now related to hard I push on the pedal rather than how far my foot is in the "treacle" - its much more linear. It allowed me to brake later and harder without locking up as the point at which the brakes start to lock is easier to judge.
There also seems to be a partial return of ABS but I`ll know better when it rains."
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The 993 MC was a direct bolt on but we had to use the 993 servo as the return spring on the 964 MC was on the MC itself but on the 993 it was integral in the servo - which was also a direct bolt on.
Thanks for the clarification and including your 'feel' comments, which is what I'd expect the benefit to be to the upgrade.
So, we add a 993.355.023.10 brake servo to the list.
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From: WhippetWorld, .........is it really only this many
When I had my m/c uprated to the 993 I was fortunate in that 9M had a used 993 system in stock so if it fitted, then OK, and if not I just paid for the time. It's helpful if you have both 993 and 964 m/c and servos in front of you to see the differences. Fortunatly even though both servo and m/c were required they both just bolted on - and then bolted off when we found the 10mmm to 6mm discrepancy 
In due course a 10 to 6mm connector was made but the details of this are lost in the mists of time
IMHO the 23.8 m/c works perfectly - I'm not sure I would want to go bigger even if this was possible.
In due course a 10 to 6mm connector was made but the details of this are lost in the mists of time
IMHO the 23.8 m/c works perfectly - I'm not sure I would want to go bigger even if this was possible.
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Bill (Gregory): I've just been informed that some of my poor pedal feel and issues with my brakes (pre and post upgrade) are likely due to a MC that's failing. So, I've asked Bob to look hard at getting the 993 MC plugged into the Turtle before Buttonwillow on Oct 1-3. I may "win" the race to get the new MC installed and have some information to share with you soon. Wish me luck!