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Max Sluiter
 
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Quote:
Originally Posted by arrivederci View Post
Great thread and watching carefully. I finally decided that the aluminum S calipers on my '72 just aren't enough any more. The inherent sponginess of the calipers isn't confidence inspiring although it will stop when you really stand on it. I talked to Steve a bit about his 930 conversion kit and while that is the ultimate for my '72 w/ 16" wheels and a 3.6L, I'm having a tough time justifying the cost. So I've been leaning toward carrera rotors and calipers even if they don't have the bling factor. It is also unlikely that I'll take this car to the track...I have a PCA E-stock car that manages fine with SC brakes, good pads, fluid, and cooling.

More options are better!
Are you sure it's the calipers? If you went with a bigger master cylinder (like if you got an aftermarket pedal assembly with dual master cylinders and bias bar) I bet it would feel better. Nice thing about the S calipers is they are monoblock, plus they are original or at least period correct for your car. Old 911s are never going to be as fast as a GT3 so it's nice to preserve the vintage touches that set them apart. Lots of the aftermarket calipers out there bolt together, unless you step up in the price range for Brembos or something.
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Last edited by Flieger; 01-07-2017 at 10:37 AM..
Old 01-07-2017, 10:34 AM
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After reading this info now you have me considering just rebuilding my stock ones for now. Maybe a caliper upgrade will be a future project. Still like to see how/what people are running for there set up. Track, street, weekend cruisers i like it all
Old 01-16-2017, 02:57 PM
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I am very happy with the 996 brakes on my 87 with a 3.8l in the back. Bill has warned about too much front bias but seems to me that I can live with it very well.
Old 01-17-2017, 12:38 AM
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I would be interested in knowing the Wilwood part numbers for calipers that would make stock replacements. It would be nice to have a breakdown, which Wilwood works for 74-77, and which for 78-whatever.

I'm tired of rebuilding expensive old Porsche calipers. The Wilwood products are very reasonably priced, it would be great to have a bolt on new alternative.
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Old 01-17-2017, 02:37 PM
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It's a 914 ...
 
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Quote:
Originally Posted by Bill Verburg View Post
Just because there are more pistons it doesn't mean the m/c needs to be changed, The driving factor here is the slave/master ratio. You want to keep the slave/master ratio in the range of ~40 to ~30, The lower the better for sporting use. The lower limit is what's physically comfortable for the driver to use for his longest stint, the high end limit(~45) is the rate of volume flow of fluid in a panic stop. Street cars tend to be at the higher end because the manufacturers have to provide for just about anyone to be able to drive no matter how frail.

I was relaying the experience from my parents' '70 911 with Wilwoods on the front. The pedal was spongier with the Wilwoods, hence my suggestion to consider a larger master cylinder.

Scott
Old 01-18-2017, 04:18 AM
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Wilwood

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Originally Posted by Cornerlot View Post
My '72 has Wilwood calipers on the front (bought it that way). Don't know what model or what rotors are being used. I can take photos if needed.

Steve
Finally took some photos. Wilwood Superlite II calipers on 3.5" front knuckles using Carrera rotors.

Steve



Old 04-03-2017, 08:37 AM
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Maybe they're these...

FS on eBay: Wilwood brake calipers
Old 04-03-2017, 11:35 AM
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I ended up running superlite 4pot wilwood calipers. Have yet to drive the car but they fit with very little modification. Had to drill out the caliper mounting holes a bit and trim the dust shield and that was it! Even used the stock hard line into a 90 degree adapter fitting. If i ever get my car on the road i can see how they work
Old 11-10-2017, 01:15 PM
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pictures of setup? wilwood part-no?
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Old 11-10-2017, 01:24 PM
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photobucket sucks
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Old 11-11-2017, 12:23 PM
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These calipers have almost twice the piston area of the stock calipers, so I suspect the brake balance will be extremely front biased.
Stock: one 48mm piston = 2.80 sq in vs 5.18 sq in for the 120-11137.

The Wilwood Superlite 2 with two 1 3/8" pistons has nearly the same area as stock (2.96 sq in), and won't mess up the balance, assuming stock rear rotors.

I have had the Superlite 2's on my car for over 15 years and about 50,000 miles.
Its not a daily driver and because of a lot of track time the calipers get attention frequently, and I haven't had any reliability issues.
Changed the piston seals a couple of times just to check the pistons and bores.
I found there is a limited selection of pads offered in the Wilwood front pattern and the stock rear pattern, although Hawk has several offerings.
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Old 11-11-2017, 02:57 PM
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How does that work on brakes,

Given X pedal pressure for the stock caliper and the Wilwood spread over a larger area the PSI is lower? Would that move the bias rearward?

I think I am over simplifying.

Check this out from the Corvette World

https://gspeed.com/product/corvette-manual-brake-conversion/

Would be so nice to have a bolt in solution like this. It is very expensive though.

I know slightly off topic
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Old 11-11-2017, 03:36 PM
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Quote:
Originally Posted by Elombard View Post
How does that work on brakes,

Given X pedal pressure for the stock caliper and the Wilwood spread over a larger area the PSI is lower? Would that move the bias rearward?

I think I am over simplifying.
Not necessarily oversimplifying but perhaps the perspective is incorrect.
With more piston area on the front calipers, the line pressure needed for any level of front brake torque will be lower than stock, in this case by 5.18/2,8=1.85 times lower.
That lower line pressure will result in the rear brake torque being 1.85 times lower, thus biasing the brakes towards the front.
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'84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff
'69 Lotus 7 Series 3; '74 Fiat X1/9
'14 X5 diesel
Old 11-11-2017, 05:33 PM
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Thanks for the explanation Bob
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Erik L.
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84 lime green back date (LWB 911R with RS rear flares) hot rod - absolute riot to drive!
RSR look hot rod, based on 75' SOLD
73 911t 3.0SC Hot rod Gulf Blue - Sold.
Old 11-11-2017, 06:07 PM
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Quote:
Originally Posted by bdonally View Post
These calipers have almost twice the piston area of the stock calipers, so I suspect the brake balance will be extremely front biased.
Stock: one 48mm piston = 2.80 sq in vs 5.18 sq in for the 120-11137.
The stock front calipers have 2 48mm pistons. The total surface area is 5.6 sq in.
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Last edited by theenico; 11-12-2017 at 07:32 AM..
Old 11-12-2017, 07:09 AM
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Quote:
Originally Posted by theenico View Post
The stock front calipers have 2 48mm pistons. The total surface area is 5.6 sq in.
Terminology problem.
When calculating the pressure exerted by a caliper, one uses the area of the pistons on one side of the caliper.
The stock caliper has one piston on each side, each with an area of 2.8 sq in
The Wilwood has two pistons (1@1.875" and one at 1.75") on each side; the piston area per side is 5.18 sq in.

If you use the piston area as per your post, the Wilwood would be 10.36 sq in.

But that number isn't of much use designing brakes because the clamping force is determined by line pressure and the piston area of one side of the caliper.
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'84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff
'69 Lotus 7 Series 3; '74 Fiat X1/9
'14 X5 diesel
Old 11-12-2017, 06:48 PM
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It may be mentioned elsewhere in this thread, but Wilwood Superlites are available in different piston sizes. 1.375", 1.5", and 1.75" I think used to be options. Maybe they make staggered sizes now to avoid the uneven pad wear issue. My parents had a 1970 911 that they tracked for many years that my dad put Wilwoods on the front of. They had I believe 1.375" pistons, and with no other mods the bias was not an issue.

Scott
Old 11-13-2017, 04:45 AM
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Quote:
Originally Posted by bdonally View Post
Terminology problem.
When calculating the pressure exerted by a caliper, one uses the area of the pistons on one side of the caliper.
The stock caliper has one piston on each side, each with an area of 2.8 sq in
The Wilwood has two pistons (1@1.875" and one at 1.75") on each side; the piston area per side is 5.18 sq in.

If you use the piston area as per your post, the Wilwood would be 10.36 sq in.

But that number isn't of much use designing brakes because the clamping force is determined by line pressure and the piston area of one side of the caliper.
You're right. That's what I get for trying to think on the weekend.
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Last edited by theenico; 11-13-2017 at 08:21 AM.. Reason: Spelling/Grammar
Old 11-13-2017, 08:21 AM
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IMG_3655 by tj Weinberg, on Flickr

IMG_3699 by tj Weinberg, on Flickr

Trying to reload images....

Should also mention I aslso installed the Wilwood prop valve as well to help with bias
Old 11-13-2017, 03:29 PM
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