4 piston, vented brake kit for 105/115

[larry]

It might show with the new owner.

[classicalfas]

What master would I use for the '67 GTV?

[fgc]

Hi Larry,

Nice set up! YOu said that it still fits in the 14" rim? Cool. I dont want to upgrade brakes and then have to change out my cromodoras as well.

Do your calipers have dust boots? I want to upgrade but as it is a daily driver, I want more "reliability".

Cheers
fgc

[larry]

It all fits in 14' alloys, Daytonas, etc. The Calipers don't have dust boots, but neither do most brembos fitted in factory produced cars, I use Brembos from 944 turbo's for my GTV-6 and Milano kit, no dust seals and they are reliable. I have used the Wilwoods daily for years no problems, and they have stainless pistons anyways. Sitting for long periods and the corrosion from the inside is what usually causes plain steel pistons to leak. Brake fluid is hydroscopic and the resulting water inside the system is the potential problem. Daily drivers rarely have any caliper problems steel or otherwise. It is always a good idea for street cars to flush you brake and clutch systems every year or two.

[tucco]

Larry, could you share model# on the calipers and also how thick are the rotors??
peter

[PSk]

Quote:

Originally Posted by bianchi1 4 piston calipers off a mazda rx-7 , and saab rotors, re-drilled to 108mmx 4. cost less than $100.00, brake calipers from local pick and pull, lots of mazda with those alum. 4 pot ca;ipers, and the rotors of a 85- 87 saab 900 turbo.easy to make the brakets to fit he calipers.

[larry]

Rotors are just over 20mm thick (.810)and the caliper part# is 120-8464 (L/R) and pad sets # is 150-8854K

[tucco]

Beautiful stuff Larry, how big are the rotors??

[larry]

To be able to fit in 14" alloys the rotor dia. is 10.75" which also allows use of the original dust shields.

[60sRacer]

Larry,

Do you have any experience in the effects of the somewhat heavier discs on suspension perfromance? For racers, a lot of work goes into small savings in unsprung weight. The 105's have been racing well for quite a while without vented rotors, and without four piston caliers. Can you give us any (quantitiative or qualitative) idea of the performance gains from better (?) braking vs higher weight?

With these kits as just front rotors, (vs the outlaw kits available that have rears available also but without vented discs), what about front/rear balance? Do you use an adjustable rear brake limiter?

BTW - Beautiful!! You do a lot of really neat stuff!

Robert

[larry]

This kit is lighter than stock, about 4lbs. per side. That was one of the considerations in doing this was to save weight. Alloy 4 piston calipers are much lighter than the stock Ate steel 2 piston calipers. The vented rotor with alum hat is not much heavier than stock rotor. The big difference is the piston area with the 4 piston calipers and larger pad area. There is a dramatic increase in braking force.

The stock setup is good for street and racing, depending on pad compounds. For most drivers they are fine and do a great job. When really run hard for racing they are really just OK. they eat up pads fast, hot spots and cracks in the rotors are not unusual. And at the end of the straight that new corvette that is heavier, going faster and outbrakes you, that is when you see they are not great brakes. Having almost run into the back of better brakes you see the need. Technology moves forward, I don't know of any serious race car that doesn't use vented rotors, let alone all new street cars, they give a more stable temp range, less dramatic spikes in temp and you can run a relatively softer compound giving better initial bite cold. I have run hard compounds on the street with solid rotors and struggled to stop cold. We are limited by the 14" alloy wheel though given 15's or better yet 16's we could really up the torque factor with a larger dia rotor. Do you want great brakes from 1970 or would you rather have something better.

[larry]

I some cases removing the rear brake press reg( full press to the rear) or a reg. on the front to relatively increase the rear braking. pad comp on the rear effects choice, Our cars are so light in the rear that vented rear rotors doesn't seem to be needed. GTV-6 and Milanos definitly need vented rears. Alloy rear calipers are appealling, I just would say just get the outlaw setup. I made my own but to much trouble.

[60sRacer]

Thanks Larry. I do see the need when you are racing against more modern cars. We already suffer from not having a SOA engine - it was ahead of its time, but gee 40 years has passed. The newer TS motor makes a better basis for an Alfa Racing engine too.

Next free paycheck I just may get a set of these. I have found the brake limits just driving (too vigorously at times) the curves of Mulholland Drive......

The one remaining issue I need to look at are the group rules for various racing formats. I guess all I'm really after is a fast car for fun and TT and autocross with my Duetto. I know that a GT is a better platform for all out racing. That's another dream.....



Robert

[bianchi1]

if you remove the brake pressure reg.( rear). doe's that not lock up the rear quicker? in the dry?, what would you think about the rainy season we have here, in n.ca.? would that not make the rear brakes more prone to rear lock up in the rain? causeing the rear to get really lose?, thanks.

[nizam]

bianchi1 - I think you have to keep in mind the context of the thread;

when you increase the braking efficiency on the fronts - e.g. with stronger 4-piston calipers - all things being equal, you have a lot less relative clamping force on the rears. This essentially makes the brakes front biased.

By removing the rear brake pressure regulator once you have installed the 4-piston calipers up front you move some of the brake bias to the rears. In most cases, the brakes will still remain somewhat front-biased. The attitude of the car should remain similar to stock -- except you can stop helluva lot sooner (assuming you have good tires, and traction at the time of braking).

But yes, your summation was correct: if you simply removed the rear pressure regulators without changing the fronts, you will lock up the rears very easily, esp. in the rain.

I don't have a 105/115 but I do have four-piston brembos up front on my 161 (75/Milano) and had to remove the rear brake pressure regulator to move the bias to the rear so I could rotate the car more readily. Keep in mind, though, that the 161's (and 116's) have that transaxle in the back so I carry more weight there than you guys with the 105/115 cars.