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Big Brakes

It would be great if we could figure out some of the brake science in layman's terms. I have read car magazines for 20 years now and always laugh when I see the $1400 big brake kit go on a car and provide very minimal or even worse stopping distances.

Some of the issues seem to be whether the brakes are reproportioned front to rear, whether a full kit that includes new front and rear brakes is used, and of course, the pads that are used. I have seen the data on the Volvo 240 proportioning valve before. I think the specs have something to do with ensuring safe braking on a fully loaded car. For performance purposes, altering the proportioning and thus the bias, reportedly can make a very noticeable difference. It can also cause potentially life threatening problems if the new specs are used under conditions for which they are not intended.

Brake pedal feel is another big issue. It can be altered when you fit big brakes that have different total piston areas, unless you change the master cylinder. You can change caliper piston area, the master cylinder, or both, to dramatically change pedal feel. Where there is power assist, the balance can be more complex.

I was planning to fit a set of front and rear Wilwoods, using custom spacers, and custom hats (Wilwood does not make any 5 x 4.25 bolt pattern hats so they would have to be Wilwood blanks that were drilled) and Wilwood rotors. With the aluminum calipers and hats, there is a significant savings in unsprung weight. We have a set of front and rear Wilwoods on a BMW 635 and they work really well. The better 4 piston Wilwood calipers cost only about $160 each. 6 piston calipers are expensive. I think I could use the better 4 piston units in the front and the lower level 4 piston units in the rear.

We also need to figure out how much brake we need. Is 12 inch enough for a 3000 lb car? Do we need 13 inch? I don't really know. I'd rather not buy too much more than I need. To fit 13 or 14 inch brakes, you need big wheels. Big wheels ride worse and weigh more, so I'd rather stick with a maximum of 17 inch diameter for my 745T. Obviously, people's needs will change depending on how they use their cars. I have never overheated my brakes, so I don't drive that hard. I would be looking for just a reduction in stopping distance from speed. I don't need to repeat it 10 times in a row without fade like a roadracer might on a fast tough course.

Philip Bradley
 
where are you guys going to get the adapter for the calipers? sounds like we have 3 guys right now. i'm in if someone's going to get some made. cant afford the rest of the items right now, but they'll be easily found anytime at the dealer.
 
n xntrx volvo said:
where are you guys going to get the adapter for the calipers? sounds like we have 3 guys right now. i'm in if someone's going to get some made. cant afford the rest of the items right now, but they'll be easily found anytime at the dealer.
Click to expand...

For what? Todd makes S60R caliper brackets, everything else will have to be custom.
 
n xntrx volvo said:
i was under the impression for this thread and this thread
http://forums.turbobricks.com/showthread.php?t=11193&page=2&pp=25&highlight=s60r+brakes
that on a 240 the only custom parts required are the caliper mounts. everything else , like lines,can be be fab'd at home. i've even checked my clearances, last time i saw paul and dave. i'm i wrong, as usual?
Click to expand...

No, Im sorry everything else meant everyone elses brakes will require something custom.

The S60R brakes a piece of cake. I'll do a nice write up on them when I get mine in the next month or so

Doug
 
so, an s60r caliper w/ how big of a rotor will clear the 15" rims? (yes, doug i know you have big'uns! ;-) ) or will it clear at all? this is for sure one of the more interesting threads in a while! later,

ben

and also, is the only way to change the total brake pressure developed changing the master cylinder size?
 
grebnut said:
so, an s60r caliper w/ how big of a rotor will clear the 15" rims? (yes, doug i know you have big'uns! ;-) ) or will it clear at all? this is for sure one of the more interesting threads in a while! later,
Click to expand...

I would be thinking about how to get bigger tires on the front before upgrading the brakes. With good pads and stock brakes, I can use up every bit of grip my sticky 205's can provide.
 
yes, for legal speeds, but at x 2 you wont, also little to no fade.
doug i'm refering to the s60r brakes, not to something fancy, pics/ article?
also should the dust shields be installed to protect the lower ball joint from dust and heat, or is this not ness? paul or dave, could you please list the parts needed, with numbers if you have them?
 
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the only issue i see is that it doesn't look like it uses a caliper bracket ala porsche style. pics below for part numbers

L hand
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R hand

large.jpg
 
Well, this is a reply to Phillip. Peter of MVP uses a 4 piston wilwood and wilwood discs with custom Hats. The wilwoods have a small disadvantage to the S60R calipers. The swept area of the pads is much greater on the S60R and that increases pedal feel. The wilwoods are cheaper for the calipers, 160 for the 4 piston and $320 for the 6 piston. As for Disc size, wilwood only makes their discs up to 13". they are also very thick, usually 1". Before I did the R brakes, I had all the info on doing a Wilwood set up. The Cost was about 900 on thelow side, and 1200 on the high side. Brackets and hats were the only unknowns. Now that we have done the R brakes, the wilwoods are still an option, since most of what we learned about the R conversion directly translates to the wilwood conversion. All it takes is a little time, and brackets can be made to fit almost any caliper and disc you want.
Phillip did also mention piston diameter and larger master cylinder possibilities. I did take that into consideration and the R calipers are only slightly larger in total diameter. Testing and proportion valves will only show us what is possible with a big brake conversion.

On a side note. I have Wilwood Hats that MVP had made for 740's The bolt pattern is correct for a 740, but they do not directly fit a 240. The stud holes, are small and only fit a 740. For a 240 to use these hats, the stud holes would need to be enlarged. 740's used smaller diameter studs than 240's. Not a huge issue, any machinist can fix the problem. I paid a good sum to have 3 sets. It was part of a master plan to develop a big brake system for 240's since MVP went out of the performance parts business. We had planned to use wilwood parts, and source the wilwood parts from Summit Racing. I even have the info on part #'s and what was needed, and some other info.

Cheers

Paul Jones

Only time and testing will tell truth
 
Guys........
The Porsche (Brembo) 4 piston calipers as installed on a Carrerra-4 are available used for normally in the neighborhood of $100.00 each cuz the guys who drive them Porkers just MUST have the huge red ones. We all know how more dollars makes that little thing bigger....I have only been able to make fade using those C-4 calipers ONCE. That was on a very long downhill section at very high speeds. This meaning 5 miles of 115mph to near zero and over again and again. Using them on the track the only issue was that they put so much braking force into the car with track tires that front suspension junk likes to bend. Stock control arms on your 240? You will bend them into the shape of a pretzel as soon as the tires warm up on braking and then wonder why the handling is sooooo creepy until the tire starts hitting the car. To the driver this is NOT amusing.
Any machinist worth his salt can make up a bracket for you. Get it right though.
Do rotors on hats and make sure that the centerline of the brake rotor ends up in the same place as stock to prevent wierd geometry issues that load wheel bearings badly. I got that geometry tee-shirt too.
John Lane
 
John,
What keeps fluid from forcing it's way out the clutch master cylinder tied to the rear brakes when you apply the pedal brake?
WE ALL need these so that we could make faster U-turns because we All know that the lame inner drum setup SUCKS.
yes PICS PICS PICS.

JohnLane said:
My hydraulic handbrake consists of a clutch master cylinder plumbed into the single brake line that goes to my rear brakes. The fluid goes in where one would have the resivior for the clutch master and comes out the normal spot. The handbrake handle is modified to operate a rod to push on the master cylinder which is mounted to a bracket welded to the tunnel behind the E-Brake handle.JL.
Click to expand...

Doug,
I know this would make it easiest to do a linelock, but do understand that the reason they are tied diagonally is so that if a brake caliper or line fails, and you lose one circuit of brakes that you still have a front and rear brake. If you tie the front and rear seperately and then lose a line or a caliper you will be having a nice little spin likely.

Snoopy Douggy Doug said:
NOW, what I would like to know is: Is there a generic distribution block that would let you keep the front of the master cylinder to the front brakes, and the rears to the rear?
Click to expand...


Very nice thread! good to see.
Sean
 
Snoop Dougy Doug said:
ahh but someone MAKES S60R adapters already, no one sells the porsche ones
Click to expand...
what i find complicated is the fact that it looks like the R brakes use a 2 ear fitting like stock brakes, so the adapter to use them would be similer to the +20mm fitting on rear of my RM-7 to enable me to run a 20mm larger disc. (sorry to go on about MTB brakes)

medium.jpg


the design for this really needs to be done so that it doesn't load up different eyelets more then one another to cut down on stresses.

while the adapter for the porka brakes is just a bar of metal with 4 holes drilled in the correct place and maybe some tapping going on. adn uses the stock eyelets which are already disigned well from the factory.
 
well right now we can only go off of those with prices, to compare fully. a r brake setup has been done, cost 900-1000, willwood has been done, cost 900-1200+, porsche hasn't been done by anyone that i personally know, cost unknown.
the porsche does show promise, your right about that, but too much is unknown about the swap for us to accurately evaluate it in comparision to the others. if you can fill in the blanks, please do.
 
As an aside... If you decide to use the Wilwoods, make sure to get the caliper with the appropriate size pistons for your MC. Wilwood offers a couple of different sizes.

Peter
 
is there a spare tire that will fit over these? riding with my buddy in his stang w/r 13" brakes, when he got a flat, had two change two tires just to get back (front left flat, swapped left rear with spare, put good left rear on front.) i don't even know what he'd do now that he has 275's in the back now.
 
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