Wilwood 6 pistons at all 4 corners

[c10seconds]

Im using the W6A Wilwood calipers up front and the SL6 Wilwoods in the rear. Both being large calipers, im unsure of what i should use to power these brakes. Is there a recommended MC/PV/Booster set up? Do i need to go to a hydroboost?

I've been told that 6 piston calipers at front and rear would never work right and that i need to go with something smaller in the rear.

Rotors are 14" front and 13" rear

I want to get this done right the first time so let me know what you guys would recommend.

Lamar
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[N2TRUX]

Originally Posted by c10seconds

...I've been told that 6 piston calipers at front and rear would never work right and that i need to go with something smaller in the rear.

Who have you talked to? I would question the supplier as to what they recommend. In a recent conversation with Tobin at Kore 3 he recommends the booster/prop valve combo that CPP sells. I would check that out.

[c10seconds]

That's info that came directly from wilwood. Its not the first time they've given me wrong info. The distributor i purchased from said it would work. Ill give Tobin a call.
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[robnolimit]

The only hitch I see is that you may have too much rear brake. An adjustable proportioning valve in the rear line will help. pedal ratio and bore size will be the key. I'd run a 1 1/8" masterm and the large GM 11" booster, or a hydro. I just put 14" and 13" 6 piston bear brakes on a truck for Boris Said (55 ford) and it stops on a dime. (3 cents back!) I'd see no problems with your plan.

[Todd TCE]

Originally Posted by c10seconds

Im using the W6A Wilwood calipers up front and the SL6 Wilwoods in the rear. Both being large calipers, im unsure of what i should use to power these brakes. Is there a recommended MC/PV/Booster set up? Do i need to go to a hydroboost?

I've been told that 6 piston calipers at front and rear would never work right and that i need to go with something smaller in the rear.

Rotors are 14" front and 13" rear

I want to get this done right the first time so let me know what you guys would recommend.

Lamar
Posted via Mobile Device
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I wanted to chime in here and say that I'd strongly discourage you from doing this. While there are two piston sizes of the W6A caliper even the largest ones will not properly pair with the BSL6 on the rear.

In short: the BSL6 is not a proper piston area caliper for a rear application. It will over bias the rears by a significant amount and net a very poor pedal feel and response. Even running an adjustable prop valve would be a bandaide solution....The only way this will work for you is if you were to run a dual master cylinder set up allowing you to greatly de tune the rear. Piston Qty is not the issue here gents; piston AREA is.

Assuming for a moment that the BSL6 you have is the radial mount 8000 series you can move to the BSL4r with 1.25 pistons and you'd be fine. If this is a lug mount caliper then you will need to visit the FSL line for some alternative ideas.

*If the W6A is the larger bore model you would perhaps be able to do 1.375 rears but in any case the rear selection should be based upon the front size and knowing that 4.1sq" of piston is way too much for a rear brake kit design.

[N2TRUX]

Welcome to the forum Todd TCE. It sounds as if you have extensive knowledge on the subject, and the Wilwood product. Please take a moment make an introduction post and share where your knowledge comes from...

[Todd TCE]

You would be correct. I did not wish to provide much chest thumping however not being a vendor....lol

I'm the owner/operator of TCE Performance Products (.com) in Tempe. (convenient, in part why I chose to post) and have been a Wilwood dealer for 17+ years. My shop produces a variety of custom TCE/Wilwood kits and if you were to call Wilwood directly and request a referral for custom work my shop would be at or near the top of the list.

No disrespect to those who would choose to go down the path above but I'm simply saying that it's not really a good plan and has a number of negatives to it. Be happy to elaborate more if so asked and can provide you with exacting bias data if necessary to help. Or for the OP, if you'd care to contact me locally that's fine also.


If the W6A caliper are the same 1.625 / 1.125 / 1.125 as the rears you're looking at about 52/48 bias split.
If the W6A calipers are the larger bore 1.75 /1.375 / 1.375 then the bias is about 58/42 split.
Moving to the smaller bore 1.25 parts puts you closer to a reasonable 70/30 split. Even that's optimistic for a rear on a pick up....

[DKN]

One major advantage to the MCPV-1 master cylinder is you can limit the rear pressure independant to the front. In other words it will help correct a badly imbalanced brake system, however I would follow Willwoods recomedation.

Danny Nix
CPP

[N2TRUX]

Originally Posted by Todd TCE

You would be correct. I did not wish to provide much chest thumping however not being a vendor.......

Todd we have a lot of the industry experts drop in here. They seem to like that we keep the forum civil and the drama to a minimum. We appreciate any expert advice vendor or not.

The CPP master cylinder I was referring to is the MCPV-1- LINK It is a "master cylinder, double adjustable proportioning valve, removable metering valve and stop light control all in one"

Besides all that it's really easy on the eyes.

[Todd TCE]

I'm not up to speed on this mc but it's promising for the right application. It sounds as if it's simply a mc/prop valve combo and that's a plus.

Using it here would remain dicey in my opinion. For two reasons; first not knowing what the maximum reduction to the value is (perhaps 35%) which would still be too much line pressure in some instances. Also be interested to know if it's dynamic- as a prop valve is or if it's static- meaning it's always at 35% for example.

The second issue with this is that the combined piston are is still very large and will net a very soft and long pedal. Depending upon the mc its possible that it would bottom out or at the least not offer the responsiveness desired. Because the rear area remains so large even a reduction in final pressure will still require a large displacement to activate.

Sounds like a quality part for this application to handle the fine tuning like a prop valve but I don't think I'd use it as a handicap for proper design change. Use it but still put the right piston sizing in place and the total package will be both safe and effective.

[Todd TCE]

That's a sweet part! I'll make a mental note of it and keep it in mind for anyone who asks for such a part. Very complete in many ways. If the OP makes some changes to the choice of caliper bore sizes this would still be a very viable mc for that use actually.

[Todd TCE]

I had the opportunity to speak with the OP on this a bit ago. I was a bit hesitant to say much about what he has in not wishing to step on anyone's toes. What I learned is that the parts were not purchased as a "Kit" so I feel a bit more open about what I have contributed.

In running some data on the set up, assuming the same pads and assuming the same size wheels and tires in use the current brake bias (at the road) comes in at about 50/50 which anyone can believe it too equally biased. Not knowing the capabilities of the above mc that seems pretty difficult to 'de tune' as well as a knowingly soft pedal. I like it, just not sure as an adjustment tool that we are not exceeding its capacity.

From personal experience the piston sizes for pairing this front kit puts the area at about 2.0-2.5sq" of area. That puts piston sizing in the 1.125 or 1.25" bore size of a four pot caliper. Given the nature of the above mc with it's adjustments I'd say we might be able to move to 1.375 or 3.0sq" if there is enough pressure reduction built into the proportioning valve. A 50% reduction in pressure will net about a 10% forward shift in bias.

Given a pick up truck I'm not sure that's really enough of a cut....I think personally I'd err on the side of conservative area and not run more than 1.25 bores.