Whoever is running Manual Wilwood disc brakes with problems read this!

[staged67gspwr]

I was having problems with my Wilwood disc brakes everytime i would hit my brakes my pedal would go down,i must`ve bled my system atleast 50 times and still the same,i was running the 7/8 bore master with 6 piston calipers all around,i called Wilwood and they told me to put a 1" bore master in there so i switched it out with the 1" and to my surprise the pedal did not go down once on me it felt perfect like it should,so if you have the same problem as me and are running a 7/8 master with manual brakes i suggest you switch it out for a 1" bore Wilwood master.

Thank you

[rsk68]

ok i'm having the same problem but have only bled it 2 times one was a power bleed at a shop and the second was me with a vacume pump, if i dont touch the brake for a while i need to pump it twice for good brake feel, I'm running the 7/8 bore, could there be a problem with a recent run of 7/8 bore masters?

[staged67gspwr]

Dude i dont think so,i think that 7/8 bore is no good with manual brakes and 4 wheel discs,as soon as i put the 1" bore in the problem went away,note that a wilwood tech guy told me to put a 1" bore in and send the 7/8 back.

Thanks

[rsk68]

i had the one inch bore and i felt it didnt give me enough pressure, i had to push way to hard, this is the reason I went to the 7/8 bore, with the 7/8 i have way more pressure being applied, i just dont like the fact it needs to be pumped up, i'm still going to try and bleed one more time, if it dosnt work i will return it for another 7/8 due to i believe it is bleeding past the MC piston.

[Vegas69]

Interesting thread.....I have noticed my pedal travel varies from time to time and drive to drive. Never anywhere near the floor though.

[6'9"Witha69]

Rick, you may need a residual pressure valve. I had the same issue as you. If the car sat more than 6 hours there were 0 brakes until pumped several times. After a trip on the freeway and no brake use it was about 1/4 to 1/2 throw before they would engage. An RPV cured that real quick.

[Vegas69]

I would also add that a 3 minute pressure test is a good idea. Put moderate pressure on the pedal for a full three minutes. The pedal should stay firm.

[Vegas69]

Rick, you may need a residual pressure valve. I had the same issue as you. If the car sat more than 6 hours there were 0 brakes until pumped several times. After a trip on the freeway and no brake use it was about 1/4 to 1/2 throw before they would engage. An RPV cured that real quick.
Did you use it just in the rear or both circuits?

[silver69camaro]

Dude i dont think so,i think that 7/8 bore is no good with manual brakes and 4 wheel discs,as soon as i put the 1" bore in the problem went away,note that a wilwood tech guy told me to put a 1" bore in and send the 7/8 back.

Thanks

George,
You need to take a step back and look at the big picture. Lots of guys are running 7/8" bores with Wilwood front and rear disc!

Measure what your pedal ratio is. Chances are it's much different that what other guys are using. Heck, I run 13/16" MC with my SLR calipers because I have a 6:1 pedal ratio. 1" is hard as a rock for my setup.

[staged67gspwr]

George,
You need to take a step back and look at the big picture. Lots of guys are running 7/8" bores with Wilwood front and rear disc!

Measure what your pedal ratio is. Chances are it's much different that what other guys are using. Heck, I run 13/16" MC with my SLR calipers because I have a 6:1 pedal ratio. 1" is hard as a rock for my setup.


This suggestion came from the Wilwood tech guy Justin to be exact.How do you measure pedal ratio?

Thanks

[ProdigyCustoms]

Measure from the center of the pivot point on the pedal (where it swings) to the middle of the pedal where you put your feet for total pedal length. Then measure from the center of the pivot point to the hole your brake rod is in. Divide into the pedal length.

12" pedal, 2" to hole, 6 to 1 ratio.

[wiedemab]

Google is my friend.

https://static1.pt-content.com/images/noimg.gif

[staged67gspwr]

Well just measured mine its a 6 to 1 ratio,im getting 12" from top pivot to center of pedal pad and 2" from the top pivot to hole.

Thanks

[rsk68]

well i just got off the phone with Wilwood,they sugested I bleed some more as it sounds like air ot them, he also explained the importance of bench bleeding the MC as apossed to bleeding it in the car, 'full stroke is very important when bleeding the MC" you may not get this while in the car.

[staged67gspwr]

well i just got off the phone with Wilwood,they sugested I bleed some more as it sounds like air ot them, he also explained the importance of bench bleeding the MC as apossed to bleeding it in the car, 'full stroke is very important when bleeding the MC" you may not get this while in the car.


I did that already and thats when they came to the conclusion to try the 1"

[6'9"Witha69]

well i just got off the phone with Wilwood,they sugested I bleed some more as it sounds like air ot them, he also explained the importance of bench bleeding the MC as apossed to bleeding it in the car, 'full stroke is very important when bleeding the MC" you may not get this while in the car.You can bench bleed in car by disconnecting the lines and looping into the MC res and disconnecting the clevis from the pedal and using that by hand. Then reconnect and bleed the lines out again. Make sure to cover the open line ends during this so they don't get any contaminants in the system.

I swapped an MC in my car in the parking lot of Cal Northridge when it failed going out to cruisers car wash one Friday night years ago. It most definitely can be done.

I will still also suggest the RPV if the pedal stays up for under a minute once pumped up but starts to lose pressure with more time.

[Vegas69]

Pulling a master cylinder off these cars is a piece of cake. Pull it off and put it in the vice. Then you can just leave your bench bleeder setup on the cylinder until you hook up the lines.
https://static1.pt-content.com/images/pt/2008/07/IMG_0932-1.jpg

[rsk68]

That would work, the idea is that the carpet or other things may get in the way of a full pedal stroke.

[silver69camaro]

6:1? Hmm, something else is amiss. That doesn't make much sense. I have the same ratio but use a 13/16". Tri-5's have about 8:1 and use a 7/8".

I agree with the bleeding. The 1" bore will push more fluid and "make up" for air in the lines. Bleed, bleed bleed. Then bleed two more times.

[staged67gspwr]

Well heres the other thing,he told me since i`m running 6 piston in the back also is why i may need more fluid,it didnt make sense to me but anyway,i bled the system atleast 50 times since last feb. and it still did the same.


Thanks

[funcars]

For brake pedal feel there are multiple contributions: size of master cylinder piston, area of caliper pistons, brake pedal ratio, and diameter of rotors. They all interact together. If you use too large of a master cylinder diameter your pedal will be hard as rock but you may need both legs to stop.

The residual pressure check valve mentioned before is worth trying, but it is wise to check every joint first and make sure you don't have a place where you are leaking in air. Another concern is a point in the lines that traps air that can't be purged. Pressure bleeding can be worth a try too.

Good luck

[orange69]

i was having a problem like that with my 7/8 wilwood probably went though a quart of fluid bleeding it and still had no brake to speak of certain there was no air in system i adjusted length of clevise rod and brakes works great. feels like power brakes.and no brakes drag i thought of that and checked each one. it was very frustrating.

[tollrae1]

Single piston is the way to go keep it simple.

[silver69camaro]

Single piston is the way to go keep it simple.

Huh? Why?

[6'9"Witha69]

Single piston is the way to go keep it simple.????

I too am baffled by such a comment.

[Jim Nilsen]

????

I too am baffled by such a comment.

I think it is just a way to say that the more parts you add to something that does a simple function , the more problems you can have with it.

Having dealt with machines that engineers have made more complicated thinking it would make them get more production only to have them broke down more and getting less and costing more to fix. I can relate to his sentiment. But we all know that to get more out of something you also have to add more to get it.

We have had the argument go on here for quite a long thread that the cost of going bigger makes you have to do it all as a package to make it all work. A budget that is small keeps your brakes small, your wheels small and your stopping ability small too.

Damn small budget minded thinking is simple minded thinking too!

You know, Keep it simple Keep it fun.

[gort69]

Has anyone considered the effect of a C-clip axle on a fixed caliper? Is it possible a little side to side slop in the axles could knock the pistons back into the bores a little, creating a low pedal?

[terryr]

If the pedal level or effort keeps changing you have a leak somewhere. Air is getting in. I check each joint with a wrap of tissue. It should stay totally dry.

[6'9"Witha69]

Has anyone considered the effect of a C-clip axle on a fixed caliper? Is it possible a little side to side slop in the axles could knock the pistons back into the bores a little, creating a low pedal?
That is entirely possible. Kickback is an issue in fixed and floating calipers on front brakes and can definitely translate to the rear end, poarticularly C-clip rears with even mild wear on the clips. That is why residual valves work well in the rear line as it help fight the knockback and keeps the brakes up a little more.

[Skip Fix]

My C clip rear had so much free play that under a hard turn you could hear a rubbing sound. Under warranty they could never figure it out, when I did a rear brake job I could see the drum was actually rubbing the backing plate.

[rsk68]

Wilwood makes a little 2Lb and 10Lb residual valve, are these the type I should use for the rear, i could mount one up around the 3rd member before the T.

[6'9"Witha69]

10 is for drum brakes, 2 for discs. Run them between the MC and dist block or prop valve.

[David Pozzi]

Well heres the other thing,he told me since i`m running 6 piston in the back also is why i may need more fluid,it didnt make sense to me but anyway,i bled the system atleast 50 times since last feb. and it still did the same.


Thanks

You should not use the same size caliper bores front and rear. It requires much more fluid be displaced and a properly sized master cylinder can't pump that much fluid. A larger 1" MC will pump more fluid but you will not be able to lock a front wheel, the rears may lock, requiring a proportioning valve adjustment, but way too much fluid will be "lost" on the rear.
David

[staged67gspwr]

You should not use the same size caliper bores front and rear. It requires much more fluid be displaced and a properly sized master cylinder can't pump that much fluid. A larger 1" MC will pump more fluid but you will not be able to lock a front wheel, the rears may lock, requiring a proportioning valve adjustment, but way too much fluid will be "lost" on the rear.
David



David since you know alot about this stuff what do you suggest?i have the prop.valve backed off almost to the end so the rears dont lock up,got a call from Wilwood yesterday cause i sent back the 7/8 bore master,they told me it wasnt holding pressure and they will be sending me out another one,should i replace it when it comes in or leave the 1" bore thats in there now?

Thanks

[Skip Fix]

David I understand what you are saying but the Wilwood kits for most of our cars use the same Dynalites front and rear.

[staged67gspwr]

David I understand what you are saying but the Wilwood kits for most of our cars use the same Dynalites front and rear.



Thats correct.

Thanks

[RSX302]

my 2 pennies...

Although I'm running the twin masters the concept would probably be the same.

Just was never solid and I was having issues with loss of pedel in hard cornering. The damn thing would drop half way. At first I thought I was pad knockback.

As much as I bled the brakes, (a gallon of fluid) no air was present. I found I wasn't getting full travel out of the master push rod during brake bleeding even thou I was doing both front and rear at the same time pushing to the floor. (hence I guess you should bleed out of the car) Since it was already in the car, I got a few people to man the wheels (or Females:)) I unbolted from the firewall and pushed the rod in by hand until it bottomed out. "BIG" slug of air at the very end end of travel. It's all good now!

[wicked68]

mine are pretty hard as well - which I have not been satisfied with. At PRI one of the wilwood guys suggested I go from the 1 inch to the 7/8 to fix the problem and said I could go to the new billet 4 piston or 6 piston on the back from the current forged 2 piston I have at the same time. He said the new one will look like the front ones and is low profile so it will fit in the rims. Now I am suspect that if I go up to the bigger ones on the rear and downsize to the smaller piston I will crate a problem in the opposite direction. As well with David P's comment to always go with a smaller setup on the back - I am tempted to keep what I have thinking it is the right setup and simply try the smaller master.

Thoughts?

I wil measure the pedal dimensions and ratios tomorrow but I am pretty sure they are 6/1

[6'9"Witha69]

I run the same calipers F/R and with the prop adjusted properly they work fine. The M/Cs are designed to push more in the front than the back, look up the product spec on Wilwoods site and you can see.

Also note that conventional M/Cs are rear outlet/front brakes front outlet/rear brakes the Wilwood 7/8 are front/front and rear/rear. So conversion will require new lines to the dist bock.

[wicked68]

I run the same calipers F/R and with the prop adjusted properly they work fine. The M/Cs are designed to push more in the front than the back, look up the product spec on Wilwoods site and you can see.

Also note that conventional M/Cs are rear outlet/front brakes front outlet/rear brakes the Wilwood 7/8 are front/front and rear/rear. So conversion will require new lines to the dist bock.


I have a proportioning valve- so you think I should try the bigger calipers in the rear first?

[RSX302]

I have a proportioning valve- so you think I should try the bigger calipers in the rear first?

Don't think by putting the 6 piston in the rear is going bigger. The SL4 4 piston (1.88/1.75) has more piston area and clamping force then the SL6 6 piston (1.62/1.12/1.12). I made this mistake. I'm very close at buying the SL4's in place of my SL6's as I need a little more front brake. I will sacifice pad taper, but I'm not sure how bad that will be, if at all. They do make the SL4 with smaller pistons for the rear.

IMHO- You don't need huge rear brakes for street and occational track. It's kinda overkill but they look cool. I'm at 55/45 weight distribution with my Camaro and the 4 piston dynalite's on a 12" vented rotor are more then capable with no overheating. I had at 50/50 but had to dial more to the front because I was locking up the rears.

[RSX302]

Also as an FYI from previous post...

With my 55/45 car weight distribution, Toyo R888's 285's front, 335's rears, SL6's on 13" rotor front, Dynalite 1.38" pistons on 12" rotors rear, Dual 3/4" mc's front and rear and BP-30 pads. This combo runs about 60/40 on the masters. On cold Toyo's (~100deg) it has pulled .85g's braking. ~250 deg front rotors and 125 deg rears.
If running the tandum 60/40. I would say it would be a perfect match. If I ran the SL4(1.88/1.75) in the front, I would be closer to 50/50 on my bias.

[Gordz32]

Just a quick note. Make sure your proportioning valve is open all the way when you r bleeding brakes as, if its not, will cause trouble bleeding and a soft pedal that goes to the floor. Had the same issue on the chevelle: 7/8 bore MC 6piston front and 4 piston rear manual brakes. The residual pressure valves ,I'm told by wilwood, are not needed unless you've mounted the M/C in a location that is lower than normal ( example is on a street rod chassis where the m/c is mounted on the frame.
Hope this helps someone

[BRIAN]

Just curious how the brakes work vs feel. If you stand on them hard how is the front to rear bias? I had a problem with a Wilwood master as some of them are set up with a ratio for front to rear. There is a difference which resv goes to front or rear vs their other masters where they are balanced.

Use a pressure bleeder and you will be surprised in the difference in pedal feel. I have a Motion one that was fairly cheap but honestly it always makes a mess but it does work great. If you are local you are welcome to use it if you clean it.