Can't Get Wilwoods to Lock Up

Can't Get Wilwoods to Lock Up - 12/15/12 09:30 PM

I have a master power brakes 8" booster and Master cylinder.

Wilwood disks front and back

changed out the stock rubber line adapters to braided.

I have gravity bled this thing, also have bled it 3-4 other times with a friend....

Brakes still suck... I can't get them to lock up

Very annoying

I have 14-17" of vacuum when I'm driving and If I nail the brakes with both feet it stops pretty quick.....but can not get them to lock up...

This thing should stop on a dime...

What the heck

Posted By: amxautox

Re: Can't Get Wilwoods to Lock Up - 12/15/12 09:36 PM

What is the piston dia in the master cylinder?

Are you getting a full stroke in the master cylinder?

How many pistons in each caliper? What are their dia?

Do you have a proportioning valve? Which one?

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/15/12 09:49 PM

Quote:

What is the piston dia in the master cylinder?

Are you getting a full stroke in the master cylinder?

How many pistons in each caliper? What are their dia?

Do you have a proportioning valve? Which one?

I am not the best with brakes....good questions The master cylinder and booster came on the car when I bought it last spring. It had wilwood 10.75 vented rotors on the front.....I installed the rear 11" rotors Dynapro low profile pro series kit. I think they are all 4 piston calipers.

I am not sure If I am getting full stroke, or know the piston Dia. I have a pic of the proportioning valve...

Attached picture 7504510-photo(93).JPG

Posted By: amxautox

Re: Can't Get Wilwoods to Lock Up - 12/15/12 09:58 PM

Whoops I forgot;

What pads are you using? What are their composition?

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/15/12 10:00 PM

Quote:

Whoops I forgot;

What pads are you using? What are their composition?

BP-10 compund? That is what it says with the paper work I got with the kit

Stock Wilwood pads that came with the kit

Posted By: feets

Re: Can't Get Wilwoods to Lock Up - 12/15/12 10:18 PM

Brakes are hydraulic. The master cylinder must be a match for the bores.
You can't slam random stuff together and expect it to work. It's kinda like buying a random set of pistons and expecting them to fit your engine.

Find the diameter of the bores in the calipers. You can probably look them up on Wilwoods site if you have the part numbers.
You need to know the diameter of the master cylinder too.

Once you have that information share it with us and we'll know more.

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/15/12 10:31 PM

Quote:

Brakes are hydraulic. The master cylinder must be a match for the bores.
You can't slam random stuff together and expect it to work. It's kinda like buying a random set of pistons and expecting them to fit your engine.

Find the diameter of the bores in the calipers. You can probably look them up on Wilwoods site if you have the part numbers.
You need to know the diameter of the master cylinder too.

Once you have that information share it with us and we'll know more.

Never knew that...Always have been more concerned with accelerating

Rears

http://www.jegs.com/i/Wilwood/950/120-11370/10002/-1?
parentProductId=2379359

Fronts
http://www.summitracing.com/parts/wil-120-4997

I am guessing I may have the wrong proportioning/combination valve I have an 8" Master Power Brakes kit with master cylinder and proportioning valve in the picture above....That is all I know.

Posted By: feets

Re: Can't Get Wilwoods to Lock Up - 12/16/12 05:39 PM

Quote:

It's most likely an 1 1/8" bore. Too big for those Dynalites unless you have Hydraboost. You are probably more in the 15/16 range.

That's what I'm thinking.

The generic brake booster and MC assemblies tend to have the wrong size bore for any given application. The manufacturer can only guess what size bore you need so they stick a common piece on there and let the user sort it out. Since there are so many possibilities out there they can't guess right every time.

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/16/12 06:23 PM

29969 is stamped on the master cylinder. And from what I have been reading it appears to be for a 4 wheel disk corvette.

The booster is a dual 8"

The car did have rear drums when I got it.

I changed the rears to disks, flushed the lines.....but never changed a residual valve.. ( I have been reading about this)

The car will not lock up the front or the rears, and the pads do not seem to drag... the car rolls forward easily if I throw it in neutral....and my driveway hardly has a pitch at all.

It does say that I need 18" of vacuum for this kit....My car idles at 11" in gear.....but If I drive down the road I can get 17" While I'm driving with that much vacuum.....if I try to lock em up it will not. The pedal does not seem like it is assisted that much by the booster...Maybe my booster is shot....The car did sit for 13 years before I got it.....the mechanical fuel pump was shot..

Posted By: amxautox

Re: Can't Get Wilwoods to Lock Up - 12/16/12 07:03 PM

stupid questain;

is there a vacumn line attached to the booster?

is that hose attached to the intake or the carb base?

Is the valve/connector in the booster working/not stuck closed

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/16/12 07:32 PM

Quote:

stupid questain;

is there a vacumn line attached to the booster?

is that hose attached to the intake or the carb base?

Is the valve/connector in the booster working/not stuck closed

I have tried with it connected to the intake, also have tried with it connected to the 3/8 barb off the back of the carb....

No difference, I get 13" of vacuum in park and 11" idling in gear....but driving down the road the vacuum is up plenty for the booster.

What is the valve connector in the booster sucked close? I gotta look into this

Posted By: amxautox

Re: Can't Get Wilwoods to Lock Up - 12/16/12 07:56 PM

Quote:

Quote:

stupid questain;

is there a vacumn line attached to the booster?

is that hose attached to the intake or the carb base?

Is the valve/connector in the booster working/not stuck closed

I have tried with it connected to the intake, also have tried with it connected to the 3/8 barb off the back of the carb....

No difference, I get 13" of vacuum in park and 11" idling in gear....but driving down the road the vacuum is up plenty for the booster.

What is the valve connector in the booster sucked close? I gotta look into this

'stuck closed'

The connector/fitting on the booster where the hose is attached usually has a valve in there. To keep the vaumn in the booster instead of it bleeding off right away when the manifold vacumn drops off during acceleration. Ya know, just in case you have to stab the brakes on a panic stop when somebody pulls out in front of you.

If it's rusted stuck closed the 'power' won't work as the vacumn can't get to the booster. Or it lessens the vacumn boost. Take it off, look inside, and rattle it. Some people will blow and suck on the valve to see if it opens and closes easy.

Also check for a leak around that seal.

Posted By: DoctorDiff

Re: Can't Get Wilwoods to Lock Up - 12/16/12 08:07 PM

If you have adequate boost, I would install a 1" bore master cylinder and Polymatrix brake pads.

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/16/12 08:29 PM

Well the check valve is good....works great and I even sucked on the booster and it holds vacuum...

Hey Cass, You are probably right.....My old man has a set of wilwoods...He said he switched pads and it made a day and night difference... Said they ate up his front rotors in a year though.

I guess a 1" bore would put a little more pressure on these things...I have an adjustable proportioning valve sitting here to throw in anyway...might as well do it all at once

Posted By: DoctorDiff

Re: Can't Get Wilwoods to Lock Up - 12/16/12 08:38 PM

The high friction Polymatrix pads are hard on rotors, but they work nicley.

Wilwood calipers have fairly small piston bores, so they need a fairly small master cylinder bore (1" to 1 1/32").

Posted By: bordin34

Re: Can't Get Wilwoods to Lock Up - 12/16/12 10:25 PM

Try pressure bleeding it before buying parts to see if you can get the feel to improve.

Posted By: cageman

Re: Can't Get Wilwoods to Lock Up - 12/17/12 02:08 AM

I tried poly matrix pads, ate all four rotors!

Posted By: feets

Re: Can't Get Wilwoods to Lock Up - 12/17/12 08:45 PM

I'd swap to a smaller master cylinder.
Get the major parts correct before you swap brake pads. The pads you have now might be fine after you get pressure to them.

Posted By: TheRamMan

Re: Can't Get Wilwoods to Lock Up - 12/20/12 03:08 AM

you cannot generate enouogh force with dinky booster and corvette master cylinder....IT WILL NEVER WORK
TALK TO SOMEONE WHO KNOWS

THERAMMAN.COM

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/20/12 03:42 AM

Quote:

you cannot generate enouogh force with dinky booster and corvette master cylinder....IT WILL NEVER WORK
TALK TO SOMEONE WHO KNOWS

THERAMMAN.COM

I wouldn't call a dual diaphragm 8" booster dinky for a 3000 lb car...
The master cylinder is probably 1 1/8" .......From what I have read it looks like I should change it..

Attached picture 7510875-cudarear.jpg

Posted By: Black_Bee

Re: Can't Get Wilwoods to Lock Up - 12/20/12 10:19 PM

I have Wilwoods on the front of my Super Bee and disks on the rear. Using a 1" Wilwood master (and regular pad compound), I can't lock the brakes to save my life either.

I posted here a few months ago asking for help too and was told that the 1" master was too big and to try a 15/16" one. Its winter here, so I havent done anything yet (I will in the spring), but I just thought Id mention that a 1" master might still be too big for your setup...

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/20/12 10:26 PM

Quote:

I have Wilwoods on the front of my Super Bee and disks on the rear. Using a 1" Wilwood master (and regular pad compound), I can't lock the brakes to save my life either.

I posted here a few months ago asking for help too and was told that the 1" master was too big and to try a 15/16" one. Its winter here, so I havent done anything yet (I will in the spring), but I just thought Id mention that a 1" master might still be too big for your setup...

Thanks! Good to know..... Much appreciated

Posted By: G_T

Re: Can't Get Wilwoods to Lock Up - 12/20/12 10:57 PM

While I dont have first hand real-world experience. The folks I worked with at Wilwood and the custom shop told me to use the 15/16" master. Thats what I have. "When" I wrap up that portion of the project I'll know how it behaves

Posted By: 65 DODGE POST

Re: Can't Get Wilwoods to Lock Up - 12/20/12 11:08 PM

I think I am going to try 15/16's also....Seems like the ticket....

Can't Get Wilwoods to Lock Up