No Brakes After Turning HELLLPPPP!!!!!!

[72_Nova]

Like titled I am having a problem with losing brake pressure after I turn. If I drive straight forever I have no problem but the second I turn semi hard the pedal falls.

I am running Wilwood 14'' spec 37 rotors front and rear. 6 piston nickel plated calipers front 4 piston rear both with knock back springs. Wilwood 15/16 Master cylinder proportioning valve and brake pedal.

So far I have changed calipers. Changed Master cylinders twice (and bench bleed twice) Changed wheel bearings Changed upper and lower ball joints. Swapped wildwood rear retainer plate to Currie retainer plate. Changed steering tie rods and bleed the system at least 200 times. I am really out of options here and need to figure this out. Any input would be helpful.

[HandOverFist]

Maybe get it up in the air an observe the flex lines while turning lock to lock?

[parsonsj]

It is almost certainly knock back causing this issue, most likely coming from the rear. Tell us about your axle setup.

[72_Nova]

So the rear is Moser M9 with tru track and 31 spline axels and tapered bearings. I have already replaced the bearings and wilwood retainers with currie retainers. Their so no play at all in the rear. I just installed these new retainers yesterday

[dontlifttoshift]

Another thing to check, make sure the front calipers aren't hitting anything when you turn. Unlikely, but check anyways.

[parsonsj]

Their's no play at all in the rearHow did you verify that? One thing to try would be eliminate your rear brakes. Cap your rear brakes at the junction where it goes to the axle. (you'll still have 80% of your brakes). Drive slowly to a secluded spot and see if you still have knockback. If you don't then you can quit worrying about the front brakes.

[parsonsj]

Also, what are your wheel dimensions? Diameter, width, offset/backspace?

[72_Nova]

When i say their is no play I mean physically as a human pulling and pushing the rear axle in and out of the housing their is no play now with the Force of the car idk if it's moving but when I push and pull it doesn't budge .

[72_Nova]

Wheels are 18x9.5 with a 20 mm offset and 6" back space

[parsonsj]

Your wheels are reasonable: "deep-lip" wheels have more leverage on the axles than centered wheels.

I'd eliminate the rear brakes, and see if the problem goes away.

[72_Nova]

I'm going to try that tomorrow since I need to know if it's front or rear.

[chpr1972]

72 Nova

Did you get the brakes cured and what did you find? I have this same problem and the answer I got was live with it or change the calipers to floating ones.

[72_Nova]

72 Nova

Did you get the brakes cured and what did you find? I have this same problem and the answer I got was live with it or change the calipers to floating ones.


not yet ive been just dealing with it but I'm installing residual valves tomorrow so we will see what that does. Still haven't figured out if its the front or back but I will do that tomorrow before I install.

[mincharlie]

Had same issue with my wilwood set up, mainly on hard slaloms. It was pad knock back, installed caliper piston springs like they have in some porshes to hold pads against rotor. Works great and didn't have to add residual valve.

[dhutton]

not yet ive been just dealing with it but I'm installing residual valves tomorrow so we will see what that does. Still haven't figured out if its the front or back but I will do that tomorrow before I install.

Lots of guys have tried residual valves to cure pad knock back without success.

Don

[72_Nova]

Had same issue with my wilwood set up, mainly on hard slaloms. It was pad knock back, installed caliper piston springs like they have in some porshes to hold pads against rotor. Works great and didn't have to add residual valve.

Ya I thought that would fix the issue but my new calipers all have the springs in them and they don't help...

[72_Nova]

Lots of guys have tried residual valves to cure pad knock back without success.

Don

Well at this point in time I have replaced everything in the car except the rear end itself which is a new M9 just purchased 3 months ago... So its either residual valves or drop 4k on a floater...

[Hugger67RSSS]

Like others have said residual valves will likely not help. They didn't for me. I switched my housing to corvette style hub bearings and fixed the problem. You can use your same housing and save some money that way.

[TheJDMan]

A call to Moser might be in order to see if they can weld floater snouts on your housing. I know Moser sells floater hub kits so you just need the snouts welded on.

[72_Nova]

Sooooooo blocked off the rear lines yesterday and guess what... Still doing it so the knock back is in the front... Where? Idk I have replaced everything but the spindles and hubs...

[dhutton]

Sooooooo blocked off the rear lines yesterday and guess what... Still doing it so the knock back is in the front... Where? Idk I have replaced everything but the spindles and hubs...
What is the clearance between the wheel and caliper? Any chance the wheel is flexing and hitting the caliper? I am pretty sure I remember David Pozzi posting a pic of this.

Don

[72_Nova]

I wish it was that simple but I have plenty of clearance I'm starting th think its the wilwood hubs...

[Hoppie]

I'm interested what you find out. I've been chasing the same demon for awhile. I converted to a full floating rear which improved it a ton but it still falls and gets soft after a couple turns.

I have a Baer system with the Wilwood master cylinder. it's really frustrating. I've ended up taking it to professionals and they are stumped too.

[another69]

Could you post a pic of your fronts? It may help. You don't have excessive play at the front wheel bearings do you?

[72_Nova]

Here are a few pictures. The bearings are new with no play I just replaced them thinking that was the problem. Last picture is the only pic I have of the arms and spindle without the rotor and hub on. It was taken a year and a half ago

https://static1.pt-content.com/images/pt/2016/04/KjXsn8z-1.jpg

https://static1.pt-content.com/images/pt/2016/04/ERaJoEJ-1.jpg

https://static1.pt-content.com/images/pt/2016/04/xCO9Hrb-1.jpg

[chpr1972]

Altho you say it is coming from the front brakes, are you sure that the rear axle bearing retainers are installed correctly? I have a lot of play in my moser rear end and according to curry and moser, the lip on the retainer goes towards the bearing, not away from it. With that 2 lb check valve in the rear brake system you will not have any play at the rear. pull the brake pads out and then shake the axle. I had 1/4 ' of play. The retainer was put in wrong.

[440AutoX]

Had the same issue with our new Wilwood 13" rotors and 6 piston calipers on our 1970 Dodge Challenger this past weekend...we would turn back and forth and push the pedal down it would go to the floor but a quick let off and push the pedal again and they were there. Dad tightened the hubs up till there was no play at all and nut was tight (set to normal tight and then back the nut off a quarter turn to begin with) and it helped so we are thinking the bearings aren't set completely tight where they are supposed to be.

[72_Nova]

Altho you say it is coming from the front brakes, are you sure that the rear axle bearing retainers are installed correctly? I have a lot of play in my moser rear end and according to curry and moser, the lip on the retainer goes towards the bearing, not away from it. With that 2 lb check valve in the rear brake system you will not have any play at the rear. pull the brake pads out and then shake the axle. I had 1/4 ' of play. The retainer was put in wrong.


Retainer plat is installed correctly with no play what so ever in the rear

[72_Nova]

Had the same issue with our new Wilwood 13" rotors and 6 piston calipers on our 1970 Dodge Challenger this past weekend...we would turn back and forth and push the pedal down it would go to the floor but a quick let off and push the pedal again and they were there. Dad tightened the hubs up till there was no play at all and nut was tight (set to normal tight and then back the nut off a quarter turn to begin with) and it helped so we are thinking the bearings aren't set completely tight where they are supposed to be.

I wish that was the case with mine. I have changed bearings 3 times now and have tried tightening with and with out the back turn. Neither works for me