Wilwood soft braking issue

[Junbug]

Question for the experts... Mk IV, complete Wilwood system, 2x.75" MC, one front one rear, wilwood disks & calipers front and rear.

My brakes have always been soft and go almost to the floor with weak stopping power (in the 100 miles on the car thus far). I've never been able to get them to lock up, front or rear, regardless of how much pressure. I've followed the Wilwood video bleeding guidance, bled front/rear simultaneously right side first, then left. I've trimmed and adjusted the MC pushrods. I've learned the hard way to ensure the pushrods are adjusted ensuring the brake pedal lever isn't touching the crossbar in the footbox. The gap between the clevis and the pivot is .22" per the wilwood guidance. I've adjusted the balance bar, centered, biased toward the front and bias toward the rear. My fluid reservoirs are on the frame in front of the DS footbox, and slightly above the MC height. I've pressure bled each system (front & rear) numerous times with no air bubbles coming out of the system. There are no leaks anywhere in the system. The brake pads are well seated, sitting true on the disks. The common thing I've found is that when I press the brake pedal, the rear MC travels much further than the front MC regardless of how I've adjusted the bias bar. I fear that something is wrong with the front MC. It doesn't travel very far compared to the rear MC. The difference is over 1" difference in movement, regardless of how I have the bias set up.

I'd appreciate any guidance and help. I know there have been reported problems with the wilwood MC's, even when brand new, I also understand some have swapped to Tilton 75 MC's. I'm trying to troubleshoot the cause before I decide what's next. The body is on so pulling either or both MC is going to be a pain, but I'm hoping there is something I've missed.
Thanks,
-Bryan

[rich grsc]

I know you have repeatedly bleed the system, but you description is certainly an air bubble. Not too familiar with Wilwoods, but are calipers on the correct side? The other thing, did you make a bunch of curly cues in the brake lines?

[Junbug]

Rich, I plan to bleed again as I'm not an expert in any way so air is potentially a problem. I followed all instructions regarding installation, but I'll re-read and see if what side the calipers are on matter. I did need to make curly-cues in two places. Curious if those can cause an issue? That's new to me. Can you explain further? I do appreciate your troubleshooting help.
My biggest concern is the difference in how far the MC pushrods move when I step on the brake pedal... seems they should move the same distance with the balance bar centered, or at least close to the same distance.

[gbranham]

***EDIT...Sorry, I missed that you've already pressure bled***

Did you bench bleed your MCs? Maybe still some air trapped in them?

I've pimped this kit out on the forum many times. It's a game changer. My Wilwood manual brakes are rock solid. I've never had an easier time bleeding brakes, and will never use anything else again. No mess, either. No need to fill this thing with any fluid. Just screw it on to the reservoir, and give it pressure. If your reservoir is already full, which I assume it is, you won't have to worry about running it dry while pressure bleeding. Spend $50 on Amazon and get this. Then thank me later.

Greg

Brake Bleeder.jpg

[rich grsc]

If you have curly cues that are vertical it's easy for air to be trapped at the top, they shouldn't be used that way, if horizontal the air will pushed out pretty easy. You said the rear MC moved more than the front. that makes me think air in the rear lines.

[CraigS]

I have to think the big clue is the rear MC moving much further than the front. W/ both MCs the same size, the amount of movement would be determined by the size and number of caliper pistons. It's like a mechanical advantage of a longer lever for instance, but translated to a hydraulic advantage. The calipers w/ more piston area (fronts vs rears) should cause the MC to move more. In your case the calipers w/ less piston area (your rears) are causing excess MC movement. Line loops, if oriented incorrectly, can cause problems but that is more likely to happen w/ push the pedal bleeding which you are not doing. I will let Rich give more detail since he brought it up. I am leaning toward a REAR MC problem. I don't know exactly how much piston travel the Wilwood MCs have but an inch of travel has to be using up a lot of the total available. That is why I think a rear problem, but since that is such a terrible pain to deal with let's let more people chime in w/ ideas.
Ah, Rich is right here. I saw his post as I sent mine.

[Junbug]

Thanks for clarifying Rich. I'll be bleeding again and will see what I can do about the curly-cues, maybe some gentle taps while pumping/bleeding. I agree the MC's should move roughly the same. I'm hoping to rule out a bad MC.
-Bryan

[Junbug]

I have to think the big clue is the rear MC moving much further than the front. W/ both MCs the same size, the amount of movement would be determined by the size and number of caliper pistons. It's like a mechanical advantage of a longer lever for instance, but translated to a hydraulic advantage. The calipers w/ more piston area (fronts vs rears) should cause the MC to move more. In your case the calipers w/ less piston area (your rears) are causing excess MC movement. Line loops, if oriented incorrectly, can cause problems but that is more likely to happen w/ push the pedal bleeding which you are not doing. I will let Rich give more detail since he brought it up. I am leaning toward a REAR MC problem. I don't know exactly how much piston travel the Wilwood MCs have but an inch of travel has to be using up a lot of the total available. That is why I think a rear problem, but since that is such a terrible pain to deal with let's let more people chime in w/ ideas.
Ah, Rich is right here. I saw his post as I sent mine.

Thanks Craig. I'll definitely be bleeding again soon, so I hope to figure things out. Bummer I didn't know about the problems putting the curls into the brakelines could cause.
-Bryan

[RoadRacer]

I always tell people to reverse bleed. Push fluid up through calipers is much more effective imo.

[gbranham]

I always tell people to reverse bleed. Push fluid up through calipers is much more effective imo.

If you're applying pressure greater than atmosphere--from top or bottom--the direction makes no difference.

[RoadRacer]

If you're applying pressure greater than atmosphere--from top or bottom--the direction makes no difference.

I certainly don’t mind if you disagree, it’s just my experience. Do whatever works for you

My assumption is that since air bubbles tend to rise - and many don’t bleed their mc’s well - the air is already up there. Why push it all the way down?

[danmas]

Jun,

Welcome to come up to my shop. I have the lift so we can stand your kit on its nose and I also have a pressure bleeder. I also have some spare flex brake line so we could swap out for your hard lines to see if that helps…easy to do and you know where I live…

And I have a spare wilwood mc as well…..
Dan

[michael everson]

Try pulling a vacuum on your reservoir. The rear master moving further than the front means you have air in the rear system.
Mike

[MB750]

Yea, your symptoms sound exactly like there's air in there. My braking system is just like yours and I get around 3" before the pedal stiffens up, and I can STAND on the pedal and get nowhere close to the floor.

FYI, I went thru almost a whole quart of Dot 4 getting mine done. I also had the wife stand on the pedal while I cracked every joint and connection in the whole system. Air bubbles like hanging out in those places.

[rich grsc]

If you have air in the line, you need to be aggressive with bleeding. Two people, pump up the brakes and hold hard pressure on them, then open the bleed screw. You need to move the fluid through the line quickly so it can move the air bubble.
Check the fluid level often

[Mike.Bray]

I had a bit of a time getting all of the air out of my brakes. Wilwood calipers and Tilton "no fail" master cylinders. I did the pressure bleeding deal and got bubbles coming out but never a "rock solid" pedal. Thought about it some and since the MC's are higher than the calipers I tried gravity bleeding using these. I let them gravity bleed for hours, keeping the reservoirs topped up of course. After that I did another pressure bleed and rock solid pedal.

I don't have curly cues in my brake lines, not sure I understand them in hydraulic lines. They might make a difference in gravity bleeding, IDK.

[Junbug]

Thanks guys. Seems I need to be more aggressive with the bleeding. It’s reassuring that the general consensus is that it’s air in the rear system and not a MC problem.
It may be a little bit of time before I can get to the bleeding as I need my “assistant” to return from college. I can do the pressure bleed by myself, but to get the pedal bleeding I’ll need his help.
May also take Dan up on his offer and get out for a drive, but I’ll also need the weather to warm up on a weekend. Recent experience tells me driving the Cobra in sub 40 degree temps on a freeway/highway isn’t that fun.
Thanks,
-Bryan

[Rian_Colorado]

Us Colorado guys need to get a group together. I think I know of at least 10 of us in a 10 mile radius!

Bryan - I have the same opinion as most others, there's air in the system, and 95% chance it's in the MC. Similar to Dan - I have a lift, a vacuum bleed setup, as well as a push bleed setup. I've done it a few times all by myself (in fact, the 1 time I had help, I could NEVER get it to bleed correctly). You're welcome to borrow any of the tools. Happy to help if you need (I drink Coors light, so I'm cheap help....lol).

I highly recommend the "push" method, as in my experience it's the most logical and reliable. I made my own setup for a whopping $20 from Amazon....

The next week does NOT appear to have great "Cobra driving" weather in store for us!

Rian

[rich grsc]

Colorado guys, the Gateway Cobra Club is headed your way August 16th. Unfortunately it looks like we are going to be a bit far from you? Going to base out of Gunnison for a few days, then maybe to Colorado Springs

[CraigS]

To elaborate a bit more on the hard loops. They should be oriented like the coil over springs. If they are oriented like a carb return spring they will be a problem.
Carb spring.png
The problem is that say the loop is 1" diameter. That is a 3+" circumference. So a bubble sitting at the top needs the fluid to move >3" to push the bubble all the way around one loop. And, like Rich says, it has to be moving pretty quickly or the bubble actually will just sit there while the fluid trickles by. Also say one pedal stroke moves the bubble 4.5". It will get to the second loop, and half way around, but when the fluid stops, it will just bubble back to the top of the 2nd loop. So you used 4.5" worth of fluid but only got 3" bubble movement. One other consideration is that you want the loop oriented so the MC feeds into the bottom and the caliper is fed out of the top.

[Mike.Bray]

To elaborate a bit more on the hard loops. They should be oriented like the coil over springs. If they are oriented like a carb return spring they will be a problem.
Carb spring.png
The problem is that say the loop is 1" diameter. That is a 3+" circumference. So a bubble sitting at the top needs the fluid to move >3" to push the bubble all the way around one loop. And, like Rich says, it has to be moving pretty quickly or the bubble actually will just sit there while the fluid trickles by. Also say one pedal stroke moves the bubble 4.5". It will get to the second loop, and half way around, but when the fluid stops, it will just bubble back to the top of the 2nd loop. So you used 4.5" worth of fluid but only got 3" bubble movement. One other consideration is that you want the loop oriented so the MC feeds into the bottom and the caliper is fed out of the top.

Interesting. But I still don't understand the purpose of loops in hydraulic lines. Steam lines, yes. Hydraulic lines, no.

[rich grsc]

Mike, mostly because of not wanting to cut and flare the lines, just use up the extra length. Some think they are needed for vibration, which isn't true, but myth's are hard to disprove. If they happen just keep them horizontal.

[Mike.Bray]

Mike, mostly because of not wanting to cut and flare the lines, just use up the extra length.

I was wondering if that could be it. I could never take a shortcut like that.

[Norm B]

In the old days of body on frame car construction, with rubber body mounts, the loops provided a flex and expansion point between the body mounted master cylinder and the frame mounted brake lines. For some reason they carried over when most car construction switched to unibody. They are still required on most real pickup trucks.
I, like Road Racer, reverse bleed the brakes. I have a large syringe with a clear hose attached that fits tightly over the brake bleeders. You start by bleeding the brakes normally with the pedal to make sure the calliper is full then push the fluid back with the syringe. The final step is to bleed the brakes normally again one time to ensure no air is in the calliper.

Norm

[BornWestUSA]

Are the rear brake bleeders at the "high" point on the caliper?

Make sure they are, no way to get the air out if they are pointed down.

[Junbug]

Rich,
It’s quite drive to get to Gunnison from the front range/northern CO, but it’s a relatively short drive to Colorado Springs. Keep us informed it would be great to link up!
-Bryan

Colorado guys, the Gateway Cobra Club is headed your way August 16th. Unfortunately it looks like we are going to be a bit far from you? Going to base out of Gunnison for a few days, then maybe to Colorado Springs

[Junbug]

Craig,
Thanks for sharing these details. I only have one coil and it is vertical like a coil-over spring. I do have a gentle loop above each rear brake. I’d followed the FFR guidance on putting in the coil rather than cutting and flaring as I don’t have the experience or tools for that. Lesson learned.
I have a pressure system I plan to use next chance I get. I’ll likely try to put a good pressure on the system, run a lot of fluid through hoping to get rid of those bubbles.
Thanks again folks.
-Bryan
QUOTE=CraigS;574443]To elaborate a bit more on the hard loops. They should be oriented like the coil over springs. If they are oriented like a carb return spring they will be a problem.
Carb spring.png
The problem is that say the loop is 1" diameter. That is a 3+" circumference. So a bubble sitting at the top needs the fluid to move >3" to push the bubble all the way around one loop. And, like Rich says, it has to be moving pretty quickly or the bubble actually will just sit there while the fluid trickles by. Also say one pedal stroke moves the bubble 4.5". It will get to the second loop, and half way around, but when the fluid stops, it will just bubble back to the top of the 2nd loop. So you used 4.5" worth of fluid but only got 3" bubble movement. One other consideration is that you want the loop oriented so the MC feeds into the bottom and the caliper is fed out of the top.[/QUOTE]

[Junbug]

Good question and yes, the bleeders are at the top and outermost point in the caliper. These calipers actually have 4 bleeders on each caliper. Upper inside, upper outside, lower inside, lower outside.

Are the rear brake bleeders at the "high" point on the caliper?

Make sure they are, no way to get the air out if they are pointed down.

[danmas]

Good question and yes, the bleeders are at the top and outermost point in the caliper. These calipers actually have 4 bleeders on each caliper. Upper inside, upper outside, lower inside, lower outside.

I think you only use the uppers. The ones on the bottom are for when you need to flip the calipers over and then they become the uppers….

[Mike.Bray]

In the old days of body on frame car construction, with rubber body mounts, the loops provided a flex and expansion point between the body mounted master cylinder and the frame mounted brake lines. For some reason they carried over when most car construction switched to unibody. They are still required on most real pickup trucks.

My father had a 73 Chevy truck and I remember seeing curly cues at the master cylinder. I had a 75 Chevy truck and it did not have them. I know this as we installed trailer brake controllers on both of our trucks, the old kind that tapped into the brake lines. It was my first experience with brake lines and bleeding brakes.

On Factory Five cars the master cylinders are mounted to the frame so there's no flex or expansion to be concerned with. The only thing curly cues are doing other than looking cute is providing a place for air bubbles to hang out. I've done a ton of brake lines in my life and never made a curly cue and not going to start now.

[Derald Rice]

Us Colorado guys need to get a group together. I think I know of at least 10 of us in a 10 mile radius! Rian

Yes,

We have been getting together every month at the Centerra Cars & Coffee, held on the last sunday of each month for two years....

https://www.facebook.com/nococarsandcoffee/

Comprised of guys from Ft Collins, Loveland, Greeley, Cheyenne, and north Denver......There are 30-35 of us and the usual turnout
is 8-10 each month, but we have had up to 14......

If you are interested, PM me with your info and I will get you on the contact list.....most pf our communication is
done via text messages.

Derald.

[CraigS]

Mike that is fine. But not everyone building an FFR has done a ton of brake lines. And not everyone has the tool, or the time on the tool, to be comfortable doing their own flares. So using pre-done lines and putting loops as needed to take up extra length works out fine as long as the loops are oriented properly.

[Mike.Bray]

And not everyone has the tool,

Dad rule, if you need a tool and don't have it, you much acquire it

[Avalanche325]

Interesting. But I still don't understand the purpose of loops in hydraulic lines. Steam lines, yes. Hydraulic lines, no.

What they are for is to make up for manufacturing tolerances. The line with a loop can be easily flexed to fit. People see them on production cars and think they are some kind of shock absorber, so they copy them.

[Presdough]

when pressure is applied inside of the tubing it is applied equally to all surfaces. if there is a curve in the tube it will try to go straight. Putting a loop in the tube absorbs the shock in the tube from some of the pressure attempting to straighten the loop. That's why it is called a shock loop.

[Waterman]

Sorry if it was mentioned but check CAREFULLY for a leak. I had a very small one and could not get a good hard pedal after several gravity and vacuum bleeds. Only when a friend came over and we did the stand on the pedal bleed did we see a single drip per pedal push. Air gets sucked back in even thru a tiny crack. Regards

[Tony_G]

Did you ever get the rear brakes to work properly? If not I would start by taking the brake line off the master cylinder and bench bleed it. (You can make a scrap piece of line to catch the fluid in a cup.) Replace it and then bleed it all again.

[CraigS]

My experience is that when looking for a leak, look at the joint first of course. But it is usually hard to get a good close look all the way around the fitting even using an inspection mirror. But then run your fingertip around the joint and look at it. I have often been able to see dampness on my finger that for some reason wasn't obvious on the fitting itself. Also rub your fingertip against your thumb. Sometimes you can feel dampness too.
BTW, following Mike's Dad Rule, if you don't have an inspection mirror that swivels on a telescoping stick, get one. It's amazingly helpful and few $.
https://www.homedepot.com/p/ULLMAN-3...TS-2/317466575

[Mike.Bray]

BTW, following Mike's Dad Rule, if you don't have an inspection mirror that swivels on a telescoping stick, get one. It's amazingly helpful and few $.
https://www.homedepot.com/p/ULLMAN-3...TS-2/317466575

While you're there be sure and pick up a magnet on an extension. Get two, one for ferrous and another for non-ferrous

[CraigS]

I was just looking through this thread again and noticed the sentence, "I’ll likely try to put a good pressure on the system,...". An FYI re; pressure. I have had recommended to me by a brake manufacturer, and also have seen it repeated by others here, keep max bleeding pressure to 10#.