Line Lock question

Demon James · Post by **Demon James** » Mon Nov 21, 16 12:31 am

I've just posted the latest on a 68 dart we've bought and after a brief but full on late season blast at Santa Pod, I have a question regarding the line lock.

After various brake bleeding methods (vac and traditional pushing) I still have a soft pedal.

I have read other posts on different sites relating to difficult bleeding of Wilwwod calipers but my question is more on the effect of line lock.

When I press the pedal down, it's kind of soft, then press the line lock button, then lift off the brake and press it down again. It is now rock solid. I let go of the line lock button and the pedal stays firm and solid.

Is this normal for line lock operation? Just thought I'd ask.

I have moved the line lock solenoid from its current location, above the master cylinder, to a new location so that it is now below the level of the master cylinder.

This came about as the car will jump forward when staged if I hold the revs up to 2500. I dont use line lock to hold on the line, just my foot on the brake but as I pre-stage, then lift off slightly to stage, the pedal goes soft and I have trouble keeping the car there before the green light.

Any thoughts? I haven't raced the car since moving the solenoid down but the brakes still feel the same as before.

Blue · Post by **Blue** » Mon Nov 21, 16 8:14 am

Once you engage the line lock, if you press the pedal again it should have less travel, as in that situation you are only operating the rear brakes you have taken the fronts out of the equation. Sounds to me like you still have air in the front brakes, willwood brakes have 4 bleed nipples on each caliper, and you do need to bleed all of them.

Demon James · Post by **Demon James** » Mon Nov 21, 16 8:47 am

Cheers Blue, I only bled the top two on each side based on a novice approach that air would be at the top if there was any

I had read a few conflicting views, as ever with the internet

, which led me to leave the four lower points alone.

I will refit my bleed assistant to the front seat when he's finished school and have another go

Thanks mate and catch up next month for Chrissy pud.

Demon James · Post by **Demon James** » Mon Nov 21, 16 9:02 am

"Q: How do I bleed a multi-piston Caliper with the four-bleed screws?
A:

After the master cylinder has been bled, begin bleeding the calipers starting with the wheel farthest from the master cylinder, usually the right rear and start with the upper outside nipple, then move to the upper inside nipple (never bleed the lower nipples). Repeat the process with each wheel, moving successively toward the wheel closest to the master cylinder. For best results the upper nipples should be pointing straight up because air migrates to the top of the chamber. If you have any questions, please contact a Wilwood Sales Technician at 805-388-1188 or email Sales/Tech Support."

This is what I had read on the Wilwood site but couldn't find a reason to specifically not bleed the lower nipples

andyrob · Post by **andyrob** » Mon Nov 21, 16 9:08 am

james try and bleed the lower nipples............... then report on here what happened

andyrob · Post by **andyrob** » Mon Nov 21, 16 9:14 am

the lower nipple are there as the caliper fit quite a few different cars and they would be the upper nipples on a different application

Blue · Post by **Blue** » Mon Nov 21, 16 9:18 am

Yes logic would suggest you would suggest you would only need the upper nipples, but that's not my experience. Sometimes gravity bleeding is a good solution when you've got air trapped somewhere. All you need to do to bleed that way is a length of tube and a jar with a bit of fluid in it, as far below the nipple as possible, open the nipple and let it run.

Demon James · Post by **Demon James** » Mon Nov 21, 16 9:31 am

andyrob wrote:james try and bleed the lower nipples............... then report on here what happened

Whats the worst that can happen

Blue · Post by **Blue** » Mon Nov 21, 16 10:01 am

The worst that can happen is it won't make any difference...another thing you can try if you think you have air trapped in a calliper is to leave it connected but unbolt it and force the pistons back with G clamps and bleed it like that. You might also have air trapped in the end of the master cylinder, it will not bottom out attached to the pedal.

Demon James · Post by **Demon James** » Mon Nov 21, 16 10:45 am

Blue wrote: You might also have air trapped in the end of the master cylinder, it will not bottom out attached to the pedal.

Interesting point, Blue. I meant to ask about bleeding the master cylinder, is there a procedure?

All I did was fill the front and rear reservoir and topped up as we bled from the calipers, have I messed up? We never allowed the fluid to drop much past half way to make sure air didn't get sucked into the system.

We also made sure the lid was secured each time we bled the system, no more than 5 pumps before stopping and topping up.

Demon James · Post by **Demon James** » Mon Nov 21, 16 11:07 am

Ah, I see the key point in that sentence is that the piston doesn't travel all the way to the end when pushed by the pedal lever in the car

Got ya

So if I disconnect the pipes at the master cylinder and make up a couple of short pipes to flow back into the reservoirs to "circulate" the fluid. Then remove the pushrod from the pedal and use a drift to slowly push all the way in instead? If I bend the short pipes to keep them below the fluid level this should let air out but not back in.

Blue · Post by **Blue** » Mon Nov 21, 16 11:11 am

You should always bench bleed a master cyl. before you fit it. You can do it on the vehicle by disconnecting the pushrod from the pedal and directly pushing it in till it bottoms out. At the same time you will have the lines off the M/cyl and with your latex gloves on press a finger over each port. Fluid and any air will be forced out but the gloves will stop air being drawn back in. You can then just connect everything back up and try it, there is no need to bleed at the wheels when you do this believe it or not.

Blue · Post by **Blue** » Mon Nov 21, 16 11:16 am

Demon James wrote:Ah, I see the key point in that sentence is that the piston doesn't travel all the way to the end when pushed by the pedal lever in the car Got ya

So if I disconnect the pipes at the master cylinder and make up a couple of short pipes to flow back into the reservoirs to "circulate" the fluid. Then remove the pushrod from the pedal and use a drift to slowly push all the way in instead? If I bend the short pipes to keep them below the fluid level this should let air out but not back in.

Yes that method will work just as well and is considerably less messy....

Demon James · Post by **Demon James** » Mon Nov 21, 16 12:17 pm

Blue wrote:You should always bench bleed a master cyl. before you fit it.

DOH

Every day's a school day

Cheers, Blue.

Are there service kits about for these master cylinders? I only ask as its not overly clear if its from spillage or slight weeping where the push rod goes in. Brake fluid seems to creep forever or appear damp on a surface forever

Blue · Post by **Blue** » Mon Nov 21, 16 12:24 pm

Seal kits are normally available, is it a Factory part or aftermarket?