Do line locks wear out? Brake system troubleshooting

[demon322]

Wondering a good place to start. My Demon bracket car is an old build that I acquired and have started to finally get to make some passes. I have slowly been replacing things along the way. The line lock seems to work, but not ‘hold’ as well as it should. The car rolls forward a bit before it grabs completely during the burnout.

It’s possible something else is the culprit though as it doesn’t seem to hold on the line (foot brake) as well as it should before trying to push through the brakes. I feel like I’m leaving some rpms on the table there.

So, where would be a good place to start? Could it be a pressure/air in line issue? I have replaced the master cylinder, but not the front calipers or even pads yet.

Thank you.

 

[jimjimjimmy]

Is it wired to a relay ? If wired just through a switch it might not be getting the power it needs .

 

[Newbomb Turk]

They do wear out. IIRC someone made some that were rebuildable.

Not sure if what you have is one of those or not.

 

[9secRR]

of course they wear out, no different then any other part.

 

[Newbomb Turk]

of course they wear out, no different then any other part.

Do you remember rebuildable line locks? I’m pretty sure I do. Haven’t seen anything g like that since the mid 1980’s though.

 

[Just Send It]

Biondo still makes the rebuildable ones I think

 

[Bobzilla]

Wondering a good place to start. My Demon bracket car is an old build that I acquired and have started to finally get to make some passes. I have slowly been replacing things along the way. The line lock seems to work, but not ‘hold’ as well as it should. The car rolls forward a bit before it grabs completely during the burnout.

It’s possible something else is the culprit though as it doesn’t seem to hold on the line (foot brake) as well as it should before trying to push through the brakes. I feel like I’m leaving some rpms on the table there.

So, where would be a good place to start? Could it be a pressure/air in line issue? I have replaced the master cylinder, but not the front calipers or even pads yet.

Thank you.

View attachment 1716520063

View attachment 1716520064

Are those brake rotors rusty from sitting around? Kind of looks like they were and then stopping rubbed some of the rust off. If so, that will reduce your braking ability even before the line lock is engaged.

 

[413]

Air in the lines, hell yes, it's a hydraulic system. They don't work well with any air on them, right??

Glazed rotors and tiny pads can't be helping. Why are the calipers and pads so small? Is that a common thing Wilwood does?

 

[9secRR]

Do you remember rebuildable line locks? I’m pretty sure I do. Haven’t seen anything g like that since the mid 1980’s though.

no i don't. i should go look at the one i took off my car, it is from 1992

Air in the lines, hell yes, it's a hydraulic system. They don't work well with any air on them, right??

Glazed rotors and tiny pads can't be helping. Why are the calipers and pads so small? Is that a common thing Wilwood does?

i just rebuilt a set of those small calipers on a friends onmi last weekend. i don't think they are available anymore. they are for very light cars, 2200 lbs and under

 

[Syleng1]

1) yes they are wear parts and do need to be replaced.
2) your front brakes also look like it’s time. Some pads need heat to stop properly. If those pads are “hard” they may need heat to start the grip.
I’m not sure what conditions you are facing 100% from just a few pictures.

There could be more going on then just a weak solenoid or bad electrical.

 

[demon322]

They do wear out. IIRC someone made some that were rebuildable.

Not sure if what you have is one of those or not.

I’m not sure, and I haven’t been able to find any kind of part number or even brand on it.

 

[demon322]

Do you remember rebuildable line locks? I’m pretty sure I do. Haven’t seen anything g like that since the mid 1980’s though.

This is an old build. Not sure if it’s quite that old but it’s sure possible

 

[demon322]

Are those brake rotors rusty from sitting around? Kind of looks like they were and then stopping rubbed some of the rust off. If so, that will reduce your braking ability even before the line lock is engaged.

The car did sit for quite some time before I got my hands on it. Looking at my picture again I see what you mean about the rotor. It looks a little better in person but I do think replacing the rotors sounds like a very good idea. The line lock does engage, so maybe it is working as it should and the pads/rotors are not doing their job.

 

[demon322]

Air in the lines, hell yes, it's a hydraulic system. They don't work well with any air on them, right??

Glazed rotors and tiny pads can't be helping. Why are the calipers and pads so small? Is that a common thing Wilwood does?

Sounds like bleeding the system just to be sure couldn’t hurt. As far as the small calipers/pads - I assume they just installed a whole wilwood setup when they built the front end. The car is pretty light, but I would just be guessing as to what it weighs (I sure would like to know though! Wish I had a buddy with a set of scales.)

 

[demon322]

1) yes they are wear parts and do need to be replaced.
2) your front brakes also look like it’s time. Some pads need heat to stop properly. If those pads are “hard” they may need heat to start the grip.
I’m not sure what conditions you are facing 100% from just a few pictures.

There could be more going on then just a weak solenoid or bad electrical.

Thanks for the replies all! I’m thinking I will start with new pads and rotors and bleed the system for now and try that. Since the problem is both during the burnout and also foot braking on the starting line, I don’t know that the line lock is necessarily the problem.

 

[perfacar]

how old are the hoses to front and rear? they can cause huge problem. they can swell and cause loss of holding pressure. just food for thought. btw , my hurst line loc is old, been in use since 1970

 

[demon322]

how old are the hoses to front and rear? they can cause huge problem. they can swell and cause loss of holding pressure. just food for thought. btw , my hurst line loc is old, been in use since 1970

Thanks. They are as old as the calipers I would assume. They are braided flex lines at least and not rubber. But still it might be a good idea to replace them.

There are hard lines from the master cylinder forward and then the flex lines going to each caliper.

 

[Inertia]

The original Hurst line-locks are rebuildable and kits are avail . Done a few.

https://www.topflightautomotive.com/products/hurst-1953-2020-roll-control-line-loc-valve-rebuild-kit/

 

[ValiantRacing]

Biondo still makes the rebuildable ones I think

These are the best ones on the market in my opinion

 

[jimjimjimmy]

My Hurst line lock would not hold for longer than 10 sec so i wired a relay in and it seems to hold good now .

 

[demon322]

Update: I ordered new pads and rotors which were much needed for sure. I tried to stay with all wilwood as that was what was on it. $390. There was only one rotor option that fit my hub (black and drilled) both had newer part numbers as mine were obsolete. I tried to get by with not buying calipers as mine seemed to be working and new ones would be another $300 and of course I would have to bleed again but now I’m thinking I might have (need) to do that also. The pistons in the old one won’t retract enough to allow the new pads to fit over the rotor. When I compress one the other side seems to protrude. This may be normal but I’ve done quite a few brake pad jobs and haven’t encountered this. Seems like I might as well get new calipers also. What would you do? Just like the pads and rotors, the calipers are old enough that the wilwood part number on them have been superseded to a new part number. I think I know the answer but thought I would check in. Happy Saturday!