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-   -   Line lock question (https://classracer.com/classforum/showthread.php?t=57939)

Dana Fitzpatrick 05-10-2015 04:35 PM

Line lock question
 
I found a drop of fluid on the bottom of my line lock,right on the stud/nut at the center of the solenoid. It's clear and odorless,are they filled with a lubricant? Thanks.

Eman 05-10-2015 06:11 PM

Re: Line lock question
 
They are filled with brake fluid if they are on a car. Is this a Hurst or a copy? You can buy a rebuild kit and replace the o-rings. You can also just replace the o-rings if you have a source for EPDM O-rings. Only use EPDM O-rings, don't ask how I know! I found what I needed in small packs on ebay so I can rebuild mine if needed.

tommy d 05-10-2015 07:32 PM

Re: Line lock question
 
Speaking of line-locks. Has anyone ever had a spongy pedal because of a line lock problem? Every single piece of the hydraulic system has been replaced except for the roll control and I still have a spongy pedal. It wil come around on the second stab and work great. I even installed a front disc conversion and went with a G.M. Corvette style master cylinder and still soft. Arrrgh!

Dragsinger 05-10-2015 08:56 PM

Re: Line lock question
 
Tommy,

what about the mounting position? Might it be mounted at a high point and be trapping air?

tommy d 05-10-2015 11:20 PM

Re: Line lock question
 
Quote:

Originally Posted by Dragsinger (Post 470256)
Tommy,

what about the mounting position? Might it be mounted at a high point and be trapping air?

Its lower than the master cylinder but not by much. I am going to by-pass it tomorrow and see what I have.Thanks for the suggestion.

tommy d 05-11-2015 03:24 PM

Re: Line lock question
 
Well I by-passed the line lock and the problem is still there. Anyone run a residual valve on their car even if the master cylinder is higher than the calipers?

Kenney Kelley 05-11-2015 07:13 PM

Re: Line lock question
 
Quote:

Originally Posted by Tommy d (Post 470245)
Speaking of line-locks. Has anyone ever had a spongy pedal because of a line lock problem? Every single piece of the hydraulic system has been replaced except for the roll control and I still have a spongy pedal. It wil come around on the second stab and work great. I even installed a front disc conversion and went with a G.M. Corvette style master cylinder and still soft. Arrrgh!

Tommy we had similar problem on a car we bought it had Strange brakes on the front and rear. On each caliper it has either 2 or 4 bleeders you need to bleed all of them. Also it had a Hurst line lock..We installed the rebuild kit and that fixed that problem.

Kenney Kelley

Mark Ugrich 05-11-2015 08:22 PM

Re: Line lock question
 
Quote:

Originally Posted by tommy d (Post 470245)
Speaking of line-locks. Has anyone ever had a spongy pedal because of a line lock problem? Every single piece of the hydraulic system has been replaced except for the roll control and I still have a spongy pedal. It wil come around on the second stab and work great. I even installed a front disc conversion and went with a G.M. Corvette style master cylinder and still soft. Arrrgh!

Is the pedal ratio correct for the conversion/disc brakes?

Eman 05-11-2015 10:28 PM

Re: Line lock question
 
Buy a couple of plugs that will fit the MC. Plug off 1 section and see what it feels like. If it's still spongy plug off the other and try it, spongy with both plugged you've got air in the MC. If plugging 1 section makes the pedal firm you have air in the section or a hose ballooning.

tommy d 05-12-2015 12:06 AM

Re: Line lock question
 
Thanks for the ideas guys. I like the idea about blocking off a chamber on the m/c and see what happens. The disc conversion company says to pick up the $30.00 Harbor Freight pressure bleeder and use it. Gonna try that tomorrow. I hear pedal ratio thrown around on other forums. Maybe I'm going to have to learn about that next. Thanks.

HandOverFist 05-12-2015 01:29 AM

Re: Line lock question
 
Yes, I use a 2 pound residual valve in the rear of both the Camaro and Mustang (Aerospace 4-pistons).

Eman 05-14-2015 08:38 AM

Re: Line lock question
 
Pedal ratio should be 6:1 so if the pedal is 12" long from the pivot to the bottom you want the rod attachment at 2" down from the pivot.
I guess 2lb isn't much but most class racers don't want any drag on their brakes and have gone as far as installing springs to release the calipers so the pads don't rub the rotors. Since disc brakes don't have return springs there should be no need for residual valves unless the MC is below the wheel cyl and fluid could drain back. Residual valves on old drum brake cars were to stop the return springs from pushing back the wheel cyl pistons way back and causing a low pedal. Much of that was overcome with those strainer looking things in the wheel cyl on the wheel cyl springs. Which is why they did away with residual ck valves in factory MC's years ago even with drum brakes.
You can back bleed brakes pretty simple and easy. Go buy a large animal syringe and a piece of clear tubing to fit it. Load the syringe with brake fluid and remove the air, just like you saw the nurses do before they inject you. Push the fluid back thru the bleeder with the syringe. This is OK but I've never had to do it on brakes, only on clutch hydraulic systems that were hard to bleed.. On calipers tapping the caliper with a rubber mallet will bring the air to the top and out the bleeder. Be sure the calipers are installed correctly with the bleeders at the top. I have seen them reversed and the bleeders at the bottom.

pmrphil 05-15-2015 06:13 PM

Re: Line lock question
 
I have had issues with the caliper not being perfectly square to the rotor, causing the caliper to "move" or twist (just a few thousandths) but it was enough to affect the pedal movement similar to what you say, a bit "mushy" on the first hit.
After squaring the caliper to the rotor the problem went away.

Bob Mulry 05-15-2015 09:19 PM

Re: Line lock question
 
Give me a call at 650 922 0407 and I'll give a trick for bleeding disc brakes....

bob

Tom Joseph 05-21-2015 09:52 AM

Re: Line lock question
 
Quote:

Originally Posted by tommy d (Post 470245)
Speaking of line-locks. Has anyone ever had a spongy pedal because of a line lock problem? Every single piece of the hydraulic system has been replaced except for the roll control and I still have a spongy pedal. It wil come around on the second stab and work great. I even installed a front disc conversion and went with a G.M. Corvette style master cylinder and still soft. Arrrgh!

Yes. Had it happen changed the LL and solved


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