Soft brake peddle cause

[Ecomike]

Great idea! I'm also thinking that your idea of taking a old brake light switch and using epoxy to hold the pin in place would work. Or, we could cut the top off, remove the spring and force a small bolt or screw through the top to hold the pin in place, then screw the switch in. It should work since the switch is plastic.

Just be careful as the old brake light switches are very brittle at the thread area. I need to easy out one already that my buddy broke off in the combo valve

Thanks for reminding me of the used brake light switch and epoxy idea.

 

[dan1977p]

I have plenty of spare fittings lying around that I can rig. I'm curious if I can get a little more solid feel by doing this in addition to my previous bleeds. To keep the shaft in place, do you have someone push the pedal enough to see the indent and then thread the adapter in place? Or can you move it with the reset port on the front of the combo valve?

 

[Ecomike]

I suspect with no pressure on the brake system the valve spool can be moved back to center with a gentle push from a pick tool or small jeweler0electronic screwdriver. It should recenter on its own I think with no leaks, a sealed system and a push on the brake peddle????

 

[Ecomike]

I have plenty of spare fittings lying around that I can rig. I'm curious if I can get a little more solid feel by doing this in addition to my previous bleeds. To keep the shaft in place, do you have someone push the pedal enough to see the indent and then thread the adapter in place? Or can you move it with the reset port on the front of the combo valve?

From what I gather our previous bleeds left air trapped by the combo valve as it sealed off or reduce the flow to the lines being bleed? The tool holds the valve wide open, centered so we get max flow to push the air out easier?

 

[dan1977p]

I'm sure there is still a tiny bit in there. I think this is the reason you don't smash it to the floor. I was ok until last night when I replaced my drums with ZJ discs. Had the line disconnected too long and got air in the system and if this will keep me from having to crack each of the fittings going into the combo valve, I'll give it a whirl.
BTW, keep your epoxy:

 

[Ecomike]

Now that is putting the screws to it, LOL.

 

[davesdetail]

Best idea yet Dan! Beats the heck out of bending a nail around the proportioning valve!

 

[dan1977p]

Yeah, I was just out in the garage screwing around for lunch

 

[Ecomike]

LMAO. This thread is getting SCREWED up now LOL.

 

[garr]

Question, If using a motive power bleeder (Or any power bleeder) to bleed brakes, since you are not pressing on the brake pedal, does the problem of the Prop valve piston shifting & leaving air in the system still occur?

 

[Ecomike]

Question, If using a motive power bleeder (Or any power bleeder) to bleed brakes, since you are not pressing on the brake pedal, does the problem of the Prop valve piston shifting & leaving air in the system still occur?

My guess would be no as the flow pressure would be too low to over come the springs in the Combo valve. Just and educated engineering guess. But I doubt any power bleeder can move naturally trapped air bubbles as fast as the pedal with the engine running and good vacuum in the booster. 300 PSI beats 20 psi any day.

 

[XJ-ARNIE]

You should always check and recenter this valve. Once it moves to cut flow to a line, it stays put. Sometimes recentering it and reinstalling the switch, and a normal bleed procedure will be just fine.

 

[davesdetail]

I found this you tube video that helps explain this issue:


https://www.youtube.com/watch?v=zT2ja_5QSdE&list=PLHcdiCthCsumTUJZH3X95mxpGcVOwhpyc&index=13

 

[jnewell]

The length of the stroke to bleed the master depends on the method used. When using tubes to recycle the fluid back into the reservoir, then 100% stroke.
If using block off plugs then short strokes are used until no bubbles rise from the ports.

Bringing this back up for clarification. I bled my MC on the bench as described in the first paragraph. I fully depressed the piston. It sounds like this was ok and didn't damage the seals in the MC?

 

[XJ-ARNIE]

It'll be alright bud. Just unscrew the the brake pressure differential switch, bend a paperclip at a 90 and move that valve back to center. Reinstall the brake pressure differential switch and do your normal bleed procedure. Should be good to go.

 

[jnewell]

Thanks, Arnie. I just popped off the switch. Question for you: I also opened the front of the valve body (which didn't tell me much). I assume there's nothing sacred about opening up the front of the valve body and then reassembling it? It's not like this is a factory-sealed assembly...?

 

[XJ-ARNIE]

Thanks, Arnie. I just popped off the switch. Question for you: I also opened the front of the valve body (which didn't tell me much). I assume there's nothing sacred about opening up the front of the valve body and then reassembling it? It's not like this is a factory-sealed assembly...?

no your good. its just how it all goes together, and that is where the spring is located to change the brake bias front to rear.

 

[jnewell]

Yet another stupid question. I'm pretty sure that the combo switch thinks I had a rear brake circuit failure (because of how I did the first bleed). I assume that I need to wriggle the valve toward the front of the vehicle? I'm having trouble getting it to move with the paper clip (in either direction).

 

[XJ-ARNIE]

Another guy on here did it with a small nail, even held it in place while he bled with the nail If you read back a few pages in this tgread, everything you need to know should be in here.

 

[Ecomike]

I like Your idea too! The way I did it may or may not work for everyone.
If you want to make a brass tool, the thread is a M10x1.0
I want that T-shirt! Lol

I just checked the thread on mine, the spare one have pulled out of JY, and the thread is 3/8 x 24tpi, US not Metric. Iwas shoping for a brass bolt...and checked the thread