Builds A New 55 Owner Intro (cgn1976 thread) (2 Viewers)

[Cgn1976]

The new MC did have the sensors installed. Fully intact unit, ready to bolt up other than a bench bleed. It does seem like that residual valve makes sense as the most obvious culprit at this point.

Take this for what it's worth, which is some random website, but I read about new MCs that can have the valves damaged right out of the box during initial pressing of the interior cylinder (not sure he right word for this part of it). Maybe a new MC sat on the shelf for years before getting touched and the dry seal gets a little brittle. Then working the bench bleed you can damage them the first few pumps because there's no fluid in there yet. Sounds like the case for an initial gravity bleed...which I think I did, and will definitely do this time. I'm quite sure I got it out of the box and pressed it fully while dry because my old one wasn't pushing back and my total lack of experience had me curious about how it was supposed to feel.

I bought a rebuild kit for the original for the hell of it, as well as a new Aisin from CO. Keeping all the original parts around just in case.

In the mean time gonna try to push the current MC all the way in open the side copper bolt, then re tighten it, just in case that is causing the problem because of my cracking it open already and maybe letting the internal parts shift inside. I suppose that means a whole other bleed! Fun

 

[RUSH55]

Crank up some AC/DC or do what the YouTube wrenches do and chill your nerves with some cool jazz

 

[Cgn1976]

Lol. Remonds me of the old Phoenix radio station adds "Smooth Jazz, the Coyote", done in that "never had, it never will" 7 up voice. Been on a Van Halen - Fair Warning kick in the garage lately, although considering the death of Humpty Hump, I'm guessing Digital Underground may make an appearance this weekend...it's pronounced with an umpty...

 

[RUSH55]

Lol. Remonds me of the old Phoenix radio station adds "Smooth Jazz, the Coyote", done in that "never had, it never will" 7 up voice.

“Ahhhhhhhh..... the weekend.”

“K-Y-O-T..... the Coyotaay”

 

[PabloCruise]

Read up on Residual Valves, I really think it's acting up in your master.

Maybe not. Cruiser Outfitters refers to them as sensors, for what exactly I’m not really sure. The residual valve/valving by my understanding is the pathway/method by which fluid returns back into the master after releasing the brake pedal. If it doesn’t work, then you get continual pressure build up. Not sure why you would have that issue with a new master, but everything is pointing in that direction.

View attachment 2652513

Man, I swore I took pictures when I pulled the residual valve out of the front circuit of my '74 MC, but I do not see them in my thread.

Here is a link: Residual Valve Removal - Land Cruiser Tech from IH8MUD.com - https://www.ih8mud.com/tech/residvalve.php

 

[RUSH55]

Excellent find TJ!

So they’re there to maintain 10psi of pressure to the brake cylinders?

Makes me wonder if one or both of the circuits have too high of spring pressure which is causing the issue.

The guys suggested getting rid of them completely. I wonder what the reasoning is behind that and what the side effects are?

 

[scrapdaddy]

Disc brakes don't need them, but the drum brakes need the pressure to hold the shoes close to the drum, so you don't have a lot of pedal travel.

 

[PabloCruise]

Excellent find TJ!

So they’re there to maintain 10psi of pressure to the brake cylinders?

Makes me wonder if one or both of the circuits have too high of spring pressure which is causing the issue.

The guys suggested getting rid of them completely. I wonder what the reasoning is behind that and what the side effects are?

You don't need them for disc brakes.
So if you are adding discs to a drum brake vehicle, you want to remove this valve from the MC circuit you added discs to.
More details here: Residual Valve - discs all around - https://forum.ih8mud.com/threads/residual-valve-discs-all-around.230333/

 

[RUSH55]

So if you are adding discs to a drum brake vehicle, you want to remove this valve from the MC circuit you added discs to.

Okay, that makes sense.

Good quick read with the link.
@Cgn1976 , I know you said you’ve adjusted the rod from the brake pedal arm into the booster a thousand times, so here’s a stupid question - does your brake pedal arm have a return spring?

 

[PabloCruise]

Okay, that makes sense.

Good quick read with the link.
@Cgn1976 , I know you said you’ve adjusted the rod from the brake pedal arm into the booster a thousand times, so here’s a stupid question - does your brake pedal arm have a return spring?

^^^ Solid question!!!

 

[PabloCruise]

Also, check your brake circuits, is it possible you have an external valve of some kind that has failed?

You can see on my 40 I have what I think is a proportioning valve hanging under the MC on the front of the booster:

 

[Cgn1976]

Well, I put the 2nd new MC in today, bench bled, total system bleed, 3 quarts through and just took a 30 min drive and sadly it did the exact same thing. Pedal got steadily higher and harder. So anyone who needs a new MC, I got one, lol.

I’ve gone over the lines, front to back 10 times. There aren’t any valves to check. It’s drum drum, so no proportioning valve. There’s just the hard and soft lines and the connections. I replaced all the soft lines and hard lines are all good. I’m confident in that because the brakes worked perfectly since I bought this thing. This all started after I put the new booster in.

That’s my next move...another new booster. This all started after I put that thing in.

 

[Cgn1976]

^^^ Solid question!!!

It does. I mean I’ve just been trying different adjustments on the pin to get the pedal feel right

 

[RUSH55]

Man, what a b****!

So far, this is something I’ve never heard of or encountered. Trying to remember - is there a rod between the booster and MC?
Do you still have the old booster?

 

[Cgn1976]

Here's the old booster.

 

[Cgn1976]

Was gonna try unhooking the booster vac, seal it up and run it and see if it happens that way. Won't have the new booster for a week or so it looks like. The good news is before the pedal gets stiff the brakes are working fantastic!

 

[scrapdaddy]

Trying to remember - is there a rod between the booster and MC?

Yes, it has to be set just right, too.

 

[RUSH55]

Yes, it has to be set just right, too.

Can we verify an adjustment on this intermediate rod @Cgn1976 ?

 

[Cgn1976]

Ok, I'm confused. What do you guys mean by intermediate rod between the booster and the MC....is this something different than the pin on the booster that pushes into the MC? I've adjusted that too many times to count...too long high hard pedal right away, too short pedal takes multiple pumps to fully activate the brakes. I have it pretty good.

 

[RUSH55]

So you’re adjusting the rod going into the booster, but there’s another rod between the booster and master(?), yes?