Disk brake problem!

okay then
bet they get better with more usage
have fun !

 

I was not aware of this... The stock MC on Lulu has the front running off the front chamber. When I replaced it with a Napa replacement MC, I hooked it up the same way, since the lines are already bent and in place for that configuration.

I'm not doubting you - but why would the factory lines from the front be running to the front chamber on the stock set-up?

Edit: Something else I just thought of... The ports on the Napa replacement are actually labeled "Front" and "Rear". You're reasoning makes absolutely perfect sense, but I can't understand why the lines and the labels are opposite of that...

 

Tim, when you get a chance swap them, I assumed mine were from a previous owner but maybe they were factory, mine would not work with disk's the other way around but stop fine once swapped around, I have put 8 miles in stop and go traffic this morning on my Jeep and Jim was right they stop much better after seating themselves. Do not have to do a death grasp on the wheel when hitting the brakes hard now.

Don't forget I'm bringing your Saginaw parts to Telico!!!!

 

Mine are rear to the rear of the MC - so I guess I'll be switching them. I assume I'll have to switch on the the junction block - so the fronts are on the top again? Or does it matter. Or should I take that thing out of the loop? Thanks.

 

Why would the factory plumb them this way.... I don't fully understand the inner workings of an MC, but this is what I experienced last night:

I have had the front rubber hoses off, during the brake upgrade, so I know there is air in the front lines. I also have the front brakes plumbed to the front of the MC. I got inside the Jeep last night, and depressed the brake pedal. It went about half-way down with next to no effort. Then it stopped and had pressure, and the brake lights came on. I just assumed that the pedal had travelled down at first b/c the front had air in it, then it hit the part of the stroke where it would send fluid to the rear (about 1/2 way down). There, it still had pressure, and it actuated the brake lights (via the pressure switch plumbed into the *rear* line). Thus, it seems that the MC still pressurizes the front brakes first, even though they are plumbed to the front chamber.

If it would definitely make a big difference, I would try to change it around before Tellico. But I hate to bend and flare brake lines, not to mention bleeding the entire system again...

[pulling hair, trying to resist the temptation to change something at the last minute]

 

Bob if you junction block is like mine the fronts have a different fitting and you can't change them there without making new lines or cutting and moving the fitting to the backs or vise versa. The thread fitting was larger on my front then the ones for the back, even though the line was the same size.

Tim all I can tell you is my front reservoir wouldn't even come close to stopping my discs, in fact they would spin down with the tire just of the ground with no load on it. Swapped the lines and it was like night and day.

Tim do you have residual pressure valves in your system, cause my NAPA M/C had none in it. Oh and by the way the speed bleeders that Steve mentioned farther up are worth there weight in gold as far as I'm concerned!
Heck if you want to do it at Tellico friday night after the run we'll do it at Crawfords, bring about 18"-24" of brake line, my tools are already in the Jeep.

 

I love these technical questions/problems !!!
I would have to agree that the fronts would be plumbed to the rear of the m/cyl OR the larger of the 2 resevoirs. Most vehicles are that way, disc or no disc.
With that being said, let's turn to our trusty FSM for early CJs.
" The primary outlet is connected to the front brakes with the secondary outlet connected to the rear brakes" ; lots of help there huh?
Makes no mention of which outlet is which on the m/cyl body; also makes no mention of which resevoir is larger and why!
My definition of primary would be the first outlet in line closest to the firewall; so the primary piston would be closest to the firewall as well. Primary piston would/should be larger than secondary, and that's my reasoning.
Interesting to see others making the comments that their m/cyl lines are plumbed the opposite.
Interesting indeed !

 

I'm glad someone else finds it interesting, cause I sure do, and I was beginning to wonder if I was the only one. R)

Who else has an "original" Jeep that can say which port the front brakes are plumbed to? Anyone buy their early CJ new?

 

I'll go look at jeepngems 70
he is the original owner
he also converted to disk many years ago
see what/how his are hooked up
it won't be till tonight, so may not help you for the weekend !

 

Many newer vehicles (especially those with a short wheelbase) with a Front/Rear split brake systems are equipped with a metering valve... AKA hold off valve. This delays the application of the front brakes slightly so the rear shoes can overcome the tension of the return springs and start to apply. This reduces the amount of "nose dive" when braking. These are most common on disc/drum equipped vehicles.

Pressure builds in the primary chamber (closest to the firewall) before the secondary chamber when the brakes are applied. If there is a hydraulic failure in the primary circuit, the secondary piston is applied mechanically- the primary piston/pushrod will physically contact the secondary piston in order to create pressure in the secondary chamber.

The only explanations I can think of for Timmy's scenario are:
1) a PO did some tinkering at some point
2) the factory made a mistake
3) Maybe Jeep intended to hook them up that way so the rears would apply slightly before the fronts to keep them more level while braking. This doesn't make a whole lot of sense to me though since it was equipped with drums on both axles.

Anyone else with brake lines hooked up in "reverse"???

 

Read farther up Mike, mine were hooked up that way to start with.

 

jeepngems stock 70 is plumbed as Mikes was (factory)
port closest to the push rod to the rears
port at the front to the fronts
go figure

 

I read that but I should have been more clear in asking if anyone has had one since it was brand new hooked up that way (like jpflat2a's buddy)....

 

Well I'll be....

Doesn't make much sense, but I'm happy to know that it's not just my Jeep that's "backwards"!

Maybe after Tellico I'll switch them around and see if there's a realized performance gain with 4 wheel drums.