juggernaught
Still battling the cj7 soft brake syndrome. Has someone found a good upgrade for 1978 cj7 master brake cylinder? I always have to pump my brakes 2-3 times.
First pump comes up half-way, Second pump comes up firmer, Third pump is just to be sure.
All drums,rotors,and brakes are new. I was told that the master cylinder had been replaced. All brakes are bled. I need a better than stock master cylinder,possibly with a longer throw. Any suggestions?
ironman_gq
I have the same problem and I've found that adjusting the rear drums a little tighter usually helps a lot. I go from 2-3 pump brakes to right now stopping brakes just by adjusting the drums. Not sure why the auto adjusters dont do it but they dont. Im thinking that discs are in my future
fifesjeep
Go over to IFSJA... there is a guy who sells stuff for cheap that will take care of your brake issues... I can't remember if you have to click wanted or for sale either way, check it out.
juggernaught
Will try to adjust the rear bracks and see if that helps.
Looked at IFSJA on most of the boards (including vendors), but did not find anything about master cylinder upgrades/fixes. If you have anything more specific please let me know. Thanks.
msalaba
I had the same problem after I replaced all the brake lines. I ended up getting a power bleeder and that solved my problems.
As previously mentioned, make sure you have the shoes adjusted so they just barely drag. The rear circuit does not have a lot of volume to actuate the shoes.
Has anyone seen the auto adjusters work? I have put never sieze on the adjuster bolts and they still don't adjust. Periodically I have to manually adjust. (This is on my S10)
If your master turns out to be bad, replace it with an OEM equivelent. Engineers spent a lot of money designing the system. The only reason to change it is if you change other parts of the system. i.e. add rear disk or larger front calipers. By changing out the master you could open pandora's box.
fifesjeep
Hmmm, couldn't find the link either but, I do have this link on my favorites... this could be another route for you.
[url]http://www.ifsja.org/forums/vb/showthread.php?t=99397&highlight=brake+upgrade[/url]
tufcj
Master Power Brakes does a dual diaphragm booster with upgraded master. Pricey though, around $450. Took a serious look at their system when I did my rear disc setup.
[url]http://www.mpbrakes.com/[/url]
Bob
tufcj
Old Rugged Crosser
[quote=juggernaught]Still battling the cj7 soft brake syndrome. Has someone found a good upgrade for 1978 cj7 master brake cylinder? I always have to pump my brakes 2-3 times.[/quote]
Your problem is not your master cylinder. You have air in your system. That is why you can pump up brakes.
Get all the air out and you will have good brakes without misspending a lot of money. :sa: :sa: :sa:
juggernaught
I am familiar with the hydroboost system and don't want to go there yet. I already had my brakes bled about a year ago without much change in the peddle pressure. I will ask them if they were "power bled". I usually only have my brakes done by shops that "power bleed", but can't remember.I will look at the rear adjustment, but have been there before and everything seemed to be good.
Lets pretend that everything is in adjustment and that there is no air in the system. Nothing is leaking. All parts are newly replaced (except the m/c). Now, what are my options (except hydroboost) for a m/c replacement? Anything besides a stock unit?
northplainsdrifter
I had D30 with disc brakes from around 78? Someone told me they were Ford. The only way I could get the air out of the front disc's was to take them off and point the bleeder straight up, then bleed them. When mounted, the bleeder was in about the 2 o'clock position and I couldn't get all the air out till I removed them.
juggernaught
I would think that power bleeding would not require you to remove the calipers. But, If I have to manually bleed the brakes that is something I will keep in mind. I think my bleed ports are mounted rather low.
Old Rugged Crosser
[quote=juggernaught]I am familiar with the hydroboost system and don't want to go there yet.unit?[/quote]
The hydroboost system will not overcome the problem you are having. I am using a hydroboost system and also had to overcome the problem you are having.
NPD was right. You may have to remove the calipers to get out all the air. It is a air problem that you are having.
Mudrat
[quote=juggernaught] Any suggestions?[/quote]
1. are you running bigger tires? If so how big
2. do you have a vacuum booster? If so have you tested it? The buggers tend to leak after a while.
Try the bleeding option first - cheapest of the lot obviously, but didn't overcome my stopping issue (35's). I had pedal pressure, just not enough grip to slow me as quick as I liked.
Disk rear's helped a lot after that. [url=http://www.ssbrakes.com/][color=blue][u][b]SSBC[/b][/u][/color][/url] and [url=http://www.tsmmfg.com/][color=blue][u][b]TSM[/b][/u][/color][/url] both have good $y$tem$ (and I have a set of TSMs for a stock D-20 rear up for grabs :wink: swapped in a D-44, with disks :t: )
You don't want a longer throw on the pedal, you want a larger diameter piston - creates more PSI in the hose. If your not ready for Hydroboost, check into a corvett MC with a 1-1/8" bore, or a dual diaphragm vac booster. BUT, you need to be sure it's not trapped air first.
juggernaught
Thanks.............thats what I needed. Any idea what years of the corvette m/c will work? No vacuum booster so thats out.
Is it really necessary to hold the pin open on the proportioning valve either while hand bleeding OR power bleeding? The books say yes and the mechanics say no. Personally, I have never bothered with the pro/valve while bleeding my other vehicles.
Somewhere in the future rear disc brakes would be nice.
tufcj
No power brakes? :shock: Maybe that's the first upgrade you should think about. My 77 CJ was a factory disc/drum with power brakes. I'm still running the factory master cylinder with Wagoneer front calipers (dana 44), rear disc, and 37" tires. It stops like it did with the factory 29" tires.
Bob
tufcj
Old Rugged Crosser
Yes it is important to hold open the pin on the proportioning valve. Here is another tip.
Disconnect the two brake lines that go into the master cylinder and fashion two more lines that will screw into the M/C and turn them up and into the two M/C reservoirs then pump the brakes slowly and do not go all the way down on the pedal. keep stroking like this until no more bubbles come. Then connect the original lines. You should see a lot of difference.
juggernaught
Tufcj...........I just don't have a vacuum booster (nothing between the m/c and the fire wall).
juggernaught
ORC.......If I have someone power bleed my system, do they still need to open the proportioning valve? So far you are the only person telling me (besides the book) that it is mandatory to open the p-valve while bleeding.
I have made an appt. to have them power bled on Thur. morning along with checking the rear drums. I did not ask this guy about the p-valve.
This is one of those issues that has plagued me for a couple years. I would like to put it to rest. I somehow doubt that I am the only one with this issue. But I am very thankful for all the solid advice.
tufcj
The vacuum booster (the canister between the firewall and M/C) is what makes "power brakes". the vacuum booster assists you in applying the brakes, without it, it's entirely pedal pressure with your leg.
I agree that the rear drums being out of adjustment could cause a low pedal that will pump up.
Have you checked that the correct lines are connected to the right place on the M/C? Generally in a disc/drum setup, the larger reservoir is the front brakes.
Bob
tufcj
Old Rugged Crosser
[quote=Old Rugged Crosser]Yes it is important to hold open the pin on the proportioning valve. Here is another tip.
Disconnect the two brake lines that go into the master cylinder and fashion two more lines that will screw into the M/C and turn them up and into the two M/C reservoirs then pump the brakes slowly and do not go all the way down on the pedal. keep stroking like this until no more bubbles come. Then connect the original lines. You should see a lot of difference.[/quote]
Are you ruling this out? I wouldn't if I were you.
