Disc brake Conversion Problem

[k5moneypit]

Well I have finally converted my 14 bolt over to disc brakes using 75 chevy brakes, problem is I still have no pedal, bleed those suckers forever, even put on the 4 wheel proportioning valve from inline tube and still nothing,and new master cylinder, no change. Inline says maybe need a 4 wheel disc master cylinder, Has anybody done this?Any suggestions would help, I've done a search on this here with no luck on this problem. I'm going to gravity bleed them today, then tommorrow its going to a shop with a power bleeder. Help! /forums/images/graemlins/dunno.gif 87 k5

 

[Beast388]

Sounds like you still have air in the lines. I gravity-bled mine and had no problems with pedal feel. /forums/images/graemlins/waytogo.gif

 

[k5moneypit]

I just finished gravity bleeding the brakes and no difference. I wondering what part does the booster play in this, could this be part of my problem?I'm hearing an air pushing sound in the cab when pressing on the brakes, I'm pretty sure that is normal, but at this point...I'll try anything. /forums/images/graemlins/angryfire.gif

 

[spearchucker]

Do you have the bleeder valve on the rear discs pointing straight up? If you don't then you'll get air trapped in there and no pedal. You need to remove the caliper and get it into a position where the valve is pointing up then bleed it and remount it.

 

[beater_k20]

spend $40 and buy a mityvac. best money i ever spent.

 

[84_Chevy_K10]

Until I broke it. /forums/images/graemlins/rotfl.gif

 

[v-3500]

You should try starting from square one with the bleeding. You should remove the master cylinder and bleed it. Try getting a cheap little master cylinder bleeding kit, which consist of two small plastic plugs with small 1/32-inch tube fittings, and two lengths of tube. First, screw in the plastic plugs into the master cylinder ports. Second, connect the tubes to the plastic plugs. Third, route the tubes back into the master cylinder reservoirs, and depress the master cylinder piston, until air bubbles stop.

Side Note: When I was a mechanic I did it the fast messy way. I just depressed the master cylinder piston and let the fluid fly, then used my fingers to cover the master cylinder ports when the master cylinder was on the backstroke

Then when the master cylinder is attached to the truck...bleed the master cylinder at the brake line ports. You should do this with the engine running.

1. Pump the peddle and hold it

2. Crack the brake line open just enough to let fluid escape.

3. With the brake peddle still held down retighten the brake line.

4. Repeat this with both brake lines, until there is pure brake fluid with no more air bubbles in it.

Next move to the front brake closest to the master cylinder (left front caliper on GM's), and bleed it (use the two person pump-and-hold method) with the engine running. Repeat for the right front caliper.

If you have an Anti-Lock Braking System (ABS), then sometimes there is a small valve on it (kind of like an Schrader valve) located on it. This valve needs to be held in the open position while bleeding the back brakes (usually only for the left rear, but if you can pull it off...do it for both back brakes). Also, try bleeding the proportioning valve the same way you bled the master cylinder by cracking the lines open, while pumping and then holing it...again with the engine running.

Your next move would to go to the rear brakes, starting with left rear first, and do the pump-and-hold for them too...again with the engine running.

If you can get your hands on a power bleeder you can do all this yourself without a second person pumping the peddle, and without the engine running.

 

[Muddytazz]

I had the same problem...bled mine for 3 days with no luck. Finally took it in and had it pressure bled and all is well now /forums/images/graemlins/thumb.gif

 

[k5moneypit]

well took off the rear calibers and bleed them, and finally no brake light, but still hardly any pedal. Am i supposed to bleed them with the engine running? I dont ever remember hearing that.I did bench bleed the new master cylinder, it came with the bleeder hoses and screws. Where did ya buy one off those power bleeders? What kind of quality can I expect out of it.Its looking more and more like I'm taking it to the professionals. Anybody know the symptons of a bad booster? Thanks guys! /forums/images/graemlins/thumb.gif /forums/images/graemlins/usaflag.gif

 

[Muddytazz]

I didn't buy a pressure bleeder, i took it in and had someone else do it for me....the cost is about $40. If you had a bad booster, it would be severely hard to even push the pedal at all.

 

[k5moneypit]

That to me is the worst feeling, doing a project yourself , only to have someone finish it for ya . Oh well, I've bathed in brake fluid enough. /forums/images/graemlins/1zhelp.gif

 

[the cork]

[ QUOTE ]
well took off the rear calibers and bleed them, and finally no brake light, but still hardly any pedal. Am i supposed to bleed them with the engine running? I dont ever remember hearing that.I did bench bleed the new master cylinder, it came with the bleeder hoses and screws. Where did ya buy one off those power bleeders? What kind of quality can I expect out of it.Its looking more and more like I'm taking it to the professionals. Anybody know the symptons of a bad booster? Thanks guys! /forums/images/graemlins/thumb.gif /forums/images/graemlins/usaflag.gif

[/ QUOTE ]

Maybe you have to much pad travel, try setting your parking brake this will pull the pads tight to the rotor, then see if your pedal firms up, if it does, then you need to adjust your parking brake levers on the calipers, just an idea.

 

[sidslc]

I had the same problem and it took me a long time and a lot of brake fluid to figure it out. I tried 6 different master cylnders and a willwood 10# residuel pressure valve before every thing came togeather. Now I can turn my russell perportioning valve up and the rears will lock up before the front. this may not be the solution for everyone but the master cylnder off a 84 1 ton truck with single rear wheels and a diesel/hydroboost has a 5/8 bore and flat out moves more fluid. This completeley solved mu soft peddal problems. good luck

later

 

[k5moneypit]

Well on the way to the shop for professional bleeding, I was very encouraged on how good this thing stops, simply put Awesome /forums/images/graemlins/thumb.gif The only thing I hope to get rid of now is how far I have to push the pedal to get the Brakes to engage, its about 1.5 to 2 inches before they kick in. The mechanic also said I put the calibers on the wrong side.
I'm not so sure I believe this, because autozone marked them for me after double checking the computer. The mechanic says their wrong because the bleeder screws are pointing down, if i switch them that put the bleeder screws on top. I did take them off and bleed them straight up though, shouldn't matter once their bleed right? So hes gonna switch them, and pressure bleed the system. /forums/images/graemlins/dunno.gifAnother mechanic there says hes done a similiar conversion and he too lacked pedal, so as usual I be waiting in limbo again til tommorrow. I keep ya posted. Thanks a crap load everyone! /forums/images/graemlins/peace.gif

 

[jimmyjack]

The mechanic is right /forums/images/graemlins/blush.gif If you put the R caliper on the right rear it will be upside down, so it needs to go on the left rear to be rightside up. And the L caliper on the right rear. Anyway, when the caliper is upside down the fluid never has a chance to fill the resevoir and goes right out of the bleeder screw.......I only know this because I helped a friend bleed his for about 3 days. Really, seriously, I got lucky and "screwed" mine up but never realized it til after my buddies fiasco /forums/images/graemlins/grin.gif Sorry I didn't read this post earlier, might've saved you some time and effort.

 

[beater_k20]

[ QUOTE ]
Until I broke it. /forums/images/graemlins/rotfl.gif

[/ QUOTE ]

you didnt break it, it fell off the bed. out of curiousity, i hooked it up to my vac guage, and it works fine. still pulls 30", and holds it. the guage doesnt work anymore though.

 

[k5moneypit]

well, got er back today. My wallet is 80 bucks lighter, there is hardly any difference in the pedal travel, but she still stops great, as i found out on the first yellow light i encountered. No pulling left or right though. The mechanic said he's changed up to five or six proportioning valves before getting that new feel. Nope not me I will live with extra travel, although he did say it might get better as the brakes start to seat. And as for the mighty vac bleeder I will stick to the conventional method. I borrowed my neighbors and every time i opened the screw the vacuum tended to leak out the fitting on the bleeder screw.Thanks to all who posted. Now its on to the next project...a new body. /forums/images/graemlins/usaflag.gif /forums/images/graemlins/grin.gif

 

[jwduke]

Take the rod that goes between the brake pedal and master cylinder, and cut the part of this threaded rod that that is not threaded. (It is in the female end) Put it back togeather, make the rod a thread or two longer. This will bring your pedel back to what you are use too.

I went thru what you did, and a buddy who is the service manager at the local Chevy dealer said to do this! Good luck!!!