Hello,

I had searched around for about an hour and haven't found what im looking for,

I traded my 2nd gen for this 1st gen in april 2011. ever since I got it the brakes have been bad. when I first got it if you pressed them once and then the 2nd time you pressed them it'd put you in the dash. But the booster was bad and the vacuum pump is junk. so i temporarly put a Audi vacuum pump that produces 27in HG ( roughly what a 1st gen pump makes ) and hooked it to my brake switch with some relays and whatnot. so I have vacuum when I hit the brakes. I plan to buy a vacuum pump off of a 93 because they are the newer style and nobody seems to be able to get me one for a 91.

at the time of the audi pump I also put a new MC and booster. brakes were still kinda crappy but i dealt with them for the summer. The adjusters for the rear never worked right so I would adjust them up periodically.

now I converted the rears to disk brakes and replaced the MC. still have a bad pedal.

here is what ive done diagnostic wise, i clamped the front and rear hoses to ensure the pedal is rock hard, ( it is ) when i unclamp the rear hose and leave the front clamped the pedal travels around an inch then gets rock hard. when I clamp the rear but unclamp the front the pedal goes basically to the floor. ive bled the system a bunch of times. never with a bottle and reservoir of fluid but I figured disk brakes didn't need that. the little button on the proportioning valve pops out when you hit the brakes. I think the RWAL is bypassed. and I know the AL brake box in the dash is unhooked. My brake light stays on all the time, but i don't pay alot of attention to the warning lights in these older trucks because I feel they are inaccurate.

So what type of advise could you guys give me? I just want my pedal to be better so I can stop when pulling my 25ft gooseneck trailer its just not safe and I can't tell you how many redlights I have blown because of my brakes.

heres a few pics for ya,


rear disks




Ya'll have a nice day

 

Disk brakes require two people, or one person with a bottle with the hose to the bleeder plug.

Sounds like there is a leak or a bad hose in front.

You should put in a vacuum canister with a check valve. Rig a switch to run the pump when the vacuum gets below a certain level.

The vac pumps on the non-IC trucks uses the same pancakes the Ford trucks used.

 

I forgot to mention,

in august I did all new front brakes, hoses, calipers rotors. I had my brother pump the brakes while I cracked the bleeder, didn't get air.

my thoughts on the the electric pump were, as long as you "charge" the booster up before you drive you will be set. because when you hit the brake pedal it will activate the pump therefore replacing the vacuum that was used in the booster. Like I said i plan to get a newer style non pancake type of pump just because of ease. The pancake style pump I have is bad. the round canisters are good, but the part of the pump that pushes the buttons on the canisters is bad. so i might aswell eliminate the whole thing and upgrade to something better.

My dad has a bleeding kit that is a canister with hose coming off of it, I will try using that and see if that gets me a better pedal. is it possible the front part of the proportioning valve could be bad? when I had the drum brakes adjusted properly and I hit the brakes hard I could lock them up.

Thanks for the help,

 

I wanna know more about the rear disc set up install & donor parts.

 

there are a few threads in the sticky

https://www.dieseltruckresource.com/...56&postcount=5


but i didn't do mine that way. I forget where I found the thread or what forum it was on. but I used Great Lakes offroad brackets, 77 Chevy K20 front calipers, rotors, and pads. 1991 dodge w350 front brake hoses, and some mechanical common sense.

it took longer than I planned, only because you need to make spacers to move the caliper and bracket away from the axle flange. My dana 70U needed 1 3/4" of spacing the make it just right. the pads will cause a little friction for a few miles but then they wear in just right. it wasn't hard just take your time.

here is GLO's website

http://www.greatlakeoffroad.com/GLO-...rsion-Kit.html

all in all it cost me around $300 for everything. With the towing I do i figured it was worth it. I can't give you advice as of now if you need a different proportioning valve to stop the rears from locking, but you may need one.

,Kody

 

If you're using the stock prop valve with rear disks that could be your problem. Or part of it.

 

you think its not gettin enough flow/pressure being the calipers hold more volume than the wheel cyls?

the brakes were still really bad before I did the rear disks though.

I ordered a new vacuum pump, going to try bleeding them with a reservoir of fluid. and Im going to check to be sure the RWAL is bypassed.

 

well,

I replaced the vacuum pump ( upgraded to the vane style found on 2nd gens and late 1st gens )

it turned out to be alot more different than I thought, but luckily ive got a wrecked 97 in the front lot for parts.

my brakes are great after the new pump was installed. I also bled them with a bottle and that made them better aswell. The only issue now is they will lock the rears up very quickly, so I need to get an adjustable prop valve.

I also need to get a manual line lock so I can have a parking brake again,

Thanks for the help,

Kody

 

When you say your using a bottle is it the set up thrashing cows used? Also when your bleeding them do you just hook the hose up to the bleeder screw on the brakes caliper?

Sent from my DROID4 using Tapatalk 2

 

I use a similar setup but this is actually a kit you can buy. My dad has had it for awhile. it is a bottle with a tube that goes to the bottom of it and you just crack your bleeder and hook the hose to it, pump the brakes to the floor a few times and move to the next wheel.

I also forgot to mention, I had changed my oil a few weeks ago and found ball bearing parts, This concerned me alot.

After tearing my vacuum pump off I found what the bearing parts were from. there was nothing left of the bear in the vac pump. Im pretty lucky the parts slipped by the timing gears without any damage. Also makes me feel better that I know what the parts are from,

thank god for magnetic drain plugs haha,

Kody

 

Couple of things to check, 1-the caliper slides, if they bind when you apply the brake instead of everything moving smoothly as it should it can bind/**** the caliper. The pads will still apply but when you release the pedal the binding in the caliper/bracket interface can cause the piston to be pushed back into the caliper a few thousandths, then the next time you apply the brakes you have to first re-extend the piston until it contacs and starts putting pressure on the pad (hence the good pedal on the second pump).

Another thing to check is if you used any of that "disc brake quiet" goop they package with some brands of brake pads, the stuff that comes in tose little plastic tubes you spread on the backs of the pads...in my experience it is a no-no and causes more problems than it solves, it causes the same clearnce issues as a cocked caliper requiring you to pump the pedal sometimes because the goop causes the pad/caliper piston interface to get all gooked up with a squishy substance. I had a similar problem with this type of issue on my own truck, the brake pad backing plates had rusted and the layer of rust between the pad backing and the friction material itself was causing the same type of squish/clearance issue because everytime I hit the brakes the rusty crap had to compress before the pressure was applied to the pad....worth checking into if your out of ideas.