1workinman

I have a 95 dodge that has poor brakes. I would like to replace the vaccume booster with a hydro unit. Is there a write up on this being done or has any one done this. Thanks

infidel

Save your money, it won't help.
Upgrade the rear cylinders to part number 37337 at any auto parts for under $15 each. A qt of brake fluid and an hour of your time and I guarantee you love the way it stops. It is a direct no hassle swap.

Also adjust your rears manually at least every 5k, the self adjusters are notorious for not working.

Read more about the cylinder upgrade here https://www.dieseltruckresource.com/...ad.php?t=46618

1workinman

Sir I appreciate your input as I always try to read your post. Here is what I have done so far. New master cylinder, rebuilt Chevy rear wheel cylinders, the big ones. shoes, new drums, adjusted twice. New front brake pads, rebuilt calipers. removed the rear only anti-braking under the master cylinder. I could not find any leaks on the lines. I have bleed the system several times. No gain.. When I step on the brakes the end of the booster seems to deform and move forward along with the brake master cylinder. IF I step on the brake long enough the pedal seems to go to the floor. This is the second master cylinder. NO change. I have changed out just about ever part. I have ordered now front hoses. Not that I think that will help. The front rotors are not new but just sitting still a soft pedal. The brakes are poor at best. Ideas ?

infidel

That certainly doesn't sound right and is the first time I've heard of anything like it.
You need to nail down the cause.

1workinman

I am not usually a parts changer but this has me guessing. I guess I need to break a line after the master cylinder and plug it just to try to isolate the problem. I had hoped that the hydro boost would at least stop the master cylinder from moving forward from the end of the vacuum booster. At least .250 or more. Perhaps more power assist. ? I am at a loss? thanks

atc250r

If your master is moving forward off the booster then I'd say that you have a problem with either the booster or the master. Since you changed the master that only leaves one thing. Thousands of trucks are running the vacuum booster type system without the problem you're having so there has to be a problem with your truck.

John

1workinman

I would not have ever noticed it but my son was watching the booster and noticed the thing deform and move out. I though perhaps this is a good time to replace the thing with a hydro unit. I have never liked the brakes on this truck. Thanks guys for the help.

nickg

I have seen bad M/C out of the box, if your pedal slowly sinks to the floor it can only be a leak externially which you would see or pressure bleeding past the piston/seals of the MC, you could test the MC by plugging the outlets with a couple of old brake lines and crimp the ends, then bleed them right at the MC, then see if the brake pedal "sinks" if it sinks the MC is faulty.
As for adjusting the brakes, (no insult intended) did you pull the axel? and adjust the starwheel until the wheel LOCKS up and then back it off till there is a slight drag?? a good indication that your brakes need adjusting is if you pump the brake pedal and the pedal seems to get higher and higher (or rise) if you pump the brake pedal and dont notice any height difference in the pedal then your brakes are adjusted properly.

I'm fairly certain its normal for the vacuum booster to deform and move a little.

blackimpala

Why would you pull the axle?

Floyd

nickg

actually I assumed he has a factory locker, and if so you cant "feel" drag when adjusting the brakes. Because your trying to rotate the wheel and you cant. even with an open diff, you will be able to adjust the first wheel easily, but when tring to get drag on the second you will be fighting the first wheel you adjusted, almost without fail folks "think" they adjusted properly when in fact they did not, as I stated above pump the brakes to confirm a proper brake adjustment.

1workinman

I probably should have removed the axle, as I have adjusted the brakes up to much and they got hot. I pulled the drums to check for damage etc. After the fact. The shoes have good contact . New drums and shoes to begin with. These brakes have been sorry for a long time. I have put up with them. There was a fellow and I had his email address but lost it in the change of computers he lived in California I think that done the conversion and had a parts list and a few notes on what to expect. I have searched the web but cant find the link. Basically he had told me that his experience was good after the change. Bill is correct on the rear cylinders as they really helped. Looking back I wish I had try ed to install 3 inch shoes as the ones I have are 2.5 . That is not the problem but if you are going to try to improve why not?
I don't have a clue but I going to build some adapters that will enable me to install a pressure Gage after the master cylinder that way I can at least establish a base line. I don't know how much the vacuum booster multiples the pressure and the hydro booster does. They may be the same. It would be nice to be able to step on the brakes and it stop.. firm brakes right off the top. Be able to lock up all 4 wheels with x amount of effort. Thanks for all of the ideas

infidel

Well it can be done.
I can lock up all four on both my vacuum assist trucks before the ABS kicks in.
I don't see the problem manually adjusting the rears with a posi rear end.
I've been doing it for 13 years, still have the stock drums and shoes with over 200k on each truck.

1workinman

I had hoped that you would reply when I first posted because of your experience and having a 95 also. I have never been able to lock up the brakes like I wonted to be able to. I can on the rear now but not a firm brake like I expect. My son has a 95 that he bought to pull the engine for a project. He is going to give me the booster to try. I am going to looking into the hydro unit some more as I had hoped it may provide more braking? I have found that the front is nine sixteens fine thread, rear is half inch fine. quarter inch and 3/16 flare on the master cylinder. Or just cut off some old lines . thanks Jim

infidel

Jim, I think the hydro-boost truck power steering pumps have extra pressure and return ports for the brakes.
You're going to have to improvise in a tight space, better take a good look first.

nickg

Some people can adjust brakes properly, and until you get a feel for it, the best way to ensure the "drag is right" is to eliminate the rest of the driveline from the brakes you are trying to adjust. I would think if you got 200K out of your rears, then they cant be working or you never stop, or do one heck of alot of hi-way driving (no insults intended)