Greetings all

In the 6+ yrs that I have had my 92 Amigo, it has always had a low brake pedal when depressed for brake actuation and I have never been satisfied with the braking capability (I could never lock the front wheels on demand on dry pavement). Recently the pedal seem to be even lower. Fearing impending brake failure, I purchased and installed a rebuilt master cylinder (brake hoses and frt pads were replaced 6 yrs ago, master cylinder appeared to be the original 14 yr old part).

WIth the rebuilt master cylinder in place the brakes ***barely stop the vehicle*** - I would not feel safe driving it in traffic. Also the brake pedal when depressed is almost to the floor. If the rebuild master cylinder is not at fault, what else should I be looking at?

The generic instructions that came with the master cylinder made mention of checking and adjusting the power brake booster actuation rod. THe generic instructions mentioned: 1) that one should be able to see fluid motion in hte reserviour (sp) when the brake pedal is depressed 3/8 to 1/2 inch, 2) that if the actuation rod is too short the result would be a low brake petal and 3) if the rod is out too far, one would not see any fluid motion and that some port in the master cylinder would not be able to funtion and that would result in brake dragging and low brake effect. My vehicle exhibits the traits of both too short and too long of an actuation rod. Have any of you ever adjusted the rod coming out of the power brake booster and what was the result?

Suggestions please on improving my brakes - sharing a car with my wife when our commutes are not in the same direction is getting very old.

Sounds like lot's of air in the lines.
I'd start bleeding at the rear and work up to the front,do the longest line first.

As for the actuator rod,dunno,sorry.

Bansil

Thanks for the response. I would tend to agree about air in the lines, but... Two nights ago, I bench bled the rebuilt master prior to putting it in and then bled at the wheels (but forgot to bleed at the rear anti-lock brake modulator valve). Once I fired up the engine and the power brake booster was in play, I had a very low pedal that went to the floor and I had no brakes what so ever with out pumping the brakes (and even then I had a lot more stopping by downshifting). Last night I re-bled the master cylinder and then the rear anti-lock valve prior to bleeding at the rear and then the front brakes. I even raised the back end of the vehicle up so that the master cylinder was level when bleeding - seems that I read somewhere that this was needed on GM master cylinders that are not horizontal so that air could remain trapped in the master cylinder.

Any one else have any ideas / suggestions? I am desperate to get my car back on the road. Since I tend to do all my own service work, I don't have a mechanic that I am familiar with that I could drop this problem off on.

The brakes really should be bled with the engine running, at least according to Helm. It may or may not make a difference in this case.

On an outside possibility, maybe you got the wrong sized rebuild MC.

Michael

Bled w/ the engine running? I have never heard of such - but thank you VERY much for posting this bit of info - atleast I have one more thing to consider.

I just wish I had done this a week ago when the temps were 30 degrees warmer. Runing an electric heater in the garage, I can get the temps into the upper 40s after a couple of hours but my bleeding assistant (wife) is still complaining that it is too cold.

When I first did my trooper up with all new brakes and stuff I couldn't get very good pedal travel either and I bled the brakes numerous times.I even took it to a shop and had them bleed the brakes with the same result.When I put the pedal down it was almost to the floor , and even then it had little effect , they were very spongy.I poked around and asked questions on the board and found out about that adjusting rod on the brake booster and I adjusted it.It doesn't take much to adjust it , a couple of turns , and my pedal travel was greatly changed to the point where the brakes came on as soon as the pedal went down a little less than 1/4 way , like they should with all new brake parts.I think if you turn it too much , the rod will stick out too far.

Also , did you bench bleed the new master?That makes a big difference too if its not bled properly.I would lean towards the rod needing adjustment though , especialy seeing you put on a new master.Just give the rod 3-4 turns and give that a try , if its not enough do it in small increments untill you are happy with the pedal travel.

Bled w/ the engine running? I have never heard of such

I don't think it makes that much of a difference. I've done it both ways. The manual claims it is to prevent damage to the booster diaphram.

Michael

Thanks for the rod adjustment testimonial.

Yup I bench bled the master, twice on two seperate days. I also adjusted the rod that sticks out of the power brake booster 1.0 mm (one turn)longer. Looks like I will try and adjust the rod for more rod extension first. I did read in the generic instructions that came with the master cylinder that one should be able to see fluid moving in the reservoir when the pedal is pressed about 3/8 to 1/5 inch. I never did see any motion. In the same generic instructions it made mention that if the rod was too far out that the fluid intake port (from the reservior) would stay permanently blocked and the brakes would not work well also. The Haines manual gives a spec of 0.717 inches of rod protrusion at a vacuum of 20 inches of Hg. For grins, I am thinking that I will fire up the engine and check the rod lenght with the engine at idle.

Late last night I tried to raise the brake pedal itself in the desperate hope that if the stroke is increased that the brakes would funtion better - for 3/4 hour of time all I was able to achieve was that the pedal was about 1/8 inch higher with no effect in the braking performance. It was definitely not worth the effort.