Brakes Not Working Well

[jrocket]

Hey all.

I recently got my car repaired where they took the back diff cradle out etc which disconnected the back brakes. When they put the cradle back in they just connected up the brakes again and bleed ONLY the back brakes. I got in the car afterwards and the brakes where VERY VERY weak with the pedal going right to the floor. I was like wtf did they do.

These dumb asses were only panel beaters so i didn't want them to touch the cars brakes again. I just figured they didn't bleed the brakes right. I check the workshop manual and they bleed the brakes myself. When i did this there was lots of air in the brake lines. But after bleeding as per the manual the brake pedal did feel a bit better and braking was better but the brakes didn't work until the pedal was about 1/2 way to the floor. The car has ABS braking so i thought maybe some air has got into the ABS unit. So i took the car for a spin and braked hard a few times so that the ABS would work hoping that maybe it might work the air through. I then bleed the brakes again when i got home and did get some more air out of the system.

But still the brake pedal falls about 1/2 way down before i get any braking force. Why is this the case. I haven't driven any other skylines so i got nothing to compare against.

I am thinking maybe i should get a brake master cylinder kit and change all the seal and see what happens.

What do you all think? Or is this problem best left to a ABS braking specialist.

Cheers

[adam-__-]

Your brakes are the only thing stopping your car while it's moving. If you don't know what you're doing I think it's best to leave it to a professional.

I assume that there is still air in your system if the peddle is going half way down to work. How were the brakes before you had people working on it?

[Duncan]

probably still air in the brake lines, you should have a lovely firm pedal when its done properly.

there are 2 bleed nipples on top of the ABS unit which you should do last, they may cause the problem- but to be honest even in the race car I've never bled the ABS and the pedal is fine.

most important is to move passenger rear, driver rear, passenger fron, driver front, and maeke sure you close the bleeder between each stroke of the pedal so air can't get sucked back in. You might need more than 1 500ml bottle to do it properly

[wrxhoon]

If you know what you are doing you should be able to bleed the whole system without touching the ABS . By the sound of it the brakes work but they have air in the system . Try pumping the pedal a few times while stationary with the engine running, if the pedal comes right to the top ( and its hard) you have air in the system .

If you are not sure how to bleed the lines take it to someone that does ,

if you want to have another go try this: You will need 2 people , one pumping the pedal and the other on the bleed nipples. Pump the pedal in quick succession several times hold load on it while the other person undoes the bleed valve , make sure you lock the bleed valve BEFORE the pedal goes to the floor , do that until you see no more tiny little bubbles comming out . Start with the caliper furtherst from the ABS unit then the next closest and so on . The frst one you do make sure you continue for a while even after you see clear fluid ( without bubbles ) a good few times . Make sure you have 1.5 lts of fluid ( you should only need 500ml to 1000 ml , more for brembos) . While you are doing this make sure the master cyl reservoir never goes anywhere near EMPTY , not even on the one circuit . If you run it empty you will need to bleed the master cyl , not easy for the inexperienced . After you finish all of them with engine running try the pedal if it feels good test drive it and see how you go.

Good luck with it.

[jrocket]

Cheers guys thanks for the feed back. I did bleed the brakes twice so far and did get some air out of it both times. I did do it in a similar method to what you have stated. I go and bleed the brakes a few more times and see what the result is.

At what stage should i think of rebuilding the brake calipers, ie new seals etc. My car is a 1995 model r33.

Hopefully i get some better results when i bleed the brakes again. On the ABS unit what are those two bolts on top of the unit. They seem to have a STAR type bolt head. Is this the bleed for the ABS? As far as i can see the only bleed valves are the ones on the calipers. There doesn't seem to be anywhere else to extract air.

[wrxhoon]

Cheers guys thanks for the feed back. I did bleed the brakes twice so far and did get some air out of it both times. I did do it in a similar method to what you have stated. I go and bleed the brakes a few more times and see what the result is.

At what stage should i think of rebuilding the brake calipers, ie new seals etc. My car is a 1995 model r33.

Hopefully i get some better results when i bleed the brakes again. On the ABS unit what are those two bolts on top of the unit. They seem to have a STAR type bolt head. Is this the bleed for the ABS? As far as i can see the only bleed valves are the ones on the calipers. There doesn't seem to be anywhere else to extract air.

I don't want to say you are not competent mate but from what I can see Don't get involved with the ABS or master cyl because they are harder to bleed than calipers . You are having trouble bleeding it from the calipers so I wouldn't go undoing the ABS .

If you had air the second time that means you didn't bleed it in the first place. at a guess i would say you let the pedal go before you locked the bleed nipples then as the pedal comes up you suck a little amout of air in it . Don't worry about ABS/ Master cyl. follow the instructions above but keep going for a long time on the very first caliper , bleed it long enough so all the fluid from the master comes out ( don't forget you have to keep feeling it up, as soon as it goes down just bellow half). Even when you have no bubbles in it keep going , you will need about 500 ml to flash it all out. If you do this any air in the system ( even in the ABS unit will come out ). Try it and see how you go .

[jrocket]

Thanks dude. Yeah i really had no intention of goin near the ABS unit as this wasn't mentioned in the workshop manual as part of the bleed process. I have bleed quite a few cars before doing mine and friends with no troubles and always get a excellent brake feel at the end. BUT all of these cars too did not have ABS. So this is a bit new for me. But i followed the bleed process as per the manual and similar to above.

When my car was getting worked on i think the brakes where disconnected for a month or so, so i am thinking that must have given it a good chance to get alot of air into the system or letting the oil drain out. I dunno what he panel beater has done. I didn't think about any problems with the braking at the time.

I will do the bleed again as you recommend and i wont mucking round with the ABS or master cylinder.

Thanks for the feed back its much appreciated.

[heslo]

Got the same problem with my brakes, VERY spongy. Bled them on the weekend, better but only marginally. Any ideas?

[jrocket]

Hmm I might buy some new slotted rotors and pads while i am buggering around with the brakes.