mx5cartalk.com

Replaced brake fluid and bled all four corners, adjusted my faulty driver side handbrake. Woot, somehow my brakes are worse than ever.... No air in the lines, pads, calipers and discs haven't changed since, brand new fluid... Yet somehow the pedal feels loose and I have about 50-60% LESS stopping power... WTF

The original plan was to replace with new fluid and get rid of the air in the rear lines. Bled the brakes, no more air in the lines and has nice new clean fluid in it now. I adjusted the manual handbrake thing on the rear driver side as that corner seemed to do nothing with the handbrake engaged.
Everthing should have been working perfectly but it seems the only thing that's improved is the handbrake (which now works fine).

The pedal now feels slacker than before and the brakes don't fully engage until it's completely depressed. Even then, stopping power is average-poor. On top of this, the fronts lock up upon quick braking.

It's really concerning me now because the only thing that's changed since was the fluid. I'm going to do another bleed tomorrow just in case to make sure there is no more air in the lines. I looked for leaks but I can't seem to find any brake fluid stains, so I'm guessing it's not a leak. I'm not sure what else to say.

The brake fluid I used was Castrol DOT4 fluid that comes in 500ml red bottles. I bought 3 of these to be on the safe side (1500ml) but only ended up using about bottle and a half (750ml).

If ANYONE knows what's wrong or has any ideas, I need to know asap as this is my daily driver and I'd like to be able to stop!!!!!!!!!!

Brake booster not working properly?
I remember I had a Nissan exa where it was stuffed and the brakes would be nothing until fully depressed and then it would still just be like pushing my foot against a wall for barely anything.

Before staring the car try pumping the pedal 5 or so times to build up pressure, then keep the pedal depressed as you start and you should feel the pedal go down a bit.

If I recall correctly this is how to check whether the booster is functional but I'm sure somebody knows better than me.

That an effective test for the booster, but I reckon theres air in the lines.

Dann

Yeah i've been thinking this over and over and I have a feeling that there is still air in the lines and may have been sucked back in when doing up the bleeder valves. Since I'm working with my 70 year old father, there may have been a miscommunication between us regarding foot on and off the brakes. I'm going to bleed it again tomorrow morning and see how I go before I do anything rash. This should solve the problem i think.


EDIT!!!!

Cerberus, I tried your test but it ultimately went nowhere as the pedal touches the backwall anyway lol. Like I said, I'll bleed in the morning and see what happens.

Bleeding should be a one person job.

Just open the valves, all 4. And then close them when the fluid runs clean. No air can possibly get in.

And it only takes 10 minutes.

Dann

I don't have car stands

Either do I. I use 8 spare wheels.

Just do 1 end or side at a time if you just want to use a jack.

Dann

nanotech wrote:Yeah i've been thinking this over and over and I have a feeling that there is still air in the lines and may have been sucked back in when doing up the bleeder valves. Since I'm working with my 70 year old father, there may have been a miscommunication between us regarding foot on and off the brakes. I'm going to bleed it again tomorrow morning and see how I go before I do anything rash. This should solve the problem i think.


EDIT!!!!

Cerberus, I tried your test but it ultimately went nowhere as the pedal touches the backwall anyway lol. Like I said, I'll bleed in the morning and see what happens.

That's a bad way to bleed brakes. Since your pushing the pedal where it has never been before the seal on the master can get damaged. Best way as Dan said is to open all the nipples stand back and watch don't touch the pedal, good luck, just make sure the fluid never goes empty or your going to have to start over.

orangemx5 wrote:
That's a bad way to bleed brakes. Since your pushing the pedal where it has never been before the seal on the master can get damaged. Best way as Dan said is to open all the nipples stand back and watch don't touch the pedal, good luck, just make sure the fluid never goes empty or your going to have to start over.

Wonder why they sell brake bleeding kits then?

The same reason anyone sells anything, because people will buy it and profit is to be made.

Dann

Did you have your ignition turned on? You need to have the solenoid on the booster open to bled the system properly.

LOL, That was a troll post right?

Dann

 Post subject: Brake Pedal going to the floor...Posted: 24 Feb 2009 11:44 am 

Racing Driver

Should have said ABS not booster, but then you might not have ABS.

Taken from another post from CT.....

Make sure you bleed with the ignition turned on and the sequence from longest lines to shortest lines for ABS cars. It is also highly possible that your technique for opening and closing the bleeders is letting air back in. If you use the Elf HTX fluid and the car is properly bled, you should not be having this problem.

_________________
<---Nemo is now.
2009 MX5 Class 2B National Champion

Charlie Brown wrote: It is also highly possible that your technique for opening and closing the bleeders is letting air back in

Pretty sure this is the reason lol. I'll give it another stab tomorrow. It's a 1990 na6 so I really don't think ABS is an issue here

Give me a break Dann!! This is the first time I've replaced the brake fluid

Like I said. Open all the nipples, go have a cup of tea (or a beer) come back close nipples, half pump the pedal until hard and bam you have a brake pedal