I'm struggling with what I assume is a very simple task. When I re-fit my rear drum brakes, Haynes states that I should set the self adjuster mechanisms and then adjust the handbrake. Sounds simple, but it doesn't say how.
I've had my rear drums on and off many times over the last couple of years, but I don't think I've ever truly set them correctly.
- If I set it so the pads don't touch the drum, the handbrake is ineffectual.
- If I set it so that the pads touch, the handbrake works fine... but the handbrake warning light comes on when I brake hard or come to a stop. However I have to move the handbrake at least a centimetre or two for it to come on. I'd assumed that the HB warning light was simply a switch triggered by pulling up the HB. Does it also warn of warn/badly adjusted pads? Also as you'd expect, braking is nice and firm but the pads wear out real quick set like this.
If adjusting manually, it's usual to adjust them so they rub slightly.
As for the warning light, how's the brake fluid level? On most vehicles the brake fluid level warning is done via the hand brake light. It could be that it's just slightly low, so when you brake hard, it's enough for the level to drop at the sensor causing the light to come on.
That's what I figured and it's what I'm now setting them at.
I did a brake fluid change using a Gunson Eazybleed (or what ever it's called). There wasn't any HB warning sign on my test drive. Only after I tinkered with the self adjuster. I had this with my other Punto as well.
I've just checked the fluid level and it's actually above max at present. When I left it yesterday it was at normal.
BTW, one thing the Gunson kit doesn't tell you that when initially testing for air leaks, if the reservoir cap doesn't form an air tight seal it turns the brake fluid in your reservoir into fizzy pop. Didn't seem quite so funny at the time.
Maybe time to hand the car over to a pro to bleed the brakes.
Sorry, a Fiat Punto MK-II. Until recently I had two of the buggers (identical in all but colour), but I'm finally free of one now :D. No DIY tinkering on the new car.
You didn't give any clues as to vehicle, you also mentioned 'pads' (disk brakes) and drums (they are 'shoes' not pads inside drums), however...
Assuming rear drum brakes.... There will be some sort of ratchet mechanism between the shoes, which takes up the slack. Sometimes it is as simple as thread inside a sleeve, with a spring to ensure it only turns one way - out. sometimes it takes the form of a cam. That ratchet mechanism needs to be free to turn and be screwed all the way back in to its starting position.
As you operate the brake repeatedly it will work its way back out, to take up the slack. If you get someone to operate the brake, you will probably hear the ratchet clicking - when the clicking stops, they are fully adjusted.
Assuming disk brakes and pads.... The usual method is a thread inside the piston, which gradually unscrews as the handbrake is operated. To retract these you usually need to turn the piston itself with a special spanner, in the correct direction.
For either type of brake... Once you are sure the mechanism has taken up all of the slack and the pads or shoes have worn themselves in a little, the handbrake cable itself may need some adjustment. Your manual should give the number of clicks the HB lever should make, as you pull it all the way on - usually around 7-ish. If it is far out from this number, follow the handbrake cables path under the car and somewhere there will be a means to adjust it for the correct play.
The HB warning light has nothing at all to do with the above, it is simply a microswitch on the HB lever, set to come on as a warning that it has been left on. Usually it also serves as a brake fluid low warning light - if it flashes as you brake it probably means the fluid is low in your master cylinder and needs to be topped up. This is just a simple float switch, in the master cylinder, checking the fluid level.
A pad wear warning light will usually be separate from the HB warning light and the pads will have a wire inside them. The wire loop in the pad is cut as the pads wear down - once the loop is cut, the light stays on until new pads are fitted.
Harry, I was the first person to reply to the OP. (At least according to the times in my newsreader!). I've re-read the original post three times, and I'm blowed if I can find where he referred to a Punto!
Sorry I didn't mention the car in the OP, when it came to drums and braking systems I thought they were all pretty similar.
OK, I've checked the brake fluid level. It was above the max, I've now got it in the middle. I've also re-adjusted the rear self adjusters so that they are quite far out. But I'm still getting the following:
When breaking, from about 17mph to 0 the HB warning light comes on. It goes off again from about 10+mph. Other than that, the braking feels good in every way. Tried a few emergency stops and no issues, just a bit of a pull to the left or right.
As I mentioned in a later post, I'd also renewed the brake fluid as the car had done 60k without a change and was for a short while pulling left when braking. Could using a Gunson Eazybleed damage this fluid sensor in the master cylinder that people have mentioned?
Other than performing another brake fluid change, I'm now out of ideas. I'll probably book it into a garage next week. But any other suggestions for the weekend?
Sorry chaps, it was my fault I didn't mention the car. Due to both my Punto's regularly having issues and not knowing any mechanically minded people, I do tend to post here with simple problems on a regular basis. Without trying to do some DIY maintenance, these cars would have bankrupted me by now.
What is strange for me is coming across another 'Tim'. I must have gone through my life only meeting a couple. This news group must have three or four regular posters by the name of Tim. I'm afraid I'm getting over familiar and forgetting the detail.
Thanks for the info on setting the adjusters. This is what I kind of figured. But I've never truly been happy with the results.
The fluid level is OK. I did perform a brake fluid change using an Gunson Eazybleed kit (a pressure kit that attaches to the reservoir). You first perform a test to ensure the system is air tight. The cap provided was far from air tight and pumped a lot of air into the fluid (it churned up the fluid, mixing in air). I wonder if some of this could have got trapped in the master cylinder. Would a master cylinder have a bleed valve? Or would you bleed the system again? Braking is fine at the moment though, just the warning light.
I think the brake ware warning lights are an extra on the Punto's. Probably the higher 16v models. I'm guessing that drum brakes usually don't have this sensor. The front shoe is certainly well worn on one side and almost untouched on the other.
If it is more likely to come on if you lower the fluid level, then I would suggest something is amiss with the sensor. They are only a float, which either operates a microswitch or more likely a magnetic reed switch, with a magnet in the float. They are usually pretty robust.
Unpredictable pulling to one side or the other on initially starting the braking, usually means their is something sticking like the pistons or the caliper sliding mechanism.
You change the fluid because over time it absorbs moisture, which can boil due to the heat created as you apply the brakes. If it boils, you loose your brakes.
Unlikely.. All those I have come across are located in the master cylinder top cover. With cover off, ignition on, handbrake off (in gear) - If you push the float up the light should go off, let it fall down away from the lid, it should come on. The coming on position should approximately match the minimum fluid level.
Never mind taking it to the garage, stick at it - you will learn a lot from your struggles for next time :')
It's now fixed, quite simple really when you know there is a warning switch in the reservoir. I must admit I had miss interpreted some of the posts and thought it was in the master cylinder itself.
As I mentioned in one of my follow up posts, when performing an initial air tight seal test with the Gunson Eazybleed, the brake fluid was heavily adjitated (a bit like opening a bottle of Coke that had been shaken) as the cap provided by Gunson didn't form an air tight seal on my Punto. It looks like the reservoir is split into sections, one of which containing a fluid level switch. This section must have formed an air bubble that couldn't escape. I detached the reservoir... Well actually the rest is pretty obvious.
Thanks for the help. Without that little nugget of information I would probably be at least £50+vat poorer next week.
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