Brakes binding?

mark66 · 1 Jul 2007 at 19:30

Earlier today I smelt what I thought was electrical burning coming from the car when I arrived at work. However a quick search found nothing, but then on driving the car again just now I smelt it again and realised it was the smell of brakes burning.

Now I had some new front disks and performance pads fitted to my MX5 a couple of weeks ago and I noticed on Thursday how the left front wheel was really grey with brake dust compared to the right. I should have thought more into it but didn't and forgot about it.

So on smelling it just now I quickly pulled over to find smoke coming from the front left callipers. I will take it into the garage tomorrow but wondered what it could be and whether it could be something they have done wrong or just something that has 'gone'. I am not sure what pulls the pads back from the disks when you finish braking, but I am guessing it has broken or gone. Is this likely to be a problem fitting or a wear and tear part?

At least this answers why the car has been feeling quite sluggish and very strange when I reversed into my parking space yesterday! Really hope I haven't balls up the new disks and pads too much though?

saitrix · 1 Jul 2007 at 19:51

The pads could be quite bad, the disc hopefully will be ok.

It is the fluid that sucks the pistons away from the pads, so the pads are just pushed out by the disc.

Have you noticed any uneven braking when you are slowing down? If so then it could be a stuck piston in the caliper.

dalin80 · 1 Jul 2007 at 20:14

jack up the front you should be able to spin both wheels by hand with only a bit of resistance.

are any of the discs going a bit red/purple on the edges? if so that's the side that's getting hot and seizing.

front brakes are easy as pie on those and should only take about an hour to take apart clean up and slap back together with some copper grease. if your happy enough to pull it apart yourself then its not much hassle to see if the pistons push smoothly as well.

adapt · 2 Jul 2007 at 13:24

I had this the other month, even posted on here. Quick clean with a wire brush to get rid of all the old crap on the calipers bit of grease on too and all works perfectly. Give it a try.

mark66 · 4 Jul 2007 at 17:24

Thanks guys.

Well I was not easily able to do any checks myself such as raising the car up or dismantling the brakes, so I took the car back to the garage that fitted the pads and disks.

They did an inspection and removed the caliper and couldn't find anything wrong. So I picked the car up and a few miles later I had the same problem of the brake dragging on the front left and plenty of smoke coming off them when I pulled up

So I drove back to the garage later that day and used the brakes hard as I really wanted them to see this 'smoking' for themselves. However when I got there much to my surprise they weren't smoking any more. So off I went thinking it was sorted and crawled back to work in the traffic, only to find the brakes smoking again on arrival!!! So it seems that this is happening when I use the brakes gently in slow moving traffic and not so much when I use them hard.

The car has been back in the garage today and the mechanic has done a complete strip down of the brake unit and still can't find anything wrong, which has been really bugging him. He says that the pads slide beautifully in their slots, that the piston is clean and unmarked and he has also drained the fluids as he thought a line may have collapsed. However their braking machine is still detecting a drag on the left side. He seemed genuinely annoyed that he couldn't locate the problem and give me some definite answers. His suggestion is now to replace the caliper for £110, but he cannot guarantee that this will fix the problem as the current one looks fine in his opinion. So not to sure what to do apart from order a new caliper?

They seem a good bunch and I have used them for many years so I am in no doubt that they are being honest and thorough, its just really annoying not knowing what is going on

dalin80 · 4 Jul 2007 at 18:19

that is a tricky situation.

hoses both metal and flexi can develop restrictions you cant see from the outside and heat can effect a piston when in use rather then just apart in a workshop.

i too would probably recommend a new calliper but it is pretty much guess work.

might be worth slapping a brake hose in as well.

Foghorn Leghorn · 4 Jul 2007 at 18:36

I'm not sure about the brakes on an MX-5, but most regular cars use a single piston floating caliper design. The problem is usually the guide pins seize up and the caliper jams in one position. The easiest way to see whch wheel is doing it is driving for a few minutes then stop and feel each wheel in turn, if you have one that is noticably hotter than the others then this is the one binding. (although you already know by the smoke :eek:

).

Chances are that everything had cooled down and freed up again by the time the mechanic had a look.

Fog

Foghorn Leghorn · 4 Jul 2007 at 18:41

mark66 said:
The car has been back in the garage today and the mechanic has done a complete strip down of the brake unit and still can't find anything wrong, which has been really bugging him. He says that the pads slide beautifully in their slots, that the piston is clean and unmarked and he has also drained the fluids as he thought a line may have collapsed. However their braking machine is still detecting a drag on the left side. He seemed genuinely annoyed that he couldn't locate the problem and give me some definite answers. His suggestion is now to replace the caliper for £110, but he cannot guarantee that this will fix the problem as the current one looks fine in his opinion. So not to sure what to do apart from order a new caliper?

Sorry hadn't read your post properly, sounds like a good bloke who knows what he's doing and more importantly from what you have posted he seems thorough and actually gives a toss.

Rather than buy a standard caliper is it time to upgrade to big discs and better calipers while you're at it ?

Fog

mark66 · 5 Jul 2007 at 14:20

Just had a thought.....is there any chance that the problem could be caused by me having low disks and pads on the rear? The mechanic explained that the cars brake lines are distributed front left to rear right and front right to rear left. As my disks and pads on the front are new and therefore have less movement to travel before they contact the disk compared to the rears, I wondered if this could upset the balance in the bias?

dalin80 · 5 Jul 2007 at 16:47

shouldnt matter. as long as they are there and working. the pistons dont fully return after each use and the pads all round should be pretty much sat on the disc, if theres was room for free movement at any corner you would have a rubbish pedal.

BigglesPiP · 5 Jul 2007 at 17:12

mark66 said:
Just had a thought.....is there any chance that the problem could be caused by me having low disks and pads on the rear? The mechanic explained that the cars brake lines are distributed front left to rear right and front right to rear left. As my disks and pads on the front are new and therefore have less movement to travel before they contact the disk compared to the rears, I wondered if this could upset the balance in the bias?

No, brake callipers release such that the pads and disks are still almost touching.

Otherwise the pedal would be really really really long on worn out pads and disks.