8 replies to this topic

[mini1976]

Right my breaks have stopped working, when breaking the pedal has started traveling further than it used to and can be pushed all the what to the floor without aloth of force. So i went and bought some break fluid and topped it up as it had gone down (which i know means it must be leaking). I topped it up and spilt a little so went and got a rag wiped it up and gave a general wipe round the master cylinder. When I did this i saw that on the reservoir it says to use DOT 3 break fluid but ive put in DOT 4. Whats the difference? Is the DOT 4 going to nacker the seals in my break system?

As far as working out what up with my breaks im going to remove the drums and chack for leaks. What are the syptoms like if the master cylinder goes? Finaly if its the calipers that are leaking where would you see the leak? Will i need to remove the pads and look at the calipers?

[Dan]

It means DOT3 is the minimum spec. Dot fluids are backwards compatible (except DOT5.1 synthetic which must not be mixed with mineral fluids). DOT4 and DOT3 will mix without major problems, but it seems like you'll be pumping all the DOT3 out soon anyhow when you overhaul your brakes.

[mini1976]

Thanks for that, I just had no idea what the dot classification ment. I read both bottles before i bought them and they seams almost identical in what it said on the bottle. So am i right in saying that the lower the dot number the lower the properties of the fluid are. For example dot 3 has a lower boiling point than dot 4

[blacktulip]

if you press the pedal and the pressure slowly deminishes but press a few times in succession and it works then it could well be the master cylinder letting by, my clutch master cylinder went last week and its as good as gold since replacing it, other than that the leaks should be visible upon inspection. by the way if your having to top up the fluid u must be loosing it (leaking) :'(

[mini1976]

Ive found the leak, back brake cylinders, just was obviouse untill it was all in bits as the brake dust has soaked up all the leaking oil. What size spanner will i need to get the break pipes of the cylinder. I only have metric and its smaller that a 11mm but bigger that a 10mm. Am i right in thinking thats a 7/16ths as I will have to buy one as my set only has metric spanners and obviously my metric sockets arent much use on a brake pipe. Come to think of it i find my socket set pretty rubbish in general on my mini, there is never room to get the rachet in so I guess minis were around before socket sets?

[Dan]

No of course they weren't! You need a proper socket set with proper long extensions and universal joints and wobble extenions and good pear headed ratchets. A small emergency toolkit set won't cut it.

You should get a flarenut spanner for your brakes, Halfords do them. You need 7/16 and 9/16 sizes for the brakes and a couple of metric ones for the master cylinder. They may not have imperial sized ones in Halfords, I can't remember off the top of my head.

[mini1976]

Out of interest whats a wobble extension and pear headed ratchets Ive got one of these socket sets (Click) which I thought was pretty extensive but I have never heard of those two.

[Dan]

That set should get you just about everywhere on a Mini. It has pear headed ratchets (the head of the ratchet isn't a huge round thing, it's the slimest shape it can be while retaining its strength). Wobble extensions are extension rods which have the drive square on the end shaped to allow some angular movement of the socket meaning you can be out of alignment a little. Get a couple of extra wobble extensions and you'll be alright with that set. Halfords do make and sell them but for some reason not in their large sets, only individually. Get some ratchet spanners too.

[mini1976]

Yeah there are a couple of ratchet ring spanners in the set but I have no idea how they chose the sizes and predictably there never seams to be the one you want. Thanks for all your help