11 replies to this topic

[Daze]

Hi everyone.

I'm almost complete on building my Milglia-looking race/road/track Mini and I'm just having a few issues with the brakes.

My setup is as follows: KAD 4 pots on front, 7.5" vented discs, yellow-tag front/rear split master cylinder, NO pressure valve, Wilwood rear bias valve, standard rear set-up. Brake pipes are all brand new, no leaks as I can see... Everything on the car is brand new and never been driven yet.

I've bled the system through a few times and I'm not getting any bubbles through now... But, I still have a huge amount of pedal travel before anything happens. The rear's are adjusted and handbrake is OK.

I was searching/reading on these forums and read that people were saying "make sure the calipers are the right way around". Is this possible with KAD's? If so - would this cause my lack of pedal?

I don't really want to come the hassle of taking the calipers both off again to find they don't fit the other way around!

Ta!

[Daze]

Oh, and I don't have a servo. I'm running on the tandem brake m/cylinder with two unions for front & rear. And, the one with the yellow-tag, as per Mini Spares website says top union is for front system. Could this be wrong...?

[MRA]

Bleed nipples to the top

[pogie]

As mra said, make sure the bleed nipples are at the top of the calipers. If they are not you have them fitted to the wrong side and any air trapped in the top of the calipers cannot escape.

I've got Minispares alloy 4 pots and they also were a right sod to bleed. I had a search and Keith Calver recommended the following to help remove air trapped in the piston bores.

Remove one pad at a time and put a thin spacer in its place (I used a piece of 3mm flat bar),
Pump the peddle until the pistons have pushed the spacer against the disk,
Remove the spacer and the small gap left leaves you enough room to get a pry-bar / large screw in to push the pistons back into the caliper,
Replace the pad,
Repeat for the other 3 pairs of pistons.

When I had finished, the peddle was much better and after another round of bleeding it was spot on. HTH

Edited by pogie, 10 April 2009 - 02:43 PM.

[Daze]

Right, cool that's all fair. Thanks for the advise - but one small detail.. The KAD calipers have two bleed nipples - one top & one bottom. I contacted KAD yesterday and asked them about the bleeding process and they said to near-enough not worry about the bottom nipple.

But, however, this doesn't solve the problem that my calipers still might be the wrong way around. They do look very similar though, perhaps a universal fit?

Interesting suggestion regarding what Keith said though. I might try that - thanks. Thinking about it - could my pads be incorrect? There does seem to be a lot of space between pad/caliper and pad/disc (about 8-10mm). I am using Green Stuff's, ordered from KAD themselves...

[blacktulip]

do the rears too, we had this problem once, we had to bleed the rears.

[Ethel]

Pads shouldn't make any difference the pistons should just push out until they hit the pads then stay there. The bleed nipples should be at the top to let air out. I'd guess KAD use the same casting for both sides with a communication port across the top and bottom. whichever ends up on the bottom will carry fluid and the top one will get a bleed screw to let the air out.

You can let the pistons be pushed out of the calipers (not fully!) then push them home with the bleed nipple open to exclude the air. It's sometimes necessary to bleed the connections on the master cylinder - Mini style vertical cylinders a good at trapping air. The cylinder is connected properly - big bore on the bottom connected to rear brakes to help with pedal travel: little bore on top to the front to give better line pressure to help you stop.

[01smartc]

Ok kinda on topic... ive got KAD 4 pots aswell... having trouble bleeding/stopping also.

Ive got kit car style master cylinders one for the back one for the front. But im not sure which way round they go!

One is 0.7" bore and the other 0.625" bore. Which way round they go?

Chris

[MRA]

There does seem to be a lot of space between pad/caliper and pad/disc (about 8-10mm).

Have you got solid or vented discs ?.............. the pistons pushed all the way "home" should just allow for the pads to be fitted 1 or 2mm at the most it would appear to me that what you actually have is solid discs and callipers for vented discs !!!

Take some measurements and get back to KAD for their advice.

[rosco454]

It says vented discs in the first post but that does seem like a very large gap,solid discs is what popped into my head as well.

[nicksuth]

For the rears (assuming standard drums?), take the drum off and put a G Clamp over the pistons so they are completly back in all the way, this ensure no air in the cylinders, then bleed with the clamps on?

Do you have any long runs of flexible brake pipe (i.e. aeroquip type hose)? If you have and it is not fixed at regular intervals you can get "kick" in the hose when pressurised which reduces the amount of pressure achieved at the cylinders?

Just a thought?????

[Daze]

Thanks to everyone for their suggestions!

I've now managed to sort it. I bled the system a few times through and kept getting bits of air through. One major thing that I think I might have done wrong - I ran out of fluid in the m/cylinder then said "DOWN" again to my friendly assistant (girlfriend!), of course which sucked in the air! My bad!....

Anyway, nice solid pedal now - works well!