Bleeding minisport 4 pots?
Turbo Mini Forums

Does anyone else on here run the minisport 4 pot alloy callipers?

Have been round antons all weekend removing his front drums and fitting brand spanking new minishite 4 pots.

trouble is after putting 3 litres of brake fluid throught eh system we still cant get a decent pedal. There's a fair bit of resistance and they *do* stop you but the pedal still hits the floor. the back wheels will lock up if you stamp the pedal but the fronts dont.

Anyone got any ideas what could be causing it?

we're thinking it could be air trapped in the callipers as they only have one bleed nipple on them, so air could be trapped on the opposite side.
to try and get round this we've had the callipers off and shook em about/hit em with hammers etc to try and get any trapped air to move.

hands are stinging from all the brake fluid now and he needs the car so his mrs can go to work tomorrow.

Cheers, Nick (bud666) :)

Got a set of these things on mine..!

Not to point out the obvious but have you got them the right way up. Bleed nipples at the top.!

An easy bleed kit works well using tyre pressure to force the fluid through but dont go to mental with the tyre pressure.

Also check what rear brake cylinders bore type. you can get a big inbalance between front and rear. eg backs doing the work instead of the fronts.

i also fitted a bias valve to help out to.

hope thats of some help.

I drill holes in everything..!

yeah they're the right way up, and we've been using the easybleed aswell as the the old fashioned manual way (which has given us better results surprisingly)
We've also cracked off each brake pipe union from the master to the callipers to try and get any air pockets in the pipes.

the rear cylinder bore is the only avenue we've got left to try now, but would having the wrong ones cause the pedal to be spongy? i know it'd transfer more effort to the rears and show up when driving but would it have any effect on pedal pressure?

Cheers, nick )

Edited by Anton on 25th Jun, 2006.

What else do you have in the system.

e.g servo, brake limiting valve.( which i binned)

Does the pedal pump up ok. then go soft. If so i could be bleed back through the mastercylinder.

Regards to rear cylinders easy check is to put the backup in the air and see if the rears lock up under light pedal pressure if so its cylinder bore dia your problem. Changing mine made a massive difference.

Also check keith carvers minispares tech about brake combinations. It gives the correct rear cylinders and part numbers to use.

After that lot i'm out...!

I drill holes in everything..!

Calver also gives an interesting method for bleeding these. It should be on his website, or on the minispares forum thing.

I have not read it in detail but it follows the lines of letting the pistons come out of the caliper a fair way before bleeding.

Might be worth checking that out.

Yes I'd also try that, I have known in the past 4 pot calipers not bleed up properly because when the pistons were fully pushed in the fluid transfer ports were blocked.

well we decided to try the gravity bleeding method earlier. opened the bleed nipple on each calliper (yes, just one bleed nipple on them!) then let them drip for about an hour while we went for pizza.
Ant just took it round the block before i left and said they're a bit better, you really have to press hard now to get the pedal to bottom out.

Will get him to give the way you chaps describe a go if they dont come up any more.

Cheers dudes :)

Thats still not very good is it, I know Nic had problems along these lines that I think he never got to the bottom of?

I'd try bleeding them with some dummy pads made out of thin plywood/MDF so that the pistons are pushed quite a long way out, when you are happy you have bled them OK then slowly push the pistons back into the caliper.

I had the same problem this weekend with some KAD callipers, still not sorted it yet

Team Racing

you could try wedging the pedal down over night and cracking off the nipples...

with suitable arangements for leaks.

Air will rise after all.

Alex

AlexF

i've had problems in the past bleeding brakes but not any more. i found the best thing is to bleed as normal and when you only get a low peddle chock it down as hard as possible, leave for a few hours or over night and try them out. this always seems to work for me.

Just a thought.

If you have changed from front drums to 4 pot discs, your master cylinder PROBABLY needs to move a lot more fluid.

Do you need to change the master cylinder as well, or are they all the same anyway?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

right, bit of an update on the brakes.

Ant's now changed the rear cylinders to the smaller bore cooper S/1275gt type that are recommended by calver. also fitted braided rear hoses, so there's no rubber hoses to balloon now.

Pedal feel hasn't changed much, but the brakes are a lot better, fronts lock up before the back now.

The one major thing we've noticed though is that the calliper seems to be swelling when you hold the pedal down. We set the DTI up on the drive flange and the calliper moves out towards the edge of the flange by 0.5mm. all the bolts are done up FT, the calliper doesn't look to be flexing on its 2 mounting bolts, it 's like the whole thing is expanding outwards.....Is this normal???

other than that ant says the brakes are fine for day to day driving but if you're coming to a corner fast and go hard on the brakes they just dont feel right, as if they should be slowing you down more for how far you've pushed the pedal and the pressure exerted.



The cars running the black tag master cylinder, which has a much bigger body size compared to my yellow tag from a later car...but will the bore size be different between the 2, and would it make any difference?

Cheers for reading if you've got this far

Nick and Ant.

forgot to add that we've tried the calver bleeding method aswell with no joy :(

Wouldnt the calpier ballooning or moving suggest that this s caused by the pressure from the pipe, so theres a blockage some were?
When the calpier balloons is the pipe from the subframe moving much?
When my four pots wouldnt bleed right i took them off in the end and put some compressed air through to see if the pistons moved!maybe thats worth ago!
Although i may also be talking a load of crap! u decide!

martin

have yoy adjusted the rear braks?
i had to and iv herd of people adjusting them so that there a little bit tighter than you usally would have them if you know what i mean!?
iv got the minispares 4 pots for 10" wheels.
it also made a bit of differnce when i changed from green stuff pads to black stuff.
i also had proplems bleeding them and still occasionly have to pump the pedal slightly, but it never goes to the floor anymore.
mine have 2 bleed nipples though.
hope this helps a bit.

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

I have heard that the minisport calipers flex quite a bit, it may be what you are seeing? I have the minispares 4 pots, and my pedal are a bit lower with these than with the S calipers I suspect, but my pedal is consistant and the brakes are good (with the correct pads!).

well the green stuff felt shit and didnt work untill they got them hot and i mean HOT. the only time i locked the wheels up with them was at donninton park at a trackday!
black stuff are good from cold but i guess there not as good whaen there hot!
the pedal felt good when braking hard and fast with the green stuff but you had to pump it more when going slowly. were as the black stuff fell better all the time.
not sure wether everyone finds this when changing pads but could be worth a go if you have green stuff unless its a full blown trackday car etc.
i also have the rubber hoses which i need to change (which i will when turbo lump goes in!!)

another thing that you could think about is the wheel bearings as mine went and the brkes were spongy but didnt have any air in! i no its a long shot but worth wobbling the wheels about just to eliminate that proplem!

hope you find the proplem soon mate.
good luck
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

i got so pissed off with my 4th set of ultrashite minispares calipers i swapped them for a broken a+ engine and a hand chucking my engine back in

O/T who makes the best type of 4 pots? I will be getting a set of either 7.5 or 7.9 if they fit under my wheels.

Which manufactuer makes the best ones that work the best and can be bled easy ha ha.

Manchester Minis

apparently KAD's are the best ones to get.....I wouldn't touch the minisport ones with a shitty stick personally after experiencing ant's.

odd, my minispares calipers are awesome

Team Racing

Which calver bleeding method have you tried? The one where you pump the pistons out with the nipple closed and then push the pistons back into the caliper with the nipple open to force out air???

If the caliper is swelling that suggests that summats up with the caliper surely?

Personally i never use minisport anymore as they constantly lie about products (for example genuine layshafts being anything but genuine or genuine quality) and produce unsafe products (such as calipers with holes in the cavities).

I've seen the future and tbh its Pie