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Brake problem
https://www.ausmini.com/forums/viewtopic.php?f=2&t=89069		 Page 1 of 2
Author:  Tassie [ Sun Apr 05, 2015 4:18 pm ]
Post subject:  Brake problem
Hi all

I'm just sorting out some issues with my newly acquired mini, and would appreciate the wisdom of the forum.

Previous owner has fitted 7.5 discs, with no booster.

Brake performance is terrible, no matter how much pedal pressure is applied - no chance of locking front wheels. Hand brake is also mostly in effectual.

So I am thinking that either the rear drums are way out of adjustment and limiting performance or perhaps the master cylinder could be playing up.

Does anyone have any ideas or suggestions?

Thanks Glen
Author:  simon k [ Sun Apr 05, 2015 4:23 pm ]
Post subject:  Re: Brake problem
start with the rear adjustment - at least it won't cost you anything and will eliminate it

can you pump up a good pedal and hold it?
Author:  Morris 1100 [ Sun Apr 05, 2015 6:04 pm ]
Post subject:  Re: Brake problem
I would try some better brake pads, it sounds like it has the old style hard pads.
Author:  1071 S [ Sun Apr 05, 2015 6:21 pm ]
Post subject:  Re: Brake problem
I would be checking inside the drums for spilt fluid.... If the pedal doesn't go to the floor then adjustment is not going to do much for you.

Years ago I finally got pinged for an ineffective handbrake during the rego check. The handle and shoes were adjusted up tight but you still couldn't lock the rear wheels. That's when I found out that the handbrake quadrants (little pivoting bits attached to the from of the trailing arms) are asymmetric. If you put them on upside down they jam against trailing arm before applying full tension to the brake mechanism....

I also believe that the booster is well worth while.

Cheers, Ian
Author:  Phil 850 [ Sun Apr 05, 2015 8:17 pm ]
Post subject:  Re: Brake problem
1071 S wrote:
I would be checking inside the drums for spilt fluid.... If the pedal doesn't go to the floor then adjustment is not going to do much for you.

Years ago I finally got pinged for an ineffective handbrake during the rego check. The handle and shoes were adjusted up tight but you still couldn't lock the rear wheels. That's when I found out that the handbrake quadrants (little pivoting bits attached to the from of the trailing arms) are asymmetric. If you put them on upside down they jam against trailing arm before applying full tension to the brake mechanism....

I also believe that the booster is well worth while.

Cheers, Ian


I had a similar problem, but the quadrants were around the right way. :| Turned out the handbrake mechanism was worn so I replaced it, adjusted the shoes up to just scrape the drums (stomp on the brakes a few times to centralise the shoes and adjust again) and then adjusted the cables at the handbake lever in the car. Now they work perfectly. :D
I also replaced 8.4"discs with 7 1/2" and they do require a fair bit of pedal pressure but it does stop well.
Author:  Tassie [ Mon Apr 06, 2015 7:48 am ]
Post subject:  Re: Brake problem
Thanks for the suggestions guys, I will have a play and let you know what I find.
Author:  deluxe67 [ Tue Apr 07, 2015 10:29 am ]
Post subject:  Re: Brake problem
Check that the rear flexible brake lines haven't perished internally and closed up. May want to check caliper pistons aren't seized.

Edit: Check ALL flexible brake lines. Unboosted Cooper S brakes should be very effective. I believe the race cars are normally unboosted? If your brake hoses are blocked, no amount of pedal pressure will give good braking....
Author:  AWOODY [ Tue Apr 07, 2015 3:39 pm ]
Post subject:  Re: Brake problem
Check the calipers as well I thought mine were working had a spare pair so I got them recoed and replaced the ones on the car and it made a huge difference.
Author:  doogie [ Tue Apr 07, 2015 3:53 pm ]
Post subject:  Re: Brake problem
Check and replace all rubber flexible lines, check to see it has the right rear wheel cylinders fitted.

Doogie
Author:  Tassie [ Wed Apr 22, 2015 9:23 pm ]
Post subject:  Re: Brake problem
Hi all, a bit of an update...

Rear drums were way out of adjustment. Now have them adjusted up nice and close.
Front callipers and pads removed and cleaned with brake cleaner. Plenty of disc pad thickness left.
System bled. Hoses appear visually ok.

Test drive reveals some improvement, but I have no doubt they won't pass roadworthy.
After test drive, the discs were quite hot to touch and pads/discs look almost shiny.

Does the disc temperature indicate poor pad performance or should I just bite the bullet and replace hoses, master and pads?

Many thanks
Glen
Author:  deluxe67 [ Wed Apr 22, 2015 9:31 pm ]
Post subject:  Re: Brake problem
Don't be misled by the outer appearance of brake hoses. You need to know if they're passing fluid....
Author:  boomini [ Wed Apr 22, 2015 11:40 pm ]
Post subject:  Re: Brake problem
Change the pads mate. They are glazed... probably been cooked a few times in the past. Thay are not that expensive.

Ideally get green stuff pads
Author:  drmini in aust [ Thu Apr 23, 2015 8:08 am ]
Post subject:  Re: Brake problem
EBC Greenstuff pads are good.
Blackstuff pads have better bite when cold but fade much sooner when pushed. Good in traffic, but not for sporty driving in the hills. I managed to totally fade them on both Kurrajong hill, and Mt Keira, without trying hard.

After many years, I finally fitted a VH44J servo under the dash. Braking with greenstuff pads now is like a modern car. 8)
Author:  Mick [ Thu Apr 23, 2015 10:03 am ]
Post subject:  Re: Brake problem
Nothing wrong with changing the pads and hoses out. The pads are easy, and are amazingly cheap given the return. Also next to no dust with the new pads and no asbestos with performance in a basic pad we only dreamed about 20 years ago from a street pad. We are these days very lucky.

Replacing hoses takes a little longer, but have a big effect on the braking as others have said. I wouldn't think about it myself, I would dive in and replace these two items.
Author:  Besser [ Thu Apr 23, 2015 12:59 pm ]
Post subject:  Re: Brake problem
Whenever I service my brakes I always deglaze the pads/shoes. Pads I rub on the concrete drive and shoes I rub with 40 grit abrasive. Remove all the dust, adjust the handbrake and centralise the shoes. I now also get ready for the lockup on first application as the fresh shoes surface bite big time.

Take the pads out and rub them on the concrete (in a figure 8 path) till the "slick surface" is a white/grey matt finish, you'll be amazed with the grip increase.
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