6 replies to this topic

[minijack67]

Hopefully not gonna open a can of worms, but looking for feedback on what people have used.
Just putting 7.5” minisport 4 pots on single line brake system - no brake servo.
Used 5/8 rear wheel cylinders on the rear. System well bled but peddle still soft/long travel.
Rears adjusted so they just bind. Any tips? Thank you

[sonscar]

Have you altered the total piston and wheel cylinder area from the original area?It is possible the master cylinder now has to move more fluid.Just a thought.Braking systems are both very simple and very complex at the same time.Steve..

[r.tec]

Yes, same with me. Followed the procedure someone of the German Mini-Forum suggested and worked fine.

 

Press brake pedal to push the pistons out. Ideally someone keeps the pedal down. Open valve. Push the outer pistons manually back in. Close valve. Let helper push outer pistons back out. Open valve. Push it again in. Repeat this several times on both sides.

 

Seemed to me that there is an air lock in the region of the outer pistons.

 

This helped me to get back a firm pedal.

 

Nearly forgot: always keep an eye on the brake fluid level in the master cylinder!

Edited by r.tec, 12 March 2022 - 04:45 PM.

[imack]

7.9" KAD 4 pots here, but I think all the after market 4 pots use metro turbo sized pistons. I'm running factory (1972) single circuit master cylinder and 5/8" rear cylinders, no servo and have minimal pedal travel.

[Spider]

Often with new calipers, as they may have sat around for a while (obviously without fluid), the rubber seals end up gripping the pistons dry and so cause them to stick rather than slide as they should. The fluid also acts as a lubricant.

If you remove one brake pad at a time, then slip in a piece of wood to hold one of the 2 exposed pistons, pump the brake pedal a few times to move one piston out say 6 mm, push it back in and then move on to the next until all 8 pistons have been done this way, they'll wet up the seals and allow the pistons to sit as they naturally will.

 

I've run with a few sets of the Mini Spares 4 pots on 8.4's and found them very good. I have a set of KADs to try.

[pogie]

I replied to a similar thread a while ago  . https://www.theminif...ing-new-system/

 

My reply - 

 

"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"

[mini13]

personally I would pull all the pads and pump all the pistons out at once, you'll need to find more spacers, but at least you'll check that there's no chance of running out of fluid  when the pads wear.