I recently overhauled my 7.5" disks and callipers with new S/S pistons and seals etc. At the rear was new slave cylinders. A new MK3 Lockheed brake booster completed the rebuild.

The system was both power and vacuum bled (have both systems), rear shoes adjusted.

Problem: I have to do a very quick pump of the brake pedal to get full pedal height. The brakes are not spongy though.

Anyway cruising the internet for some possible cure to my problem, I came across several reports of the need to exercise the calliper seals, by exerting a pressure on the brake pedal for a period of time.

Not having one of those devices you see wheel alignment specialist use to apply pressure to to the brakes
I used a axle stand wedged between the brake pedal and seat.

Skipping forward by around 11 hours, the brake pedal is now very high. In my garage rocking the car back and forth, I could brake it by just the movement in my big toe (the Jim test!).

Road test proved a huge change in feel, I now have to get out of the habit of pumping the pedal as it is not needed.

Hopefully time will tell if this fix sticks.

Jim

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'68 Morris Mini 1310 A+ (Now Sold!)

I was thinking it might be a dodgy seal, didn't realise you could fix them by holding pressure in the system - that's handy

my solution to holding the pedal down is a bit of allthread in some RHS, but that tool is nifty, might have to make one next time I need to bleed something

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did I tell you that I won a trophy?

I have the same problem, I will be trying this

Another thing I found re rear wheel cylinder bleeding is its best to slacken the adjuster right off so it moves the trapped air closer to the bleed nipple by virtue of the cylinder moving closer to the nipple.


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'68 Morris Mini 1310 A+ (Now Sold!)

So your saying just to keep pressure on the brake pedal for a few hours and that fixes the pump the pedal problem ?

Did you use caliper assembly lube?

Yes i used lube.

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'68 Morris Mini 1310 A+ (Now Sold!)

Yep. It did for me.



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'68 Morris Mini 1310 A+ (Now Sold!)

I found this motorbike thread on the same subject http://www.southbayriders.com/forums/threads/120967/

The reply from a RobertHass I think hits the nail on the head.


All I can say is it made my brakes better. I've rebuilt both drum and disk brakes on Mini's and MGB's and to my recollection this is the best feel and pedal height I've had.

Edit: If you read all of the thread as per above, you will see it turns into a bit of chest beating and mental masturbation. I guess I will never really know what the science is behind this.

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'68 Morris Mini 1310 A+ (Now Sold!)

Very interesting

https://www.youtube.com/watch?v=krD4hdGvGHM

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"Show me the Mini!"

Yes, very interesting!

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'68 Morris Mini 1310 A+ (Now Sold!)

I was thinking of buying a brake/clutch jack tool like the previous image I posted, when I had an epiphany.

I had left over a 24" 600mm Craftright quick action clamp https://www.bunnings.com.au/craftright-600mm-2-piece-quick-action-clamp_p5860152 which work very well. I would put some rubber padding on the end that presses against the steering wheel, as to not mark it. Not bad for $20 (for 2, give one to a mate), and available at my favourite hardware store, Bunnings. You could also put a rubber stopper on the end that pushes against the pedal.

Looks like this:

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'68 Morris Mini 1310 A+ (Now Sold!)

Great idea.

Could you take both pieces off the bar, reverse them and then put them back? That way you have nice rubber pads pushing against the brake pedal and steering wheel (or whatever else you use for the anchor point).

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Yes you can reverse them. I just did this to a spare, just involves removing a scroll pin on end, reversing the quick grip, and undoing the end one and reversing it. Wha la you will have this:


It shall hence forth be known as: Jim's Brake/Clutch Jack Tool or just Tool #181!

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'68 Morris Mini 1310 A+ (Now Sold!)

I've used an adjustable steering wheel lock that were popular some years ago as a theft prevention device. Put it between the brake pedal and the steering wheel to lock the front brakes in order to free off a stubborn CV hub nut. Just make sure you've got the key to unlock it afterwards.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)