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SP250 Brakes Double Pump

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daimlernorm
Posts: 12
Joined: Tue May 02, 2017 5:48 pm
Location: Preston Lancs England

SP250 Brakes Double Pump

Post by daimlernorm » Mon Apr 08, 2019 8:27 pm

I have recently completed the refurbishment of my Brake Callipers & Brake Master Cylinder, however
when driving the Dart I notice when you press the brake pedal it goes down quite a way but if you lift your foot and brake again brake pedal is solid so not sure why.....
I have bled the brakes a few times without any change.
I am thinking maybe a fault in one of the brake hoses, has any member thoughts or anyone else experienced this braking problem.

Cheers

Norm

Sydsmith
Posts: 743
Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: SP250 Brakes Double Pump

Post by Sydsmith » Mon Apr 08, 2019 9:16 pm

Ah Ha! the ubiquitous SP250 double pump. Norm this was discussed in depth several times on the old forum with several theories and solutions suggested over the years. Sadly it is a feature of the system and it is sirprising how quickly you get used to a double pump when on the road.

There are solutions but most involve changing the master cylinder and slave cylinder.

One thing that makes it worse is incorrectly set up wheel bearings and incorrect positioning of the calipers especially on the front, it is essential to set them both up as per the manual.

Go into the old forum and search SP250 foot brake double pump.

Hope that helps Syd

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#100910
Posts: 34
Joined: Sat Feb 13, 2016 2:32 pm
Location: Austin, Texas

Re: SP250 Brakes Double Pump

Post by #100910 » Tue Apr 09, 2019 3:40 pm


wejxf03
Posts: 50
Joined: Wed Mar 09, 2016 7:36 pm
Location: Kent UK

Re: SP250 Brakes Double Pump

Post by wejxf03 » Tue Apr 09, 2019 8:55 pm

I had the double pump on my Dart until I carefully set up the brake calipers to be absolutely parallel using shims between the hub and caliper.
Worked perfectly after that.
John Foskett
Kent UK
SP250 B spec.

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Vortex O'Plinth
Posts: 771
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: SP250 Brakes Double Pump

Post by Vortex O'Plinth » Tue Apr 09, 2019 10:03 pm

wejxf03 wrote:
Tue Apr 09, 2019 8:55 pm
I had the double pump on my Dart until I carefully set up the brake calipers to be absolutely parallel using shims between the hub and caliper.
Worked perfectly after that.
Just out of interest, what were they parallel to?
Nick

Pas d'elle yeux Rhône que nous.

Ian Slade
Posts: 421
Joined: Sat Feb 13, 2016 9:54 am
Location: Akrotiri Cyprus

Re: SP250 Brakes Double Pump

Post by Ian Slade » Wed Apr 10, 2019 10:25 am

The only time you would need a double pump on the road is if there is something wrong with the bearings, rear axle or caliper alignment, competition possibly as more torque is applied to the rear axle causing the axle tubes to distort and the disc becomes misaligned with the caliper. I fitted new rear axles to both my cars at the same time, a club special order in 1971 and never had the problem again either on the road or in competition., for some reason it has been accepted as a standard feature, it isn't.
Owner since the 70's, Genghis is slightly to my left.

wejxf03
Posts: 50
Joined: Wed Mar 09, 2016 7:36 pm
Location: Kent UK

Re: SP250 Brakes Double Pump

Post by wejxf03 » Wed Apr 10, 2019 12:47 pm

Vortex O'Plinth wrote:
Tue Apr 09, 2019 10:03 pm
wejxf03 wrote:
Tue Apr 09, 2019 8:55 pm
I had the double pump on my Dart until I carefully set up the brake calipers to be absolutely parallel using shims between the hub and caliper.
Worked perfectly after that.
Just out of interest, what were they parallel to?
Pads parallel to discs
John Foskett
Kent UK
SP250 B spec.

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