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Home > Technical Chat > Reducing rear braking performance.

minimole23

4299 Posts
Member #: 1321
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Wiltshire

With a light back end, despite binning the standard brake limiter and fitting an adjustable one my car still has the tendency to want to lock the rears.

Would changing the rear wheel cylinders to increase pedal effort be the 1st port of call, or should I be investigating other issues first?

Regards

James

Edited by minimole23 on 12th Jun, 2017.

On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding


05bwardl

149 Posts
Member #: 9991
Advanced Member

lichfield ,staffordshire

bigger bore cylinders on the rear should help i would think


Joe C

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12307 Posts
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Carlos Fandango

Burnham-on-Crouch, Essex

3/4 cylinders should be std fitment on anything after the early 70s I think, that's the largest.

On 28th Aug, 2011 Kean said:
At the risk of being sigged...

Joe, do you have a photo of your tool?



http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1

https://joe1977.imgbb.com/



minimole23

4299 Posts
Member #: 1321
Post Whore

Wiltshire

Hmmm, I did change them 10 years ago, but they're just what the parts guy gave me, so maybe worth a shot. well, after a measure.

Edited by minimole23 on 12th Jun, 2017.

On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding


miniminor63

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1849 Posts
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The oversills police

Oslo, Norway

Small rears gives less rear brakes. 1/2" is the smalest.


Sprocket

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Preston On The Brook

Yeh, you need smaller bore cylinders on the rear to reduce the braking effort.

I've got the 1/2" cylinders on the rear with the standard limiting valve and you can turn the rear wheels by hand when the brakes are applied hard

On 26th Oct, 2004 TurboDave16v said:
Is it A-Series only? I think it should be...
So when some joey comes on here about how his 16v turbo vauxhall is great compared to ours, he can be given the 'bird'...


On 26th Oct, 2004 Tom Fenton said:
Yep I agree with TD........


Joe C

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Carlos Fandango

Burnham-on-Crouch, Essex

doh i was thinkingi t was the other way, brain fart!

think I'll check whats in mine at some point.

On 28th Aug, 2011 Kean said:
At the risk of being sigged...

Joe, do you have a photo of your tool?



http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1

https://joe1977.imgbb.com/



jamiestevenbell

336 Posts
Member #: 9941
Senior Member

Derby

I don't know if it's technically the best way to do it but can't you just slacken the rear adjusters off on the drums a little?


Tom Fenton
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15300 Posts
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Fearless Tom Fenton, Avon Park 2007 & 2008 class D winner

&

TM legend.

Rotherham South Yorkshire

All that will achieve is a longer pedal.


On 29th Nov, 2016 madmk1 said:


On 28th Nov, 2016 Rob Gavin said:
I refuse to pay for anything else


Like fuel 😂😂


stevieturbo

3569 Posts
Member #: 655
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Northern Ireland

Are all bias valves the same ? Which one have you fitted ?

9.85 @ 145mph
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speed didn't kill me, but taxation probably will


wil_h

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Betwix Harrogate and York

What master cylinder are you using? Single or twin?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

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On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


minimole23

4299 Posts
Member #: 1321
Post Whore

Wiltshire

Useful suggestions. Seems worth changing the rear wheel cylinders.

Steve, its an unbranded one, and was an improvement, but not quite enough.

Will, its a 1988 Twin Master cylinder.

On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding


minimole23

4299 Posts
Member #: 1321
Post Whore

Wiltshire

Dp

Edited by minimole23 on 13th Jun, 2017.

On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding


wil_h

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9258 Posts
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Betwix Harrogate and York

I've never had an issue with locking rears with the same setup you have.

But my car was maybe heavier art the rear, full subframe and I was sat as far back as possible.

Have you filed the leading edge of the shoes? is there any contamination in the drums? Are the hand brake levers free?

These are thing that have caused locking for me in the past; rather than an system issue.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


minimole23

4299 Posts
Member #: 1321
Post Whore

Wiltshire

I may change the brake backplates as they are not straight which won't help. Also handbrake levers are free and everything is contaminant free as went over it all the other weekend.

The rear fact I can almost pick the back up probably doesn't help with the locking.

On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding


Mirage

538 Posts
Member #: 119
Post Whore

Staffordshire or Northamptonshire

I would go with smaller slave cylinders.

Ive been looking into proportioning valves of late and they can be a bit of a blunt tool. In my mind you cant make a one size fits all valve as even with adjustable ones you are stuck with the same spring rate in it. There is no tech information on how they behave.

So smaller rear cylinders are larger master cylinder ( if thats an option)


Turbo This..

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1767 Posts
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Previously josh4444

Australia, brisbane

perhaps the back is fine and the front isn't up to scratch ? no idea what the car is just an idea..

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