 | Home > Maintenance & Modifications > Brakes! Or lack of…. |
 
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| miker Member Since: 13 Sep 2015 Location: Surrey Posts: 1784   
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Is there a difference between 90 and 110 master cylinders normally?
It kind of sounds like you may have a lot more slave cylinder capacity (bigger 100 calipers and 6 pot fronts) but no more fluid being pushed to them.... Just a theory mind you. |
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19th Jul 2025 10:13pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5979 
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Can you manually bleed them?
Are you able to get fluid out of bleed? What does pedal feel like, any resistance? Have you adjusted the brake actuator rod? Are your wheel bearings all spot on? Last edited by landy andy on 20th Jul 2025 6:19am. Edited 2 times in total |
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20th Jul 2025 2:36am |
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| jim4244 Member Since: 13 Apr 2014 Location: Bedfordshire Posts: 976  
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Hi
Have you checked the seals in the slave cylinder? Jim |
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20th Jul 2025 4:25am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8331  
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Insufficient travel in master cylinder. Increase pedal stroke. Will need to displace fair amount of fluid to push all pistons in.
How are you bleeding it? Pressure kit? Cheers James 110 2010 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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20th Jul 2025 7:30am |
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| rich_allen Member Since: 10 Jun 2016 Location: Rutland Posts: 21 
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I did wonder this but even if this was the case surely I’d have some sort of pedal? |
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20th Jul 2025 12:57pm |
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| rich_allen Member Since: 10 Jun 2016 Location: Rutland Posts: 21
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Been using a pressure bleeder, fluid comes out the nipples lovely, just as you’d expect. I’ve probably flushed 2-3 litres through… Very little resistance on the pedal… a little but not a lot. Bearings all feel nice and tight. Haven’t touched the brake actuator rod, (what would I need to do to that, does that make a huge difference?) Cheers |
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20th Jul 2025 1:00pm |
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| rich_allen Member Since: 10 Jun 2016 Location: Rutland Posts: 21
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Yes, pressure kit, even with the amount of fluid needing to be pushed I would have thought id have some pedal.. I’m sure there are plenty out there with bigger brakes and normal master cylinder? |
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20th Jul 2025 1:02pm |
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5979
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If you manually bleed them, can you get a good squirt of fluid out?
That is what I would be trying for |
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20th Jul 2025 7:19pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8331
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I have uprated front 6 pot calipers. I would be checking your getting sufficient stroke from the mc to displace enough fluid.
But yes you should have something from any press. Try the manual bleed option. Calipers right way up? Nipple at top? Cheers James 110 2010 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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20th Jul 2025 10:18pm |
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| rich_allen Member Since: 10 Jun 2016 Location: Rutland Posts: 21
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Yes, calipers all correct, have been fitted for a few years… brakes have just got gradually worse over time to now being non existent..
Will try the manual bleed. Can anyone tell me how to check/adjust the actuator rod Thanks |
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21st Jul 2025 9:33am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17869 
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If you pump the pedal does it go hard?
Assuming you have no leaks then either the m/c doesn't displace enough fluid to apply the brakes, or the m/c is leaking internally and doesn't apply pressure the brake line. If the former, pumping the pedal should give you brakes, if the latter it won't. |
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21st Jul 2025 10:40am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8331
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check if you can get a pedal first and manual bleed it. unlikley to be rod now as you state that setup has been fitted for a while. so they were working with that caliper setup no problem then you got more and more pedal movement for less and less braking and now with brake pedal pressed all the way in the vehicle brakes are not applied? is that correct? assuming Yes, and confirm it was like that before MC was changed ? assuming yes to 2nd Q then with new MC fitted is made no difference? if you are not using fluid, its the same setup as before, its the same no pedal with 3 x MCs and no brakes then there must be air in it. If you had sticky pistons you would have a pedal. if you had pressure you would have a pedal as you dont have a pedal you dont have pressure and as your not using/losing any fluid then there must be air in it. Cheers James 110 2010 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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21st Jul 2025 3:14pm |
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