uprated master cylinder

[tiddy1]

I have just fitted one of the uprated AP master cylinders and the brake pedal is so hard it feels like wood. I have 4 pots on the front but standard on the rear but you now have to push the pedel so hard it feels positively unsafe and I am seriously considering reverting to the old master cylinder

 

Is this normal?

 

or is it just that the brakes are cold and it may be better on the track??

 

Simon

 

Watch thic space for an uprated master cylinder for sale!!

 

 

[Nick M]

The choice of friction material in the pads has a big impact on how the brakes feel.

 

I've got Red Stuff pads on mine for now (they were cheap when I fitted the Wilwood calipers) and they feel a bit wooden too until they get hot. Haing looked back through the archives on here, it seems that with the uprated master cylinder you need a high friction pad like those supplied by Pagid in order to get some feel back into the pedal.

 

I'm going to try some Hawk Ferro carbon pads and see if that makes a difference. So don't give up on it yet - I much prefer the solid feel of the uprated master cylinder.

[murph7355]

It does make the pedal much firmer - I prefer this over the rubbery feel with the std cylinder.

 

Pad material will make a difference but if you've changed nothing else, the m/c will be showing you the main difference.

 

Presumably the pedal feel on the std one was why you switched?

 

 

[scooby dooby doo]

This is the principle benefit / purpose of the race master cylinder:

Your foot is MUCH better at regulating pressure than position so ideally the brake peddle shouldn't move AT ALL. so you can hold the wheels on the point of lock up much more easily.

 

Further to this - if they do lock up you can cadence brake and modulate the pressure very rapidly without actually having to move you foot (which would take more time)

 

It is also better made with less flex - so you don't have to do as much to the brake peddle to make them do anything.

 

It also means that when heal and toeing under braking the throttle is still just to the right of your foot. with the normal master cylinder its so far above your foot that you can't do a clean blip. if you make the throttle pedal really low to combat this then its in the wrong place when you're not braking. This is perhaps the biggest benefit that i value the most.

 

With race rear brakes it will be even firmer. most of the movement you feel at the moment is the rear brake calipers flexing. The squeeze the disk against a claw instead of against another piston (like the big fronts and race rears do).

 

HOOPY R706KGU CYCLE WINGS AEROSCREEN K SERIES CUCUMBER

[JAG]

I believe the main difference between the standard and uprated master cylinder is simply an increased bore diameter. This will make the pedal travel shorter put the pedal effort higher - assuming nothing else changes. The pedal will 'feel' different, fitting different pads can help but you may have to try several sets before you get what you want.

 

The increased bore size also has the advantage that it displaces more fluid per mm of pedal travel. This is useful if you start to get pad fade (reduced pad friction due to elevated temperature) whilst driving enthusiastically because you can keep on pushing on the pedal to generate extra pressure and compensate for the reduced friction with less chance of bottoming the master cylinder.

 

JAG

[JP]

Get used to it! The uprated cylinder (I think) also alters the brake balance...

[scooby dooby doo]

good point. it shifts it forward a bit - so its perfect for big front brakes and small rears (assuming the std fittment caterham pads for those items)

 

HOOPY R706KGU CYCLE WINGS AEROSCREEN K SERIES CUCUMBER

[Rob Walker]

It is possible that you have the low ratio peddles on your chassis Simon. This compounded by a standard road friction material could give the lack of initial bite you describe. Much greater peddle effort is required over the standard M/C. 😬

[murph7355]

I just reacquainted myself with big brakes and an uprated master cylinder. It really is the only option so bear with it for a while and then try a car that has a std one again.

 

The ability to get some retardation without 6in of pedal travel first is not to be sniffed at, nor is the ability to set the pedals perfectly for heel and toe without other crap compromises.

 

Yes it's firm, but easy to modulate once you're comfy what you're dealing with...

 

 

 

 

[Peter Carmichael]

The race MC does not alter the balance. Standard and race are both equal bore master cylinders.

 

There is a correct weight for a pedal. As the car decelerates, the weight of your leg is pressed onto the pedal. You get pedal feel when this is doing most of the braking for you and you modulate the exact amount you need on top with small muscle movements. To praise the race MC for being heavier is nonsense unless you have heavy legs and wear lead boots.

 

The relationship between barke pedal force and retardation should never stray very far from a happy medium. If you change the MC, you should change to a high coefficient of friction pad. If you do this you get the best of all worlds with lots of feel and not much movement. Daft not to.

[markc]

Hi

 

I posted an article last week - Brakes - or lack of.

 

I to suffered from lack of confidence in the brakes after upgrading to race m/c and 4 pot clipers.

 

I have now fitted Pagid pads and the brakes are fantastic 😬

 

Now do I upgrade the rears

 

MarkC

 

[scooby dooby doo]

Peter - I've been told (by a caterham dealer) that it does alter the balance - but I was puzzled as to how. You have confirmed to me that it doesn't. So why does the myth perpetuate 🤔

 

HOOPY R706KGU CYCLE WINGS AEROSCREEN K SERIES CUCUMBER

[murph7355]

The "correct" weight for a given pedal, though, will very much depend on the individual pressing it.

 

Whilst I agree that better pads are also a very good complimentary route, some people (me for example) definitely preferred the brakes with the uprated m/c simply because of the extra heft required and the lack of travel. Hey, I never said I was subtle . I've tried this more or less back to back and a drive yesterday confirmed my preference (pad materials are the same, calipers are slightly different (00 v 02 vintage) but the main difference is the m/c).

 

Then again some people don't like it.

 

Having given your (PC) brake pedal a shove my initial thought was that it required too much effort for my liking. But thinking about it later I reckon it'd be pretty bloody awesome on a circuit, and there's a big difference between a pedal that feels one way or the other in a garage at 0mph and one that's needed urgently at 130mph

 

Simon - persevere for now as mentioned and I'm sure going back will not be an option for you. Next change should be pads and only then sell it.