Brake Master Cylinder Up-Grade

[Barney]

Hi Guy's

I remember reading some posts on changing the brake master cylinder when fitting larger calipers.

As you may know i have fitted Wilwood calipers and now the brake pedal is a bit long, but thats not that major problem.

The main concern is that the front brakes are sticking on. when i brake hard it take ages for them to fully release, they release enough to drive again but they still drag quite a bit. To give you an idea i was almost flat in 4th gear and i could only reach 90kph.

I think the problem is that beacause the master cylinder is now being depressed further, it is working in a place it has never done before, and the piston is sticking, does this make sense?

Anyway Has anyone actually up-graded their master cylinder? if so what route did you take?

TA

ASHLY

[Cookiemonster]

Are both front brakes sticking? If so then it points to an M/C problem.
However if the pedal completely returns then the M/C should be OK.

Can you get the brakes to stick whilst you're standing still? Or do they only stick when you are driving? If they only stick while they are driving then you may have the calipers mounted slightly off square to the rotors. Check the pads for uneven wear.

Othewise the other cause may be a sticking caliper piston. The solution to this a rebuilt or new caliper. This sounds unlikey though as your calipers are new.

Another cause is dirt and corrosion on the sliding mechanism which does not allow the caliper to retract as it should. Cleaning the sliding points and replacing the dust shield s can sometimes cure this problem. Again unlikely due to new calipers.

The most unlikely but possible is a bad brake hose. These hose deteriorate on the inside and once in a while develop sort of a flapper valve inside. That is a piece of the hose wall tears partially free and on occassion blocks the return flow of fluid thus causing the caliper to drag. It sometimes bleeds back down over a period of time so it very hard to detect.

Heres the brake conversion file (right click - save as):
http://members.ozemail.com.au/~cookiemonster/brakes.doc

[Barney]

Thanks for that good advise Cookie.

Both front brakes are sticking. It only started doing after i first applied the brakes in anger.

When they are stuck on, the pedal is at it's normal height but is very hard.

I can sit there and pump the brakes whilst stationary and they will be stuck on when i start to drive and reamain like that whilist driving. If i give it a few hard shap jabs whilst driving they will eventualy realse.

After they are stuck on and i return home they release after about 15 minutes

Ashly

[Cookiemonster]

It points a faulty M/C.

If it is a caliper problem then it's very unlikely that both calipers would stick.

I'd source a Nissan Patrol M/C as per the brake conversion file and see how it goes (PBR part number J1715).

Merlin is using a J1715 M/C with Wilwood calipers to good effect.

[Barney]

Thanks MAte

I went for a drive and jot it to stick, then put the car on a hoist and it turns out that both front and rear brakes were stuck on.

After cracking one of the bolts on the M/C they all released, this eliminates the calipers.

Then i went for another drive and got the brakes to stick again. I then checked the temperature of the brake fluid in the M/C it was 110deg C. I then ran cold water over the M/C after about two minutes it released :? I did this twice and both times they released after a few minutes of running cold water over the M/C.

I will pull the M/C off this weekend and get it checked out.

I thought it could be the booster shaft to the M/C, but i loosened the bolts that mount it to the booster and it still remained stuck.

Thanks again
:beer
ASHLY

[Cookiemonster]

No probs. Let us know how the new M/C goes. It should good give you a nice firm peddle.

[rxtoy]

just wondering if this nissan patrol M/C takes any mods to fit?

i've just swapped my rear end (a while back but the car hasn't really been on the road) to disc brakes and apparently because my current master cylinder is setup for drum brakes it may have a non return valve to the rear end (not sure why, just what i got told) which could cause my rear brakes to stick on. apparently you can pull the non return valve but if this is a decent upgrade i'd rather just buy another master cylinder.

cheers
Matt

[Barney]

Not sure about your car, what sort of car is it, as all Starions had disc brake rear end.

I am a bit concerned about direct bolt on mods, as every time someone told me a mod bolted straight on, it never has. And becomes a complete nightmare

ASHLY

[dirty sanchez]

I am using the Nissan Patrol Master Cylinder with Wilwood calipers to good effect.

I agree about things never being a 'bolt-on' fit.

The master cylinder fits (just), but requires bending of the brakelines and one of them only just reaches. The top also touches the strut tower, but seems to work fine like this.

A word of warning though, the part number originally given on the tech article was wrong, might want to check (with Merlin I think) that this is now the correct part number.

I also have the Nissan part number, if you would like this, let me know and I will find it for you.

[rxtoy]

my car's an EX lancer with starion engine and EX1800 running gear (same as starion except live rear axle). i'm pretty sure the bolt pattern is the same but i think there's less distance to the strut tower in my car, might have to see what else i can find.

cheers
Matt

[Barney]

my car's an EX lancer with starion engine and EX1800 running gear (same as starion except live rear axle). i'm pretty sure the bolt pattern is the same but i think there's less distance to the strut tower in my car, might have to see what else i can find.

cheers
Matt

Good luck :)