Crap Brake Pedal - LC Lancer

[MRGNLC]

Hey guys, recently i have transfered my spare gn sigma front bits into my LC.
I've fit the gn's brakes, struts and lca's in, with the LC's Strut tops and the LC's Brake hoses, as the GN's had a different flare on the pipe.
I bled the sytem from back to front, but only have half a pedal.
So i kitted both the calipers (being a bit old, they prob needed it anyways)
Still the same.
So i then replaced the master cylinder.
Still the same.
i've adjusted the rears, and there are no leaks anywhere.
Is there an adjuster for the pedal between the booster and Master?

any help would be greatly appreciated!!

[Scorpma82]

no adjustment...but sounds like the stroke length and pushrod length in the booster is different

[MRGNLC]

Unfortunately I didn't change the booster, and the new master cyl, is exactly the same

[Scorpma82]

So when you replaced the B/M/C, did you replace with an LC one or a GN one (i was going by the fact you put a GN one on)

Are the calipers and rear wheel cylinders bigger in capacity (i.e. requiring more fluid to operate)
Certainly sounds possible that you've increased the capacity of the calipers and the rear wheel cylinders. . .and the B/M/C simply can't supply that much fluid

[MRGNLC]

That's what I was thinking, I have a master cylinder from the gn but if I were to bolt it to the LC booster, the reservoir would sit on a 45 degree angle, which is pretty useless for keeping the fluid in it. The size of caliper is bigger, not by much, but definitley bigger.
So the Master cylinder I replaced it with is a brand new LC master.
I've been told the master cylinder may not be bled properly, but I bled it myself in a vice on a bench and am pretty certain that it was bled thoroughly.
If anyone knows of a direct bolt on replacement from another car that is bigger that would help!?
Also, If it's any help, whenever I bleed it, there always seems to be a lot of air in there? The first one you bleed you always expect some air as there'll be air in the hose between the bottle and nipple, but the other two have almost as much.......
Thanks - Michael.

[Scorpma82]

On the back of the master cylinder.....is the last component a circlip?....or a rubber seal?????

If it's a rubber seal...you can't bench bleed it...it MUST be fitted to the car, and bled with the engine running....the cylinder will need vacuum to seal onto the booster shaft and the easiest way to get it is to run the engine (manifold vacuum)....but this will only work if the last component is a rubber seal

[MRGNLC]

Geez, I hope it's the type you said! I'll look straight after work....

[MRGNLC]

Just got home from work, unfortunately it's the type with a circlip....
I tried adjusting the rod a bit that sits at the top of the pedal, but still the same...

[Scorpma82]

Hmmmm

I've got all the old B/M/Cyl catalogues at home (used to work at PBR)...i'll have a look at home and see if the bore sizes are different.....I'm thinking it's a fluid displacement issue....i.e. the B/M/Cyl can't displace the amount your 'new' calipers/wheel cylinders require

(Hugely common on the VT brake upgrade conversion on older model Commodores)

[MRGNLC]

yeah i think you're right. the first half of the pedal is a giant sponge, although even spongey is still doing something, its just not hard until 1/2 to 2/3 mark

[MRGNLC]

Definitley needs a bigger master cylinder, I'm off to race brakes in a fortnight to check for a bigger unit that will bolt straight up