V6 and V8 master cylinder differences

[J_D]

How can I tell the difference between the V6 and V8 master cylinders on S1VN. I want to buy a rebuild kit but dont know which master cylinder is in the car as the previous owner put V8 discs and calipers on but I dont know if they did the master and booster as well. The only numbers I can see on the master is 17A3, if this means anything.

[Doctor Bob]

should all be the same from memory

Rob

[Tree cutter]

The v8 cylinder has a 1" bore and the 6 cylinder has 15/16" bore. The size should be cast into the cylinder on the right hand side.

[J_D]

Just had another look at the master cylinder and it has a 1 cast after the PBR lettering on the front of it near the master cylinder support brace, does this mean its a V8 master cylinder.

[pandaman]

Just had another look at the master cylinder and it has a 1 cast after the PBR lettering on the front of it near the master cylinder support brace, does this mean its a V8 master cylinder.

I think so yes.

[savage1987]

just out of interest, what's the brake booster actually do?
*scratches head*

[pandaman]

just out of interest, what's the brake booster actually do?
*scratches head*

As I understand it, it boosts pressure in the brake lines so that it's not just the pressure provided by your foot that appears at the calipers. If ya wanna try a little experiment to see how much difference it makes, when you're rolling down the driveway stick it in neutral and kill the engine, then try braking, just be prepared to apply a fair bit of force.

[savage1987]

to see how much difference it makes, when you're rolling down the driveway stick it in neutral and kill the engine, then try braking, just be prepared to apply a fair bit of force.

don't need to do that - my engine's stalled on me before (although it's auto) - doesn't like the Canberra cold . . . yeah it's surprising how much power assist does . . .

cheers for that info, pandaman

[1991_Vn2nV]

If I put V8 brakes on my car, which I will have on the rear soon anyway, will it make the brakes spongey if I dont change the master cylinder and booster?

There doesnt seem to be a massive difference so is it absolutely necessary?

[xcop5l]

If I put V8 brakes on my car, which I will have on the rear soon anyway, will it make the brakes spongey if I dont change the master cylinder and booster?

There doesnt seem to be a massive difference so is it absolutely necessary?

when i bought my vn it had a v6 master cyinder on it and the brakes were verry spongy but im not sure if it was just stuffed, i put a v8 one on ant the brakes improved 80% there great now. but its got cop brakes all round

if you keep the v6 master on the peddal will feel spongy because it wont be abil to delivere enough fluid to the calipers because the v8 calipers are bigger

you wont have to change the booster

[1991_Vn2nV]

Cheers for that man

[xcop5l]

just out of interest, what's the brake booster actually do?
*scratches head*

correct me if im wrong but basicly it works by vacume.
the rod thats conected to the brake pedal goes threw the booster and in to the master cylinder. this rod is conected to a diafram inside the booster.when the engine is running it creates a vacume in the chamber where the diafram is.the diafram is held back by a spring. when you press the brake pedal the vacume acts to make the pedal eayser to push down
Attachment 25383

[pandaman]

correct me if im wrong but basicly it works by vacume.
the rod thats conected to the brake pedal goes threw the booster and in to the master cylinder. this rod is conected to a diafram inside the booster.when the engine is running it creates a vacume in the chamber where the diafram is.the diafram is held back by a spring. when you press the brake pedal the vacume acts to make the pedal eayser to push down
Attachment 25383

Very well explained.

[xcop5l]

just think i actually learnt something at tradie lol