I've been busy with a disc brake upgrade om my ute and everything that could go wrong did, this simple converstion has become a absolute nightmare over the last couple of weeks. Without going into to much detail, here is my problem.

The discbrakes work great for about the first 10mins that im driving around but after that it slowly starts to build up pressure and starts braking all by its self. Ive narrowed it down to 2 things, 1 being the shaft on the booster is too long and consistantly applys pressure on the master cylinder or 2 my master cylinder is stuffed.

I think its the master cylinder cause when I blow on the hole for the rear brakes I can blow air through but when I try to blow air through the hole for the front brakes nothing. No air goes through.
Is it suppose to be like this or is this the root of my problem?
I asked the brake "experts" and got a reply "I don't know"

strange to have an ATE master on a datto
it could be a clearance problem or a booster issue
when its all locked up and you pull the master away from the booster do the brakes release ?
if so look at the booster clearance
if not then the master may be at fault

isnt the line for the rear brakes usually at the front of the master cylinder?

what car did the master cylinder come from?

dattoman_1000
ATE Master Cylinder? Is it good or bad?
Ive removed the vacuum hose while the brakes were locked and it didn't do much so its safe to say its not the booster but wil check the clearance on next attempt.

PIGDOG
AFAIK the front brakes must be on the front point of the master cylinder or so i'm told
Quote: Funny story that. Wreckers claim its of a Nissan 1400 bakkie, the one brake repair shop says it looks like it caim of a ford sierra and the other brake place says it looks like a nissan sentra's booster and cylinder

Thanks

[edit:add]found this on the net, seems like I should be able to blow air through.

In a disc/drum cylinder, the front section [nearest the radiator] is for the rear brakes & these usually have a residual pressure check valve in them which is designed to maintain some pressure in the line. This could have the effect of causing the front brakes to drag. Have you checked this out?
Have a look under the bonnet of several cars & check out which way the pipes are plumbed. In Australia, the rear chamber is for the front brakes & I have not yet seen an exception.

If the cylinder is a 'used' example that has not been dismantled, cleaned & overhauled, then it's possible that one of the tiny ports at the top of the bore that allow brake fluid to return to the resevoir, might be blocked. This could have the result of 'pumping up' the brake circuit & locking on the brakes.

i think all the standard nissan ones(in austraila any way) have the front brake line at the back of the master cylinder

EDIT: what he said
EDIT junior: looking at that pic you posted, it is clear that the primary resivour is at the back of the master

I'll swap the brakelines and see wat happens, thanks.

Will keep you up to date on progress.
Thanks all

Quote:

I have to agree with dodgeman here, I checked when they removed my booster/master from a 05' Nissan ute, to make sure I got the brakelines the right way around when I assembled again, and the front brakes came of the rear hole.

Looking at the pic you posted it only makes sense, since you want the front brakes to apply first, otherwise you'd be more likely to go into a spin if the rear brakes locked up first. Also the 1400 ute's master has 2 holes in the rear, so that you'd have two sepperate lines running directly from the master, and not from a distribution block like the old 1200 system.

just frt disc upgrade or 4 wheel disc upgrade

For a 4 wheel upgrade
if you swap the frt and rear lines you will still have a locking problem now with rear than frt.
you need a master for a 4wheel disc set to remove the pressure check valve for the rear drums depending on size of your brakes I would try one off a 4 wheel disc 280z or a 4wheel disc 240sx

It doesn't matter a whole lot which way around the pipes are actually
Many cars have them one way and many the other
Its not the important thing here

This cylinder doesn't run residual valves

ATE is a common use brand in SA
German infiltration

I say its a clearance issue....... got a pic of the front of the booster ?