Outer Limits 4x4 Board

Doing a disc front conversion on my swb 40. got a complete disc front diff which i have put under. only prblem is the brake master is not the same for drum f & r as the disc front drum rear. i have purchased a master from the wreckers that they said was right which is type 44610-6017 no 4f00217. but the brakes are still pretty horrible. what have i done wrong?

What year is you 40?

the very first year model 1964. but with the modern model diffs, power steering etc

Is there a brake booster?

Is the booster working correctly?


do you have good vacume?

only the master with the diaphram thats it. the vacuum is perfect. the brakes have been bled 3 times now to make sure no air is in the line. am i meant to have a master and a booster for the front disc? never new the 40's had them

my 82 with disk front does have a booster.

you will need a booster for disc brakes.

What is the exact problem?

are the brakes spongey or just had to apply?

the main problem is that the brakes dont work. the pedal goes straight to the ground.

could be a stuffed mastercylinder

i've decided that im just going to find a new brake master to suit drum front and rear and forget about doing the front disc brake conversion. what sort of price should i sell a disc brake front diff for?

Hardzy wrote:i've decided that im just going to find a new brake master to suit drum front and rear and forget about doing the front disc brake conversion. what sort of price should i sell a disc brake front diff for?

Why? Disc front is one of the best things you can do to a 40, that and power steer.

Generally speaking, if you have no pedal then you have one of 3 problems.

1: Insufucient fluid displacement. That is fluid is not getting to the rear wheel cylinders or front calipers either due to a significant leak, large amount of air in the system or a faulty master cylinder which is by-passing fluid.

2: Rear brakes are way out of adjustment and are pusing the rear wheel cylinders out to their extermety and still not engaging the drum and/or faulty/seized calipers.

3: A combination of 1 and 2.

At the end of the day if you do decide to run front discs you will need to fit a booster and plumb vacuum to it. From what I understand you will not be able to bolt a 40 booster straight onto the early firewalls. A spacer bracket will need to be made up to clear whatever it is on the firewall that the booster will foul on (stiffening rib??).

Once you go discs, you just don't go back. Believe me, it's worth the effort.

ok, so i assume i will be going ahead with discs then

so what sort of brake booster and master must i run to get the disc front drum rear to work propery?

A booster/master from an '80-'84 model 40/45/47 should work.

Yep. Send a pm to "Ol'40" http://www.outerlimits4x4.com/phpBB2/pr ... ile&u=9191

He has fitted disc brakes to an early non booster 40 and made up a bracket and custom pushrod to mount the booster. He might be able to help you out with some tips/pics.

Anyone know how to adjust how much braking power goes to the front vs rear on a BJ40 with disc front?

De-lux wrote:Anyone know how to adjust how much braking power goes to the front vs rear on a BJ40 with disc front?

Pretty sure the factory 40 disc front is proportioned in the master cyl itself. Whats the issue?

Well I've spent the last 2 days putting in new rotors and pads (previous ones were cactus), but now when I stand on the brakes the rears tend to lock up pretty easy... I've bled both front and rear brakes, but still the rears locking up... durrrr....

Were the fronts locking up first before hand? Have you got the rear drums over adjusted? Did you use brake cleaner to clean off the discs before you road tested it? Have you bed the pads in? What sort of pads did you fit? How many more questions do I need to ask before I get to 20?

De-lux wrote: when I stand on the brakes the rears tend to lock up pretty easy... I've bled both front and rear brakes, but still the rears locking up

I have the same problem !!!!

You need a preportioning valve between the Drum and Disc brakes other wise the rear will lock up first and little braking effect on the front.

You can either add an adjustable one or pick up one off a late 40 that had factory discs. May find one on a 60 series too will do.

Also make sure you dont have an air lock in the matser cylinder it's self.

Thanks for the help Matt... from what I read on IH8Mud I need to get one of these proportioning valves.


I'm sooo miffed at my BJ40 - mainly what year it is. From all the docs it says it's a 78, but the discs appear factory (with 14mm studs), that was only offered on the 1980 and up model. The other thing that confuses me is the engine has a stamp on it saying "Made to comply with 1979 ADR".

matt.mcinnes wrote:You need a preportioning valve between the Drum and Disc brakes other wise the rear will lock up first and little braking effect on the front.

You can either add an adjustable one or pick up one off a late 40 that had factory discs. May find one on a 60 series too will do.

Also make sure you dont have an air lock in the matser cylinder it's self.

Can you elaborate on this a little more mate?

De-lux wrote:

matt.mcinnes wrote:You need a preportioning valve between the Drum and Disc brakes other wise the rear will lock up first and little braking effect on the front.

You can either add an adjustable one or pick up one off a late 40 that had factory discs. May find one on a 60 series too will do.

Also make sure you dont have an air lock in the matser cylinder it's self.

Can you elaborate on this a little more mate?

Basically its a valve that balances the braking, as the front require more to clamp on the disc, the toyota one is non adjustable and part of the mastercylinder I think. Aftermarket you can actually adjust to suit. Ideally correctly adjusted all 4 wheels should lock up at the same time in a perfect world.

Mud will have plenty of info if you can't find it here.

I'd be looking at answering a few of the questions mentioned here before spending money...

Wood

60 series cruisers have a separate proportioning valve under the master cylinder, I just used all 60 series stuff when I changed my 82 troopy to disc front end. I am pretty sure that the disc front end cruisers have smaller rear wheel cylinders that 4 wheel drums. Some people change them, some dont.

I recall years ago a mate put a chev diff under his Monaro, kept locking up the back brakes. changed the slave cylinders back to standard size and it was fine.


As said previously, discs on the front of a 40 series is a MAJOR improvement over drums