Brake Bias after brake conversion

[paddles]

Hey guys,

 

I'm just sorting out the braking system on a 260z and am a little unsure about what to do about brake bias.

 

The car is running a 1" Patrol master, hilux 4pot vented fronts and single pot r31 disk rears. I'm also planning on adding an adjustable proportioning valve in the rear line to tune brake balance.

 

I haven't yet plumbed in the new master (the front and rear outlets are reversed compared to the original 7/8 unit) and was wondering what to do about the standard proportioning valves/distribution blocks. There are two of these blocks in the engine bay, do I need to keep these plumbed in or should I just ditch them given that I will run a screw-type adjuster in the rear line?

 

Any advice would be great!

 

Alex

[nizm0zed]

ditch them...

 

 

You need to have seperate lines to each of the front wheels, some masters will have 2 fittings for the front lines (one to each wheel) otherwise just use a distribution block to split the lines.

For the rear line, go from the master into the proportioning valve and on to the rear calipers.

Make sure you dont have any inline residual pressure valves in the system.

They are located in the standard proportioning valve so you shouldnt have an issue there anyway.

 

There are pictures in my build thread of my setup.

http://www.viczcar.com/forum/index.php/topic,2902.60.html

[RLY240]

Hi Paddles,

I"m running exactly the same brake setup as you (1", Hulix 4 pots, R31 rears) on my rally car and I have retained all of the factory plumbing save for removing the residual pressure valve from the master cylinder.

I'm not running any other bias adjusters and the bias is fine.

Roger

 

 

[Ben]

Lose the factory bias valve in the engine bay but you can keep the pressure differential switch (the one with the brake fail warning wire attached), but be aware that is will probably need a good clean out as the internals get gummed up.

 

A couple of new lines, a tee in the front lines and your new adjustable prop valve in the rear circuit should be pretty much it.

 

From memory I used a joining piece somewhere in my engine bay (from the firewall of a Mitsubishi Sigma).

 

I'll take some photo's of my engine bay tomorrow and post them up.

[paddles]

Thanks for the replies guys, much appreciated - seems like there's a few ways to do things!

I was hoping to replumb the whole car and ditch the stock valve etc. but I can't see how I'd be able to do a decent job of it with the engine and gearbx still in the car. So I thought I might just run the stock prop valve for now and see how it goes once the car is finally on the road. If the bias turns out to be a problem I'll have to bite the bullet, ditch the stock gear and replumb with a bias valve.

[Ben]

I just went out to the shed & tried to take some pics of my setup, but there are just too many hoses in the way...

 

You can do it easily enough with everything installed. I ended up ditching the differential pressure switch assembly as it insisted on leaking.

 

So my setup is as follows:

Rear circuit goes to adj. prop valve on firewall, then via (shortened) standard line to rear tee above diff.

Front circuit goes to tee piece where original differential pressure switch was mounted, then uses original RH line and re-uses another line to a joiner on the firewall on its way to the LH brake. Less connections, and less pipes than original. It's a pity that I hadn't noticed the there was that leak before it softened all my shiny orange paint on the chassis rail.

 

I think I'll redo that section of the paintwork when I have the engine out, otherwise it will rust...

 

But the brakes work great!