L Series, rear brake line , valve ?

steptoe · Post by **steptoe** » Thu Jun 08, 2006 1:15 pm

Under LHS at rear of L series 4WD 4 wheel disc set up there is a junction of fluid lines that has a big access nut at one end.

Is this a pressure adjuster of some sort ?

damo666 · Post by **damo666** » Thu Jun 08, 2006 1:47 pm

Yep, its the bias valve (got a spare disc rear one?!).
I'm still trying to work out if there is a difference between the drum & disc model bias valves. I'm assuming that the rear disc models had a different biasing ratio to rear drum models......anyone??

Most of the other cars that I've swapped from rear drums to discs also needed the Master Cylinder looked at. Rear drum cars usually have a little valve in the master cylinder to supply a little pressure to the drum brake shoes - which isnt needed/a good thing when you swap to discs.

Its common practice to remove this when swapping to rear discs on Datto's & Toyota's, but i've never heard of people taking this out when doing the swap on Subaru's??? I plan to have a look when I get mine apart .

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Thu Jun 08, 2006 4:49 pm

Not from technical info but from just swapping the rear over to discs i have found that there is no noticable difference in the 2 setups even the master cylinders have no problems.

subarursliberty · Post by **subarursliberty** » Thu Jun 08, 2006 7:20 pm

I would love to find this out. Can anyone here help. I might just have to give subaru a call tomorrow and find out.

damo666 · Post by **damo666** » Thu Jun 08, 2006 7:36 pm

Whilst I'm sure it feels the same during normal braking, i'd love to test a a factory rear disc car and a converted car in an extremely hard emergency braking situation....

subarursliberty · Post by **subarursliberty** » Sun Jun 11, 2006 12:40 pm

damo666 wrote:Its common practice to remove this when swapping to rear discs on Datto's & Toyota's, but i've never heard of people taking this out when doing the swap on Subaru's??? I plan to have a look when I get mine apart .

You wouldn't remove it unless something was built into the calipers them selves. Libertys have them but they sit next to the master cylinder not under the rear like early subaru's.

damo666 · Post by **damo666** » Sun Jun 11, 2006 12:57 pm

You wouldn't remove it unless something was built into the calipers them selves. Libertys have them but they sit next to the master cylinder not under the rear like early subaru's.

Nah, not the bias valve, biasiing is a different issue.

I'm referring to the residual rear pressure valve - on other late 70's/early 80's cars its a little spring loaded valve built into the rear circuit (usually within the master cylinder itself), and supplies the required few pounds of pressure to the rear drums. This is the bit that needs to come out when doing a disc swap on those cars. I'll see if I can find a pic of the one I pulled out on my Datsun.

Biasing is seprate from this. I'd be really surprised if the switching point in the bias valve would be the same for both drum & disc rear ends (but funnier things have happened!).