22 replies to this topic

[gooley]

Just want to know what I need to Convert my Rear Drum Brakes to Disc's....On a 1970 LC

I already have Disc's on the front but i want disc rears now.....do i use HQ discs?? do i have to change Diff??

Edited by gooley, 20 October 2007 - 05:52 PM.

[RIM-010]

Well for a rough start, HQ's didn't come with disc rears...

Shortened VN/VL/Skyline diff seems to work alright.

Tim

[rodomo]

PBR have a listing on their site for rear rotor WB statesman but NLA.

[piquet]

Years ago I converted the diff of an L34 from drum brakes to disc brakes. It was a bit of a nightmare but was well worth the effort.

I would think that if you were able to find out whether the mounting hats for an LX/UC torana with the rear disc brake option were the same as the HZ mounting hats then it would probably be an option and a way to go.

Obviously the rear discs for an LX/UC may be hard to find but it would be a really worthwhile way to go. They would be the right stud pattern and the rught offset for the discs.

maybe the best way is to get a spare diff housing and go about it that way and set it up on some axle stands to get it right before trying on the one in the car.

cheers
piquet

[rodomo]

Some utes (Hi-lux springs to mind) have a load sensing valve that adjusts the rear brake pressure depending on the load in the tray from the factory.

Virtually what you need but not adjustable from the cabin.
It is adjusted under the car via an adjustable rod.

Sort of a set and forget set-up.

Maybe it could be argued via an engineer to fit it?

Subaru Brumby's came from the factory with a "Hill-Holder".

Effectively a line lock that trapped the hydraulic pressure to the front brakes and was conrolled by the clutch mechanism to release the pressure at the friction point of the clutch.

Another useful argument perhaps?

[ls2lxhatch]

The brass olive in the master cylinder is required to seal the brake line to the master cylinder. When converting from drum to disk brakes you remove the rubber residual value that sits behind the brass olive.

Adjustable proportioning valves are legal as long as they can not be controlled from inside the car. If the factory proportioning valve has a brake fail switch or you have ADR 31 listed on the compliance plate then you have to fit a brake fail switch.

I have not been able to find an adjustable proportioning valve with a brake fail switch Incorporated. SSBC an adjustable proportioning valve which has a brake light switch but not a brake fail switch. SSBC intend to release an adjustable proportioning valve with brake fail switch early 2008.

SSBC A0730

I have heard that fluid level sensors in the master cylinder are a legal alternative to the brakes fail switch mounted in the proportioning valve.

[Dr Terry]

Some utes (Hi-lux springs to mind) have a load sensing valve that adjusts the rear brake pressure depending on the load in the tray from the factory.

Virtually what you need but not adjustable from the cabin.
It is adjusted under the car via an adjustable rod.

Sort of a set and forget set-up.

Maybe it could be argued via an engineer to fit it?

Hi rodomo.

Late HZ & all WB One-Tonners use this same set-up, as do VG to VS Commodore utes.

I think the best set-up would be to use the Willwood adjustable proportioning valve & keep the original junction block & switch that only the LC/LJ/HQ have. It looks like the LH/LX (& other) prop' valve but there is no valve, as such, in it, it's a smaller unit.

Dr Terry.

[rodomo]

[quote name='LJ_MAN' date='Oct 21 2007, 09:03 PM'] I was thinking of running the wilwood adjustable proportioning valve but am worried about the legal requirments, have not spoken to an engineer yet but im pretty sure they are illegal for street use.
Do the Willwood ones have and external adjustment or shims inside?
I think the issue with engineers and RWC would lean against external adjustment.

If the Willwood adjustment is external, maybe the Holden ute set-up as Dr Terry mentioned would be the most palatable from an engineer's point of view?

Edited by rodomo, 22 October 2007 - 05:08 PM.

[rodomo]

OEM proportioning valves in the LC/LJ's dont have a brake fail switch, its just a brake light switch so i cant see any disadvantages in not having the switch.

Mate, have a read of Dr Terry's post.
The switch in the valve is a brake fail switch.
The valve is not a proportion valve.
The brake light switch is on the brake pedal.

[enderwigginau]

HQ-WB utes have a load sensing proportioning valve in the engine bay.
With no weight on the rear (or the rear rising during braking) more bias in dialed toward the front to prevent rear lockup.

Get DBA HX rotors in Torana pattern, and find a set of HX caliper hangers and calipers. UC rear calipers will fit.

Grant..

[dattoman]

no

[Dr Terry]

HQ-WB utes have a load sensing proportioning valve in the engine bay.
With no weight on the rear (or the rear rising during braking) more bias in dialed toward the front to prevent rear lockup.

Grant..

Hi Grant.

No, that's not quite correct.

All HQ-WB (except One-Tonners from 1978 onwards) have a normal 'fixed' proportioning valve. HQ's have it located under the floor halfway along the rear brake line. HJ to HZ had theirs located in the distribution block near the RH front suspension (so do LH, LX[not A9X] & early UC Toranas). WBs had theirs incorporated into the brake m/cyl (A9X & late UC are the same as WB). HQ/HJ 4 wheel drum braked cars have no prop valve at all.

These valves are fixed & have no load sensing, so have no way of putting more bias to the front or rear at will. The late HZ & WB One-Tonner do have a load-sensing valve located on the chassis directly above the rear axle housing & connected to it by a short piece of chain.

I've found the best way to legally fit an adjustable proportioning valve, is to fit the Willwood item & use a distribution block (with pressure switch) from an LC/LJ/HQ. The adjustmement knob must be out of the reach of the driver so fit the valve near the brake m/cyl.

Dr Terry.