Thread: 1981 RR Brake conversion

when my 2 door started to run out of brakes i discovered the flex brake line to the front caliper 4? from memory were perished on the inside and bits of rubber were in the caliper

after a rebuilt the brakes were awsome.......well with standard road tyre

As mentioned below a few things affect RR brakes, normally they are excellant! A change in the brakes to disco items I think would need an engineering certificate and be quite a bit of a pain in the neck. Also the early 2 Doors have an imperial braking system - whereas disco's are all metric and you cant mix the two, so you would need to replace it all. (Was 1981 the change over year??? I can't remember now)

1 - Disc wear - If the front and read disc rotors are worn greatly, then the calipers will contain a lot more brake fluid and it will be prone to feeling spongy. A new set of rotors all round will make a difference.

2 - Wheel bearing wear. If the wheel bearings are loose then the wobble of the wheel will push the pistons into the calipers, with the result that the pedal sinks much lower on first application, but can be pumped up.

3 - Low vacuum - If your V8 is worn, then it will not generate much vacuum at idle. There is a spring loaded one way valve at the inlet manifold , that can be removed. There is a separate one in the booster box. The one on the manifold can get stuck or restrictive. Removing it can make some difference.

4 - Worn Vac Booster - There is a rubber diaphram and valve that can wear, makes a very big difference to have this reco'd but can be expensive. Last time I had this done was 10 years ago, and I found that I kept skidding at first because the pedal was so much better afterwards.

5 - Rubber hoses - these should be replaced every 3 years according to the manufacturer - no one does... But they do get spongy and that will make a big difference. Don't forget the rubber brake lines to the rear axle.

There's no point changing to disco brakes, they're exactly the same other than the plumbing arrangement.
The upgrade is defender brakes (pistons 25% bigger), but unless you're way heavier than stock or running way bigger tyres you shouldn't need them.

84-86 was the changeover from imperial to metric. My 85 has metric brake lines.

Just for comparison for you the brakes in my 76 rangie were better than the brakes in my current 90 rangie, not sure why, but they just were. So as mentioned I wouldn't bother swapping. The newer rangie has the ventilated front discs also.

Originally Posted by GuyG

Just for comparison for you the brakes in my 76 rangie were better than the brakes in my current 90 rangie, not sure why, but they just were. So as mentioned I wouldn't bother swapping. The newer rangie has the ventilated front discs also.

Newer rangie is probably 20% heavier.
They started out weighing less than 1700kg and got porkier quickly.

Originally Posted by shotlister

My 2 door RR has awful brakes.

I am wondering if this is just how they are, or can they be improved?

I have heard that disco discs and calipers will just bolt in.

I would also assume I need to change the booster and master cylinder as well.

Any ideas as it goes MUCH better than it stops.

Do you hear a hissing sound under dash and idle speed changes when on the brakes?

Hi,

The body on my 74 2 door is an '81 and I used the '81 brakes, which are metric. M/C is Lockheed with the warning switch screwed into the side.

I was going to go down the Dougal path, but I have 15" rims and the calipers may not have fitted inside.

Instead got new M/C, 2" extended stainless braided lines, all new pistons, seals, Mintex pads, split pins and pad springs from Paddocks in the UK. $480 odd inc. freight.

Installed all with DBA slotted rotors (solid like orig) which were $300. Discovered that the front plumbing was wrong, probably from the factory. Wouldn't bleed properly, easy fix. Brakes are now sensational.

Can't tell what made the most difference. Pads are really good though.

cheers, DL

Siezed calipers can also be a reason for poor brakes - if one pad on a caliper is wearing faster than the other, the other is suspect.......