Rear disc conversion

If your antique drum system is set correctly I'll venture to say you would notice no difference.

After a water crossing is the only time I notice any difference....as I still have rear brakes

Mine is much the same. Brakes are in good order, braded brake lines, fresh fluid and bled several times.
The brakes work ok, passed the mot no problem but the pedal travel is more than Kate's Jimny and not as sharp.
Only thing I have not changed is the servo.

Would a new servo improve the peddle travel/feel ?

A bigger servo will increase the brake assistance and make the brakes feel like they are sharper. It won't make the brakes any more effective or alter pedal travel.

A bigger master cylinder will reduce pedal travel, making the brakes feel firmer. It will reduce braking power, requiring more force to achieve the same level of braking.

A combination of a bigger servo and master cylinder will make the brakes feel very 'modern' and direct, and should retain close to normal braking power.

How a disc brake conversion affects the brakes depends mainly on the volume of the pistons. This affects how much pedal travel is needed to apply the brakes and the front/rear braking bias. Get it wrong and you may have too much braking power at the rear, making the car unstable under heavy braking and liable to spin.

11/60, if your brake pedal only occasionally feels mushy then there is a problem somewhere. Could be a caliper starting to bind, could be a wheel bearing, could be detritus in the rear drums.
Brakes should feel much the same all the time, right up to the point where the pads overheat or the fluid boils.

Busta wrote: 11/60, if your brake pedal only occasionally feels mushy then there is a problem somewhere. Could be a caliper starting to bind, could be a wheel bearing, could be detritus in the rear drums.
Brakes should feel much the same all the time, right up to the point where the pads overheat or the fluid boils.

11/60 possibly flexes the front stub axles pushing the pistons back with the discs when cornering...on a private track of course!

One thing which can affect the pedal feel over time is the rod which contacts the master cylinder from the servo can wear......be careful adjusting it.....if it even can be on a Jimny.

I have a master cylinder to fit to mine so I'll find out at that point if it has adjustment.....possibly only the main dealer would be able to find out the actual setting.

Brake parts are not so expencive and when we service our own cars we save so much money that most of us can easily buy new parts more often. Generally..

When changing to disc brakes it is difficult to get the proportioning right between front and rear. Some use valves that constricts the flow to the rear brakes to adjust it.
For my SJ i have plans to use a master cylinder from a impreza WRC. According to "the interwebs" it should fit and do the job properly when converting to disc brakes. Not sure what size calipers it actually has been designed for but i will look into this before building. I guess if you pick parts together that have roughly the same sizes between them and they where designed for, it could come out correct in the end.
Likewise if you start playing with this you really should be knowing what you are doing..

yakuza wrote: Brake parts are not so expencive and when we service our own cars we save so much money that most of us can easily buy new parts more often. Generally..

When changing to disc brakes it is difficult to get the proportioning right between front and rear. Some use valves that constricts the flow to the rear brakes to adjust it.
For my SJ i have plans to use a master cylinder from a impreza WRC. According to "the interwebs" it should fit and do the job properly when converting to disc brakes. Not sure what size calipers it actually has been designed for but i will look into this before building. I guess if you pick parts together that have roughly the same sizes between them and they where designed for, it could come out correct in the end.
Likewise if you start playing with this you really should be knowing what you are doing..

Exactly So the WRC more than likely has 4 pot callipers same as the ones I have from a WRX..which are simply so huge as to not fit inside a 15" rim.... My point is that you won't find a new dual circuit master cylinder to fit and proportion the brakes correctly.

You'll need 2 master cylinders and an adjustable balance between the two to do it correctly.....or just fit discs on the rear and the existing brake proportioning valve will do a splendid job!