Repairing front Discbrake calipers

The car has Sport brakes at wery early stage. I will keep & maintain them. It would be too easy to change new ones and more important thing; I think its important that it really looks that these parts have been long time in this special car. Something that you can´t get with big vallet by using only new parts.

Historical thing, you know !

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First step; My method is to take brakepads out and push brakepedal so that calipers piston comes out. Then I use rope and multioil to piston cleaning.

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After cleaning you can valuate piston condition. These looks good. The problem was, that the piston didn´t get back again. SO i thought sealing rubbers was too hard and it was time to change them.

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I took the other pad out also and push both pistons agains the brakedisc. After that I remove the calipers.

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To reduce the piston friction, I took the outer dustsealings out.

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From local store i find cheap amateur tool to press in the piston. Notice plugged temporary brakeline as a ”special tool”. By pushing the other side ( the side where brake line goes to the caliper) piston inside sametime when the hole caliper is still full of brakefluid influence that left side (in this photo) piston move out. It works well in this case.

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The second piston will be more challenging to take out. Because these were not totally stucked, it works well by pressing cloth to the empty sylinder and then using pressured air via brakeline connection. After some minutes trying the piston ”pop up”.

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Calipers where lighty surface rusted and thatfore i put them to the citric acid bath.

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After some hour calipers look as I will. Rost was mainly away and still the nice patina on it.

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To hold the patina, I sprayed tiny layer of matt lack over calipers. The idea is, to keep patina as it is, and slower future corrosion.

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Notice Saab Sport brake pistons speciality; pistons are asymmetric. You can see the difference her where the screwdricer is. I measure some 0,2-0,5 mm difference.

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Round 2/3 of the piston area is deeper ( brighter are in the right). This side must install underside. This due the brake pad wears and due reduce squeaking.

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Brake discs were just little bit rusty and near thickness of brand new disc`s.

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”Open” sanding strip works well, and I can warmly recommended similar for many purpose. In this case I used P60.

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Many times brake hoses causes problems. They look good, doesnt leak etc. But; they can be defective inside. Sometimes hose has ”puff up” inside and it causes ”check valve” effect; brake fluid has tight canal to come back from calipers to the reservoir and that fore brakes can get stuck. You can check it easy by blowing into to the hose. If you look like in this photo, it might be time to change the hose; its too tight inside. You can check it also by open the bleed screw; if brake fluid comes out strongly and if you after opening can turn easily the wheel/disc by our hand, it can mean also that hose is ”puff up” inside. In normally eweryday cruising you should be concerned about if one or the other front brake/rim feel warm after you have drove without any stronger braking.

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Upper one, The original ”Snake”surface brakehose. It´s original in early Saab Sports, and the lenght is 285mm. If you have later Sport ( 1964 forwards) or Monte Carlo, yours is 220mm and then you can use same hose than Saab V4 rear.

In this case, the car has still the original hoses and brakepipes to the calipers ( newer installed the uppgrade kit with shorter hoses). I find out, that you can find wery similar hoses easily which are 290mm long. These inch threated hoses has used many British cars such; Ford Cortina/Escort/Capri, Sumbeam, Hillman and also Volvo Amazon front (with disc brake)

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Here you can see why the uppgrade kit has become. If you are not wery careful in your install, it might be that hose hit the calipers brakeline. If you turn hose too much other side, it will hit the drivesaft velocity joint. Observe also white stripe on the hose; its helps you to keep the hose in line.

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The difference between early Sport brake hose (upper) VS. Uppgrade kit (under copy from service bulletin year -64)

Sport Brakeline Uppgrade kit

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One usefull hint is to use plastic bag under reservoir cap. It will reduce the fluid leagage during hose change.

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Ready. Repaired but not looks too new & shiny.

Rear brake pressure valve checking

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Under rear seat is located one valve. I was curious and opened it. Main idea for this valve is, that it limit brake pressure to the rear brake, and keeps pressure with certain maximum level during full power braking. The idea is to prevent rear wheel locking.

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Surprise; nothing rost inside. Just cleaning, and installing with brake rubber grease. Im not sure if its good to have it, because of Disc brakes front and tiny smaller brake sylinders rear. Lets test drive it, and if it limit too much i take it out from car.




Written by Tikkis

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