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Discussion Starter #1
Hi all

The old girl just passed on the OS handbrake efficiency so thought I'd take a look.

Whipped the calliper off and removed the piston, it was a bit tarnished so gave it a good clean. Turning the armature the cable attaches to by hand seemed smooth enough and the coarse worm thread the piston screws onto had a fair bit of movement in it.

I screwed the piston on, turned the handbrake and there was nothing like as much movement in the piston, seems as if the movement in the worm was being lost in the gubbins inside the piston.

I've had a look at various refurb kits but they only seem to be seals, boots and so on.

Anyone know what the hell I'm talking about?

Pub
 

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Did you seat the pads with the brake pedal/hydraulics before trying the handbrake?

I'm pretty sure the handbrake mechanism auto-compensates for pad wear, but requires pads to be set initially with pedal first.
 

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Discussion Starter #3
Did you seat the pads with the brake pedal/hydraulics before trying the handbrake?
This is all with the calliper off the car. With the piston removed I can see the worm moving back and forth when operating the arm on the calliper by hand. Still with the calliper off the car if I put the piston back on and operate the arm again the piston moves very little.

The inside of the piston has a fair few bits and bobs all held in with a circlip. This is free to rotate inside the piston which is why you have to use a rewind tool to wind the piston back, if all you did was turn the piston it would simply rotate around the inner bits.

In my mind it's the internal stuff in the piston that has too much play in it so the movement in the worm is lost.

Pub
 

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There is a certain amount of lash engineered into the mechanism between the handbrake mechanism and the threads of the piston self adjuster. This is needed to allow the piston to retract sufficiently after footbrake operation to prevent brake drag. What you found is completely normal.

The handbrake actuator in the calipers can wear but it is normally due to someone over adjusting the cables and not allowing the caliper handbrake lever to return to its fully off stop when handbrake is fully released.

If handbrake cables are properly adjusted, the calipers should last the life of the car if there are no seizures which are left unattended to. The biggest clue to a developing seizure in the handbrake is the handbrake lever in the car does not have a progressive spring action from the very start of its travel. (There is an unsprung void and then it quickly goes hard to pull further.)
People with the stupid electronic handbrake miss this as they apply the handbrake by pressing a button in the car. It ensures repairs are more expensive especially when not caught early.

Progress?
 

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Discussion Starter #5 (Edited)
Resurrecting a thread from last year. Finally got round to replacing the calipers as the weather has improved. Now have a handbrake that'll hold it on quite a slope, forgotten what it was like.

One thing that bothers me though, I hadn't really looked that closely at the old calipers, now that the new ones are on the offside calliper cable support and armature are not aligned when the handbrake is on, causes quite a bend in the cable. As the handbrake is on more that it's off this can't do it much good.

The NS lines up quite nicely whether on or off, why would the OS be different? It can't be efficient as the cable isn't pulling the armature in the direction it wants to move.

I rescued the old one from the bin and it's the same.

Must get some replacement rubber boots, wonder if cycle brake lever boots would do the trick.

All the best

Pub
 

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That's all very interesting. One the 2 156s, strangely it is the older car which has a more powerful handbrake. I've recently fitted new rear discs and pads on both cars. On the old TS, I freed off both caliper pistons. The JTS had one which was a bit tight. The cables on both cars are within 30 months old and they all move freely.

The TS has a nice, light and powerful handbrake. The JTS in comparison feels a bit dead and heavy and requires greater force on the handbrake lever to achieve the same effect through its larger discs.
@pubsinger, did the new calipers make the handbrake lever feel more springy and require less force?

I have a theory that previous owners seem to think that a handbrake lever is a test of strength and this is what causes premature wear of the cam/worm mechanism in the caliper. As yet, I've never found new mechanisms available.

Have you tried the bicycle brake cable gaiters as the ones on our cars seem to be very low quality?
 

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Discussion Starter #7
did the new calipers make the handbrake lever feel more springy and require less force?

Have you tried the bicycle brake cable gaiters as the ones on our cars seem to be very low quality?
Couple of clicks is enough to hold it on a gentle slope, another click on a reasonable slope. I still wouldn't trust it on a steep slope although it will hold...just. Yes, does feel like it has more resistance but it may be my imagination.

I've ordered the cycle boots, waiting for them to turn up. I'm hoping they'll have enough give to get them over the cable end with a bit of grease.

Pub
 

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Thanks. Silicone spray will be the best thing to ease them on.
I never noticed the cable angle on one of the calipers before yet have seen it a hundred times.
 
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