Handbrake cable question

Started by The Don of Croy, February 22, 2018, 13:52

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The Don of Croy

Car failed the MOT this week - lack of effort on ns brake, parking brake little or no effort etc

The caliper was replaced after last year's MOT (still looks new).

Just slipped off the handbrake cable at both ends (whilst also loosening the petrol tank anticipating some fun) and the cable moves freely...does this mean the cable is OK for now and the binding is caliper related?

I note the rubber end on the caliper is perished/torn and probably means trouble later, but right now I need to fix the brakes to get my free re-test within the 10 day cut off.

Ideas/comments welcome (I have bought some Pagid cables just in case) but I'd like to avoid the new cable if at all possible. For now.

Carolyn

Worth checking that the sliders on the caliper are moving freely. If they're stiff, clean the sliders and lubricate with Ceratec. Then slacken the cables right off and do the old 'pump the brake pedal' at least ten times with engine on.  Then re-tighten the cables.
If that doesn't cure it then the piston may be seizing in the caliper.
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The Don of Croy

Thanks for the speedy reply.

Have now sheared off the caliper bolt. Ho Hum. Can the caliper be removed 'in situ'?

I'm assuming the bolt can be drilled out on the bench later.

Carolyn

#3
Helps to have some brake hose pliers (most car parts shops have them).  Pinch off brake hose, loosen nut that holds the banjo (round thing on the end of brake hose).  Much easier to loosen this with caliper still on car.  Disconnect handbrake cable.  Two 10 mm bolts hold caliper to hub (17 mm socket and extension needed) .
You'll need a new bolt from Toyota (very special bolt).
Good luck,
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Bossworld

Rear slide bolts are less than £2 each from Toyota, I was pleasantly surprised with that one.

m1tch

Quote from: Bossworld on February 22, 2018, 16:16
Rear slide bolts are less than £2 each from Toyota, I was pleasantly surprised with that one.

Probably as its a commonly replaced part!

The Don of Croy

Well the caliper has been removed and - as far as I can tell - the piston works fine (pumped it out using the handbrake lever on the back of the caliper). The inside brake pad exhibits uneven wear - one corner is well down - but overall both pads seem to have plenty of life in them.

Just faffing about trying to remove the remains of the stud bolt - words have been spoken (luckily no-one is here to be offended). Will ask local units if someone has an extractor.

Carolyn

The uneven wear indicates that the pad could not float in its seat.  Take out the Stainless steel spring clips and clean up the slots in the caliper with a square file. Clean the spring clips too.  Note which one came out of which slot (they are 'handed'). If in doubt, do one at a time, so they don't get mixed up.
That could also be the root of the handbrake problem!
Worth finding someone with a milling machine to drill out accurately and run a tap through.
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The Don of Croy

Some progress - managed to drill out the offending slider bolt and re-tap the caliper carrier (£95 + VAT for a new one!!).

How do you wind the piston back in - it's very stubborn and I think there's a mechanism in there to do with the handbrake that's stopping it?

Ideas?

Carolyn

You'll need a wind-back tool.  Many on Ebay.  https://www.ebay.co.uk/itm/Universal-22pc-Disc-Caliper-Brake-Piston-Rewind-Tool-Kit-Set-Wind-Back-Car-Auto/222614906531?epid=2178323904&hash=item33d4e1e6a3:g:MXUAAOSw~M1ZlAVv

If it's still stiff with a wind-back tool, the piston is sticking in its bore. (So let's hope it's not).

Wind it in all the way and then back out 1/2 to 1 turn.  Make sure the slot in the face of the cylinder is dead vertical as it locates a nipple on the back of the brake pad.  Unless that nipple is engaged, the piston won't wind out.

You're right about the handbrake mechanism in there.  The piston winds out on a threaded rod inside the cylinder.  It winds out when you pump the brake pedal and gets the pad sitting in the right position for the hand brake to work.  It's not likely to be the cause of your problem though.

The pad not sitting straight almost certainly was.
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The Don of Croy

Needle nose pliers seem to work - many thanks for your assistance!

How do you wash copper grease off clothes?

Mechanic booked for tomorrow afternoon to check over my handywork then bleed the brakes ready for Thursday re-test (snow permitting).

Carolyn

Hope you haven't used copper grease on the sliders.  Works for a while and then goes sticky!!

If needle nose wound the piston, it certainly isn't sticking!

Did you clean the slots with a file?

Good luck with it all.
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The Don of Croy

The new pads are much looser fit than those that stuck - I've had the mechanic in today to bleed the brake and give it a once over before MOT retest.

The pins have copper grease and the mechanics own tube of gloop. Between the two I'm hoping the pads will continue to slide.

1979scotte

Copper slip will turn sticky.
A previous owner used it on one of mine.
First they came for the socialists, and I did not speak out—because I was not a socialist.
Then they came for the Jews, and I did not speak out—because I was not a Jew.
Then they came for me—and there was no one left to speak for me.

Free Ukraine 🇺🇦

Ardent

Copper slip, back of the pads. Maybe.
Sliders. No.

The Don of Croy

MOT re-test passed without advisories. Phew!

Thanks for the input chaps.

Carolyn

Excellent result. Well done.
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The Don of Croy

Spoke too soon?

Having passed the MOT test, I've popped the car back up on the axle stands to replace the part worn pads on the other axle.

Now the other caliper will not retract...I've disconnected the handbrake cable, the reservoir lid is off, but the piston will not rotate either way?

What have I forgotten?

Carolyn

Piston stuck to the seal inside the cylinder, I'm afraid.

You were lucky with the MOT.  Try having someone gently push the piston out a little with the pedal, then see if it will rotate.
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The Don of Croy

I've tried the handbrake flange - no movement. Cannot believe the MOT passed it or it's just decided to seize the very moment after it was tested.

Is stripping them a big job? How does one seperate a stuck piston from the body? Or is it better to just buy a refurbed caliper off the shelf?

Bluddy cars  - the Volvo dropped off (corroded through) a rear silencer bracket this morning. That's two sodbags in one day - I must be blessed.

Carolyn

#20
As I said.  The piston can be pushed out using the brake pedal. The Handbrake lever doesn't exert much force, the hydraulics (brake pedal) WILL shift the piston.  I'd just try pushing it out a little and see if it frees it off. 

If not, then you can push it all the way out.  Then you'll need to clean the piston and replace the seals.

Otherwise, you'll need a rebuild kit.  But perhaps better to get a re-furbished one.

I believe 'Bigg Red' does them for a decent price and prompt service.
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tfmorton

You really need a wind back tool...they're very cheap on eBay. Needle nose pliers usually aren't strong enough.

Also, people forget to mention that you need to slacken off the handbrake cable completely when working on the rear brakes.
Wind the piston all the way back, then turn out until the slots are vertical.
Reassemble, and pump the brakes until hard.
Check the piston is sitting in the brake pad slot (i.e no gaps between the piston and pad)
Take up the slack in the handbrake cable. Test and keep taking up the slack until 5 or 6 clicks is enough to hold the car.

Enjoy a working handbrake!

The Don of Croy

Wind back tool it is - less than a tenner from the factors and surprisingly easy once the 3/8 drive is engaged (Laser 5541 cube).

Phew - progress at last. All re-assembled and tested.

Many thanks for all the help from the forum.


Carolyn

And there's me thinking you'd got one when first advised.

That'll learn yer!
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