Troubleshooting handbrake - rear caliper

Started by Padge, December 7, 2022, 00:05

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Padge

Hi all,

I know this has been done to death but I've tried searching and am unable to see something matching my sitatuation. Of course regarding a poor handbrake  :)

Old cables both had torn boots and did not move freely within the sleeve, so I replaced both however I still have a poor handbrake (after adjusting properly - start engine pump brakes etc). The arms on both calipers move freely and move the piston (enough so I cant turn the hub by hand). I've adjusted the handbrake as far as it will go in the car (if I go any further the brakes bind slightly) and still with the handbrake on I can push the car on flat ground and hear it start to give, so its definitely working somewhat just not enough. 

I have no other indication of a sticky caliper - wheels move freely when no brakes applied, wheels don't feel hot after a drive.

Is there a way to be certain this is the caliper at fault as I don't want to replace unless necessary (also considering rebuilding myself). I assume so as there really isn't anything else to go wrong however

JB21

#1
I'm having the exact same issue, and my car has now failed its MOT and its left me stranded where I cant even drive to a garage for repair as the handbrake is classed as a dangerous defect.

I had to change one of the calipers as the handbrake mechanism wasn't doing anything, but this doesn't sound like your issue if you can see the piston moving when manually actuating the lever and they bit when manually moved. FYI the lever shouldn't travel more than 45 degrees on the car, if in good condition they will bite with less than a cm of movement on the lever.

From reading there are different cables for PFL & FL. The PFL cables are shorter, so if you have fitted FL cables to a PFL car this could be your issue as the cables will be to long and not actuating the handbrake lever enough on the calipers.

I have ordered Borg & Beck FL cables for mine and I've now got to risk a heavy fine to drive it to a garage for fitting.

See below on B&B cables.


Padge

Thanks for the response, I did indeed fit FL borg&beck cables as you have ordered following a positive review from someone else online. A little tip but I'm sure you're aware - be very careful which side the cables go as they're slightly different lengths.

To be honest I can't think of it being anything but the caliper but I've got a lot to learn when it comes to mechanics so didn't want to just be throwing parts at the problem without troubleshooting first.

Joesson

@JB21

It is legal to drive without an MOT certificate, but only to a precooked appointment at a MOT test centre/ Garage.

Gaz mr-s

Quote from: JB21 on December  7, 2022, 07:53FYI the lever shouldn't travel more than 45 degrees on the car, if in good condition they will bite with less than a cm of movement on the lever.


Interesting.....where did you learn that?

Carolyn

Have you changed the pads?  If so, have you run them in?
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

JB21

#6
Quote from: Gaz mr-s on December  7, 2022, 09:47Interesting.....where did you learn that?

By checking a good caliper vs a shot one, however the travel should be 2-3cm when free of the cable for the bite not 1 cm. Just been out and rechecked. The 1 cm is when the cable is attached.

Call the midlife!

I'm sure you did everything right as far as fitting goes but 2 basic things to check are that the nipple on the pads is engaged in the slot on the piston and that you backed the piston out a bit after refitting the caliper etc?
60% of the time it works everytime...

Gaz mr-s

Quote from: JB21 on December  7, 2022, 09:51By checking a good caliper vs a shot one, however the travel should be 2-3cm for the bite not 1 cm. Just been out and rechecked.

Thanks....I'm dealing with the same.

JB21

Quote from: Joesson on December  7, 2022, 09:23@JB21

It is legal to drive without an MOT certificate, but only to a precooked appointment at a MOT test centre/ Garage.


If I'm reading it correctly online, not since the new 2018 MOT rules. If you can find me a statement on the gov website stating I can still drive to a pre-booked repair appointment with a 'DANGEROUS DEFECT' then this would save me a ton of cash on garage labor. It even states on the fail cert 'DO NOT DRIVE UNTIL REPAIRED'

JB21

Saying that, just rechecked the GOV site, and I interpratate this as I can take it away for repairs?




JB21


mr2garageswindon

When you have got a dangerous defect on the mot you are not supposed to drive it until it is repaired.
I do KNOW of some garages using the wording to their advantage and insisting it gets repaired with them.. this is a main dealer!
By driving the vehicle KNOWING it is classed as unroadworthy will be what you can be prosecuted for.
When I fail a car for a dangerous defect I advise them of this but also say it is up to them and I have no power to stop them.
You gotta be pretty unlucky to get stopped.

Padge

Pads have been changed in May, EBC Yellowstuff, been on a few trackdays with them too

Yes pads installed correctly with the nobble going into the slot on the piston - I didn't at first and wondered why they wouldn't fit  :)

JB21

Quote from: mr2garageswindon on December  7, 2022, 10:29When you have got a dangerous defect on the mot you are not supposed to drive it until it is repaired.
I do KNOW of some garages using the wording to their advantage and insisting it gets repaired with them.. this is a main dealer!
By driving the vehicle KNOWING it is classed as unroadworthy will be what you can be prosecuted for.
When I fail a car for a dangerous defect I advise them of this but also say it is up to them and I have no power to stop them.
You gotta be pretty unlucky to get stopped.

I'll only get stopped if I go past an ANPR equipped police car and it pings for MOT. Like you say if I do get stopped, I have no case to fight.

Call the midlife!

Quote from: JB21 on December  7, 2022, 10:37I'll only get stopped if I go past an ANPR equipped police car and it pings for MOT. Like you say if I do get stopped, I have no case to fight.
If you get pinged on the way back from the failed test and it's already updated on the system then YES technically you could be prosecuted but if you're driving it TO a pre booked retest then you're ok, as long as you're not knowingly driving with a dangerous fault.
But again that's making the assumption that you're aware of a dangerous fault, as far as you're concerned you've sorted it before taking it back.
60% of the time it works everytime...

Gaz mr-s

Quote from: mr2garageswindon on December  7, 2022, 10:29When you have got a dangerous defect on the mot you are not supposed to drive it until it is repaired.
I do KNOW of some garages using the wording to their advantage and insisting it gets repaired with them.. this is a main dealer!
By driving the vehicle KNOWING it is classed as unroadworthy will be what you can be prosecuted for.
When I fail a car for a dangerous defect I advise them of this but also say it is up to them and I have no power to stop them.
You gotta be pretty unlucky to get stopped.

Should his MOT station classed a u/s handbrake as 'Dangerous' in this case?

Call the midlife!

Quote from: Gaz mr-s on December  7, 2022, 10:46Should his MOT station classed a u/s handbrake as 'Dangerous' in this case?
Fairly confident the handbrake is classed as an "emergency brake" and should be able to stop the vehicle from rolling away in the event of brake failure. If there's potential for it to roll into another road user etc then I would say that's the dangerous aspect.
Although I imagine there's a great many driving around with similar handbrakes and full tickets...
60% of the time it works everytime...

mr2garageswindon

Defect   Category
(a) Parking brake efficiency:

(i) below minimum requirement
(ii) less than 50% of the required value   

Major
Dangerous

From the mot manual

JB21

Right I've figured a way around getting it home. I'm going to re-book an MOT locally. That way I can state I have had the defects fixed and its essentially going for re-test which is allowed.

Funny as the handbrake works fine, its just weak on the N/S so its not like police can check if I have or haven't rectified the MOT fail.

MR2again

Interesting. My car recently failed its NOT for the next brake binding and n inefficient handbrake but the test centre, a Formula1 Autocentre, had no car park so so I couldn't leave my car there.  I had to drive it away.

MR2again

I'm in a similar situation.  My car's handbrake failed the MOT.  The left-hand cable didn't move as much as the right and the boots of both were falling apart so I got new cables from MR2BEN.  My wife wasn't keen on me dropping the fuel tank on the drive so I took the car to a local mechanic who seemed to have changed MR2 cables before.

However, after fitting the new cables, he concluded that the callipers needed replacing.  I got new callipers from EBay and they were duly fitted but he was still unhappy with the handbrake performance. As he has little storage space, I took the car home while waiting for a replacement calliper mounting bracket to arrive (that's another story).  I had a look today.  I disconnected the cables from the callipers and pumped the footbrake hard 20 times with the engine running.  With the cables reconnected, I adjusted the handbrake but to get only 6 clicks, the left-hand side started binding.  Even so, I can't get the handbrake to lock the rear wheels. 

My mechanic has already said he thinks the new callipers are no good but I can't see where the problem could lie as it's just a cable pulling a lever which pushes a rod against the piston and pad.  With the parts being free to move, I don't see where something could be wrong.

Any ideas?

Ardent


Gaz mr-s

Some have bought 'new' calipers (they're probably reconditioned) & they haven't worked.  The internals of the caliper are not a clever design.  Some say it's better to get the genuine ones refurbed. Dedent results from Big Redd reputedly.

MR2again

I and my tame mechanic are still battling this problem.

I have fitted new cables from MR2BEN, new callipers, new discs and new pads yet we can only get 15% handbrake efficiency at best.  The mechanic tried some other callipers but they were no better.  He got some more cables from.his regular supplier and found they were the same length as the MR2BEN ones.  His only suggestion now is that may be the brackets that the outer cable butts up against at the calliper end is flexing.  They are being differently from each other.  Next step is to weld gussets onto them to stiffen them up.

What else could it be?  He goes through the back off cables and piston and pump 20 times procedure so I'm out of ideas of this doesn't work.

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