MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: Padge on December 7, 2022, 00:05

Title: Troubleshooting handbrake - rear caliper
Post by: Padge on December 7, 2022, 00:05
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
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 07:53
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.

(https://i.postimg.cc/9fXBFGrs/Handbrake-cables.png)
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Padge on December 7, 2022, 08:31
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: 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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on December 7, 2022, 09:47
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?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Carolyn on December 7, 2022, 09:50
Have you changed the pads?  If so, have you run them in?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 09:51
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Call the midlife! on December 7, 2022, 09:53
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?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on December 7, 2022, 09:55
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 09:59
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'
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 10:12
Saying that, just rechecked the GOV site, and I interpratate this as I can take it away for repairs?

(https://i.postimg.cc/gJ64Bv56/Capture.png)

Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 10:26
But then found this...

(https://i.postimg.cc/hG5Yf4Tc/Capture2.png)
Title: Re: Troubleshooting handbrake - rear caliper
Post by: mr2garageswindon on December 7, 2022, 10:29
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Padge on December 7, 2022, 10:32
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  :)
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 10:37
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Call the midlife! on December 7, 2022, 10:43
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on December 7, 2022, 10:46
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?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Call the midlife! on December 7, 2022, 10:55
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...
Title: Re: Troubleshooting handbrake - rear caliper
Post by: mr2garageswindon on December 7, 2022, 11:14
Defect   Category
(a) Parking brake efficiency:

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

Major
Dangerous

From the mot manual
Title: Re: Troubleshooting handbrake - rear caliper
Post by: JB21 on December 7, 2022, 11:53
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on January 14, 2023, 23:40
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on March 23, 2023, 22:02
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?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Ardent on March 23, 2023, 22:52
Correct length cables?

Pfl vs fl.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on March 24, 2023, 00:36
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on April 17, 2023, 22:35
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.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Ardent on April 18, 2023, 00:14
might the mr2ben and other supplied cables both be the wrong ones?
Pfl vs fl

New pads discs cables. The pad nipples in the piston slots. The pedal pressed a few times to take up any slack.
With handbrake off, the pads should now have an interference fit to disc.
Is the adjustment now being done at the handbrake end?
How many clicks are you getting on the hand brake
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on April 18, 2023, 08:59
I would have thought the mechanic would already have identified if the calipers actually operate well enough. Use a pipe or deep socket over the lever & see how much movement it takes to lock each wheel. Are they comparable?

Don't use MR2Ben.....expensive.  I'm not sure if's one or both, but there is a difference in length of pfl & FL cables.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Carolyn on April 18, 2023, 09:20
I'm suspecting duff pads.  It happens.  I had new pads on one of my bikes just not work effectively.

If all else is as it should be?

The brackets are plenty strong enough. 
Title: Re: Troubleshooting handbrake - rear caliper
Post by: normanh on April 18, 2023, 12:00
I've had new calipers, pads and discs installed on old cables, one was repalced last year the other serveral years back. Both had plenty of free free travel before connecting to the calipers and adjusting the handbrake which needed a fair bit of adjustment needed but they worked well.

Norman
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on April 18, 2023, 19:48
I'm pretty sure the cables are post face lift.  One is slightly longer than the other.

One of the brackets is bent compared to the other so, if no get them stiffened up, I won't have to worry about them yielding in bend when the handbrake is on.

Valid point about the pads.  My.mechanic got them from his usual supplier so they should be OK but it maybe worth getting some others just in case.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: normanh on April 18, 2023, 20:13
Did you fit the cables correctly - on mine PFL they are colour coded for N/S and O/S they have to be fitted to the correct side!!!

I had no issue with MR2BEN's offside cable fitted last year fitted perfect a little pricey but it worked. N/S is 18 years old and still working fine.

Norman
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on April 21, 2023, 22:34
If the cables were out of adjustment, shouldn't you still be and to get the handbrake to work, just not with acceptable lever travel?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on April 21, 2023, 22:45
Quote from: MR2again on April 21, 2023, 22:34If the cables were out of adjustment, shouldn't you still be and to get the handbrake to work, just not with acceptable lever travel?

No. Use the method I mentioned above to see if operating the lever operates the braking action.  Easy for a mechanic to make a judgement from that. Then take it from there.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on April 28, 2023, 22:35
Spoke to the mechanic yesterday and he said he had done that test and pulling the lever on the scalloped did lock the wheel so does that mean the new cables are suspect?
Title: Re: Troubleshooting handbrake - rear caliper
Post by: normanh on April 28, 2023, 22:48
The cables are different lengths and colour coded, I still wonder if he fitted them correctly. Colour coded red and blue and must be fitted to the correct side. I cant remember what side is what colour though.

Norman
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on April 29, 2023, 10:05
Quote from: MR2again on April 28, 2023, 22:35Spoke to the mechanic yesterday and he said he had done that test and pulling the lever on the scalloped did lock the wheel so does that mean the new cables are suspect?

The mechanic should be telling you that one way or the other. He should know if the amount of lever travel needed is acceptable/within what the cable can do.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on June 14, 2023, 22:08
Sorry it's been so long since I last posted.  A friend and I took some measurements to try to find out what was going on. 

Pulling the handbrake on led to 0.1 to 0.15 movement of the cable brackets so the whole brackets bending or yielding was a red herring.

With the handbrake levers pulled up hard it took 80Nm to turn the right hand wheel while it needed 160Nm to turn the left.  Pulling the handbrake on moved the lever on the left hand calliper 7.4mms while the right hand one moved more than 20mm.  Most of this extra movement occurred in the first part of the handbrake levers travel as though it was taking up play.

So we replaced the calliper and, at last, it passed the MOT.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Joesson on June 14, 2023, 22:50
Quote from: MR2again on June 14, 2023, 22:08Sorry it's been so long since I last posted.  A friend and I took some measurements to try to find out what was going on. 

Pulling the handbrake on led to 0.1 to 0.15 movement of the cable brackets so the whole brackets bending or yielding was a red herring.

With the handbrake levers pulled up hard it took 80Nm to turn the right hand wheel while it needed 160Nm to turn the left.  Pulling the handbrake on moved the lever on the left hand calliper 7.4mms while the right hand one moved more than 20mm.  Most of this extra movement occurred in the first part of the handbrake levers travel as though it was taking up play.

So we replaced the calliper and, at last, it passed the MOT.


Well done, I have mentioned previously that persistence is one of the best tools in the tool box.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Gaz mr-s on June 15, 2023, 00:20
Quote from: MR2again on June 14, 2023, 22:08So we replaced the calliper and, at last, it passed the MOT.

If you haven't binned it, keep that caliper.  Numerous people have had problems with replacement calipers not lasting long.
If you can, try a rebuild yourself, or if necessary in the future use Big Redd to refurb it.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: MR2again on July 1, 2023, 22:12
Too late. I've sent it back and got my money back.
Title: Re: Troubleshooting handbrake - rear caliper
Post by: Carolyn on July 2, 2023, 08:31
 Contaminated pads?