Hand Brake not working

kellybax23 · March 10, 2011, 19:57

Had the car a few weeks now and I love it, i've started to tart it up and get it looking as it should, the issue is the hand brake no mater how far i pull it up it wont hold the car, it comes on but would roll of the drive if i didn't leave it in gear. Is there an easy fix for this? could it be the pads or cable?

Curlytoppz · March 10, 2011, 20:00

I have the same thing. I had the garage tighten the cable and that worked for a couple of months but has soon loosened up again. Got my MOT next month so I am assuming I will be having to have a new cable.

Fergster · March 10, 2011, 20:24

Hi guys

Im a new owner myself but i had the same problem. I tightened the handbrake cable as instructed in the "how to" section and was running out of adjustment so i was begining to worry.

The real problem is that whoever replaced or fitted your brake pads didnt set the rear handbrake mechanism up correctly.
What needs to be done is the pistons wound back completely then wound forward 180 degrees. As far as im aware this sets your handbrake correctly.

Sorry this isnt much of an explaination but if you do a search or trawl the internet you will find more on the subject. Frogger on here seems to know his stuff about the braking system another guy is Phil Woods i think thats the correct name.

Just dont worry it shouldnt mean new handbrake cables.

Hope this is of someway useful.

Andrew

Curlytoppz · March 10, 2011, 20:54

Oh thats good then, will see at the MOT and will mention that to the garage who does my service and MOT s:D

s:D Thanks

Fergster · March 10, 2011, 21:57

No worries. Glad to give a little something back to others which i have gleaned off this great forum. Hope you get sorted.

Oh and if the pistons are being wound back with the system connected make sure they open the bleed valves and take the top off the brake reservoir other wise you risk damaging your master cylinder.

Steve Green · April 23, 2011, 12:34

I am new MR2 owner. According to the garage I bought the car from the rear pads were replaced. I am not happy with this so I have been reading this forum.

There seems to be a lot of discussion over setting up the handbrake when fitting new pads some of which is valuable info. Until I have the wheels off, I wont really know but the calipers look very similar to those used on an MGF. When I fitted these to a kit car, I found a great deal of information from an MGF workshop manual.

I think there is a misunderstanding reagarding the operation of these combined calipers with brake that dates back to drum days. Back then the brake cylinder pushed the shoes apart and the handbrake was a seperate mechanical lever that mechanically pushed the shoes apart. Added to this was a ratchet screw that supposedly took up the wear in the pads. This frequently failed to operate, poor maintenance led to the belief that the cable had stretched, not so.

Todays calipers are very different.
Consider for a moment the front calipers alone, there is no adjustment. As the pads wear, the volume of the cylinders increaces and the fluid level in the master cylinder will drop.
The rear calipers are the same except that they have an additional mechanical device to operate the handbrake. As the pads wear, the piston moves further out of the caliper, away from the handbrake mechanism. This distance needs to be closed mechanically, and to achieve this there is a threaded rod that pushes against the handbrake mechanism and the piston. It is along this threaded rod that you are screwing the piston back into the caliper.

There is a good write up on the operation of the rear handbrake brake system

A video that decribes the function is at
http://www.youtube.com/watch?v=SKseK_k7YfM

If you read this it suggests that, assuming the calipers are working correctly, all the brake adjustment happens inside the caliper mechanism, it is here that the auto adjusting takes place. You should NEVER need to adjust the handbrake unless the autoadjust mechanism has seized. The only reason the cable will stretch is if excessive force has been applied, perhaps in an effort to lock both wheels when one caliper has seized.
What you will not know if you simply wind the piston back in from where it was, that that was the pointwhere the mechanism seized! With the brake pads removed, operate the handbrake arm as shown in the video to ensure that it works!

This means that the the only setting needed for the handbrake is the 1- 2mm clearance as shown in

Notice that the the adjustment at the handbrake end is for the gap on the rear caliper, not how many clicks, or how close to the roof the handbrake lever gets. If the calipers are working correctly and the handbrake adjusted properly as described it will be fine.

The calipers are not identical as the handbrake cable is in a different location but the general principle must still apply.

The components that make up the caliper are shown below.

These look remarkably similar to the MR2

When I got my MGF calipers from a breakers yard I checked them over carefully. When operating the caliper lever by hand the caliper piston slowly came out without turning. I could then screw it back in by hand, or with the special tool. This suggested that all the internal mechanism of the caliper was working OK.

Now for the 180Deg turn of the piston question. The first thing to notice is that there is a pin on the back of the rear pads. This must locate inside one of the slots in the piston, otherwise the piston will push on the pin and not flat on the back face of the pad. This pin is there to stop the piston from rotating.

It is possible to strip the calipers down and replace the internal seals and clean up any corrosion. The best guide I found was for a Rover 800 caliper, mechanically similar to the MGF http://www.rover800.info/forum/viewtopic.php?t=4094&postdays=0&postorder=asc&start=0 but many cars use the same system including a Sierra.
It has to be said that the amount of work required etc its probably worth buying recon calipers.

Until I have the rearwheels off my 2003 MR2 I wont know if I am right.
If I have been typing rubbish then perhaps someone can put me right.

Edit:
Now with aprroval. s:D

s:D s:D

s:D by Wabbitkilla s:bowdown: :bowdown: s:bowdown: s:bowdown: :bowdown: s:bowdown:

Wabbitkilla · April 25, 2011, 08:44

That's actually really useful ... the video really brings it home too.
I'm going to be taking a closer look at my callipers later in the year when I replace them (not that there's anything mechanically wrong with them).

Considering Toyota won't allow publishing of the technical data for the car and aren't a great source of help for the diy-er this kind of information is important.

frogger · April 26, 2011, 18:48

Good bit of info. Reinforces my belief that people shouldn't be adjusting their handbrakes from the level end as the first-port-of-call with handbrake issues, only for minor adjustments to lever travel.

The rotating out of the pads by 180*-ish of course needs to coincide with aligning the pads with the slots. You seem to have read up a fair bit so you may have already seen this, but just in case, here's more discussion on the 180-ish degree thing... m http://www.imoc.co.uk/forums/viewtopic.php?t=4945 m , and the endless debate on the issue in a subsequent thread m http://www.imoc.co.uk/forums/viewtopic.php?t=6372 m

I'm not sure from your post what issue you're encountering with the rear brakes, but by understanding how the caliper works i'm sure you'll be well on your way to sorting it out anyway!

Keith · March 24, 2012, 16:43

OK, so a long while after the last post, but if like me you read the older stuff trying to sort the problem this might help. 3 months ago I had the handbrake adjusted by Mr T. Since then it's been getting worse, with no usable handbrake for the last month. Reading the forums I first checked at the handbrake lever end (rightly or wrongly). I found that the handbrake lever adjustment was wound up tight.

When jacked up, I also spun the rear wheels by hand and had swmbo stand on the brakes - checked both sides- seemed to work perfectly, so I guessed that the callipers hadn't seized.

Thinking about it overnight I wondered if the handbrake cable had been wound on too tight at the lever, would this stop the auto-adjustment? To try this theory, options where to release the cables at the forks or slacken it at the handbrake. Given that I thought that the cables may have been too tight at the lever, I slackened this right off.

Start engine, 20 plus pumps of the footbrake at varying rates and pressures - then tried the handbrake. This gave me about 7 to 8 or so clicks - a check of the rear wheels showed handbrake now appears OK.

SMALL readjustment to cable at lever to take up a little slack - reassembly- (not forgetting to hoover under the seats whilst they're out!), gentle test and handbrake now works fine. This ties in with the argument about resisting temptation to adjust handbrake at the lever and suggests that if it's over tight then no room for the self-adjuster to work correctly. s:D

s:D

Hope that this helps.

kidkarter · March 24, 2012, 18:57

hmmmmm ! very interesting !!!! i did not know this ! and although it has just passed an mot there is a lot more travel on my mk2's lever than i would like ! almost to its limit ! s:bowdown: :bowdown: s:bowdown:

Steve Green · March 24, 2012, 19:27

Just a note to reinforce what I have said on this thread and on the How To I wrote.

Most adjustment is done on the handbrake cables because the autoadjuster mechanism inside the calipers is seized. The hydraulics might be fine, but if the autoadjuster is seized no amount of adjustment at the handbrake lever end will change things. The chances are that the cables have not stretched and replacing them will have no significant effect.

Most garage mechanics have never been inside a caliper to see how they work. We on this forum are the expert amateurs, and a few specialist expert mechanics in things MR2. Most Toyota Mechanics never see an MR2, yet some still think they are the experts!

Aways start at the caliper end if you have handbrake problems, otherwise you will waste your time, money and effort. Read my How To first. If you can show me to be wrong, let me know and I will happily make the necessary changes.

Bossworld · May 12, 2017, 08:10

This is a great write up!

Can I ask one question about the auto adjuster? If the arm still moves relatively freely, and you can see the piston moving slightly as the arm is pulled, can the adjuster still be seized?

I've freed everything I possibly can, done the 180 trick and still my OSR is poor in comparison to the nearside. I can turn the piston using the tool in or out so that doesn't appear to be stuck.

I'm just wondering if the small amount of movement I'm seeing means that it's sort of working, but that the adjuster itself is seized?

Presumably if it wasn't seized and was working properly, eventually moving the lever enough times would bring the piston much further forward and it would stay forward?

Carolyn · May 12, 2017, 08:35

If the piston moves only 'slightly', you might have a problem in the adjuster or the bearing for the lever. The movement is very obvious on a good one.

These types of handbrake calipers are not unique to our cars. They were installed on many models and makes during that era (my civic had them), so no reason why a real mechanic wouldn't understand how they work. Unfortunately many 'mechanics' just replace calipers rather than fix them.

For the piston to move out further with repeated operation, it has to be prevented from spinning (which is what the nipple on the back of the pad and the notches in the piston do,as pointed out in this thread).

Also limited piston movement can be down to the piston sticking in the bore as it moves out . The only way to know is to take the caliper apart.

Bossworld · May 12, 2017, 09:05

Thanks Carolyn, makes a lot of sense. I'm going to see if I can sneak through an MoT (it passed last year and when I got the car four months later the OSR cable clearly had no effect) and hopefully save up for getting the calipers refurbed

Steve Green · May 12, 2017, 10:59

It's good to see that my advice is still holding up after 5 years

lamcote · May 12, 2017, 12:10

Are these videos any help?

m https://www.youtube.com/watch?v=nPRNbn9bdJg m

m https://www.youtube.com/watch?v=opjdu8DdVeA m

smarty72 · May 12, 2017, 12:24

I believe the handbrake only has to reach 16% efficiency to pass an MOT. So one side working well and one side working badly may well 'sneak' through an MOT.

Carolyn · May 12, 2017, 12:34

I think the main point (and Steve pretty much says so) is the caliper has to be sorted and working correctly. The cable adjustment is the very last bit once the rest has been done.

Bossworld · May 12, 2017, 13:02

The videos look an interesting watch, sorry I'll have to have a proper watch over the weekend. I think there's a chance the internal parts of the auto adjuster have seized and hence as Carolyn says I'm not seeing much in the way of movement for the amount the arm is being moved.

I'd love to say I've got the confidence to take mine apart but to be honest I'll probably be looking at a Bigg Red refurb if I get through the MOT. If not it'll be plan B.

With regards the previous MOT, the OSR can't have been doing any pull at all, and the NSR cable was in a terrible state too, cable tied on as the clip was missing as well (all since sorted).

It does hold on all bar the steepest of hills, but I suspect the NSR is doing the lion's share of the work.

Steve Green · May 12, 2017, 13:21

Videos are close but not quite the Toyota method.

Where I started from was that it seemed clear on the forum that people were changing their handbrake cables, because an MOT inspector reported that it needed adjustment, and not reporting more correctly that the auto adjuster had seized on one or more sides of the car.
So time and money were being wasted.
I fully admit that my How To is perhaps beyond some people's skills. But, it illustrates exactly the problem and a solution.
Some will try it and learn a bit more about their car, others will buy reconditioned calipers, but they will also learn how to set up the handbrake properly, and what points may need a little more TLC when it comes to servicing.

lamcote · May 12, 2017, 13:39

Can you explain the key differences between the videos and the Toyota method? I found the videos useful to help visualise the sort of thing that is going on with the handbrake mechanism, which I find helps me think through the solution. If you could point out what is different it would be helpful to arrive at a proper understanding.

Steve Green · May 12, 2017, 13:44

Quote from: "lamcote"Can you explain the key differences between the videos and the Toyota method? I found the videos useful to help visualise the sort of thing that is going on with the handbrake mechanism, which I find helps me think through the solution. If you could point out what is different it would be helpful to arrive at a proper understanding.

I would have to direct you to my How To where there are multiple photos.
I no longer own an MR2 and I don't have an extensive garage to store parts here in Spain!

lamcote · May 12, 2017, 14:43

OK thanks, I've looked at that and now think I can understand it a lot better. The message coming through from you and Carolyn is that the key is having the 1mm gap between the handbrake mechanism on the calliper and its stop. I think I can see that the Toyota doesn't have any ability to rotate the piston independently of rotating the handbrake mechanism which is what the Eldorado video shows.

So, if you have more than 1mm gap to the stop, what can you actually do to reduce it back 1mm? Assuming the rest of the calliper/sliders etc are OK, does it need a rebuild of the adjuster mechanism as per your How To or is there another more simple option to try first?

Steve Green · May 12, 2017, 15:34

Quote from: "lamcote"OK thanks, I've looked at that and now think I can understand it a lot better. The message coming through from you and Carolyn is that the key is having the 1mm gap between the handbrake mechanism on the calliper and its stop. I think I can see that the Toyota doesn't have any ability to rotate the piston independently of rotating the handbrake mechanism which is what the Eldorado video shows.

So, if you have more than 1mm gap to the stop, what can you actually do to reduce it back 1mm? Assuming the rest of the calliper/sliders etc are OK, does it need a rebuild of the adjuster mechanism as per your How To or is there another more simple option to try first?

Not sure if I can rake up anything more from what I researched 5+ years ago. The gap, with the handbrake cable properly tensioned is, I believe simply an indication that the system is properly adjusted, rather than being a definitive value.
Better that the auto adjusters work correctly.
Sorry, that's all I can offer.

Ardent · May 12, 2017, 16:27

The bit that gets me, what might be the root casue of the sleeve nut seizing on the adjusting bolt.

Corrosion? moisture in brake fluid? Rust? Different metals reacting?
How much of a job is it to properly "repair". To arrive at the sleeve nut freely operating as it should.

Makes me wonder how refurbed some refurbs are. Fully stripped to components etc etc and rebuilt or just external tarting up?