Simon's new Xantia V6 and Leaf blog

[bobins]

When refitted, the drums can be a bit of a snug fit against the backplate - not touching, but not much clearance. Make sure the edge of the drum and corresponding part of the backplate are cleaned back of rust and crud so the drum can rotate freely - a simple wire brushing will do the trick.

With modern drum brakes and braking systems in general, there's only three main issues that'll cause you to fit new shoes - mega mileage, the handbrake doesn't completely release, or you drive everywhere fully loaded. The average car will rarely - if ever - need new shoes on the back.

[CitroJim]

Those drums are even more conventional and old-fashioned than the drums on small ICE FWD PSA cars like my Saxo...

They look a lot more Japanese than European to me... Not unlike the rear drums on the Pixo. Good to see proper wheel studs rather than bolts...

It all looks pretty immaculate in there Simon and here's hoping a good dust-down, a clean-up and reassemble will do the trick...

[white exec]

One place you can gainfully smear a little copper grease is on the drum/hub mating surface, which should stop the drum rusting to the hub. For next time. If there is. Which there hopefully won't be. Unless...

[Mandrake]

All finished, and pretty successful I think!

When refitted, the drums can be a bit of a snug fit against the backplate - not touching, but not much clearance. Make sure the edge of the drum and corresponding part of the backplate are cleaned back of rust and crud so the drum can rotate freely - a simple wire brushing will do the trick.

Yes I noticed the right hand drum had a lot of rust on the lip - I ended up sitting it down flat on the concrete and rotating it by hand - smooth concrete does wonders here.

With modern drum brakes and braking systems in general, there's only three main issues that'll cause you to fit new shoes - mega mileage, the handbrake doesn't completely release, or you drive everywhere fully loaded. The average car will rarely - if ever - need new shoes on the back.

It's even more so the case with an EV due to regeneration doing all the light braking for you. The friction brakes don't even act at all until you brake moderately rapidly or press them to hold yourself stationary. Apart from coming to a complete stop I can do the majority of my driving on regenerative braking alone. There are plenty of documented cases of Leaf's front brakes lasting 100k miles let alone the rear. (Not sure if a Leaf has discs or drums at the rear)

For EV's I think it's going to be the case that brakes will never need to be replaced because the linings have worn thin - front or rear, they'll need replacing due to other things like rust, warping, lack of use etc.

Those drums are even more conventional and old-fashioned than the drums on small ICE FWD PSA cars like my Saxo...

They look a lot more Japanese than European to me... Not unlike the rear drums on the Pixo.

It is Japanese! It's a Mitsubishi hiding behind the Peugeot badge remember Jim.

Good to see proper wheel studs rather than bolts...

I couldn't agree more! After years of driving Xantia's with their infernal and awkward to fit wheel bolts its so nice to have a car with studs and cap nuts again...so easy to fit and locate the wheels and the lug nuts compared to bolts. I never really understood the reasoning behind going from traditional studs to bolts for wheels...all older Citroens like GS/CX etc had studs as well.

Anyway I stripped everything down and gave everything a good clean (I was impressed with Wynns brake and clutch cleaner, it just dissolved the grease and sticky muck instantly leaving it spotless) and found what I think was the main reason for the brake stickiness/binding.

Apart from everything being coated in greasy sticky brake dust, it appears that the baking plate has some sort of hard black enamel paint on it which has worn through to the metal on the little raised ears where the side of the shoes contact, and they were snagging in the resulting depression:

Before clearing the backing plate there was hardly any grease on these ears and it was a yellow gummy stuff - not sure what it was. I ended up deciding to use copper grease for the backing plate ears, as well as the bottom shoe guide: (not visible)

I used normal lithium grease in the thread of the self adjuster, which was a bit gummed up with a dirt/dust/grease mixture. I also sanded the rusty lip off the inside edge of the drum where the edge of the lining would touch, and chamfered the trailing and leading edges of all the shoes slightly.

Put it all back together and adjusted the handbrake adjuster so that the hand brake started applying at 3 clicks and was on hard by 5.

The only thing I wasn't completely happy with is the drum on the right hand side seems to be slightly eccentrically located - there is a tiny bit of dragging noise at one point in its rotation - and I also noticed that if I pulled the hub off and turn it around on the studs that it was a lot worse in some orientations than others when in theory if everything is true it shouldn't make a difference. So I just fitted it in the orientation where it did this the least, and it seems very minor. The left hand side came out perfect and doesn't seem to care what orientation the drum was fitted.

I've taken it for a drive and so far it seems to have completely solved it locking/grabbing when pulling to a stop, in fact when I pull to a stop now it does so nice and smoothly. There is also no scraping or squealing anymore.

As tomorrows weather is also predicted to be dry I'm now seriously thinking about doing the front discs tomorrow - I don't have the rubber bush and silicone grease to do the slide pins yet, but that doesn't stop me replacing the discs and pads... and the pins are a relatively quick easy job that can be done later. The important thing is to get the big part of the job done while the weather is good...

[bobins]

All finished, and pretty successful I think!

Marvellous, and a lot cheaper than taking it to a garage

The only thing I wasn't completely happy with is the drum on the right hand side seems to be slightly eccentrically located - there is a tiny bit of dragging noise at one point in its rotation - and I also noticed that if I pulled the hub off and turn it around on the studs that it was a lot worse in some orientations than others when in theory if everything is true it shouldn't make a difference. So I just fitted it in the orientation where it did this the least, and it seems very minor. The left hand side came out perfect and doesn't seem to care what orientation the drum was fitted.

That's entirely normal. As Mr Humphries used to say on Are You Being Served - "It'll ride up with wear"

I've taken it for a drive and so far it seems to have completely solved it locking/grabbing when pulling to a stop, in fact when I pull to a stop now it does so nice and smoothly. There is also no scraping or squealing anymore.

Might be best to schedule in another clean-up for two years time to keep those brakes working nicely ?

[Michel]

As Bobins says, a drum dragging very slightly can be (or would have been) considered normal after reassembly. My experience with drum brakes leads me to believe "they all do that sir". Indeed, some of the vehicles I have had, most lately the Renault 4 based DRK didn't have self adjusters, so I used the ancient "tighten them up until it locks then back it off so it just binds a tiny bit" way of doing it. Essential to get right when adjusting each shoe on the front axle separately, and more than a tad frustrating.

Glad you've solved your problem! I'm watching with interest as I'm considering an electric small replacement for one or two of our 3 cars..

[Mandrake]

Indeed, some of the vehicles I have had, most lately the Renault 4 based DRK didn't have self adjusters, so I used the ancient "tighten them up until it locks then back it off so it just binds a tiny bit" way of doing it. Essential to get right when adjusting each shoe on the front axle separately, and more than a tad frustrating.

I actually ended up doing exactly that! The official PSA procedure Richard sent me says:

Remove the blanking piece (16).
Adjust the notched wheel (13) so that the shoes are just touching the drum.
Refit the rear wheel.

Umm, OK PSA...

The blanking piece is a rubber bung in the backing plate that lets you manually turn the handbrake adjuster with the hub fitted, so they're telling you to turn it until the shoes are touching the drum, and then leave it there... great, but how can you tell they're touching except by noticing them dragging. And then surely you'd want to back them off a bit so they're not dragging all the time ?

I wasn't happy with this procedure so I did what you describe - I manually adjusted each adjuster to get the handbrake biting correctly. I'd left the handbrake adjuster under the centre console alone on the basis that the handbrake was adjusted correctly before and I was refitting the same shoes, so I adjusted the individual adjusters in the drums so that there was no drag on 1 click, starting to bite but still turnable on 3 clicks and on solid after 5 clicks, which is about how it used to be. And I made sure that both drums were biting the same amount on 3 clicks.

After this and giving them a little bit of bedding in there is no drag at all with the handbrake off but they bite nicely with a moderate pull of the handbrake.

It's important that the adjusters aren't too tight, not just to avoid range killing parasitic drag, but to allow the regenerative braking to work effectively. About the first 30mm of brake pedal travel is supposed to be regeneration only, then the friction brakes are blended in seamlessly beyond that point. If I'd left them adjusted tight as the official procedure describes as soon as I touched the brakes lightly the rear drums would be coming on together with regeneration and you'd loose the efficiency of regeneration on light braking. How I've set it seems to have ended up just right.

Glad you've solved your problem! I'm watching with interest as I'm considering an electric small replacement for one or two of our 3 cars..

I doubt any of the other available EV's use drum brakes, although I'm not sure. As this car is based on an ICE vehicle it has just inherited the brake design from that. Even if they do its very unlikely there are any other rear wheel drive EV's with rear drum brakes!

The only other rear wheel drive EV's I know of are Tesla's and I think the BMW i3 is rear wheel drive as well (naturally) but all the Japanese and Asian models apart from this one seem to be front wheel drive at the moment.

One thing for any RWD lovers though, is that rear motor, rear wheel drive makes a lot of sense for an EV - large or small, from a packaging perspective. Tesla has shown just how effective the packaging can be with the motor basically hidden under the boot floor and a more or less empty front engine bay for storage...

And on the Ion there more or less isn't a front engine bay! The bonnet opening is barely wide enough to replace the 12v battery and there's not much stuff in there...just a few ancillaries like ABS controller, power steering, brake fluid reservoir, fuse box etc.

Once the EV market matures I think we'll start to see a lot more small RWD cars than we typically see today where FWD dominates.

[Mandrake]

So I decided to brave the -4C temperatures and aches and pains from the previous days drum brake work to do the front brakes yesterday.

On the whole it went well and the front brakes on this car are a dream to work on - very easy to disassemble, so no problem there. I could have done the whole job in a fraction of the time of the drum work, were it not for a couple of snags...Here is everything stripped back:

And here are the new discs sitting in place:

There are no locating screws holding the discs on this car - in fact they have the same M8 threaded holes to use as pullers to get the disc off as the rear drums... I didn't have any M8 bolts within reach without searching through countless containers spread around the house and garage so I just carefully tapped it off from behind with my block hammer - took a while working my way around to keep it even but off it came.

The two bolts that hold the caliper assembly onto the hub I was initially worried about - I couldn't get them undone with my normal ratchet and I don't have a breaker bar but then I remembered that my torque wrench had a 17mm socket with half inch drive, and that got them undone easily, and I later used it to do them up to their correct 100Nm.

The major snag I ran into that turned an otherwise very smooth easy job into a bit of a pain was that the new pads didn't fit in the caliper!! The ears protruded too far and physically could not fit. And if I forced them in, they were so tight that they would never move freely so they wouldn't work properly.

They measure about 0.5mm longer tip to tip than the original pads - which themselves were wedged in kind of tight as well... These calipers have well designed stainless steel shims with built in anti-rattle springs which you can see in this picture:

I checked there wasn't any rust build up behind the stainless steel shims but there wasn't, and I'd already cleaned the shims as well, but there was no way they were going to fit. So I did a little bit of googling to see if other people have this problem and whether it was an acceptable fix to file a bit off the ears of the pads!

Apparently its a relatively common problem on some cheaper pads that the ears aren't stamped very precisely and they often don't fit very well if at all. I didn't like the idea of filing them since I'm filing the protective paint layer off them which will inevitably lead to the tips of the ears rusting in the future but I don't see what other choice I have ? At least in this case the ears only contact stainless steel shims so they're unlikely to actually rust solid into the calipers like they do on calipers where it is just steel to steel contact.

I ended up having to take about 0.8mm off the total length of the pad measured from ear to ear before I felt they were fitting and moving well with a little bit of clearance of around 0.4mm to allow for rust growth in the future without them getting tight again. The way the shims are designed the spring loaded part keeps them tightly in place even with a little bit of vertical clearance so they don't rattle at all. I also put a little wipe of copper grease on the shims.

I have to wonder how many out of spec pad ears there are on 3rd party pads which are too tight but loose enough to be jammed in that people just go ahead and forcibly fit without considering that they will seize and not work properly especially as they get rusty... In this case they were so over size that they just wouldn't go in so I was forced to file them.

The other half expected snag I ran into was the rubber bush on the lower slide pin which wouldn't go back in easily on the right hand side last time I had the brakes apart decided it wouldn't go back in at all on either side now - it's swollen enough now that it just snags in the hole and tries to ride over the pin jamming the pin and preventing it being inserted.

I didn't have the new rubber bush or the silicone grease I needed yet, so I was always going to have to redo this bit of the job, so I ended up just leaving the rubber bush off altogether and not greasing the pin since I don't have the right grease yet - there is enough of the full diameter pin to hold everything together, it just means the caliper may rattle a bit over bumps - and it turns out it is rattling slightly but not much. I'd much rather a slight bit of caliper rattle than the caliper slide pin jamming - even if I could have got it in!

I'll pick up the rubber bush and silicone grease this week then next chance I'll whip the pins out again fit the new bush and grease the pins, which is a relatively easy job.

To be honest I think the rubber bush is more trouble than it's worth - I don't see the point of it, and don't see why they didn't just fit metal pins for both. The top metal pin fits the bottom hole perfectly and is identical besides the bush so if I felt so inclined I could just buy two of the top pins to fit in the bottom and dispense with the stupid rubber bush and its tendency to swell and jam altogether! Since I've already ordered the bush and silicone grease I'll try that first though and see how it goes. But if it gives any trouble in the future I think I'll replace the bottom pins with the solid variety.

I took it for a good 30 minute drive to bed the new brakes in - which took a surprisingly long time. Also the rear brakes didn't seem very sensitive (including handbrake) since the work the day before and then suddenly about half way through the test drive I noticed the brakes were a lot more sensitive - and on trying the handbrake I found it MUCH more sensitive than before, so apparently the automatic adjusters in the drums had finally decided to tighten themselves up a bit! (They took their time, I'd probably done about 30 miles since the rear drums were done!)

The handbrake now starts to grip with only 1 notch on the lever so I might actually slacken the handbrake cable under the centre console slightly now that the self adjusters in the drums have tightened so much.

Towards the end of my test drive the front discs have finally started to bed in and are starting to "bite", but I think even now the front discs/pads are not fully bedded in. I found it was useful to slip the car into neutral before braking hard during the bedding in process to disable regeneration so all the braking effort is friction brakes only instead of the motor helping. (hindering in this case)

I read somewhere that for disc brakes to bed in there needs to be a microscopic coating of brake dust over the entire swept surface of the disc, which takes quite some time on brand new discs/pads. Apparently this barely visible coating of brake dust fills in the microscopic groves in the disk and that the braking effect comes not through friction between the steel of the brake disc and the pads, but largely between the coating of brake dust adhered to the disc and the pads, so it is actually friction between pad material on the pad and pad material coated on the disc. When you think about that you can see why replacing discs and pads together takes some time to bed in vs just replacing pads as old discs would already have this coating.

Another factor is I think new discs have a thin protective coating to prevent them rusting during shipping that the pads have to wear through to get to the real metal surface ?

[white exec]

Note that you didn't check whether there was any run-out (lateral wobble) of the new discs on the old hub. You could be lucky! (Not sure whether you have a surface micrometer and magnetic stand.)
If you do get any front brake vibration when the brakes have settled in (and that you can't check with a micrometer), then just rotate the disc on the hub bolts by 90deg, and try again. Four possibilities for minimum run-out, which should be 0.002"/0.05mm-ish. A cleaned hub mating surface also helps.
Those backplates etc could do with a coat of wax, back and front; they're very rusty, and can vanish altogether if not protected. There's no danger of applied wax getting on to the brakes.

[CitroJim]

I've had the same issue with after-market brake pads being a bit long or inaccurate in the ear department Simon...

A few seconds on the grinder soon sorts it... Never painted over it. just smeared a thin layer of copper grease on...

[Michel]

I've used the grinder on pads that don't quite fit many times. I was taught to do this when I was only 13, helping out in my Nan's friend's back street garage on a Mk2 Escort. Imagine that now, a 13 year old being allowed to use a grinder in a working garage!

Made me laugh with your careful tapping of the disc to get it off. Most discs I've done, have needed rather more than that

[CitroJim]

Made me laugh with your careful tapping of the disc to get it off. Most discs I've done, have needed rather more than that

Me too.. I've smashed 7 bells out of them with a bloody great sledgehammer before now...

Great for relieving frustration...

[Michel]

Made me laugh with your careful tapping of the disc to get it off. Most discs I've done, have needed rather more than that

Me too.. I've smashed 7 bells out of them with a bloody great sledgehammer before now...

Great for relieving frustration...

When we did the Berlingo at yours it needed a good smashing!

[Mandrake]

Note that you didn't check whether there was any run-out (lateral wobble) of the new discs on the old hub. You could be lucky! (Not sure whether you have a surface micrometer and magnetic stand.)
If you do get any front brake vibration when the brakes have settled in (and that you can't check with a micrometer), then just rotate the disc on the hub bolts by 90deg, and try again. Four possibilities for minimum run-out, which should be 0.002"/0.05mm-ish. A cleaned hub mating surface also helps.

Well actually I did check for run out, I just didn't mention it. I don't have a dial gauge or anything fancy like that but I did a careful visual check along the edge while turning the hub - on the old discs there was definitely visible run out, on the new discs there is none that I can see, they look absolutely spot on no matter which way I orient them! So maybe I am lucky... There's also no vibration during braking now. I was careful to clean the face of the hub first and I put a thin layer of copper grease between hub and disc.

Those backplates etc could do with a coat of wax, back and front; they're very rusty, and can vanish altogether if not protected. There's no danger of applied wax getting on to the brakes.

Not sure what piece you're calling the back plate ? Are you referring to the two fingers that clamp over the outer pad from the caliper ? Or are you referring to the hub face that the disc goes onto ? If the later, I put a thin coating of copper grease over the face where it meets up with the disc, also around the edge where as you say it had quite a bit of surface rust. Better than no protection, probably!

[white exec]

It was the thin steel backplate (arrowed) that I was thinking ought to be wax protected, both sides.
They have a habit of progressively rusting away, especially in salty conditions, and have been known to be annoying MoT failures.