Simon's new Xantia V6 and Leaf blog

[Mandrake]

Return (pull-off) springs normally link shoe-to-shoe.
In that picture, the RH end of the spring does seem to be pulling on the adjuster (or is it the handbrake lever?), but where it pulls is so close to the pivot that it will be pulling on the shoe as well, I guess. Perhaps that one spring is made to do two jobs: shoe return and handbrake relax.

As bobbins amended post says, there are two springs there - the one you can see is the automatic adjuster spring. The shoe to shoe spring is behind and under the cylinder. I've highlighted the ends of the shoe to shoe spring here as well as a tiny glimpse of it you can see at the arrow behind the front spring:

Simon, a latest photo above does show six (copper-greased) pads.
I'm puzzled by this photo, though. Not sure what I'm seeing there. Looks almost as if a pad had been partly ripped away, and turned upwards. Can you clarify? I'm certain those pads should all be flat.

That's the top right backing pad from the photo with the grease before the grease was applied. It's not ripped away its just a flat raised painted pad with a big gouge in the middle cut into it by the edge of the shoe...

[Mandrake]

Just to clarify from a previous post of yours - the book method of adjusting the shoes up is to put it all back together then....


brake adjuster.jpg

The notched wheel (at 13) that they refer to is what you, I think, refer to as the self adjuster.

Yes I have that service page - I initially followed it but the problem is if you follow it literally you are tightening the adjuster to the point where the shoes are dragging when the handbrake is left... doesn't seem right to me even if it is listed in the service manual...

The article I linked from earlier today had an interesting comment on this:

Brake shoe adjustment is another common cause of rear brake lockup. It is generally accepted that rear brakes should be adjusted until a slight drag is felt. This procedure only applies to a small handful of older vehicles. The methods listed by the vehicle’s manufacturer’s vary widely and sometimes incorporate some rather odd steps. A good generic approach to use is to quick set the shoes to the drums and then use the vehicle’s self-adjusting system to complete the process. Vehicles with duo-servo rear drums (Figure 61.1) should have several stops made when backing up. This will complete the adjustment. Most FWD vehicles self adjust when braking while the vehicle is moving forward (See Figure 61.4). Once the rears are quick set test drive the vehicle to finish the adjustment process. It should be noted that this procedure will only work if the self adjusting system is functioning properly.

I pretty much came to the same conclusion independently - which is that it was better to start with a bit more slack and let the self adjusters find their natural adjustment point after a test drive.

[Mandrake]

The tilting of the shoes was an oft found thing on drums when problems of operation arose. If you tourniquet or cable tie the brake shoes in a circle, so that wheel pistons don't pop out, then get an assistant to gently press pedal with that drum off, as you press the shoes in, it may just give an indication of what is happening when it starts to operate. Maybe try a finger nail inside the drum for any raised wear or scores. If there is, a flap disc in a drill would feather it down even as you go round. I used to rub the drums inside with 120 grit to rough up( with new shoes anyway)

I did actually give the inside edge of the drum a light sand with sandpaper - mainly at the edge where there was a slight rust lip though. The main contact area felt perfect to me with no sharp edges or bumps.

Adjusters normally fail for fun on the Jap drums like Honda, but it is usually that they don't keep up with wear and you have to turn them manually. Yours may be Akebono system, with it being Japanese derived car?

Not sure. The adjusters seem in perfect condition to me. I didn't take any pictures and a bit hard to describe but basically a U shaped hook at one end and W shaped at the auto adjuster lever end, the toothed wheel in the middle that the adjuster ratchet arm turns is threaded into one half and is just a free turning bush in the other half.

[Hell Razor5543]

If you look at the upper of your two pictures, Simon, it looks like the pad to the right has slipped around on the mounting plate. If you compare it to the pad on the left, there is obviously a difference. Not having the whole pads to compare against does make it tricky, but the end of the pad is near to the fold (left pad), while the pad on the right is over the fold.

[bobins]

Does applying the handbrake only act on one shoe on each side or is there a mechanism to apply to both shoes per side ?

[white exec]

IMG_0457-1.jpg

Simon, a latest photo above does show six (copper-greased) pads.
I'm puzzled by this photo, though. Not sure what I'm seeing there. Looks almost as if a pad had been partly ripped away, and turned upwards. Can you clarify? I'm certain those pads should all be flat.

That's the top right backing pad from the photo with the grease before the grease was applied. It's not ripped away its just a flat raised painted pad with a big gouge in the middle cut into it by the edge of the shoe...

Sorry, but you've lost me there.
All six of those pads should be flat, surely. The one in the photo above really doesn't look it.
What is the turned-up edge? How deep is the gouge in the pad?

[bobins]

Sorry, but you've lost me there.
All six of those pads should be flat, surely. The one in the photo above really doesn't look it.
What is the turned-up edge? How deep is the gouge in the pad?

The wear marks circled red:

Wear marks - Mandrake (modified)

Correspond with the brake shoe frame circled blue:

Brake shoes - Mandrake (modified)

[white exec]

I've looked and I've looked, but I cannot make sense of what's in that red circle.
The pads should be flat and smooth. That one - presumably - needs plating over or something put in its place. It cannot have ridges and be expected to work.
A bolt-head in the backing plate, in contact with the back of the brake shoe, would do the job.

[lexi]

Don't know if this wee link has been posted: http://www.engineeringinspiration.co.uk/drumbrakes.html

[Mandrake]

If you look at the upper of your two pictures, Simon, it looks like the pad to the right has slipped around on the mounting plate. If you compare it to the pad on the left, there is obviously a difference. Not having the whole pads to compare against does make it tricky, but the end of the pad is near to the fold (left pad), while the pad on the right is over the fold.

If you mean the two shoes are not centrally located at the top, horizontally - no they probably aren't in the photo, because I almost certainly moved the shoes back and forth sideways after removing the drum but before taking the photos. So that's not a problem. Remember the drum will force the two shoes to centrally locate themselves when you apply the brake with the drum in place - assuming they can slide freely to do so of course!

Does applying the handbrake only act on one shoe on each side or is there a mechanism to apply to both shoes per side ?

Good question, to which I don't have an answer off hand. The hand brake cable comes in at the bottom and attaches to a long lever towards the rear. Looking at the picture you posted a few pages ago, it looks like the handbrake lever pushes on the handbrake adjuster rod from the rear end and in doing so pushes the front shoe against the drum, which would be the leading shoe. It's not clear to me without disassembling it again whether it would also somehow push against the rear shoe or whether only the front leading shoe is activated by the handbrake.

Sorry, but you've lost me there.
All six of those pads should be flat, surely. The one in the photo above really doesn't look it.
What is the turned-up edge? How deep is the gouge in the pad?

I think you're getting fixated on what is either just a shadow or a reflection in the paint. The edge is not "turned up", all the pads are raised, flat sections, albeit with some wear grooves in them. The gouge is the full depth of the paint down to bare metal.

Don't know if this wee link has been posted: http://www.engineeringinspiration.co.uk/drumbrakes.html

Thanks - that looks really good and I haven't seen that page before. I'll have a read.

[RichardW]

I'm pretty sure the handbrake will act on both shoes, put probably sequentially, only moving the second one when the first is in contact with the drum.

Reading that link is interesting - read the bit about grabbing and spragging; particularly the last sentence about not being able to release the brake. I think this definitely points the finger at a sticking shoe - perhaps one is not moving at all, and this is putting the other shoe into a position whereby it is grabbing / spragging. I would be getting those pads sanded back ASAP! Weather might not be too bad at the weekend - if you give it a go and it's too hard, give me a shout and I'll pop over with the grinder

BTW - how is it in the snow on the Quatracs??

[Mandrake]

I'm pretty sure the handbrake will act on both shoes, put probably sequentially, only moving the second one when the first is in contact with the drum.

I can't quite remember what it looks like, but I think it acts like a lever pushing the handbrake adjuster rod "apart" at one end - in which case it probably would act on both shoes.

Reading that link is interesting - read the bit about grabbing and spragging; particularly the last sentence about not being able to release the brake. I think this definitely points the finger at a sticking shoe - perhaps one is not moving at all, and this is putting the other shoe into a position whereby it is grabbing / spragging. I would be getting those pads sanded back ASAP! Weather might not be too bad at the weekend - if you give it a go and it's too hard, give me a shout and I'll pop over with the grinder

We're still under quite a bit of snow here with more to fall yet - I haven't got around to buying a snow shovel yet. Would a grinder not risk gouging into the metal and ending up with it being less flat before ? I do have some small grinding stone attachments for my drill including a cone shaped one that might work and be a bit more gentle. Otherwise wire brush and/or sand paper!

BTW - how is it in the snow on the Quatracs??

Pretty good! On the first morning of heavy snow fall on the way to work it was unsalted fresh snow fall everywhere, and was especially bad in Coatbridge where we drop Joshua off. There's a few different routes I can take to his Grans just before we get there and of course I thought I'd try the steepest one to see if it would get up the hill at all! No salt, plenty of fresh snow and pretty steep, I did have to accelerate fairly gently and the traction control was chattering on the rear left wheel from time to time (annoyingly the one with the sticking shoe!) but it made it up without any real difficulty. I was most impressed.

Then that night on the way home after not having any real problems myself during the day despite terrible conditions, just down the road from us I encountered a lorry stuck near the top of Merry Street, spinning his wheels, and further behind him were littered about half a dozen cars all in varying degrees of stuckness spinning their wheels unable to move up a slight incline! And behind them were 3 more lorries and a queue of cars sitting there like numpties waiting for... I don't know what ? If that was me I would have turned around and tried to find a less slippery or shallower route as there are several ways around that bit! They were all sitting there like sheep in headlights not sure what to do, including the guy sitting in the middle of the roundabout I needed to use blocking it until I tooted him to move up a bit... which he did with spinning wheels.

I drove carefully past the lot of them without any problems at all and without so much as any wheelspin. Sure, if I put my foot down a bit or tried to chuck it around corners in those conditions I'd loose traction too, but it was very controllable and I was able to start and move off from stationary without any wheel spin and never felt like I was in any danger of losing control or skidding. If anything a little bit of controllable power on oversteer on snow can be quite fun...

Then later that night while home we heard the sounds of various vehicles getting stuck trying to get up Jerviston Road - I watched one transit van for about 5 minutes as he made about 10 metres progress, inching forward then slipping back... It's not even particularly steep!

It's been the worst snow/ice conditions I've driven in by far since I've been here (I didn't have a car during the infamous 2010/2011 winters - I just pointed and laughed at other people ) and I had no real concern that I was going to get stuck as long as I drove carefully and to the conditions. Even on patches of black ice I had enough grip to get going and keep some control, and the grip on fresh snow was amazingly good, not really any worse than you'd get on a metal road! I'm feeling quite smug about going for All Season tyres now, and they perform adequately in summer as well, (not quite as good as the dedicated summer tyres that were on before, but close enough) so I'll use them year round.

I've also found them really excellent in deep standing water with heavy rain - I don't really notice any difference in grip between a wet road and a road that has standing water - and that wasn't the case with the old tyres.

[RichardW]

I've got a wirebrush and a sanding disc for the grinder...

Pretty much mirrors my experience on winter / all season tyres. The current ones on the 307 are more or less worn out, so are a bit of a handful, but still outperform others on summer tyres. Dunlops with complete circles of rubber seem to be particularly bad; must organise some new ones! I find that snow tyres are best on fresh snow too - in 2009/10 I drove the Xantia on winters in deep snow - it was only when I tried to get out that I realised it was actually deeper than the bottom of the door. It had just kept going no bother. Often if you're on a rutted road it's better to move over a bit and drive on the fresh snow to get best traction.

[white exec]

Handbrake acts mechanically (via levers, usually) on both shoes, and virtually simultaneously. Applying braking to only one shoe would be to induce unneeded stresses on the drum, and be unstable (could let go when parked).

Sorry not to be able to interpret the photo. Getting rid of the ridges on the pads is definitely a first step.

[Hell Razor5543]

Since I have seen a wider shot photograph might I suggest you look at the shoes and pads. On the earlier shot (first photograph, first post on this page) you can see that the left pad ends at the crease, while the right pad bridges the crease. However, in the lower photograph in the seventh post on this page you can clearly see that the pad bridges both creases on the metalwork. I wonder if the pads might have been put on the wrong way around (so the left pad and the right pad are in the wrong position)?