406 seized rear caliper change & pressure bleed

[ex-vaux]

Decided to do an brake check on the wife's 406 and found to my alarm that the rear calipers were seized, solid! Someone had fitted new discs and pads at some time, but the discs were hardly worn and had a fair bit of rust on them! I sourced a pair of recon calipers and pads from ebay for £115. If your on a budget or really keen, you could just replace the piston seals at around £20 a pair. The pistons will come out with some compressed air, a foot pump is sufficient, don't forget to put a rag between the piston and caliper and keep your fingers out of the way! If the pistons won't budge, soak overnight in magic juice (WD40).

Decided to replace both rear wheel bearings and stabilser bars as well for another £95, they are a weak link in an otherwise good set up. I also decided to go the whole hog and do the front discs and pads for a measly further £25, shame not too reallly at that price!

I had expected to have some problems bleeding the system after reading about the ABS module draining down when removing any part of the hydraulic components. Haynes claim you will then need to take the car to Peugeot to rectify! Nope, that ain't going to happen, under any circumstances! However, in my case, it was'nt necessary even though I took both rear calipers off and left the pipes to drain overnight!. Haynes recommend disconnecting the battery, which I did'nt bother doing at first but did when I bled it up. You could clamp the brake pipe's as an option, but I wanted to completely flush the system out. You could also remove the master cylinder reservoir and give it a clean, mine was filthy.

I initially used my vacuum bleeder fitted to the workshop compressed air tank. No problems on the front calipers, but the rears were a different matter. I could'nt get any fluid out with the vacuum bleeder!
Time for the big guns to come out. Borrowed my mates pump pressure bleeder and had the whole system done in no time! Needed 15+ pounds of pressure. Good solid peddle as well!

Apparantly some ABS systems can 'store' air in the ABS module and the pressure bleed method is best for trying to shift it. To be sure, I will give it a couple of hundred miles and bleed the system again.

A further point to note, is if your 406 is fitted with a pressure compensator to the rear suspension (ours is'nt), it will need to be fully bled with all four wheels on the ground due to the valve needing to be fully open. The compensator can be a problem and may not bleed properly even with the wheels firmly planted. May need some attention if this is the case! This is where a pressure bleeder will make the job a bit easier if you don't have a pit or some other method of raising the car up on its wheels you can just about reach the rear calipers from underneath.


Sorted!

[Peter.N.]

I had a similar problem with mine, in fact it failed the MOT because the n/s rear brake was binding. I tried unsucsessfully to free it off but got a good secondhand one from ebay for about £25.00. The union had severly corroded to the pipe so I unscrewed the caliper from the pipe after clamping the pipe, on refitting I just let gravity bleed it and its been fine.

What hasn't been though is the handbrake, I replaced the disc/drum assemblies plus shoes and pads and it still won't hold on a steep hill. Everything seems to be fairly free although the cables have rusted somwhat but I am having difficulty finding reasonably priced replacements as there seem to be several different types.

Peter

[addo]

When fitted, wire the pressure regulating valve fully open for bleeding; it's a simple enough mechanism. The other reason for rears being hard to bleed on some Peugeots, is the 180° bend in the flex hose to each rear suspension "corner". Sometimes you can be better off fitting a wood spacer into the caliper and holding it upwards (above the spindle) so the flow purges air towards its bleeder.

Cracking the ABS block fittings to bleed, is another old trick for expelling much of the air.

[ex-vaux]

I believe the handbrake cable shrouds can wear through and then rust inside preventing the cable moving properly. I noticed this on my wife's cables where there is a round support just before they enter the disc backing plate. They are still working okay but will require changing at some point. Might be a reason your handbrake is not holding if the cable won't move freely!

[Peter.N.]

One of mine has rusted right through the outer but it still seems to move OK, especially after I squirted some oil in it, but I expect they do need replacing.

Peter

[poddack]

I discovered a similar problem this week, the bottom slider bolt on the rear left caliper was totally siezed in the off position and the right side was ok to engage and stiffer to release.
I found replacement bolts and gaiters from bigg red for £29 all in.
Some hard work with my brake piston pusher and loads of WD40 got them out and the new one's just slipped in with a dollop of copper grease.