Rear Disc Guard / Backplate - Possible MOT Fail?

[GiveMeABreak]

So had a bit of a shock getting out of the other car yesterday, when I noticed something not quite right near the C5s rear discs. Got out and gave it a good poke - then shot off to check what is was - turned out to be the 'Brake Disc Protector' had rotten through in places, leaving an odd shape - which is what initially concerned me:

Oh, ignore the surface rust on the discs - they are newish, but the car doesn't get used for days on end!

I checked the part (4209 A8) £37.06 Each! - A lot for a piece of cheap tin by the looks of it.

So looking at it, the pads, calliper and disc has to come off to get to the bolts that hold it on - but thankfully not the hub as some would seem to be fixed to.

So with the MOT due in Feb I thought I'd better get these replaced and as a precaution, went to research a little as to whether this would be an MOT fail.... This is where the fun starts. There seems to be a lot of opinion as to whether this is a fail under the Section 3.5 J:

Section 3.5J
Check: "presence and security of brake back plates, wheel cylinders and calipers"
RFR: "a brake back plate, wheel cylinder or caliper securing device loose, missing or excessively deteriorated"

MOT Tester Forum - Can't Make Their Mind Up!
Volvo Owner was MOT-Failed
Audi Owners Comments

My own thoughts are that it is down to the terminology used in the MOT manual. A 'Brake Backplate' would seem to be applicable to vehicles with Drum Brakes - and not the other term used for what is basically a 'Dust shield'. As the Dust shield has no electrical or mechanical interaction / effect on the braking system, I can't see how it could be a fail.

I'll probably get a set ordered and locally fitted - but would be interested in opinions from others as to whether it could be classified as a failure. If the MOT testers can't agree, and with some users being failed for it and others not - it really seems to be down to the tester on the day

[wurlycorner]

I wouldn't expect it to fail, unless they are flapping around and in danger of falling/flying off. I know my latest Xantia passed it's last mot with one plate completely missing.

The backplates are absolutely terrible quality on all Citroen's. They rot so easily but as you say, are horrendously expensive to replace for what they are (a thrupence pressing, basically!)

[CitroJim]

I've had a Xantia pass without the protectors being fitted...

I say you'd get an advisory at worst but I would replace it as they do keep a lot of crud out of places it's not good to have crud accumulating...

[Oldpug]

As said it would only fail if its insecure,leave it alone. If you attempt to replace it expect one or more of the bolts ( 3 ) to snap off causing more grief.

[CitroJim]

If you attempt to replace it expect one or more of the bolts ( 3 ) to snap off causing more grief.

Yes, agreed. They always do on Xantias unless great care is taken or lady luck is smiling on you...

[GiveMeABreak]

So if they were completely removed it should't be an issue for the MOT (out of sight, out of mind), but if they are on and breaking apart, then it could be a red flag to a bull?

I may as well get them replaced as to get them fully off will be the same amount of labour to replace them. I think I'll probably give the new ones a good coat of Hammerite before getting them fitted.

Looking at the Brake Plate for a 406 with Drum brakes - this would seem to be the part referred to in the MOT as it has a lot more gubbins on:

I don't like the look of the offside one, as that has the flaky part left after some has broken away. As you say Jim, I think it better to replace as they would seem to keep a load of crap away from the other components, plus I wouldn't want any more bits breaking up and getting into places that could cause more damage.

[miked]

If you attempt to replace it expect one or more of the bolts ( 3 ) to snap off causing more grief.

Yes, agreed. They always do on Xantias unless great care is taken or lady luck is smiling on you...

2nd agreement sort of. Changed mine, but with the axle in bits off the car. cleaned up all around all the bolt heads to get a good 6 point 10mm socket on. was advised to use impact wrench to 'shock it'. First side 2 out of 3 sheared. Other side, first one sheared so switched to manual 1/2" wrench and gentle increasing pressure and it came out fine (As in, i'm a weakling and was shocked how easy). Same too with the last one. A C5 is possibly similar to my 2003 Xsara and I've never attempted changing one on a Xantia but all I can advise is don't use brute force.

The grief with the ones that sheared was fixed by tacking them on with a little bit of weld through the open holes. Also, the new plates look like uncoated mild steel so give them a lick of paint first.

I gave mine 2 brushed on coats of what I think was silver body shop spray paint, then got loads of black hammerite on it off my gloves as I was painting other parts at the same time.

[bobins]

Looking at the Brake Plate for a 406 with Drum brakes - this would seem to be the part referred to in the MOT as it has a lot more gubbins on:

Indeed. The 406 one would best be described as a drum brake back plate, whereas yours would be best described as a disc brake dust shield/plate.
Drum brake back plates really do need to be sound as they have quite a few forces put through them as most of the braking components (excluding the drum itself !!!) are mounted to them !

The MOT confusion seems to come about as 'brake back plate' can be interpreted as covering both disc and drum plates, whereas I'd assume it's meant to be directed at drum brakes or brakes that have braking components directly mouted to the plates - and NOT disc brake dust shields.

[wurlycorner]

Yep. Drum brake back plate definitely need to be solid.
Disc brake back plates are just heat/dust Shields. Definitely advise that they are still fitted, but don't worry about that one on yours, for the mot.

I would be tempted to get any news ones powder coated.

[Michel]

I wouldn't expect it to fail, unless they are flapping around and in danger of falling/flying off. I know my latest Xantia passed it's last mot with one plate completely missing.

I've had more than one Xantia go through the MOT with missing backplates. They're made out of tinfoil anyway. I'd be very, very surprised if Marc's would fail. They need to be loose and flapping around dangerously, surely?

[Paul-R]

So if they were completely removed it should't be an issue for the MOT...

Indeed. Back in the day it was de-rigeur to remove the disc backplates on rally cars to help improve cooling.

[Bandit12]

Hi guys I have had one missing from back of my c5 for several years and cars passed MOT with no advisories for 3rd year in a row.

Bandit

[GiveMeABreak]

Mine’s actually not quite missing - yet! Some of it is broken off, so it might be worth me waiting until the rear discs need doing again before getting them done.