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Rusty Rear Brake Discs

16K views 14 replies 12 participants last post by  Rubik 
#1 ·
My rear discs have been rusty from new. The front discs are smooth and shiny. My Citroen garage don't seem concerned and say it all boils down to braking efficiency.

Now the car has gone in for its 18,000 mile service and the agent says the back wheel brake discs are rusty and I need to drive the car faster and brake more to prevent the rusting up problem. I have never heard such crap. They are asking me to exceed speed limits and brake at the last minute, i.e. use the brakes more. I tend to stick to speed limits, judge the road ahead, lift my foot off the accelerator when approaching hazards and then brake to stop.

Has anyone else got his problem... Rusty rear brake discs??? :?:
 
#2 ·
This is the same issue owners with A2 1.6FSi and TDI 90's have, namely under-used rear discs due to the lack of effort they provide - unfortunately it means you will never likely replace rear discs and pads for wear, more likely for corrosion.
 
#4 ·
Personally I'd be taking it to another dealer for second opinion.

Regardless of how much "use" the brakes see in normal daily life, any use should be enough to clear any surface corrosion. Braking efficiency isn't regulated by load or frequency of vehicle use - a press of the pedal compresses the equivalent amount of hydraulic fluid every time and hence the same amount of movement on the caliper.

You can just make out the rear discs in this pic...two years use with an empty boot and probably used once or twice a year with 4 up, otherwise 2 or one.
View attachment 1051

You shouldn't need to break any speed limits as a few emergency stops should clear the surface it other wise I'd be suspecting a seized caliper(s). Either that or its standing for long periods without use.
 

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#6 ·
Chances are the rear brakes are load sensitive. Fill up the boot with lots of heavy stuff and go for a spin round the block, should get them working and hence clean them up.
 
#7 ·
I have corrosion on my drums. It is cosmetic, but I know it is there and did check and it is excluded from the warranty. Any heavy breaking isn't going to help as the weight will transfer to front, lift the rear and the ABS will (I assume) reduce the breaking force in rear. You could try (gently) applying the handbrake when on the move, I expect that will apply rear brake only and give them a polish.
 
#9 ·
BristolRich said:
Personally I'd be taking it to another dealer for second opinion.

Regardless of how much "use" the brakes see in normal daily life, any use should be enough to clear any surface corrosion. Braking efficiency isn't regulated by load or frequency of vehicle use - a press of the pedal compresses the equivalent amount of hydraulic fluid every time and hence the same amount of movement on the caliper.

You can just make out the rear discs in this pic...two years use with an empty boot and probably used once or twice a year with 4 up, otherwise 2 or one.
View attachment 1051

You shouldn't need to break any speed limits as a few emergency stops should clear the surface it other wise I'd be suspecting a seized caliper(s). Either that or its standing for long periods without use.
The Cactus is driven every day covering about 250 miles a week so it doesn't stand around idle. I am thinking of drawing a line across the disc with permanent marker and just see how much is rubbing off.

I freewheeled down a long hill at 50+mph and just used the brakes to slow down. The front discs were boiling, the rear discs were touch warm, not even hot. Interestingly one comment saying they could be load sensitive? No idea but worth investigating. "Matressontheside" suggesting gentle use of the handbrake, I have already tried this. The discs got very hot but no significant rust removal but Citroen agent didn't approve of the handbrake technique. I think I am going to take the car into another garage and stick it on a rolling road to check their efficiency versus peddle pressure. As someone said, I am more likely going to be replacing because of corrosion before disc/pad wear.
 
#10 ·
Interesting. I have driven 15000 miles in my Cactus since December 2014, so not a high mileage car. Just checked the rear discs and they are shiny not rusty.
 
#11 ·
Peyote said:
Chances are the rear brakes are load sensitive. Fill up the boot with lots of heavy stuff and go for a spin round the block, should get them working and hence clean them up.
This brought back memories! My last Citroen with hydraulic everything was a Xantia, brilliant car, the brakes were to all intents an purposes an on/off switch arrangement with the pressure governed by the load in the car as the self leveling suspension acting as master. In those days we did numerous "booze cruises" to France. The more weight the car had to carry the more braking force was applied. Did stretch this well beyond published limits on occasion.

Time and space permitting retirement will grant me the opportunity to rebuild a deserving DS and really get to grips with what a wonderful system Citroen came up with. Few years off yet but it is on the bucket list.
 
#13 ·
I have a new cactus registered June 2017 and it has all round discs the same as my old cactus did. No rust. In my opinion rusty rear discs must be an imbalance in the braking system, otherwise all cars would suffer from it, which they don't.
 
#14 ·
Somebody made a suggestion (last year I think) to drive slowly in reverse a short distance while applying light foot brake pressure, to clean the rear discs.
For some people their normal daily routine might include this without any conscious effort, but for others it might need to be a deliberate activity...
 
#15 ·
I am glad it wasn't just me who HAD rusty rear brake discs.

I protested, complained and eventually my Citroen garage offered me a goodwill gesture and charged me £200 to fit and supply new rear disc brakes. Lets see how long they remain looking like new.
 
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