Rear Brake Squeal And Grind

[JASWC1]

ON MY C5 2.0 HDI IVE RECENTLY BEEN GETTING A SCRAPING NOISE FROM THE REAR AS IF THE BRAKES WERE METAL TO METAL,

ON INSPECTION THE CALIPER HAS BEEN TOUCHING THE WHEEL RESULTING IN THE TOP CORNER OF CALIPER BEING WORN AWAY AND A RING WORN IN THE INSIDE OF THE WHEEL.

?????? ANY IDEAS ON THE CAUSE ???????

[paul.h]

Welcome to the forum.

 

Are the wheel bolts tight and the hub/wheel contact surfaces clean ?

 

Is the wheel distorted (pothole damage) ?

 

There may be a problem with the wheel bearing - with the car jacked up is there a lot of play, does the wheel turn smoothly ?

 

A possibility which I have read on this forum (but not experienced) is that corrosion can occur where the rear brake caliper joins the suspension arm which causes the caliper to move out so the disc is not in the middle. If this is the case, then the solution would be to remove the caliper and clean off the corrosion. Care needs to be taken since the fastening bolts have lock tight down their length and are difficult to remove. Also the caliper can split so after removing the pads, the pad cover retaining bolt should be refitted to hold it together or the caliper may end up needing replacing.

[old'uns]

 

 

A possibility which I have read on this forum (but not experienced) is that corrosion can occur where the rear brake caliper joins the suspension arm which causes the caliper to move out so the disc is not in the middle. If this is the case, then the solution would be to remove the caliper and clean off the corrosion. Care needs to be taken since the fastening bolts have lock tight down their length and are difficult to remove.

 

this is most likely cause, mine went summer last year.

whilst in france on hols got puncture rear d/s. put spare on & got a knocking noise :blink:

turned out that 'blob' at start/end of weld on inside of spare wheel was catching caliper

might be worth trying this as it doesn't need much movement of caliper

[Johndouglas]

 

 

A possibility which I have read on this forum (but not experienced) is that corrosion can occur where the rear brake caliper joins the suspension arm which causes the caliper to move out so the disc is not in the middle. If this is the case, then the solution would be to remove the caliper and clean off the corrosion. Care needs to be taken since the fastening bolts have lock tight down their length and are difficult to remove. Also the caliper can split so after removing the pads, the pad cover retaining bolt should be refitted to hold it together or the caliper may end up needing replacing.

 

I agree that this is the likely cause. I had it on my previous Xantia and after the corrosion was removed and new pads fitted, things were back to normal. What I disagree with is the statement that the fixing bolts have locktite on them. Knowing that corrosion between the caliper body and the steel bolts can build up over time, I removed the bolts on my C5 when it was only a year old and coated them with copper grease. The bolts were easy to remove.

[iannez]

done qute a few of these but none so severe the calliper made contact with the wheel. surely it would lock the disc up before it gets that bad.

[old'uns]

done qute a few of these but none so severe the calliper made contact with the wheel. surely it would lock the disc up before it gets that bad.

 

didn't hit the wheel as such, where the outer & inner parts are welded together, at start/finish of weld there is a small raised 'blob' this is what was catching enough to make noise. wheel is painted black, 'blob' was shiny where paint was rubbed away by caliper catching

[iannez]

i see. remove calliper m8 and clean the 2 faces where the calliper sits flush with the axle and cover with copper slip. the bolts do have locktight on them and can be a nightmare to get out. you will have to fit new pads as they will have worn at an angle and as said earlier dont forget to replace the bolt that holds the pads in. no need to have pads in and make sure its tight or the calliper will split when you remove the fixing bolts. good luck mate.

[Stuart js]

Hi all, this seems to be a problem, I had to replace rear discs on my 2.2hdi last year, and just a a matter of course I coated the aliminium faces with a fine smear of blue hylomer (non setting instant gasket) wont know until the next time but it shold be OK, as my other form of transport is a motorcycle, being extra careful in respect to dissimular metal corrosion is natural.

As for get the bolts out, my tip is loads of tea!!! - undo each bolt a little at a time, spaying penetrant as you go, then when it get very tight, spray a little more and have a cuppa! or 2 or 3..... works fine.

 

good tip with the pad bolt, as if it falls apart bleeding the brakes would be required!!

 

stu

[JASWC1]

i see. remove calliper m8 and clean the 2 faces where the calliper sits flush with the axle and cover with copper slip. the bolts do have locktight on them and can be a nightmare to get out. you will have to fit new pads as they will have worn at an angle and as said earlier dont forget to replace the bolt that holds the pads in. no need to have pads in and make sure its tight or the calliper will split when you remove the fixing bolts. good luck mate.

 

ITS FIXED,IT WAS BUILD UP BETWEEN CALLIPER AND SUSPENSION ARM,THANKS FOR HELP;;;;;;;

[shallishanti?]

Does anyone have a torque setting for the caliper mounting bolts?

[kfk]

Does anyone have a torque setting for the caliper mounting bolts?

 

70Nm

[shallishanti?]

thanks kfk

[paul.h]

Had a slight twist to this rear brake squealing problem, one of the caliper retaining bolts snapped on refitting. All the warnings from kfk about this being a problem job due to the loctite are fully justified. Here is the saga. (2004, 2.2 hdi, hatchback mark 1, 23k miles).

 

Rear drivers side squealing on gentle brake application which just applying copper grease to the pads did not cure. On close inspection the disc was not central in the caliper. 18 inch breaker bar was enough to undo the caliper bolts against the locktite in the caliper. After pad removal refit the pad retaining bolt tightish. Undid the caliper bolts with the breaker bar just enough to clear the suspension arm and was able to move the caliper enough without disconnecting the brake pipe (to save bleeding). Lots of corrosion between the arm and caliper, removed with a file and applied copper grease. Refit caliper without much bother although the bolts were tight due to the locktite and required effort to turn.

 

For completeness then started the other side, found no corrosion but still applied grease. On this side the bolts were even tighter to turn and on doing up one snapped. Appeared the threads had cross threaded but I did not notice due to the loctite. Anyway, fully removed the caliper - had to saw off the broken bolt between the caliper and suspension arm. Loss of brake fluid stopped by a bleed nipple cover over the end of the brake pipe. Then drilled out the bit left in the suspension arm but threads were not recoverable. Hammered out the bolts from the caliper and drilled out the locktite. Applied copper grease in the caliper bolt holes and to the bolts so they do not corrode - I suspect this was the reason for the loctite. The caliper bolts are grade 10.9, M10 diameter, 150mm long with metric fine threads, usual high tensile bolts are grade 8.8 which are not as strong. So far I have been unable to get a hex head bolt long enough (160mm) to fit through the suspension arm with a nut on the back that is grade 10.9 so I have used a cap head bolt (allen key type) that is grade 12.9 with a nut on the back. Grade 12.9 is stronger than 10.9 so is ok but looks different.

 

I bled the brakes using a Gunsons easibleed with pressure on the reservoir - worked well and also did the clutch (awkward from under the car). At 3 years it should have been due a change of brake fluid so time not wasted. However, without the code reader/scan tool it is not possible to operate the abs system to change the fluid fully so I will get that done at the next dealer service.

 

The rear brake pads took a couple of weeks to bed back in again since they had slightly worn at an angle but with 7mm minimum left they will be ok for a year or 2. After several weeks the squealing has not returned.