Brake Judder

[swordfish210 20]

Hi guys. I'm having some fairly serious brake judder on my 306 when i push the pedal down over half way. It seems to happen when i'm slowing from about 50mph+ and it gets very bad as the car slows i.e. the whole car starts to shake, but then i'll get down to about 20 and it goes away. If i'm braking from say 30mph i get some vibration in the pedal but none in the car.

 

The brakes other wise seem fairly good, the pedal is nice and firm and the stopping distance is good. Is it fair to say that it's a warped drum as it feels like it's coming from the rear. Thanks. Mark

[jimistdt 1]

The judder may be the pads/shoes trying to tell you something. I had this on mine last week, and I almost convinced myself to buy new pads and disc. Luckily it was just the pads, they were very very low, well one side was, and it was starting to eat the disc.

 

New pads, or shoes in your case may be just the ticket.

[swordfish210 20]

I was thinking along the same lines. I don't think it's the fronts as i checked them when i had the wheels off and although the pads looked a bit on the thin side they were still what i would call serviceable. I didnt check inside the drums because i hate removing drums. I may do it at Uni so i can stick the drums on the lathe with a DTI and check the run-out. Thanks mate.

[welshpug 1,645]

good plan re-checking the runout, most drums can be refaced too as long as they're not too oval or worn, thankfully if they're not seized 306 self adjusters do work very well, only if the handbrake cables are in decent condition though.

 

specs from Haynes are 180mm new, 181 after machining. shoe thickness 4.85mm new 1.5mm Minimum.

 

if you have ABS the drums will be 228.6mm, and will be secured like a disc, i.e you don't need to remove the hub nut only the two screws.

 

judder could also be the front mountings on the beam, these can cause a clunk going over speedbumps.

[swordfish210 20]

Thanks mate, i'll try and get it on the ramp at uni tomorrow and have a good look at everything.

[jengis 0]

On a previous 205 I had a similar brake judder that new front brakes didn't sort.

 

*Try this at your own risk*

The best way to check if its front or back brakes is to use the handbrake. Pull it on steadilly on a dual carriage way type road. This showed up clearly that it was my rear drums that were at fault - on inspection it looked like a previous owner had used a hammer to remove them, rendering them scrap in the process!!!

 

More recently, a worn steering rack solved a high speed brake judder problem, evidence was vertical and latteral play in the steering arms, this was causing them to vibrate under the inward load imposed by heavy braking forces.