When I bought my NC two years ago, it had slight brake judder.
The rear disks looked to be almost new, the front ones i thought wouldn’t hurt to replace and would probably cure the judder at the same time.
It didn’t, which leads me to believe the judder is infact on the rear.
I’m pretty sure i can get hold of a dial guage, any idea what degree of runout would be enough to cause brake judder. ?
Hi ,using years of experience,(I do not have a workshop manual for the Mazda ) I would not want run out of more than 2 thou .002 ins ,but ,before going down that route there are a few basic checks you could make . I would guess the front is at fault , check and clean and grease the caliper sliding pins and ensure the calipers move freely ,pistons not sticking. Remove the discs ,clean and degrease throughly to remove any coating on the disc surface ,ensure the face that mates with the hub and the hub itself is de greased and very clean ,remove any traces of rust with light emery . if this does not work carefully check the maximum runout over the disc face
Hope this helps
Dave
When I replaced the front discs last summer, I had the pins out and greased up etc.
I knew within 50 yards of fitting the new discs that the judder was still there, exactly the same.
This is what makes me think it might be on the rear.
I guess it’s not going to hurt to get hold of the gauge and spin all four corners.
Brake judder is usually caused by thickness variations caused by uneven pad transfer it may not show up on a dial gauge.
The wheel face can also pull discs out of shape if they are not flat. It is a common problem on refurbished or painted wheels where there is over spray.
Working on the rears last night, I found it really difficult to truly measure any runout.
Firstly, there was no where substantial to attach the magnetic base, so i eneded up attaching it to my took box off the car.
Sneeze and it moved.
Anyhow, the best I could measure was 0.04mm, but having said that, the moment i even touched the disk, the dial moved slightly, so I’m not sure how accurate this was.
This was around the same on both sides.
For my next test, I applied the hand brake 1 notch.
On the passenger side, the resistance was consistant.
On the drivers side there was definately a small drop in resistance at a certain point in the rotation.
After rubbing both pads briefly, the resistance was consistant.
Then laid in bed last night, i realised, that I didn’t align the pin on the pad into the grooves on the piston, so I’ve to take it apart again this evening.
I’ll set about playing on the front maybe tomorrow evening, but I guess the drivers rear gives me a starting point.
EuroCarParts has a 15% discount code and with free same day delivery.
Pads & Discs for £41 delivered, it’s not worth messing about. I’ll change the rears, and see where it goes from there.
Yes similar to a used oil analysis that is the same cost as the oil and filter. Therefore in a lot of cases just as cost effective to change components.
And the time involved.
Last week, I had both rear wheels off and tested with a runout gauge.
The drivers side, I removed the caliper, carrier, pads etc to remove and inspect the inside of the disk.
I might as well have just changed them then.
Whilst I guess my time is free, I often wonder how much my personal life is worth per hour.
Might be best to change them
Ha ha… They are already on.
Got home at 5. Had my dinner. Sat down in front of the telly for 6.30.
Need to test drive it but it looks like rain so it will have to wait a few days.
Well, it looks like what ever it was, it was on the rear.
A 50 mile country drive yesterday, and the judder has gone.
Annoyingly I can’t find any substantial runout on the discs, I see nothing that looks like hot spots etc.
Everything looks as you would expect it.