Judder Under Braking, NC3.75

Technical Area Wheels, Tyres & Brakes
1
  1. My model of MX-5 is: NC3.75 2.0
  2. I’m based near: Hereford
  3. I’m looking for technical help or recommendations on: Trying to solve an issue with judder under braking that has not been solved by changing discs and pads.
2

We’re the hubs thoroughly clean before you mounted the new discs?

3

I had a judder/shake on mine when I first got it - it turned out the slides and pistons were sticking.
Full caliper rebuild, fresh discs and pads sorted it out.

4

I believe so.
Had a set of discs and pads under warranty and things seemed better for a while but then problem recurred.
Even had the osf hub replaced as there was a binding issue.
Am planning on finding a new garage/specialist for them to take a fresh look.
Thank you

5

Thanks. Thats interesting.
Anyone recommend a specialist in the SWM region who could take a look?
Cheers

6

Slider pins.
Mine did exactly the same, new discs and pads cured the issue for a few thousand miles, just enough for the pads to fully bed in and the fault came back.
I chased the fault for a while.
I borrowed a laser thermometer thing and went for a short run with some heavy braking, and found the o/s front was much warmer than the others
One of the front slider pins has a rubber sleeve and it was this rubber sleeve which had swollen.
Not enough to sieize the pins, but enough to cause judder.
Just to prove the theory, I took the rubber sleeve off and refitted the pins, the judder went way.
News pins cost about £12

7

Great, thanks for all the advice!

8

If you are reasonably DIY savvy - the slide pins are pretty easy to replace.
These are the ones I used

9

Thanks for the part info!

10

If vibration comes back after about 3,000 miles, it usually means the discs were fitted with excessive runout (dirty hubs). The pads kiss the disc on the same high spots on either side with every single rotation and you end up with slightly thinner discs at those two points, giving judder on braking. Then you need to do the job again properly with more new discs and pads.

11

Even if you not into DIY, it doesn’t need much in the way of tools to service your own brakes. Often judder just needs the calipers off and clean up the pins the brakes slide on to operate properly. It often needs repeating ever few thousand miles and that’s money saved with little skill needed.
A few miles drive, check the discs, if one is hotter than another it’s probably binding on it pins.