I've got a pulsing wobble when applying the brakes that I feel through the steering wheel. It's at a constant rate that's directly related to my speed. It is variable in it's intensity but can be present from a cold start and can get more prominent after a longer drive. 

My first thought was a patch on a brake disc because I did have a binding problem that was eventually fixed but it isn't this. I've been reading about ABS issues and loose caliper guide pins but after a recent trip to the garage I was wondering if the following symptoms pointed to a particular cause of the problem. 

I had a hub replaced due to a caliper guide pin being loose which turned out to be a stripped thread. At the same time I also had my drop links replaced due to clunking noises over bumps.

When I got the car back from the garage the brakes were perfectly smooth (ruling out a patch on the brake disc and isolating the problem to that n/s/f corner).

This lasted for about 10 days but the pulsing when braking then returned.

So it seems that everything was initially perfectly in place after the work was done at the garage but has since settled back to where it was? (During the 10 days I took the car on holiday and had to drive over a year's worth of speed bumps).

 

Does this point to a particular part that could be the cause by becoming misaligned? 

 

Thanks for reading

Maybe an uneven air gap on one of the sensors. I'd suspect the one with the replacement hub, unless a correct press was used to install the new bearing.

I would think the bearing hasn't been fitted correctly and the increased air gap is messing up the speed signal.

 

Live data check with diagnostics would confirm if it is the same wheel as the new bearing.

Assuming the new hub/bearing were fitted correctly - I suspect you have 'run out' on one of the disk.

Thanks for the replies. 👍 

 

Would the air gap just cause issues with the abs sensor causing it to activate or does it mean that the bearing itself is also misaligned, meaning the brake disc is not on a correctly aligned base? 

 

In terms of fitting the bearing correctly can the existing bearing be reinstalled correctly with the correct tool or does it mean a new bearing is needed? 

 

Seeing as the problem disappeared for a short while after it was last at the garage but then reappeared does that suggest a particular part that has moved and rule out a runout issue?

 

Thanks

I've just been out for a drive with the abs fuse removed (the 40a fuse in the battery fuse box) and the juddering was still there when braking. The abs light was on and the stop light was flashing on the dash. 

 

When I got the car back from the garage last time the braking couldn't have been smoother. It was unnerving seeing as I was so used to the judder. 

 

Could the bearing have slipped? 

@DaveSk - That's pointing to disc or bearing run-out then. The ABS light was correctly reporting an ABS fault (no power to system) and the idiot light was being idiotic.

Thanks.  

So I'm into this territory then:

 

Brakes are a common misconception, and brake judder is very very rarely caused by a warped disc. In the huge majority of cases it due to deposition of brake pad material in some areas, and wearing of the steel in other areas if the disc isn't running true. Imagine the hub is running slightly out of true, so the disc oscillates are it rotates through the caliper. Some points of the disc will get worn more, and others will get brake pad material transferred to them more. If you fit new discs to slightly wonky hubs, they'll run slightly out of round. This doesn't matter when you first put the discs on as it's too small to notice. Over time this wearing/deposition builds up to a greater extent and what you end up with is not a warped disc, but a disc with a a thickness variation around it, i.e. some bits thicker/some bits thinner. You feel this when you brake. The rate of increase of wear/transfer increases over time, so it gets worse faster as it goes on. New discs will fix it, but only for a short time and it'll then come back again. Ask me how I know...

For me it took around 500 miles for the judder to come back on a front brake, after the hub bearing had been very slightly knocked by someone driving into my parked car. I never noticed at the time, until 500 miles later. New discs and it came back again 500 miles later. Rather than get new hub bearing put in I scrapped it (very old car) and got something new - I'd already invested a lot of time/effort trying to fix it and just gave up.

On the new car a wheel bearing went after 20k miles. I got a new one pressed in by a specialist garage. 500 miles later I got brake judder again... Effing mad!!! Armed with more knowledge, I didn't bother getting new discs. I got the current discs re-skimmed ***on the car***. This is important, you can't skim them off the car and refit, it won't work. I used a tool by a company called Pro-Cut (no affiliation to me whatsoever). The first garage couldn't work their own tool. The second garage did it in half an hour, cheaper than new discs, and the car was fine for another 20k miles until I sold it.

http://skimmydiscs.co.uk/why-skim-your-discs


This is all assuming the discs have been fitted correctly, spotlessly clean disc/hub etc and properly torqued wheel nuts. If not, try that first. If yes, check the hub runout. If it's even slightly out I bet getting your discs skimmed on the car will fix it. Sorry for the essay, but I've learned a lot after having this problem several times, and there's a huge amount of poor/misinformation out there.

Still baffles me why my old juddering disc, when put onto a new hub, ran smooth for 10 days. 

You'd think that the judder would've been there straight away. 

As suspected by posters on here. The problem was related to the bearing being changed without using a proper press. Possibly an air gap, but at an MoT a keen eyed mechanic spotted a bent bit of the steering knuckle (the protruding bits that the pads sit between). I've replaced the knuckle with a scrap part that included a bearing and the problem has gone. No juddering, no overheating on that side and improved mpg.