ABS problem + clunking noise.

I have a 2000 X Reg TD4 Auto and since I bought it in April I have constantly had a problem with the brake pedal/brakes. When I apply the brakes gradually, I can feel a slight shudder and the brake pedal forcing my foot upwards. I took it back to the garage 3 months ago and although the problem has not worsened, it has'nt improved either. All the garage advised was that it was most likely one of the 4 abs sensors, but they could not identify which one until the problem got worse. They said ALL 4 abs sensors could be replaced to eradicate the problem, but this would be expensive, as I could'nt do it myself and they suggested I left it until it got worse, but my Mrs does'nt feel save driving it. Also, I am concerned this problem could be an MOT failure, is that right anyone??

The other problem I have, when I am turning quite sharply round a right corner, a left turn does'nt affect it, there is a loud thudding or clunking noise as if something is jamming underneath, but as I straighten out the noise goes. It appears to be coming from the rear or middle of the vehicle, but it's difficult to pinpoint it. Any ideas what this could be?

Thanks
Steve

Sounds like the VCU is knackered (seized) and so will either or both of the diffs be soon if you don't replace it.

Thanks for your reply. How can I tell whether it's the viscous coupling unit? It appears it's hard to identify if its worn, as I believe i'ts a sealed unit? I don't want to go to the expense of buying another VCU if I can't identify the source of the problem?

Any ideas on the ABS problem I'm having??

Thanks

Have a look at the rear UJ at the diff for your clunk. Jack up both wheels on one side and turn the shaft by hand to check.

Thanks for your tips, I will get the UJ looked at on the rear diff.

There's a sticky at the top of the page which details how to check the VCU.

You abs sensor sounds definitly the problem with you foot being pushed back as this is how they work, try jet washing from the back of the wheel to get rid of any crud on the abs ring and then get a tourch and have a good look at them, failing that you will need to replace. If they are really stuck in you need to undo the stub axel and get a hammer and a drift small enough to fit down the hole and hit it from the middle when you put your new one in it comes with grease smear this all over, and push it home(when the driveshaft is back in) and when you move the car this will ajust it to its correct position hope this helps