AWD Rear clicking under normal braking

[befarrer]

I have been noticing my 98 V70 AWD has had a clicking noise when applying the brakes in a normal situation, and I only notice it under about 50KM/h. If I panic stop, it doesn't seem to do it. The noise can be heard inside and outside the vehicle. From inside, it sounds like someone tapping the rear suspension with a small hammer, from the outside (with head hanging out door at slow speeds), it sounds more like a creak. It doesn't seem to make the noise until the brakes warm up, after a few KM of city driving. I have had both calipers apart, pads are less than 25% worn, anti rattle springs are good, I added that goop to the pads to stop noise, but it doesn't seem like the pads have been moving (no shiny spots where they touch caliper, etc...). I get no noise when driving, only under braking. My park brake works normally, and I rebuilt the park brake shoes and hardware a few months ago. I have my AWD disabled by removing the driveshaft, but everything else is intact and functional, I only have my driveshaft removed because my summer tires are used and not worn evenly, it gets re-installed for winter. Could it be a wheel bearing? I cant see it being a driveshaft as no power is going through it.

[Richard99]

My guess would be torn CV axle boots. Have you checked the condition of those? If they're torn, they could be the culprit. It would be unusual for the rears to tear, though.

Eric

[scot850]

If the clicking is coming from near the back, as you have an AWD it may be the VC (viscous coupling) 'nose' bearing failing. I had a similar issue with a 98 V70 XC and went through everything until I found this. The bearing fell apart when removed.

Other issues you can check are:

1) Parking brake shoes de-laminating in rear hubs
2) Center bearing or front bearing on the prop-shaft. Usually a good wiggle on this will show this up.
3) Finally, check the rear axle CV boots are still good.
4) Check the heat shield above the cat has not holed around the mounts above the cat. If I recall it might be able to get close enough to touch the prop-shaft.

I think the last 3 are least likely but quick to check.

Neil.

[scot850]

Oops! Should have added to check the rear brake dust shields are not rubbing in the rotor, and that both rear calipers are working correctly.

Neil.

[befarrer]

Prop shaft is good, it has been sitting on my garage floor since April. Would any of the rear driveline make noise only under braking when disconnected, as the load on the driveline will be minimal, and not change. All of my CV boots are good, rear diff fluid is full, it was changed about 10 months ago.

[scot850]

Are you 100% sure it is only making noise while slowing down and you are just not hearing it until you get your foot off the gas?

Does this happen when the brakes are pressed or will this happen when just taking the foot off the gas and slowing down without brakes being applied?

As the prop-shaft is out we can obviously ignore that for now!!

I'd still check the angle gear for bad bearings. They can show up with noise once you take the foot off the gas. It could even be the connecting sleeve between the trans and the angle gear is damaged.

I'd still be looking at the brakes at the rear for properly moving and free calipers and the parking brake shoes being solid.

Is it possible to record the noise when it happens. That may help to identify the cause more easily.

Thanks,

Neil

[Richard99]

+1 on the parking brake shoes idea.

[befarrer]

Update: I have done nothing to the car, and the noise has stopped, I have not noticed it for the last 2 weeks. IT has cooled off outside now, and its below freezing now, but will keep an eye on it.

[abscate]

We still charge $150 for problems that self fix. It’s a management fee.

I’m guessing brake plate was source, those noises can come and go in a funny way, even from changing the load in the trunk.