850: scrape/judder/rubbing when turning right @ low speed

[notyap]

Thought i'd make a new thread for my issue as the previous one wasn't fully accurate to what i'm experiencing!!

I have a 1996 850 2.5 estate with 196k (drives likes its done less than half of that). During the COVID-19 lockdown I didn't drive it for about 3 months, and since then it has developed a weird noise when turning right whilst braking, only at slow speeds.

For example, on coming up to a junction and turning the wheel slightly right as if to start to pull out (nowhere near full lock) and applying the brake to slow down. It feels like a scrape/judder coming from the front drive side wheel, but can also be felt through the brake pedal. Will also do it when parking, again with the brake applied lightly and the wheel turned slightly to the right - e.g. if turning to pull across a lane/space to park. Almost feels like something is catching, but only at a certain amount of steering input and only with the brake applied lightly.

I can't make the noise/judder happen when turning lock to lock when stationary, whilst driving over about 20mph, or any kind of left turn. It only happens when the brake is applied, but even then it doesn't have to be a lot of brake to happen.

Originally I thought power steering as it felt a bit on the odd side, but having done power steering fluid and bled it all nothing has changed.

Engine mounts look fine, and no juddering on idle.

CV joints look in fairly newish condition, and the issue can't be made to happen lock to lock steering at a slow speed.

Steering stops were a bit dry, but presumably these only matter for full lock.

No noises when going over speed bumps or bumpy roads either.

Annoying I don't have a driveway so i've done about as much as I can on my hands and knees looking for anything out of place, but am out of ideas!

[andrewc1267]

Possibly you could have a high point on the break discs where the pad was when the car was parked up for awhile if it is that it should get better with use

[notyap]

Originally Posted by andrewc1267

Possibly you could have a high point on the break discs where the pad was when the car was parked up for awhile if it is that it should get better with use

i did think that, but it only happens on a right turn and never when braking in a straight line/turning left...

[Martin Cox]

Is it possible this could be ABS related?

It might be that the cable or connector to the ABS sensor on one front wheel has developed a fault such that at one particular angle of the wheels, the ABS module loses contact with the sensor. The ABS system might then regard this wheel as having stopped or at least rotating at a wildly different speed to the rest of them. This might activate the ABS which would be felt through the brake pedal.

This is pure conjecture on my part: What do people think?

Martin

1998 V70 Tdi auto 226,000 miles

[Luxobarge]

Originally Posted by Martin Cox

Is it possible this could be ABS related?

It might be that the cable or connector to the ABS sensor on one front wheel has developed a fault such that at one particular angle of the wheels, the ABS module loses contact with the sensor. The ABS system might then regard this wheel as having stopped or at least rotating at a wildly different speed to the rest of them. This might activate the ABS which would be felt through the brake pedal.

This is pure conjecture on my part: What do people think?

Martin

1998 V70 Tdi auto 226,000 miles

Interesting theory, with a good deal of merit. Could also possibly be a cracked or corroded reluctor ring? Maybe the rings are marginal and the very slight change in alignment of the wheel when turning is just enough to tip it over the critical point and mean it doesn't deliver a smooth ABS signal?
Cheers

[notyap]

Originally Posted by Luxobarge

Interesting theory, with a good deal of merit. Could also possibly be a cracked or corroded reluctor ring? Maybe the rings are marginal and the very slight change in alignment of the wheel when turning is just enough to tip it over the critical point and mean it doesn't deliver a smooth ABS signal?
Cheers

Ah the braking system - now we're into the realms of what I can't do on the street outside my house..! I've got a pretty reliable independent Volvo garage locally, the number of different things it could be means i'll have to give them a call!

[amazondean]

ABS related, sounds the obvious answer to me also!

[Martin Cox]

To add a little weight to my hypothesis, I don't believe the ABS operates at very low speeds and almost certainly not at the speed at which one could comfortably turn from lock to lock. This might be why you can't reproduce the problem under those conditions.

Cracked or corroded reluctor rings certainly wouldn't help.

Do let us know how you get on.

Martin