98 V70 front end wobble

Post by **98v70dad** » 16 Apr 2017, 17:57

I may have a giant clue in my otherwise unsolved front end wobble. I've replace everything in the suspension and both front wheel bearings and its still there. I don't regret replacing those parts because other than the wobble at 65-70 mph my ride is extremely smooth now - like a new car.

Whats the clue? Apparently taking the brake caliper off to replace the left wheel bearing made the wobble (pulsing?) much much worse. It now also pulses when I put on the brakes at high speed when it didn't before. I have rebuilt calipers, new pads and new rotors to put on next weekend. While they were off I noticed that the rotors are worn half way through. I was surprised by that since they brake just fine. They are probably warped and the calipers are probably sticking.

Why the wobble/ pulsing only happens in the 65 - 70 mph range doesn't make sense to me. Any ideas? The pulsing on braking only happens in that range too. It doesn't make sense to me. If I have warped rotors or sticking calipers they should pulse at all speeds. I have had the tires balnced 3 times and replaced once so I'm confident that has nothing to do with it.

Post by **E Showell** » 17 Apr 2017, 07:31

Usually wobble in a particular speed range indicates a wheel balance issue. Could be a bent wheel rim.

Post by **98v70dad** » 17 Apr 2017, 08:32

E Showell wrote: ↑17 Apr 2017, 07:31 Usually wobble in a particular speed range indicates a wheel balance issue. Could be a bent wheel rim.

I have had the tires balanced 3 times and replaced them once and I bought new rims so I'm confident that has nothing to do with it. After doing all of this I've changed wheel positions too - no change.

Teddy1975 · Post by **Teddy1975** » 17 Apr 2017, 08:59

It may be the warped rotor that makes the wobble. Why it only happens at 65-70 mph may be due to the resonance/vibration generated at that exact speed. While you're replacing the brakes etc next weekend, double check everything for tightness too when you have easy access anyway.

Post by **scot850** » 17 Apr 2017, 10:08

One of the mistakes I made in the early days was not cleaning all the rust of the mating faces between the rotor and the axle bearing plate. A also had a V70 XC that when I fitted new rotors the new Zimmerman (my preferred aftermarket option) rotors were warped on the rear out the box. Also had issues with the fronts that was only resolved by turning the new rotors!

Hopefully once you have done all the repairs on the brakes all will finally be good I hope for your car in regards to the 'wobble'.

Neil.

Post by **98v70dad** » 17 Apr 2017, 11:02

scot850 wrote: ↑17 Apr 2017, 10:08 One of the mistakes I made in the early days was not cleaning all the rust of the mating faces between the rotor and the axle bearing plate. A also had a V70 XC that when I fitted new rotors the new Zimmerman (my preferred aftermarket option) rotors were warped on the rear out the box. Also had issues with the fronts that was only resolved by turning the new rotors!

Hopefully once you have done all the repairs on the brakes all will finally be good I hope for your car in regards to the 'wobble'.

Neil.

Thanks,

I've had both rotors off to replace the wheel bearings. There is very little rust on the rotors (and the wheel bearings are new) but this weekend they will be replaced with Zimmerman rotors and rust wont be an issue.

I'm going to start with the front brakes but the back needs to rebuilt also. I have the parts but I don't have the time to do both front and back next weekend. I slightly over torque the wheel bolts because the specified 89 ft-lbs is just too easy to loosen. I torque to 100 ft-lbs which is only about 10 percent over. That said, 100 ft lbs may be too much for rotors as worn as mine. I was shocked at how thin they are when I had them off last weekend. They still brake just fine, but its good that they are getting replaced in a few days.

I've witnessed more than one wheel coming of at 70 mph in Atlanta traffic and I don't want it to be me....way too much excitement. The Volvo seems very sensitive to wheel lug torque, though. Every other car I've ever had you could just over torque away and it wouldn't be an issue.

Post by **scot850** » 17 Apr 2017, 12:48

They can be, but what I do is make sure the back of the wheel rims is flat as they can get a build up on the seating face that sits against the rotor.

Also, when I tighten my cars lug nuts I do a 2 stage. First just a nip up until there is a little resistance, then a star pattern the same with the other 4, and then tighten to the 110Nm/81ft/lb level. I then do a go around after that to ensure they are good and it has worked for me for years. Only time I had an issue was once when I was in a hurry and didn't re-check. I also will do a re-check after a short run. As I have 4 cars with winter and summer tires and rims to swap over every year it is something I check on regularly, and clean any rust on the rotor faces and rim seating faces each time.

Maybe a little anal, but it works so far!

Neil.

Post by **98v70dad** » 17 Apr 2017, 13:28

scot850 wrote: ↑17 Apr 2017, 12:48 Maybe a little anal, but it works so far!

Neil.

Engineers are paid to be anal.

I've worked in Nuclear power and Aerospace. Mistakes have really serious consequences there. Being anal only adds a little to the cost. Being anal on DIY jobs adds a little time and effort.

I do my wheels in 2 stages also. I tighten to snug in a star pattern with a breaker bar and then use the torque wrench to 100 ft lbs. I then drive them for a day and check the torque again.

Post by **scot850** » 17 Apr 2017, 14:22

A like-minded person. Great but can be a curse!

Neil.

Post by **98v70dad** » 17 Apr 2017, 16:37

scot850 wrote: ↑17 Apr 2017, 14:22 A like-minded person. Great but can be a curse!

Neil.

Agreed.