Occasional vibrations at speed - 850 1997

DennisCA · Post by **DennisCA** » 02 Nov 2025, 01:28

This doesn't happen all the time, but often and usually around 80-100kph or so, which is like 50-60mph. But the car vibrates, it feels like something might be unbalanced. It's not the engine as I can just press down the clutch and coast and it makes no difference.

So I've previously done the following:

-Replaced the right side outer CV joint on my 850 (FAG brand, should be quality)
-I also refurbished the OEM driveshaft, squeezed new grease into the bearing too.
-All tires are brand new 205/55/R16s and the wheels got balanced.
-Front brake rotors and pads replaced weeks ago.
-Rear brakes cleaned and exercised, rotors got cleaned up with a rotary steel brush and they looked to have much life left.
-Parking brake refurbished and new wire on left side.

I've otherwise not done anything to the suspension, I do plan on replacing the front struts and I have some aluminum lower control arms I am gonna refurbish as well.

Personally I am still thinking it might be the tires having some slight unbalance, because while it got better with new tires, I primarily experienced these issues last year with these wheels. When I put on the winter tires (195/65/R15s) last year the problem became much better. I haven't yet put on the winter tires for this season because the weather has been so mild and looks to continue yet, and it's dumb to drive 60km/day with studded tires on asphalt for weeks.

Still at the same time, if it was the tires, why doesn't it happen every single time?

Post by **abscate** » 02 Nov 2025, 04:57

If the car sits for a week or more it can take some time to eliminate flat spots onthe tires ,especially with soft rubber winter tires.

The other wear item that can do this is ball joints/control arms. - I have experienced that.

Post by **erikv11** » 02 Nov 2025, 08:03

Do you trust the shop that balanced the wheels? I got mine balanced at a chain store and the vibration wasn't fixed so I thought it was somewhere else. Then the Volvo mechanic told me both front wheels were out of balance, one of them badly. He re-balanced them both and the problem is now greatly reduced. It's not gone, something's still off, but it hardly bothers me now.

My point being, make sure you can trust whoever is balancing the wheels.

Post by **scot850** » 02 Nov 2025, 11:34

If you are driving on Alloy rims, especially 16" or larger, they can get bent without noticing. Mainly on the inner edge where there is less bracing. With our crappy roads up here and hidden potholes in the winter it is easy to do.

Neil.

Post by **erikv11** » 02 Nov 2025, 12:28

Agreed - I know one of the rims is slightly bent (the same mechanic noticed it when balancing) and that may be causing the small, residual vibration.

DennisCA · Post by **DennisCA** » 02 Nov 2025, 21:12

It's quite possible I suppose the rims are bent, they just came with the car when I bought it. Still it ought to occur all the time then I would think at the same speeds. That's what does me in here, that it's not consistent.

I suppose I can live with it for now, gonna address the control arms later and see if it makes a change.

Post by **misha** » 03 Nov 2025, 03:35

What is the brand of tyres you have on the car?
If they are budget tyres that is the problem.
They are bad.
If not...it's bad balance or bent rims.

DennisCA · Post by **DennisCA** » 03 Nov 2025, 04:29

I got GT Radial tires. Not expensive tires but not bottom of the barrel.

Today I drove to work and no vibrations, maybe once it happened as I was slowing down, so maybe brake related

Post by **scot850** » 03 Nov 2025, 08:38

You could have a sticky caliper piston, or partially collapsed flexi hoes if they have not been replaced in many years. That can act to prevent complete retracting of the piston on the caliper. After a drive, carefully (do not burn your hand!) feel if any of the wheels are warm or even hot. Ideally a digital thermometer gun is a better way to do it.

Last option would be a failing wheel bearing.

Neil.