98 V70 Continuing front end wobble saga

[98v70dad]

You haven't heard from me in a while but my front end wobble is still going on between 65 and 75 mph. This is after EVERYTHING if the front suspension including the drive axles and wheel bearings has been replaced. Today for whatever reason I let go of the steering wheel and noticed that the wobble stopped. If I'm not holding on to the steering wheel my ride is as smooth as glass. When I take hold of the wheel at the 65 -70 mph speed range the wobble starts - let go and the perceived wobble stops - hold the wheel and it starts again.

So whatever is going on has to do with my steering system. Inner and outer tie rods are new. Steering rack and pump are original. The wobble doesn't show up in colder temps. ALWAYS shows up on the afternoon drive home. Any ideas experts?

[j-dawg]

Theory: there is some minor amount of play in your steering system, and all of your wobble lives in there. When when you put your hand back on the wheel, you inadvertently take the wheel to one end or the other of that dead zone, whereupon the wheel begins wobbling again.

[98v70dad]

Theory: there is some minor amount of play in your steering system, and all of your wobble lives in there. When when you put your hand back on the wheel, you inadvertently take the wheel to one end or the other of that dead zone, whereupon the wheel begins wobbling again.

Here's the thing. When I let go of the wheel the steering wheel is oscillating back and forth (a little less than 1/8 of an inch) but the ride is as smooth as glass. The steering wheel is still moving but I don't feel the pulses because I've let go of it. During all of this the front end goes right where its pointed and there is no vibration from the front wheels and suspension. Its almost like the hydraulic pressure in the steering system is pulsing somehow.

[98v70dad]

Theory: there is some minor amount of play in your steering system, and all of your wobble lives in there. When when you put your hand back on the wheel, you inadvertently take the wheel to one end or the other of that dead zone, whereupon the wheel begins wobbling again.

I think that you are correct about play in the steering system. I'm pretty sure I have a good bit of play and I think its inside the steering rack since everything else in the steering system (except the pump) is new. Is there a good way to diagnose that? Would replacing the rack be the only way to fix that - I'm not really enthused about having to do that.

This all started about 18 months ago when I got new tires. I had removed/replaced the steering wheel prior to that and was it off center by about 3 degrees when I put it back on. The alignment tech said I didn't need an alignment and he "tweaked" the steering to straighten out the steering wheel for me. I have no idea he meant by that. At the time I attributed the wobble to a poorly balanced tire but for a while have suspected that he somehow damaged the steering rack - not sure. I know only a little about whats going on in there.

Any thoughts on what he might have tweaked? Sometimes I think that he loosed the joint (if one exists) where the steering wheel axle ties into the rack and didn't get it tight once he straightened it out. Its really hard to see way down there so I've never looked at it

[wizechatmgr]

Happen to get all of the tires balanced? Have you triple checked the torque on all the lug nuts with a torque wrench? I had a single lug that wasn't torqued to spec on the rear causing something like this.

What are your alignment numbers for toe-in/out on both front wheels last time around on the alignment? Wheels are rarely "perfectly" aligned. Doesn't take much...

[98v70dad]

Happen to get all of the tires balanced? Have you triple checked the torque on all the lug nuts with a torque wrench? I had a single lug that wasn't torqued to spec on the rear causing something like this.

What are your alignment numbers for toe-in/out on both front wheels last time around on the alignment? Wheels are rarely "perfectly" aligned. Doesn't take much...

I've had the tires balanced 3 times. Rotated the tires multiple times, bought new wheels, bought new tires AND I always use a torque wrench to torque the wheel lugs (81 ft-lbs is spec and I torque them a little more than that - 90). Torquing a nut is not all that accurate - you want to be in the range. Torqued to the 81 ft pound spec has the nut practically coming loose on their own.

Its actually been aligned twice also. I'm tired of dealing with it. There is play in the rack and I know its internal because I investigated it when I replaced the inner/outer tie rods. With no pressure on the system (car not running) there is some slop inside the rack. I figured that it must be normal since I don't know much about steering rack internals other than the basics.

[98v70dad]

Anyone else?

[scot850]

Well if you have had all that done (and I recall your threads over time on the subject) there is only one more option and that is to replace the rack. You are on the same attempt to fix something that appears un-solvable and un-fixable just like the front suspension groaning on my 'R'. I really feel your frustration. I can't recall if you replaced both the inner and outer tie-rods. I think you did but now don't recall.

Oh, on the 81-ft/lb/110 Nm, wheel torque on Volvo alloys for P80's. I have been using that for years and so far no issues.

Neil.

[mrbrian200]

If you haven't already, rotate the wheels/tires front to back just to definitively rule out a defective tire or bent wheel.

If the wobble remains on the front end...
Sounds like a toe alignment issue to me. Bungled toe induced wobble often centers around a certain speed due to a mechanical resonance between the spinning wheels under lateral tension and the suspension. The new tires have different dampening characteristics, are probably more 'grabby' than your old tires, and thus the bad front end toe-set became more apparent.

Ride quality smooths out when you take your hands off the wheel because at that point you're not 'fighting it'. If you had play in the suspension/steering it would be unlikely to make a difference.

Try a different alignment shop. Just because it doesn't pull to one side doesn't mean the alignment is good, it merely means the thrust angle good. Results vary vastly depending on the method/machine/technician in my experience. On most cars the front end (adjusted while sitting) likes to be a little toe in, the rear end likes to be straight ahead or just a hair toe out.
Many vehicles have a front end toe spec up to +0.1" or more toe-in because the bushings squish a bit under loading while rolling down the road and you'll find at speed that slight toe-in setting will actually point more perfectly parallel while moving.

For example. The way I set toe I am able to calculate the final setting in degrees with a laser pointed at a reflective target a fair distance away (at night on a very rural side road). My '06 S60 with the front-end camber set at zero, the suspension loaded (coast/brake lightly to a stop, don't back up), likes the front @ +0.22 degrees total toe-in, rear end somewhere around -0.5 degrees toe out. In shorthand that means my laser pointer hits a small road sign from both front sides at 1400 feet away. Turn the car around-- from the rear wheels pointing back the laser will hit a target from more than twice that distance. Your setting would vary depending on brand/condition of the LCA bushes and camber position.

I went 129 miles on a little over 1/8 tank of gas last week...40mpg+... If I'm behind a truck or with a strong tail wind it'll shoot up higher. With a drag coefficient of 0.28/frontal area 2.2 m2, that's what a FWD S60 should get @60mph assuming you keep parasitic losses/rolling resistance low and a well designed/efficient powertrain.
At one point I tried toe settings closer to zero, I didn't like it. Beside econ tanking down closer to epa rating (high 20s/low 30s), I seem to recall a very slight wobble felt through the wheel around 75mph.

[98v70dad]

If you haven't already, rotate the wheels/tires front to back just to definitively rule out a defective tire or bent wheel.

If the wobble remains on the front end...
Sounds like a toe alignment issue to me.

Try a different alignment shop. J

Thanks. I've rotated the wheels/tires around a bunch of times with no effect.

I've replaced all of the parts but most of them were well worn and needed replacement. The inner tie rods were an exception but since it took a while to get to them I replaced them. I've used nothing but high quality parts

My plan has always been to take it to Butler Tire for a road force balance and full alignment when I'm done restoring various things. I still have the back brakes to do. Butler is a local chain that services expensive European cars and using them will possibly be prohibitively expensive for me. Since this will be expensive I don't want to do it until Im confident there are no other possible issues. I wish I could find another option. I've called around and haven't found anyone else. Its been aligned at NTB (twice) but they don't seem to know that much about my car. ...they tell me that the rear can't be aligned which I've read here is not correct.

You may be onto something with the toe adjustment... here are some additional symptoms

- wobble almost always starts when decelerating down to 65 mph (or any speed in the 65-75 mph range). I can USUALLY accelerate up through the same range without starting the wobble.
- oddly the wobble is less prone to happen in cooler temps. Almost never happens in the morning. Always happens in the afternoon.
- The steering wheel is wobbling slightly when I let go of it. The car tracks and rides smooth but something is oscillating because ?I can see it in the wheel. Of course when I hold the wheel I can then feel it.