Hello all. I’ve got a strange drive train issue. I’ll try my best to describe the symptoms I feel:

The car jerks to the right. Not all the time, but in spurts. Almost like the left and right front wheels become unsynchronized and the right one spins a little faster than the left and jerks the car to the right.

It only happens when I apply very light throttle. When I’m accelerating it doesn't do it. When I’m coasting it does not do it. It seems to only happen when it rains and when the car has been driven at highway speeds for about 1.5 hours. It has never done it in the city, only on the highway.

More recently, once I got off the highway after driving for 3 hours it was doing it as I came to a stop on the off-ramp and at the following two red lights, slowing in frequency as I stopped. I shifted the car into neutral as I was slowing down at one of the red lights and it still did it while coming to a stop.

I took it to my Volvo person and there were no error codes on the computer. I haven’t been able to reproduce it and the only other times it has done this to me was earlier this year in May after driving for 4 hours on the interstate and then again this year on a trip to Colorado from Florida it did it only once and I pulled off to the side of the road leaving the car on and in park, took some pictures by the “welcome to Colorado” sign, got back in and continued to drive and then not a peep.

An alternate description of what it feels like is that it feels like only the right caliper engages the brake at light throttle, pulling the car to the right. My brake lights work fine. Cruise disengages when I tap the brakes as it should.

If I hold the throttle lightly, to try and induce the jerking and hold the wheel, if I do that long enough the whole car begins to shudder rather violently until I let off the throttle or accelerate.

Go figure. Any ideas?
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-Hector

Is it possible that you have a sticky caliper? The next time this happens, find a safe place to pull over and coast to a stop (don't brake hard). Then check the temps of both front wheels - don't touch the rotor, just the lug nuts. If one wheel is very hot, that is your problem.

I doubt that the ABS sensor is dirty, that would signal an error code to the ABS computer. If the axle slots are dirty only on one side, that could fool the ABS into thinking the wheel is slipping. To check the axle, the wheel must come off because you need to look at the back side of the rotor where the axle is attached. Much easer on a lift, I wind up removing the rotor because I don't like crawling under the car.

Klaus
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Volvoless. Sold the R. There is now a void...

I'm pretty much a novice, but this might have something to do with the stability track system. Perhaps a sensor at the wheel is not picking up or is intermittent causing the other sensors and the "brain" to over react? I would think what I'm guessing would have an associated code, but you stated "no code". Perhaps some of the experts can comment on this possability? Take my advice lightly.

Jerry
01 V70 T5a

Sadly, the car doesn't have TRACS.
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-Hector

Gee whiz, sounds dangerous! Has anyone had a look under it to inspect the suspension, brakes, hubs and driveshafts? I would think that with a problem like you describe the offending part would fall under the "gross and obvious" category.

You mention it happening both while at part throttle and in neutral. Does it only happen at a particular speed? Is there any noise along with the jerking/shuddering? I want to guess that you have a failed intermediate shaft carrier bearing or CV joint. That would almost certainly involve a bunch of noise though too.

-Will

First of all, let me thank you (and those that will hopefully follow) for reading my very long post.

Recently I had the suspension looked at because the car always pulls to the right. They replaced the left A arm (the right had been replaced 2 years ago). The struts were fine, my mechanic said. The hubs were changed not even a year ago. The brakes have enough pad on them, I wouldn't know what else to check for in them. The right CV joint was replaced about 2 years ago. The left one was replaced about 2 months ago. The car still pulls slightly right but what are you gonna do.

It has only done this to me in neutral that one time. It seems to happen at any speed on the highway. I've tested it from 50-80 mph and it does it anywhere inside of there but only during the light throttle. I dare to say it only does it after 45, when the transmission shifts into its last gear.

There isn't any perceptible noise that I've been able to hear, other than the sound of the shudder itself which just turns out to be a clunk I suppose.

The engine sounds fine, RMP's don't move at all, so I'm fairly certain it isn't misfiring or anything like that.

If I hold it on light throttle and try to keep the shudder going, I find myself fighting the car. It is bordering on dangerous, especially under rainy conditions. Since I can't induce it and the problem seems so incredibly strange, its hard to get a mechanic to diagnose it.

I shot a video the last time it did this to me which is only video of the steering wheel jutting to the right while I play with the throttle to make this happen. I'll put it on you tube and link here, maybe that will get us somewhere.

Thanks again.
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-Hector

It sounds to me to be an ABS sensor or a broken hub problem on that left front wheel. If the ABS is sensing the left wheel not turning, it will apply the brake to the right wheel.

I'll give cleaning the sensor a whirl.

I figure just take the wheel off and clean it with brake cleaner? Will the sensor be obviously located?

Would the abs apply the brake while not pressing the brake pedal? I've never been pressing the brake pedal when this happens.
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-Hector