Wheel Wobble/vibration

[MrF]

Hi, we've got a late mk2 galaxy which has had a slight vibration through the steering.

When we first bought it a year old, it was perfectly smooth, but developed a light vibration through the steering after a incident with a cow (it sat on the front left wing and dented it, I had to pop the dent back out myself as the cow made good its escape without leaving its insurance details).

Its been to numerous garages for geometric checks including our local ford dealership who gave it back saying "nothing is wrong" and a vast bill for their time, tracked at various establishments, new tyres fitted, wheels swapped front to rear, the bearings have been inspected for wear etc. Its recently had a full inspection at the local technical centre, and they lift the car up and have various moving plates to wobble the suspension round and check damper performance, tracking and geometry and other facets, and the tester could find no issues at all with anything. We've asked various garages to road test, and they say they cant feel any issue.

 

Im fairly competent with vehicles and we have a good workshop that we use to fettle our diggers and tractors and landrovers etc but Ive tried to avoid working on it because its my wife's "new" car but its come to the stage that its going to be less time and effort to try and resolve it myself.

 

So far Ive found it its hyper sensitive to power steering fluid level, if the fluid drops towards the low mark the steering starts to become notchy and starts to almost kick the wheel between your hands. If you go slowly (20-30mph) and take your hands off the wheel you can see it gently kicking between two positions, almost as if it has a bucked wheel rim. Restore the level to the top mark and it almost goes away, but I can feel a gentle kicking still which is what my wife is calling wheel wobble. Afterwards the wheel got a knock dropping down a large kerb and it started to pull to one side, which with the kicking feels downright dangerous as you are constantly countersteering. Im guessing the tracking has been knocked out and its being exaggerated by the original problem.

 

From wracking my brains back many years ago to engineering college, I have some vague recollection of a spool valve in the centre of the racks working that when it senses the movement of the actual rack opens the hydraulic ports which provide the assistance.

Im wondering if perhaps the spool in the power steering rack possibly got damaged (maybe the cow's weight pulled the rack across via the trackrod linkage and the spool got damaged internally?) and its floating around in a worn region and the knocking is the assistance kicking in between the two edges of the spool wear.

However, I don't know this model at all, and I'm not used to working on cars, is there anything else I should be looking at first before paying for a new rack? Is there anything else in the PAS system which could cause this feeling?

I have a feeling its going to be a nightmare to change too, I have done a similar job on a mondeo estate while changing engines (wife's last car, and the reason I paid for a new one so I wouldn't have to keep fixing that one!) and ended up making a special spanner to curl round the subframe and rack.

 

Finally is there any known gotchas a more experienced person can think of on the galaxy which could contribute to this and need checking while its over the pit?

 

thanking you in advance for any advice :angry2:

[Mirez]

A Cow? WTF were you doing parking up in a field? No wait... don't need to know that :angry2:

 

Unfortunately there are a number of possible causes for this so diagnosing won't be easy! The two highly common issues that can cause notcy steering are seized strut top bushes and a seized or seizing alternator pully - the latter being the more common and pronounced. Its certainly not uncommon for a seizing alt pulley to give a 'variable' level of power assistance that can manifest itself as wheel 'wobble'.

 

Tracking never just go's out unless the lock nuts been left undone - its caused by something being pushed, pulled or bent out of shape so if its now pulling to one side you need to investigate the bushes, mounts and assemblies around that side for wear or damage. I'd also take another look at the bearings, I've seen two now that were causing wheel wobble (albeit at higher speeds) yet the bearing showed no sign of movement or noise until the hub was removed for a more detailed inspection.

 

Finally, if it is worst case then on the plus side fear not as the rack is one of the easier things to change on the galaxy and is nicely accessible from below :lol:

[MrF]

Thanks for the steerage as it were.

 

The incident occurred on the road believe it or not. My wife had dropped one of our kids off at the nursery/school and was parked up about to depart when a herd of cows came wandering past on the way into a village (we live in a rural area) having managed to pop the field gate or something, not an uncommon local occurrence and just part of life here. Only this time one of the (female) cows got a bit frisky as it wandered past and tried to mount another, the other cow flicked it off backwards into the side of the car. They weigh 3/4 ton+ apiece and it made a large dent but didn't break the paint. She (wisely) wasn't up for chasing the culprits and hadn't thought to walk round and check for damage, then spied the dent once returned home. I promised to spoon out the damage as at that point my concern was more for my wife who was at that point in tears than a dent in a front wing.

 

Ill take off the alternator drive belt while I'm prodding things and see if the pulley feels ok or is notchy to spin, on a wet road it does seem worse at times which also fits that possibility as the belt might loose traction earlier in wet conditions. Theres also the possibility of the top strut bearing being at fault because that was quite close to the damaged area, after reading your post I read the galaxy has a rather unique design in how to check for play and stiction there so will do some more research into that.

 

All good suggestions, thanks, anyone any more ideas ? I'll work through them this weekend as we have the motorhome in bits right now with bad diff output shaft bearings to sort out.

[sparky Paul]

The only thing I can add is another question...

 

When you say...

 

If you go slowly (20-30mph) and take your hands off the wheel you can see it gently kicking between two positions, almost as if it has a bucked wheel rim.

...does the frequency of the twitching vary with the road speed just like a buckled wheel, i.e. does it slow down as the car slows down? Or does it remain constant, or dependent upon engine revs?

 

If it alters with road speed, then I would say something is out of true, either a damaged hub or wheel.

 

If not, then I would go with Mirez's alternator pulley suggestion first. Another possible cause for twitching steering is low pump pressure caused by a faulty pump or relief valve. Possible, but probably less likely, is damage of the torsion rod or associated components in the rotary valve inside the rack.

 

I would think suspension problems are unlikely to give the exact symptoms you describe.

[MrF]

Well, changed out a wheel rim and tyre and mostly the vibration died away but still there in the background, but back up on the ramps and I think the halfshaft splines are worn at the diff end and there is play in the cv's. So have ordered a pair of driveshafts and the diff flange and drop links for good measure.

Fingers crossed that will fix it. I can't believe the diagnostics garage missed the knackered cv's...

[MrF]

Well, changed out a wheel rim and tyre and mostly the vibration died away but still there in the background, but back up on the ramps and I think the halfshaft splines are worn at the diff end and there is play in the cv's. So have ordered a pair of driveshafts and the diff flange and drop links for good measure.

Fingers crossed that will fix it. I can't believe the diagnostics garage missed the knackered cv's...

I should add Im not ignoring the above pump suggestion either, I am just a bit of a believer in fixing everything you find until something goes away.

Im ordering new belts with the driveshafts and Ill fit them and check the pump for free running then. I think this car's days of going the dealer to be serviced have ended. Its actually going to be easier to do it myself and know its been done properly first time I think...

[Audiman]

I'd go for the seized alternator pulley. It rotates in one direction when there's no fault.

 

When it's fauly, locks up and works like a pulley.

 

I had a similar problem and replaced the pulley from GSF. Ford (or rather FRAUD) wanted to sell me a whole alternator instead of replacing the pulley - cannot buy pulley separate from Ford.

 

Otherwise you may have a buckled wheel if it's a constant wobble.

 

My wife once told me she had a puncture, only to find a chunck missing about the size of a tennis ball, and a buckled wheel......she'd hit the kerb and buckled the alloy...

[cyborg]

After reading all posts above I hope you haven't overlooked basics as a low rear tyre pressure can cause same effect :unsure: Edited April 21, 2011 by cyborg