Wheel Alighnment On V6

[citroenxm]

Hi All!

I have my 3rd V6 XM, (after passing my second to David Hallworth) and you can all call and shout me Tight Fisted, but me car is pulling ever so slightly to the left..

Can we experts adjust the wheel alignment ourselfs, its just that £25 a go each time its nudged out seems a bit steep....

What is the setting for a 1993 V6 SEi, running Exclusive or 24valve Alloys..

What sort of procedure do I take to adjust it...

Many thanks

citroenxm

[Masterclock]

It is possible, but you have to take much more care than a local Kwik Fit. The optical kit they use, when used by skilled hands, can diagnose a whole range of steering ailments that basic alignment alone canot measure. Steering pulling to one side is unlikely to be caused by basic tracking alignment and before checking and adjusting alignment all other causes must be eliminated. Poor tracking alone will always manifest itself as tyre wear on the inside or outside edge of both front tyres and a 'sawtooth' feel to the blocks of tread if you run your hand from the inside to outside edges of the tyre. Uneven wear, like the inside edge off one tyre and the outside edge off the other, point to more serious misalignments.

The basic tracking adjustment is simply to enshure that the front wheels run parallel to each other when the car is moving in a straight line. When the car is moving the wheels present a significant rolling resistance and are effectively pushed back in the wheel arch. Because all the mounting points are rubber mounted this pressure results in a small amount of movement which disarranges the alignment. So when making the adjustment with the car stationary a small amount of 'opposite' movement has to set in so that when the car moves the wheels run parallel.

The geometrys that allow the car to run straight and true are unadjustable and held fixed by items like rubber bushes and ball joints. You will first need to check the condition and wear of these joints first. Also, how bad is the pull? A very slight pull can normally be always felt on some particularly steep road cambers. You can eliminate this one by driving the car on the oposite side of the road (an empty road!) and see if the steering pulls to the opposite side. Another potential for pulling that the optical kit can see very easily is what is known as the thrust angle. This basicly means that the rear wheels are parallel and point directly forward and are not pointing to one side or another. This is not as daft as it sounds when you realise that the rear wheels are mounted on a sub frame, in turn mounted to the body by rubber pads. I seem to remember reading somewhere that the mountings on the xm were designed to move under lateral loads and provide a very small degree of rear wheel steering, I may be wrong on that, but if the rubbers are worn or damaged they can cause problems.

Another point that must be checked before undertaking alignment, and tyre fitters are notoriusly bad at checking this before starting, is that the steering rack is properly centralised. If the track rod ends have been replaced badly in the past, not making shure that they are both screwed on by exactly the same amount of threads, or not changed as a pair the rack can be displaced to one side or the other from normal center. This is normaly immediatly apparent from the fact that the steering wheel is no longer level when driving straight ahead, but, people have been known to unbolt and move the wheel round one or two splines rather than adjust the rack properly. This will cause a fault whereby the tracking is correct when driving in a straight line, but when the wheel is turned in a corner the wheels no longer move to the correct angles relative to each other, so tyre wear starts again. This can easily be checked by turning the wheel from lock to lock and ensuring that the wheel stops at exactly the same point either side of center. If not, unbolt the wheel and move it round until it does.

If the wheel has to be adjusted then the track rod ends will need recentralising as well. This can be done by removing each end counting, exactly to a half turn, the number of threads that each end comes off. If the two numbers are different add them together and then divide by two then screw the ends back on by exactly the number of turns given in the result. This assumes that both ends are identical. If the vehicle is road tested the wheel should be very near to, if not exactly, central.

Once all the above has been checked then you can proceed to checking and adjusting the wheel alignment.

As this post has been a nececarily long one and I'm short of time just now I'll post the actual method later on. With a simple bit of toolmaking it is a relativly simple matter, but the above checks must be made first.

Ian

[Masterclock]

Christmas shopping over and sat with a glass of beer, I'll describe the checking/ setting operation. The tracking tools that I have were made by Gunsons years ago and I don't think they make or sell them anymore. The principal is simple though and with a bit of care a similar pair of tools could be made.

They are basicly a length of pressed steel u channel. The top edge has been relived back to form four points. The channel is positioned, horizontal to the ground, against the wheel. The inner two projections rest against the wheel rim so that the whole channel becomes parallel to the wheel. The outer points project beyond the diameter of the wheel, so by passing a tape measure under the vehicle the distance between the front and rear of the channels can be measured. The clever bit is that the distance between the outer points is such that every centimeter difference between the front and rear measurment points equate to 1 degree of toe-in or out. So the alignment can be theoreticly set to 0.1 degree steps, i.e. 1mm.

The important dimensions are that the centers of the outer points are exactly 573mm apart and the inner points are 190mm apart, all equaly spaced either side of the beams center line. All the points should project so that they all sit in contact with a flat surface, as in the enclosed photo. A similar pair of tools could be made from a length of light alloy angle. The four contact points cold be four long bolts with nuts either side of the angle and adjusted so that they are all in line and that the angle lies parallel to the surface that the bolt heads contact. A useful adition would be a pair of cheap spirit levels on the top of the beams.

To use the tools, drive on to a nice flat piece of car park or drive. Get out of the car, engine running to maintain running height and hand brake off. Let the cars height stabilise for a minute or so and then gently push or pull the car backwards and forwards for a couple of feet. This is to unload any stresses that may have built up in the steering bushes etc. With the help of an assistant, place a beam against each front wheel, as mentioned above and measure the distance front and rear. If the front distance is greater than the rear the wheels are toed out, wider at the back, toed in.

As far as I am aware, all models of XM have the same tracking settings, irrespective of engine size, tyre size saloon or estate. This figures, as all the bushes and ball joints are 'one size fits all' there are no harder bushes for the 'spots' model as in some other manufactures cars. The citroen handbook quotes, 0 to 27' minutes arc, toed out. So with this tool the front distance needs to be set to 0-4.5mm wider at the front. Note, this dimension is not the same as the 0-3mm often quoted in Citroen manuals. The 0-3mm dimension refers to the distance between the tyre sidewalls.

To adjust the tracking the track rods are screwed in or out of the ball joints as appropriate, both rods are adjusted exactly by the same amount to maintain centrality of the rack. The adjustments can be made with the wheels on the ground at the test site. Before rechecking the car must be rolled backwards and forwards again to allow the wheels to find the new alignment. As a guide, a quarter turn on both sides of the car makes about 3mm movement on the gauge, so adjust by small amounts.

Once the setting has been found, road test the car again and note any offset in the steering wheel. There should be none, but smal adjustments to the track rod endscan be made to level up the wheel, but remember to turn the rod ends exactly equaly and in a drection that wont upset the tracking setting.

And thats it. It sounds very complicated, but I have a well trained wife and can check and adjust my own tracking in about 10-15 minutes on the local asda car park. The benefits, the last but one pair of new front tyres I put on the 2.0L lasted very nearly 40,000 miles.

[Peter.N.]

I have for many years used simple home made tracking tool consisting of a length of conduit tube, into which is slid a length of appropriatly sized threaded rod fitted with two nuts. I dont usually use the wheel rim but the tyre itself to check the difference between front and back and it is surprisingly accurate, the tread wear being pretty well equal across the front tyres on all my cars. On the XM, I set it so that there is only a slight tow in, something around 1/16". It is important of course that you check at the same height both ends of the tyre. It wont of course check for all the adjustments to which Masterclock refers, but it has so far proved to be all that I have needed.

Also, as he says, the 'pulling' is unlikely to be due to tracking error, it is far more likely to be caused by uneven tyre wear, inflation or unmatched tyres.

Peter.N.