Occasional light clonk from steering

[Murray Betts]

I've had this for as long as I can remember, never repeatable and only on odd occasions. I recall someone else commenting on this and not finding a solution or cause, having checked all the joints and splines etc.

While doing the cambelt change on my car I had a look around and contemplated the steering rack, condition of boots etc.
I noticed there is a plug arrangement where the column meets the rack and I wondered if this was for lubrication so checked the manual. It appears it's supposed to have a cap over it but this seems absent on mine, I can only presume from new since I bought the car with just pre-registration miles on it. The absence of the cap does not seem particularly detrimental, just a dirt/dust cap over the plug really.
The plug is a fairly large nylon type plastic thing with a large square projection and just screws in normally. It secures a spring loaded damper block which presumably stops the rack slider from rattling. The manual says use regular LM type grease, typical for bearings etc. As removed it was not entirely dry but didn't have much lube on it.
I packed a fair amount of grease in the hole and pushed the block home to force the grease in, then refitted the spring and plug, nip it up not too tight. The spring loading is not excessive, it won't "explode" when you undo it, just be aware of a spring in there so keep the plug covered when undoing.

I've done a couple of hundred miles since and have to say I haven't noticed the clonk at all. I can't say it is totally cured but it looks pretty likely that this damper block/lube is the source or where the clonk comes from.

[Collette Dobson]

I noticed this and tightened the plastic nut as you suggested. It reduced the clonk but made the steering sticky, so I am loosening it off again. There must be something else near to it that has word to make the clonk. A winter job perhaps to take off and service the steering rack, but I can't feel anything obviously loose. Have you found out any more?

[Martin Williams]

This adjustment is sounding like the subject of a (rather long) treatise on an Alfa forum. https://www.alfaowner.com/threads/major ... t-17908687

Cutting a long story short it does sound like there may be a bit of wear in the central section of your rack, hence the stiffening up following adjustment.

Note that the author tries very hard to explain phenomena and seems to put across cogent arguments based on his observations and experimentation, however, it is not a quick read!

[Murray Betts]

A very interesting article there on the Alfa.

I noticed with mine that the steering felt absolutely perfect until the car warmed up thoroughly in the summer, say 40 or 50 miles, and then it began to lose the free self-centring action. Presumably the rack warming up will have reduced some clearances somewhere. If we are looking at nominal clearances down in the 0.1mm range it might not take that much to close it up, especially with some nylon/plastic materials which tend to expand quite a lot.

My car has only just passed 25k miles from new and excessive wear in the rack is pretty unlikely. I backed off the damper/yoke plug adjustment slightly and this seems to have eased the effect, I suspect I might need to back it off slightly more to eliminate it completely, a bit of suck-it-and-see. I still haven't noticed the clonk at all, so I'm pretty sure this is where it takes place.

If I get the opportunity in the spring here in the UK I might try to introduce a bit more lube, maybe trying the moly grease/oil type mix as described. Bear in mind that if there are any bronze type bushings in there it is advisable to avoid most gear oils which contain much sulphur as it can attack some bronzes, safer to use an engine oil although GL4 grade gear oils ought to be OK, definitely not GL5.