Clubman Estate Part 4
The little car performed very well on the trip to the IMM, but once again, wrong specification of materials led to what could have been a catastrophic event. The newly fitted adjustable suspension was in many ways a great improvement over the old system but I was slightly suspicious of the rear extension pieces supplied by Minisport. They are 22mm diameter bar of some sort of aluminium alloy with a plated steel pin pressed into the end which slides into the adjustable trumpet. I was not very happy with the sliding fit of the new knuckle joint into the hole in the alloy. I realise that it would be difficult to use a press fit as per the original, as there would be no easy way of removing the knuckle when it becomes worn. One side was better than the other and I really ought to have sent the 'sloppy' one back. All was well for over 2500 miles until one side of the rear looked a little low when I approached the car from behind as it was parked. At first I wondered if the adjuster nut had slackened and allowed the main thread to 'wind in' a bit. We jacked the car up and removed the wheel and all seemed tight enough, but I decided to adjust the trumpet a bit further to give some more height. This worked for a few miles before the tyre rubbed on the arch, even though there had previously been at least 2" of clearance when fully loaded. Further investigation showed the real problem - the end of the alloy extension piece where the knuckle joint was fitted was bending under load and being of aluminium alloy was staying bent.
This shows what I found when I returned home I have now contacted Minisport, but had no intention of asking for another pair - in my considered opinion, they are 'not fit for purpose' and require a re-design with a different material and slightly larger diameter and a better controlled fit for the knuckle. Having had many emails from them and returning the pieces for their workshop to investigate, I have been informed that 'I must have fitted them incorrectly'. I fully understand that they have all sorts of customers, from skilled time-served engineers to cack-handed spotty yoofs, who should really carry on with skateboards if they need 4 wheels - but having been around Minis for over 40 years I find their comments insulting. I also accept that I was carrying stuff in the rear to the equivalent of two normal weight people and that many of the 'normal customers' only use their cars occasionally and just 2 up, but if you are going to offer any aftermarket parts, they should be of at least equal specification to the originals. The original tapered trumpets are 25mm at the end which accepts the knuckle joint, the replacements are only 22mm. Also, the knuckle joints supplied have a really large chamfer where they sit next to the extension pieces and on a piece of soft aluminium alloy that encourages the knuckle joint to hammer it's way into it, which could easily be at a small angle, thus starting the eventual failure.
Not very clear but I think you can just see where the knuckle joint chamfer is starting to flare out the end of the bar - this is on the 'good' one!
This shows how precious little shoulder remains due to the over-generous chamfer.
This is one of the original MPI struts, plus knuckle joint - I've never had one of those fail at that point. The tolerances on the parts supplied were also rather generous, producing a sloppy fit.
I have now made a pair from 25mm Stainless in one piece, one of mine is on the right!!
The other small but annoying fault was from the front subframe top mounts which decided to supply an irritating squeak after about an hour of driving. This occurred each day once the whole engine/gearbox/subframe got hot. I have now replaced the originals with poly bushes - we'll see how they fair in the long term.