Historical Article - Nov 1992 - Directional Stability and Safer Wheels

It is widely known that when cars have suspension designed for standard road use, shortcomings are exposed when under, erm, “progressive road driving.  The situation is even worse under competition conditions where regulations inhibit use of rose jointed suspension.  The Mini is no exception.  The soft rubber tie rod and bottom arm bushes produce excessive weaving under heavy braking and wandering under fast cornering.  Both problems being created by self-altering track as the compliance of the standard bushes fail to hold the wheel in check.

To greatly reduce this problem, Mini Spare have produced direct replacement bushes in superior materials for both of these components.  Careful research into what the bushes have to do, and the variety of conditions in which they have to operate allowed exacting selection of the correct materials and Elastomer grading for each item.  Bearing in mind that a borad variety of criteria has to be covered, points of consideration were;  sufficient compliance to allow the suspension to operate;  be hard enough to restrict deflection as much as possible;  keep road noise transmission to a tolerable level;  have a reasonable operation life, and – of course, be a sensible price.

One of the biggest problems encountered when we produce anything is the horrendous tooling costs that be incurred – so ease of manufacture at a sensible cost level was also important.

C-STR629 is a tie rod bush.  This has been produced in a rubber Elastomer grade rather than a hard nylon as it has to allow the tie rod to rise and fall.  Use of a hard poly-nylon restricts this to a negligible amount, forcing the tie rod to flex as the suspension moves up and down.  Inevitably this permanently bends the tie rod, with eventual metal fatigue causing the tie rod to break.  When using heavy duty tie rods, this situation is slightly alleviated, however it is not uncommon for the forward subframe bracket that the tie rod is attached to come adrift.  Much like being in a piece of metal backwards and forwards – eventually it will break.  The result is pretty horrendous as is the damage that this can cause.  The use of this special material also greatly reduces flexure under braking, providing superior suspension location over the standard item.  The rubber grade keeps road noise transmission to a minimum.  Price is £8.46 inc VAT for a set of 4.

An alternative rubber bush is also available under part number C-STR628 for ordinary road use.  This is harder than the standard bush, but not as hard as the poly-nylon type.  Price is £2.35.

C-STR631 is the inner bottom arm bush.  A poly-nylon Elastomer grade has been selected for this component.  As it acts mainly as a bearing to allow the bottom arm to rotate around its locating pin on the subframe, the harder compound was better suited.  Price is £11.28 for the set of 4 bushes.  A slightly softer alternative is the C-STR632 bush.

While researching these components, we also looked into the bushes for engine stabiliser bars.  We found that uprated bushes available previously, had the effect of transmitting increasingly intrusive levels of in-car noise through the bulkhead.  A little more research allowed, once again, the selection of the right grade and type of Elastomer to give the best all round solution.  This proved to be of the poly-nylon type providing much better engine location – thereby reducing breakage of the exhaust manifold and the steady bar bracket breakage.  It also virtually eradicates carburettor jet damages on the later cars – where worn movement that the jet was continually hitting the bulkhead!  A by-product of utilising these bushes is less transmission snatch as the clutch is let out, therefore a somewhat better gear change can be effected.  Part number C-STR630, and the price is £5.64 for one bars set.

SAFER WHEELS

We now have 4.5 and 5.5 original shaped Minilite wheels as used by the Competition Department.  The only difference is that we use a tapered washer where the wheel nut fits to bring it up to latest specification for safety and wheel centralising.
All the nuts we supply for our own Minilife range are stainless steel.  As an extra bonus for our customers we supply stainless steel nuts, with Revolution wheels.
Wheel nut and washer            £1.94 each
4.5” or 5.5” x 10” Mag Alloy SPECIAL    £160.00 each
4.5 x 10” LM25 Alloy            £49.35 each

All prices are historical

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