Knock On Hub Spinner Nuts - faults, 29th August 2011.  - Updates are at bottom of the page in date order as we find out about this dangerous 'fault'

Whilst preparing & racing 1 DB2 & 2 x DB2/4s at the Woodcote Trophy at Oulton Park 29/08/11, we have suffered loose Knock On/ Off 2 eared spinner nuts on the rear of the DB2 & the front of one of the DB2/4s.

Investigating this problem we have concluded that most if not all of the spinner that you buy at present (most of the cheaper types are produced by just one company) are now being made slightly wrong.

When comparing the depth of the tightening taper for an original Knock On spinner nut, we found this was around 3/4" or 19mm, this has been reduced to just 1/2" or 12.7mm on the new (bought 2009), with the similar opening across the mouth of 3.17" or 80.5mm, this means that once the spinner has been used a few times it bottoms out on the inside of the taper before locking the wheel up, this starts happening once the mouth of the spinner has expanded to 3.228" or 82mm.

This isn't a lot when the nut is made from brass as they should be, when the wheel isn't correctly tightened the nuts will come loose quite quickly & the splines on the wheel & hub will wear.

The other problem which we are coming across regularly is the hub thread is bottoming out internally on the nut before the wheel is tight, this wears the hub & spline very quickly.

The other thing that both of these problems give you is loss of control with the car, with the feeling of low tyre pressures or flat tyres. 

We have some choices here, only buy Knock On Spinners that are made to the original Rudge Whitworth drawings, fit 3 eared Borrani spinners that are made to Borrani's original drawings or make our own Spinner nuts to the original drawings.

Update 10/09/11

We have found the Knock On Spinner nuts have cracks on the outer taper & cracks on the thread

Update 4/11/11

Since writing the last update we have found that the original Knock On nuts were made of Manganese Bronze, not Brass, we are not sure when the change occured but unless the Brass is of the correct type it will crack not deform as its supposed to.