Technical Article

Proper “Knock-Off” Tightening

(as appeared in the Feb, 2006 TSR)

By John Wright

For this installment I thought this article by Mike Allison of triple M fame and contributor of many, many technical articles relating to prewar MGs may be of interest here. It is a portion of an article entitled “Mike Allison advises how to tackle a front axel overhaul on your pre-1956 MG.” This section deals with the proper tightening of the k/o spinner.

Seems simple enough, but many of us are guilty of just the methods Mike advises against. So have a read and file it away for use later. The only thing I would add is that inspecting the splined hub and the splines within the wheel hub for wear is always a good thing to do as part of your seasonal check list. Worn, loose splines will cause a wire wheel to become very loose and potentially quite dangerous. With Mike’s permission, the article follows.

“The last item on the list is the fitting of wheel nuts. If you have a 14/40 or an M-type just do the nuts up to 40/50 lb.ft. torque, but with the Rudge pattern wheel, with its “knock-off” spinner, hardly anyone seems to know the correct procedure for wheel fitting. It grieves me to see people banging seven shades of something brown out of the wheel nut with a copper hammer in the mistaken notion that you can give the job too little effort.

Firstly, thoroughly clean both the male (stub-axle) and female (wheel) hubs, and then coat each with a thin layer of fresh grease, paying particular care to grease the cone areas on which the wheel sits and slide the wheel into place: it should slide right home with no great effort. Now clean the nut and grease the thread and cone areas, and make sure that there is grease on the male cone of the wheel. Now fit the nut by hand, spinning it until it is hand tight on its seating. Let the jack off, and allow the full weight of the car to fall onto the wheel and then with the hide end of the mallet give the nut two firm blows, and the job is done.

Since I was shown this method by Reg Jackson, who was in turn instructed by Nuvolari himself, I feel this really is the correct way to make sure the wheels stay where they should and my feelings are backed by personal experience.

The routine of removing the wheels and regreasing the hubs should be carried out at each service for all wheels or once every month, and it becomes more important if you have done a lot of wet weather driving. You need not worry about the wheel falling off. If you’ve done the job properly it cannot because the nut self tightens onto its seating. Hammering the wheel too tight onto the hub does two things, firstly it spreads the female cone of the nut damaging this and preventing the cone from seating on the wheel, and secondly it allows the wheel to float on the splines of the hub wearing these out and preventing the wheel from driving without a knock.”