9 replies to this topic

[Frankcutler]

Please can I have some wisdom on this .......I have just about finished a complete rebuild of my Mk3 and got to the fitting of my nice new chrome wiper arms........the problem is that the splines on the shafts are very fine and close pitched. The splines on the new arms appear to be thicker and are pitched at about 5 deg. around the mounting cap. Is this normal? Should I just hammer it on or are there different spline / wiper arm variations?

Frank.

[tiger99]

The splines are the same on any Mini that I have ever seen, and would be the fine ones. Other, very different cars, have coarser splines. The actual wheelboxes and spindles did change a couple of times, different number of teeth on the gears, to suit different motors, and the wiper arms changed a few times for reasons of appearance, but they are all interchangeable. You have been supplied with the wrong arms, and should take them back to the supplier, as it is their mistake. Don't under any circumstances try force, as you will only dent the scuttle and break the wheelboxes.

[Frankcutler]

Thanks for that. Got them from Mini Sport so I will have to get back to them and see what they say.

[dklawson]

I am not sure the splines were the same throughout production.  However, my knowledge about this is limited and from non-Mini applications.

 

It is my understanding that the wheelboxes with the 6-sided nuts are different from those with the 8-sided nuts.  I am certain the threads are different and I believe the spline pitch is also different. 

[grumpy dad]

Hi 

if I understand the question 

the only bit of the wheel box is the bit you see

and the wiper arm go on

and the arm

 

Yes the splines on the bit you see are all fine 

yes the bit in the wiper arm is course

yes they do fit together

 

sound all right to me

so fit them together 

[Frankcutler]

No they wont go on more than half way using a big rubber mallet. Bends the scuttle. Definitely a casting or finishing issue with these arms.
Now on their way back to Mini Sport. Have asked them to check any replacements first.

Frank.

[tiger99]

I have done some more checking, and it seems that there was indeed a change, from 6 sided to 8 sided nuts in 1969 for saloons, later for vans, which I knew about, but did not seem relevant. I vaguely recall that the thread pitch changed, and the nuts were changed to avoid confusion and stripped threads, the male thread on the wheelbox being diecast and not very strong. However, at the same time, the wheelboxes, of which the splined shaft forms a part, changed from 22 tooth to 32 tooth gears, to suit the new-style cylindrical can motor. The arm length changed from 10" to 11" in 1980, and there were multiple changes to the arms, some cosmetic, including the current and best "hook" fitting for the blade in 1990. But, item 84 (see link below) is said to fit all Minis, which confirms that one thing did not change, the splines. My most recent Mini was 1984, not a year when anything changed, and definitely had the same fine splines as the early 1970s and the 1962 van. So I am still confident that they are all the same.

[dklawson]

I did some additional checking also and agree, it was not the splines that changed, it was the the nuts and the pitch on the wheelbox for them.  The 6-sided nuts have a rather unique size/form and Ithe 8-sided nuts were a more common industrial thread size/form. 

 

Sorry for the red-herring on the splines.  The problem the OP is experiencing does sound like a quality issue with/from the supplier.

[tiger99]

Yes, the 8 sided nuts are allegedly metric (I assume metric fine, 12mm diamater, 1.25mm pitch), but I remember way back in 1969 trying to find a replacement 6 sided nut, which is allegedly 1/2" UNF (although Minispares, not for the first time, contradict themselves by mentioning bicycle thread, which is 26TPI for all diameters, UNF is 20TPI and UNEF is 28TPI for 1/2" diameter), and eventually had to go to the local Austin dealer and get them to order a nut, for my Morris van, as the Morris dealer was useless. The supply of spares in those days was remarkably poor compared to how it is nowadays, because it has become focussed on less than a dozen main specialists, over half of whom are only interested in Minis. And, we have on-line parts catalogues....

 

I think there are the makings of another screw thread flame war here, like the infamous crankshaft thread, so I had best go away. Someone probably has more definitive information....

[dklawson]

Sorry for the continuing sidebar but...

For more info on the nuts and changeover from 6-sided to 8-sided nuts, see the application information at the bottom of the web page found by seraching eBay for item number 200666980260