Mk1V Steering Wheel Differences

Comparing 3.5 & 1.5 litre steering wheels there is obviously differences such as wheel diameter & steering column shaft diameter. I have also noticed that the 3.5 boss is shallower compared to the 1.5 boss by approx 10 mm where the bottom plate bearing of the manette is held by the two grub screws.

Does this mean that the 1.5 manette is different to the 3.5 manette, if so what are the differences?

Also does anyone have a diagram of the wheel boss & manette as I am unsure how trafficator mechanism cancels & works.

Cheers Peter

The 1 1/2 litre inner column is asmaller diameter than the 6 cylinder cars and likewise so is th eouter column.
My experience is that all MK IV steering wheels are 18’ diameter
However I think early 1 1/2 litre , about 1936/7, were 17" dia.
The early wheels had a cast aluminium rim, later was all pressed steel tubing . The early [ mushroom button] manettes had a different alloy centre compared to later manettes.
I would not have thought the depth of the manetes was different on 1 1/2 litres as I thought the manette was the same as 2 1/2 , 3 1/2 . Up to mid Mk IV the manette had a manual adv/ret but from meory that didn’t affect the rest of the manette or wheel.
The early wheels hada different arrangement of rivets holding the spokes to the alloy centre, where each spoke had 3 rivets, on later cars 2 rivets and the 4 remaining were for spacers.
The last pic shows the fitting that operates the trafficator cancelling, different between early and pate models.

Attached pics of the 2 types of centres and an early wheel after restoration.


Thanks Ed for your comments, what my problem is that I am trying to fit a 3.5 manette into a 1.5 wheel & when I try the Bakelite manette surround bottoms out on the steering wheel spokes. I assume this is because the bottom bearing plate of the manette, held by the two grub screws doesn’t reach the step in the steering wheel boss as it does with my 3.5 steering wheel.

If I put the manette in the in the 3.5 wheel there is a 1.5 mm gap between the Bakelite surround & the wheel spokes.

Measuring the distance from the step in the boss to the top of the boss there is a 10mm difference between a 1.5 & 3.5 wheel, the 1.5 being the greater.

My 1.5 boss is the same as the left hand boss in your first photo & my 3.5 boss is the same as the right hand boss in the photo & the trafficator cancelling rings are the same as shown for the bosses.

So is there a difference between a 1.5 & 3.5 manette or am I missing something?

Cheers Peter

There is a flat [ish plate which keeps the manette from pulling out ,via grub screwsin at th e side
Is this diameter compatible with the section of th e wheel is sits down against.?
Are both wheel and manette from MK IVs?
Do you have the wheel the manette came from?


Yes, the diameter of the bottom bearing plate held by the two grub screws is the same diameter as the stepped section that it sits against in both the 1.5 & 3.5 wheels.

As far as I know the two wheels are from Mk1Vs & the the 3.5 wheel is the one the manette came from.

Cheers Peter

Peter I suggest that you lengthen the three feet that attach the horn/trafficator assembly to the flange on the tube. The advance/retard
lever will also need to be modified. Photos show a 36/7 trafficator
switch, each foot being 11/16". I have handled two types of 2/12 /3/12
wheel boss, so it might not be a 3/12 /1/12 issue.
When the control is activated a small lever moves to a outboard
position, this enables one of the protrusions, on the sleeve within the
boss, to make contact with this lever, returning the control switch
to the off position. See photo.
If poss post photos of the bosses in the horizontal position.
Peter B.


Thanks Peter, my foot measures 22 mm or about 7/8" so there are obviously differences in the manettes. Perhaps to overcome my problem of the the bottom plate not reaching the recess in the boss I could either lengthen the leg & associated other fastening attachments or machine a spacer disc & attach it to the bottom plate of the manette to locate it in the recess & secure it with the grub screws.

I will try & attach some photos of my bosses showing the depth differences.

Cheers Peter

Well, Ive learned a new word: ‘manette.”



How time flies, I am a great one for starting something, getting halfway through it & then starting another challenge. I have solved the problem as Peter suggested by lengthening the feet/legs so the bottom plate now can be locked by the two grub screws & the manette controls work.
My question is why is there a need for so much adjustment in the ring at the top of the steering wheel boss that cancels the trafficators? I have to modify a low ring to make a high ring as shown in Ed’s photo at the top of this topic. It will be easier for me to make the modification so that it has no adjustment. Surely if I set the modified ring up so the cancelling lugs are equidistant from straight ahead then the trafficators should cancel on que?

Regards Peter

Hi Peter,

That is the ideal, but for this to work on-centre, you must have the wheel on-centre with the road wheels in the straight ahead position. I think this adjustment is for those cars that have a slight off-centre setting relative to the road wheels. It can be corrected by sliding the wheel up and rotating to a different spline. This off-centre situation is most likely to occur when in service, but not out of the factory.