There is nothing to argue. The factory did fit 12 and 13 inch rim sizes and did so without engineering changes, although they did fit rack stops to the cars with 13 inch rims to prevent wheel scrub on the inner guards.

Although to work under this, you would need to ensure that the tyre spec was comparable, the rim width (at least in NSW) is with 25 mm of the factory one and the off-set was the same.

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There were engineering changes on the 13 inch wheeled coopers:
Wheel arches were cut away at the front under the sportpack arches and the steering rack arms are actually thicker than standard as well as stopped to prevent them scrubbing on the inner guards...
However the ERA ran a standard rack...

Yes, there where body mods but these did not alter the 'engineering' or structual components of the car. The thicker arms were not at all unique to cars with 13" wheels and were fitted long before these cars were made. The thicker arms were fitted as a result of a steering rack change not additional wheel / hub loadings

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I stand corrected. I understood the new stronger steering rack was introduced at the same time as the 13 inch wheels because the larger wheels put higher loads into the steering rack... and under extreme conditions the steering arms could bend (Curb strike?).

Essentially - from the UK - there were only 2 racks. Up to 67-ish and 67-ish on. The later racks did undergo a few small changes along the way, but nothing that made them 'stronger' or 'up-rated'. At some point, they even used metric bolts , but the threads on the rod ends stayed at 1/2" UNF.

The later racks were introduced to improve the turning circle and these also entailed the use of a different steering arm on the hub. These were different lengths (only slightly) and angles. The Cooper S at some point while still having the same length & angle on the later types had a heavier and stronger arm. Not 100% sure on the date that this arm was introduced but was around 68. The 1275 GT continued to use this arm while the other mini models used the 'lower' spec arm up to about 74 or 75 when the heavier arm was used across the board.

At the time of Rover fitting 13" wheels (~90) the same late rack was used however they fitted stops to the racks to reduce the turning circle.

Silly isn't it. They went from the early rack to the later one to increase the turning circle and then later modified it to reduce it again

I've said it before and I'll say it again - it's no wonder they went broke!

The Ozzy (Cam Gears) Racks as far as I am aware were the same from start to finish, except for the pinion. Perhaps the Doc could shed some more light on this?

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The Oz Cam Gears racks (2.2 turns lock to lock) were all much the same, except early pinions have a slot for the bolt, later ones have a groove right round.
Not sure of changeover date, but John Smidt might remember.
I have some NOS pinions here in Leyland bags and they are the early type, go figure..

The Oz Mini rack is a shorter version of the Oz Morris 1100 rack, the rack itself (the inside <-> bit) is bigger diameter than the UK ones.
This rack fits late Mokes better if 1100 tierods are fitted to it. Mini King stocks some assembled like this.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm not entirely sure, however I thought the differences between the early and late Oz pinions was that the early ones had a machined (ground) shoulder on the 'top' end for the bearing to sit on and the later ones had a seperate spacer. The ones with the continous groove or just a slot where at all times in the later ones. As I say, not 100% sure on that. Might explain that type of pinion being in the Leyland bag?

<EDIT: the early Oz Pinions had more poking out of the rack housing too>

The early big wheel mokes, that had the UK rack factory fitted also used a similar lockstops to those of the 13" wheel Rover Minis. Damm poms, stealing our technology again!

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Pinions are all the same length between bearing shoulders.
However on later racks they machined the bearing recess in the housing deeper (seal end)- this moved the bearing out, and they fitted a spacer on the pinion.
These are easier to get the pinion in....

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yes, come to think of it, I have come across these and they are a bit more tricky to get in.

Cheers

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I have a 67 deluxe with drum brakes (non-offset) and flares, I want to fit new wheels but I don't want to cut the guards. Will 13x5.5 fit without the need to cut?