Morning all. I need to replace rh steering arm on my mk2. (On top of the hub and the part that connects to the tie rod) I went through the list looking for numbers and cross references without much success.
I have aya1604 and a ayg409?(probably a 5 or 6)
I also have a aya4116 on the shelf that looks like a perfect fit for the damaged one. (Once I mill down the outer face as per factory for disc clearance)

However, the wide range of numbers that are stamped into these things has me second guessing myself. Some of my numbers don’t appear in the Mini Kingdom spare parts book.

I get that there’s a thick and a thin but I am comparing thick to thick.
Are the different part numbers significant or was it a change in factory or something like that.
Thanks for your help
Neil

I can't help with information regarding the differences in the various steering arms but below is what the last of the round-nose parts books says for the hydrolastic front suspension.

Note: If the part number three alpha prefix has a Y in the second position, such as AYA and AYG, then this is an Australian part, otherwise it's a UK sourced part.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Thanks for your help. I will study the table and see what I can find.
Neil

Had a look at my 8/'70 S.
The casting number I think, is AYG4034. My son thinks the '3' is a '9' which would tie up with the parts catalogue for the De Luxe mk II (mini K) which did have a lot of common components with the S mk II. Couldn't get a better photo but the numbers are readable in the flesh.
The problem is the casting number isn't necessarily the part number.
Hope this is some help.

My 3/70 mk2 S has AYG 4094 & 4095 on them (R & L) . I have a spare set the same from a pair of disc/caliper/hubs I bought years ago.

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1970 Mk2 Cooper S under restoration

Where does BTA894 fit in the picture?

Dunno but it’s down the rabbit hole for me trying to find out what the different numbers mean.
I will try to put up a table of the various numbers so far in the next couple of days.
Neil

Thanks for your help Bill.
I will try to pull the numbers together in a couple of days
Neil

Thanks for your help mate.
Seems like a lot of different numbers.
Maybe it’s the pressing factory id number.
Dunno really.
Let’s see how it looks when I put the numbers in a table and we can see them side by side
Neil

Part numbers are different to casting/forging numbers, often by one digit.

BTA 894 is a Right hand Cooper S arm. It was 21A 1464 (whatever that means) as per Winabbey’s post.
The Cooper S arms are machined flat on the disk side but the drum brake arms are round on the edge.
Neil

Sort of like these....

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1970 Mk2 Cooper S under restoration

I started out in steel foundries which made things like these. if the geometry is the same, and so is the material then there won't be a physical reason you might see for the casting numbers. It will be down to batches, contracts UK/ Australian provenance and the like. Other differences like the grinding/rounding will be down to the way the patterns came together for casting and the subsequent need to remove the flash mouldings. Its nothing to get too wrapped up over, but it is easy to find the right numbers at least if you have a pile large enough.

Here's one, were the disc brakes Australian manufacture or UK manufacture? I've never thought about that one?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Yep, exactly like that[THUMBS UP SIGN]
I am getting the flat edge put on one that I had today ready for the rebuild.
Thanks for your help and the photos.
I’m very impressed with the wide range of mini parts photos that members have in their collection and how everyone is willing to help out with questions and issues.
Thanks again
Neil

Thanks for the explanation Mick.
Your advice sounds very reasonable. I have a twin to the damaged arm in my bits and pieces pile and I will be using it on my car.
I am getting it machined today so it’s got the flat outside. The inside face of the disc hub is machined flat and without the flat surface on the arm it is overhanging that edge. In this case it seems to have been done by BMC for a specific reason.
As for the Australian vs English disks... I’ve never thought about that either. There was a push for minimum Australian content in cars back in those years so I am gonna say Australian based on that. Let’s see what the rest of the group say.
Cheers
Neil