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Westbury
United Kingdom
2010 Posts |
 Posted - 21/08/2023 : 09:28:55
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Hello, Duncan.
Further to your query above, the K3 brake drums were made from electron and had the liner shrunk in like the E.R.A. However, a series of countersunk screws were fitted around the inside edge of the drum not on the outside like Racing Rileys. I tried unsuccessfully to post a picture.
Chris |
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Gerhard Maier
Germany
873 Posts |
Posted - 21/08/2023 : 13:24:41
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Here is some information regarding the Girling brake drums (using the H&H Holden & Hunt Patent), as they were used for the Q-type and the R-type, .
Although unlike the Q-type, on the R-type these drums were dished .
A while ago Q-type brake drums were offered for sale on ebay. (see below)
But this offer is of course "old news".
Gerhard
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DK6780
United Kingdom
249 Posts |
Posted - 21/08/2023 : 14:23:04
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An impressive process given the limitations on welding in period. I wouldn't have thought that "high tensile steel" is an ideal friction surface, but it clearly worked well enough in period.
I see that Andy King makes replica K3 drums in aluminium with the screws arranged as described:
I guess that the dished design precluded the screws being fitted the other way around as with Riley/ERA. |
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coracle
United Kingdom
1940 Posts |
Posted - 21/08/2023 : 15:12:22
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Gerhard's information is most informative but clearly rules out machining from billet other than for "decorative" purposes.
The eBay offering was Tony Gould so you could ask him if is able to track down any more? |
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DK6780
United Kingdom
249 Posts |
Posted - 21/08/2023 : 15:46:29
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quote:
Originally posted by coracle
clearly rules out machining from billet other than for "decorative" purposes.
Why? Surely the process was just designed to cut down on the material costs and not related to grain direction etc. |
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Gerhard Maier
Germany
873 Posts |
Posted - 21/08/2023 : 16:47:13
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In the late eighties, I thought it would be beneficial to have a complete magnesium brake drum on the shelf as a spare, just in case, for K3013.
Liners were cast in grey iron, and magnesium cast blanks for the drums.
With my old lathe it was a patience game to machine the parts.
The drum heated, liner cooled and in addition to the shrink fit, the original safety screws were used.
It was a challenge for a non-expert.
Gerhard
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coracle
United Kingdom
1940 Posts |
Posted - 21/08/2023 : 17:26:06
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quote:
Originally posted by DK6780
quote:
Originally posted by coracle
clearly rules out machining from billet other than for "decorative" purposes.
Why? Surely the process was just designed to cut down on the material costs and not related to grain direction etc.
Well, reading from the Patent text Gerhard supplied above:
"The rim of the brake drum is formed from a length of high tensile steel bar rolled into a circle, the ends then being electrically butt welded. This is fixed to a mild steel face plate, a recess being formed in the latter's inner face..."
So two different steels for differing functions, so not just designed as such, to cut down costs. |
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DK6780
United Kingdom
249 Posts |
Posted - 21/08/2023 : 17:32:36
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Truly impressive work! I couldn't contemplate doing that myself.
Just a point of order - the Magnesium alloy was elektron not electron, originally an I G Farben product although a UK licence was held by Magnesium Elektron who presumably supplied the material for MG and others.
https://en.wikipedia.org/wiki/Elektron_ alloy
Apologies for the thread creep, but it's been very educational. |
Edited by - DK6780 on 21/08/2023 17:39:55 |
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Westbury
United Kingdom
2010 Posts |
Posted - 21/08/2023 : 20:45:38
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Having carried out extensive machining operations myself including manufacture of brake drums, back plates etc., yes, it is hard work but extreme enthusiasm ( or is it madness?) knows no bounds!!
Chris |
Edited by - Westbury on 21/08/2023 20:46:27 |
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paul55
Luxembourg
731 Posts |
Posted - 23/08/2023 : 07:07:52
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| as suggested I contacted Typecast, very helpful and it does seem that that can manufacture as set of 4 without any issues. But at £539 +VAT each I'll have to think about it. Will probably try to get the shoes relined with a soft compound first and see how that goes. Paul |
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Westbury
United Kingdom
2010 Posts |
Posted - 23/08/2023 : 21:44:21
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If anyone is contemplating machining up magnesium castings please take proper precautions.
I learned the hard way and experienced an alarming fire by using a too high cutting speed! Took me quite a while to calm down after that!!
Chris |
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Topic |
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Q Type Brake Drums
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