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Alloy Engine Plates - Bad Idea?


Anthony

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They may or may not be a good idea - I've heard a few stories about cracks around the bottom holes!

I actually bought one but didn't fit it in the end because of my concerns about it. I think if the bellhousing bolted up at the top and the bottom to the block and the plate was just sandwiched between them it would be fine. Unfortunately, whilst this is the case at the top, it is not at the bottom. The part of the plate between the engine bolts and the bellhousing bolts must take considerable stress...

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i had no end of lunched clutches over the course of a year or so because of a bent standard back plate. im not sure, but i think alloy would be softer ? and more prone to bending ? if thats the case i wouldnt want to be anywhere near one. my bent standard one cost me 4 or 5 clutches before i worked out what the problem was.

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I'll let you know in a year or so. Because I'm fitting a kit to my GT6 designed to mate a Toyota gearbox to a TR6 engine, and the kit's bellhousing is specifically designed to mate to a TR6 back plate, I've bought an alloy plate. By the time I factored in postage from the UK, alloy was cheaper than a heavier used steel TR6 plate!

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willcolumbine wrote:
They may or may not be a good idea - I've heard a few stories about cracks around the bottom holes!

I actually bought one but didn't fit it in the end because of my concerns about it. I think if the bellhousing bolted up at the top and the bottom to the block and the plate was just sandwiched between them it would be fine. Unfortunately, whilst this is the case at the top, it is not at the bottom. The part of the plate between the engine bolts and the bellhousing bolts must take considerable stress...



I cracked one as described by Will around the bottom holes where the block bolts to the plate. Back to steel now.

AndyV

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1903 wrote:
There's nothing wrong with the front ones though is there?


I have heard a theory that the standard part acts as a bit of a 'strut brace' between the front turrets and that the alloy part allows a bit more flex than the standard one but I've got no direct experience of this myself.

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willcolumbine wrote:


I have heard a theory that the standard part acts as a bit of a 'strut brace' between the front turrets and that the alloy part allows a bit more flex than the standard one but I've got no direct experience of this myself.


Maybe on a Spitfire, but not on a GT6.  :)

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Once, when I didn't understand alloys, I made my own engine plates.    They cracked, around the plate-to-block holes, but  fortunately I spotted it before the crack could propagate.

The best fatigue resistant aluminium alloy is 2024, but like all such recipes you gain one feature by losing another.  2024 has poor corrosion resistance.   See: http://www.markusfarkus.com/reference/aluminum.htm

Has anyone asked what alloy the commercially available plates are made of?

JOhn

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JohnD wrote:

The 6000 series alloys are the among strongest, and 6082 is the strongest of them, with excellent anticorrosion properties.

John


Hope so, cos I got one last Christmas for the Herald! Haven't fitted it tho.. long way to go yet.

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