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MG Midget and Sprite Technical - 1098 backplate.

Quick question.
Is the engine backplate on a 10CC 1098 engine steel or cast iron?
Thanks.
Bernie.
Bernie Higginson

Hi Bernie, I think it is cast iron. It's very difficult to weld (in case you are worried about a crack).

Rob
Rob aka MG Moneypit

Thanks Rob. I was wondering if it's cast steel rather than iron. If steel it would be weldable if the crack was grooved and welder cranked up a bit.

Bernie.
Bernie Higginson

cold you use yours as a template and modify a Morris Minor one?
David Smith

Cylinder heads can be welded but it is a very skilled job i.e. cost a lot.

To stop a crack just drill a hole at the end of the crack. It helps to relieve any stresses involved.

The one on my 1275 in the Frog has a split from the crank hole to the oil pump hole but it's got as bad as it's ever going to get so I just ignored it.

You could get some ally plate off eBay. 6 or 8mm would be ok and cost about £25. Use the old one as a template. You will get through many jigsaw blades and have blisters on your fingers due to all the filing, but it will be stronger and lighter. It took me a couple of evenings (hard) work.

Rob
Rob aka MG Moneypit

It's not a problem that I have. I was asking on behalf of one of our MASC N.West members,Steve Kiel.
Steve is a very competent engineer and I'm sure he could carry out Rob's suggestion of making one from aluminium.
Bernie Higginson

I had my 1275 welded becuse of some cracks ... its didnt go well, ...maybe a high end pro with a TIG welder ....but not for the joe blow guy with a $89 gasless clark mig

.
Prop and the Blackhole Midget

Another vote for alloy. Wood cutting bandsaws work a treat on it if sharp. I prefer 10mm.
Paul Walbran

I checked my 1275 back and front plates yesterday. They don't look cast to me.

Would the 1098 plates be different?

Here's a pic of my engine front plate, showing a stamped hole. I posted it previously on the oil sucking threads, and it was concluded that the hole was stamped, causing it to look laminated.

Would a hole be stamped in a cast item?

So if not cast, why not weld it?

Lawrence Slater

Lawrence,

The front plate is punched steel but in my experience the backplate is cast and prone to cracking between a couple of the holes.
David Billington

I looked at my back plate david, and it seems to be(look) exactly the same as my front plate. I'll get a wire brush on it and have a closer look.

Why would the back plate be cast and the front not?

I don't know, I'm just guessupposing. ;)
Lawrence Slater

Lawrence,

Cheapness to manufacture at the required thickness. The earlier 948 was pressed steel but the later ones are quite a bit thicker. From memory the front and back faces are ground flat but the edge of the plate is likely to be the give away, also even if cast iron it may be a malleable iron.
David Billington

It also has the part number cast into it, in many cases.

Like this...

Dave O'Neill 2

I think the difference from steel front and cast iron back is the forces put on the front, the front is where the engine mounts attach and the front plate tends to warp... mine was warped badly and took a couple of years to figure that out.but if the front where cast, then you would see alot of metal fatigue and failure

But thats my guess as to why the front is steel and the back is cast iron

Im a huge fan of ally back plates also .. they do sell them on ebay from time to time, my datsun 5 speed conversion has a thick ally back plate


Prop
Prop and the Blackhole Midget

Just as well I never hit my backplate with a hammer then. lol.
Lawrence Slater

This thread was discussed between 22/10/2014 and 25/10/2014

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