Curses - cracked my back plate

[dixieflatline]

I finally managed to secure my diff to the work bench (I was pleased with my solution - going to post a photo when I've extracted it from my phone) but pride comes before a fall because I then rounded the fill plug, and cracked the back plate trying to force the rounded plug with a chisel. *

Any idea where I can get a new back plate from? I found a couple of 7" back plates on eBay but no 7" ones.

* I didn't actually do this bit personally.

[Gerald-TVR]

dixieflatline said:

I finally managed to secure my diff to the work bench (I was pleased with my solution - going to post a photo when I've extracted it from my phone) but pride comes before a fall because I then rounded the fill plug, and cracked the back plate trying to force the rounded plug with a chisel. *

Any idea where I can get a new back plate from? I found a couple of 7" back plates on eBay but no 7" ones.

* I didn't actually do this bit personally.

Got a complete one if you are stuck!!

[dixieflatline]

Think that's probably the answer!

[tozerman]

Just a thought, could you not weld it ?

[GreenV8S]

tozerman said:

Just a thought, could you not weld it ?

I've never welded cast iron but I gather there's a bit of a knack to it. But if you know (or are) a really good welder I expect it would be possible.

[tvrgit]

What about some of that "instant metal" type crack repair - it's not as if it's a stressed part. Heat might be a problem though.

[phillpot]

GreenV8S said:

I've never welded cast iron

Mine looks like some form of cast alluminium?

If the crack goes out from the thread I suspect it would just open up when the plug is tightened (taper thread) if repaired with "chemical metal" or similar?
If welded thread may need re-tapping, half inch BSPT I think?

[Alan Whitaker]

Hi All
Just had a look at mine and its cast aluminium so it can be ground out and Tig welded, as Mike said you would have to tap out with a parallel thread and use a sealing copper washer like on a sump plug but should repair ok.

Alan

[dixieflatline]

Thanks all - yes, welding is an option apparently. The guy I was working with is an experienced welder, and he said that if I have trouble finding a new back plate then it can be welded back together. If I can't find a new back plate soon that's what I'll do. Hoping one will turn up though - as Norman said, probably easier to find a scrappy old diff, take the back plate off and chuck the rest away! Also hunting around the car builders forums - some of them seem to have a stash of parts like these.