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Forum Index : Other Stuff : Austin 1300 GT - Subframe nasty....

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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9755
Posted: 07:26am 09 Nov 2025
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Well, this ain't all that good:





Rear subframe mount, where it bolts to the body on the LH side.
Stress fracture galore!    

They are known for going here, as I am sure many UK members will attest.
Most of them just rust-out here, but we caught this before that happened.

Probably need to remove engine and front subframe, so we can weld this up.

Lovely BLMC....    
Edited 2025-11-09 17:27 by Grogster
Smoke makes things work. When the smoke gets out, it stops!
 
Godoh
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Joined: 26/09/2020
Location: Australia
Posts: 591
Posted: 08:26pm 09 Nov 2025
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It may be the light but it looks like there is a bit of brazing there from an earlier repair.
Are you going to weld the stress cracks only or plate over the spot as well.
Often welding can make the steel harder and more likely to crack next to the welds.
So plating can help it to last longer.
i am sure you know what you are doing, have fun
pete
 
Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9755
Posted: 10:59pm 09 Nov 2025
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Yes, well spotted, I think you are correct!
I was concentrating on cleaning up around the cracks, so I could see how bad it was, so was not really paying any attention to that.

There is a big stress-fracture crack just above that area of brazing too.

I've involved some mechanic chums of mine, and we are all thinking about what is the best way forward.  As you say, just welding up the cracks is not necessarily the best way forward, and can make matters worse!

We are currently thinking along the lines of cutting that entire section out of the body shell, and replacing it with one cut from a wreck.  The body is plated there where the subframe bolts up to the body(standard from factory, to stiffen/strengthen that area), so this cracking is around and under the stiffener plate, so that's not really ideal.  

I think a cut-and-weld the entire section of the body from a doner car is the best way forward.  I'm not a big fan of just welding up cracks, for the very reason you pointed out.
Smoke makes things work. When the smoke gets out, it stops!
 
Godoh
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Joined: 26/09/2020
Location: Australia
Posts: 591
Posted: 01:09am 10 Nov 2025
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A friend of mine had a Suzuki Jimny, it had cracks in the chassis where the front shock absorbers mounted. I was very surprised when he sent me a photo of the repair that a workshop did on the car.
All they did was weld the cracks in the chassis up. It looked a bit like a spiders web.
I doubt that the repair will last long on his car. It was one I would definitely have plated over.
Your idea of cutting the cracked section out and fitting in a donor section sounds good.
Good luck with it
pete
 
Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9755
Posted: 07:44am 10 Nov 2025
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Yeah, that was my thinking also.
Welding up the cracks is ultimately self-defeating.
THIS IS WHERE THE STRESS IS, so welding up the cracks, just makes the cracking area EVEN MORE prone to even more cracking.

You've gotta RELIEVE the stress, by moving the stress away from the problem area.
Welding up the stress area, is nothing but a band-aid on the problem.
Smoke makes things work. When the smoke gets out, it stops!
 
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