Thread: Series III (burned) rebuild

Looking good mate.

Ok, got a mate over today with boiler-maker/welder skills to cut and shut the rear cross-member.

Still welding as we speak, but looking good!

Two pics of the new one tacked into place, and a pic of the old one opened up to expose the reason it had to go.

Did you use a jig of some sort to keep the crossmember from moving/warping?

Or did you just tack it up and take it slow...?

Originally Posted by Shonky

Did you use a jig of some sort to keep the crossmember from moving/warping?

Or did you just tack it up and take it slow...?

No jig.

We measured to the rear spring hangers and also noted that the cross member was vertically square with the rear of the spring hangers, so the process was to fit the cross member at the right distance from the spring hangers, and ensure its vertical surfaces were parallel with the rear vertical surface of the cross member. To hold it in place when we had it right we tacked a piece of angle iron on each side. Then re-checked, gave it a few taps, and started tacking the actual joints. You can see the angle iron in one of the photos.

We seam-welded the whole way 'round then added 6mm plates on all four surfaces. Whew! More exhausting than a jig!


I'll take a couple more photos now and you'll see how it ended up.

Here you go, Andrew:

Just a note of caution for all people carrying out chassis repairs. If you use 6mm plate to reinforce joins, you need to realise that this is about three times as thick as the chassis material, so that there will be a major stress concentration at the edge of the patch unless great care is exercised in designing the repair.

The stress concentration can be minimised by avoiding straight patch edges across the chassis rail by having triangular ends, or ending them at a join to a cross member. Although less of a concern, straight edges along the length of the chassis rail are better where at least one edge of the patch is on the corner, which is reinforced by the other side of the chassis rail. Of course the other approach is to use patch material no thicker than the chassis material, although I realise that in some cases you may want to use thicker material to give more scope for loss due to rust in the future.

Stresses are highest close to spring mounts and crossmember or outrigger joins, and are highest in the upper and lower faces of the chassis rails.

John

sound advice

That's why they say experience is the thing you always get just after you needed it.

I'll keep an eye on it and see if it cracks.