Thread: Drilling or welding to defender chassis

I don't know if a Defender (or any LR) has a high tensile (HT) steel chassis or a mild steel chassis.
Looking at some of the welds on LR chassis and where they are welded I believe they are mild steel.
But any weld on a structural member will change the metal next to the weld which can cause cracking alongside of the weld on the chassis side.
I make it a rule never to weld directly across the top or bottom of a chassis rail, HT or not, same with drilling.
On the sides of a chassis rail I usually place a base plate, same thickness and material and stitch weld that to the chassis and then weld whatever bracket/brace to that, if you have to weld to the top or bottom of chassis rail, I make up a U-plate, fit over or under and weld on sides of rail, then weld whatever to that.
Just remember welding metal changes the characteristics of that metal, Regards Frank.

Originally Posted by Toxic_Avenger

I've got approx 6 brackets I wish to attach to the chassis of my defender, and it's looking like 2 of them may need to be attached directly to the chassis. The remainder I'll get away with mounting to the bolt on body / cable support brackets or wheel arches.

I've got the option of tack welding the bracket to the chassis (on the long side of the chassis, directly below the driver's side seat box), or drilling existing holes in the chassis out 1-2mm and using a m6 or m8 Riv-Nut to secure the bracket.
I understand any modifications to the chassis is not ideal. I've read other threads regarding the 130 chassis cracking, and threads on chassis repair sections, but interested if there is a best practice for modifications in this area, or if it's a complete 'no go'.

Plan B is to knock something up where the brackets will attach to the vehicle floor pan.

This is what I need to affix. It's a weld plate for a cable support, made by Stauff. The weld plate can be mounted to the chassis, or I can get away with bolting the weld plate to the chassis, or the clamp body direct, if I have a suitably sized threaded hole.

Yeah, not sure of the metallurgy of the chassis, but looking under mine, some of the factory welds leave a bit to be desired.

You refer to the old HAZ- Heat Affected Zone. It's usually a case that the weld deposit is stronger than the parent metal, but the HAZ is where most of the issues occur.

I've crawled back underneath, and I might even be able to get some brackets attached to existing fasteners, which will negate the need to mess with the chassis, but it's still good to get some ideas of what's possible if all the right protocols are followed.

Can't get by with 'P' clips? Usually easier to work around where space is limited.


Stauff type clamps are good, but bulky. Can always ditch the bottom plate and bolt direct a threaded hole too. Notch the lower shell, they can sometimes hold water in the cavity behind them.

Good thinking about notching them. I have not yet got them, but they are on order thru work.

I'll be supporting 2x 70mm2 cables for the winch. Just want to make sure they are not going to go anywhere. Ever.
I've got some P clamps of a suitable ID (19mm) but running these side by side is a bit fiddly, but probably what I'll use in the tight quarters where the cables run down the DS wheel arch, and onto the chassis outrigger below the DS footwell.