E36 - Chassis material. Rear subframe reinforcement plates

[glen.riley.1990 25]

Hi All,

I have an E36 i'm planning to put through the LVVC for a motor swap, as part of that im looking to weld in the factory M3 rear subframe re-enforcement plates. The certifier is onboard with this but has asked me to confirm the plate and chassis steel on the car is mild steel. I have dropped BMW NZ a query and am awaiting a reply.

Has anyone else done the same or similar (e46?) and gone through LVVC and have a suggestion or line on where to confirm the body material? i have found a few build threads on here, but nothing specifically on confirming the body / chassis material before welding to it.

Next Stop will be to talk to panel beaters and / or repair certifiers if BMW is unable to provide a suitable statement/evidence for the certifier.

 

Cheers G

[Vass 937]

My certifier told me it's not even something that needs to be certified per se but could get picked up in the process if certifying for something else. Unless you're moving the suspension mounting points (you're not) and the welds are done to a "tradesman-like standard" you should sail straight through. Visual inspection and no further questions. Sounds like your guy is being difficult just for the hell of it, quite a weird question to ask and request proof for. Of course it's mild steel, what else would it be? Carbon fibre honeycomb?

[aja540i 1909]

2 hours ago, Vass said:

My certifier told me it's not even something that needs to be certified per se but could get picked up in the process if certifying for something else. Unless you're moving the suspension mounting points (you're not) and the welds are done to a "tradesman-like standard" you should sail straight through. Visual inspection and no further questions. Sounds like your guy is being difficult just for the hell of it, quite a weird question to ask and request proof for. Of course it's mild steel, what else would it be? Carbon fibre honeycomb?

Medium or high tensile steel, which have different welding requirements.

[glen.riley.1990 25]

2 hours ago, Vass said:

My certifier told me it's not even something that needs to be certified per se but could get picked up in the process if certifying for something else. Unless you're moving the suspension mounting points (you're not) and the welds are done to a "tradesman-like standard" you should sail straight through. Visual inspection and no further questions. Sounds like your guy is being difficult just for the hell of it, quite a weird question to ask and request proof for. Of course it's mild steel, what else would it be? Carbon fibre honeycomb?

It’s being certified for an M60b40 engine swap + manual conversion with brake and suspension modifications to boot. He wanted to determine its not high tensile steel and or that there hasn’t been heat treatment applied to ensure correct consumables for welding process, and that no heat treatment or post cool is required. 
 

I agree with you, probably 99.5% certainty it is mild steel, and a bit frustrating that I can’t just take it to someone who knows what they are doing and be done with it (thin gauge is out of my capability, especially in a structural location). However I don’t have a lot of options for a certifier an around me, and I’m not inclined to swing backwards and forwards because I’ve been asked to clarify one thing. I’d rather that than have the cert rejected because I’ve welded to a significant structural component of the car and decided not to disclose it. 
 

thanks for the input, if it becomes insurmountable then I’ll consider traveling and swapping Certifier.

 

[Cement 909]

My certifier was interested in mine and came to my place to inspect the welding before I seam sealed / painted etc. Now complete, it's noted on my cert as "Rear subframe mounting reinforced". I'd suggest working in with your certifier of choice ... a bit like dealing with building inspectors really !!

I have looked in my emails and can't see any discussion of body material, but it does ring a bell 🤔 

EDIT: Maybe your guy can talk to my guy (or others ?) to form a sort of standard approach yard stick.

Edited Tuesday at 06:54 AM by Cement

[Vass 937]

29 minutes ago, glen.riley.1990 said:

He wanted to determine its not high tensile steel and or that there hasn’t been heat treatment applied to ensure correct consumables for welding process, and that no heat treatment or post cool is required.

Welding must be his area of expertise, I imagine 98% of certifiers wouldn't know enough about it to even think to ask such questions. Probably overcomplicating things a bit though, in all the research I've done when reinforcing my chassis I can't remember seeing any mention of steel grades or any special procedures. Most reinforcement plates out there don't even mention steel grades and ones that do are mild steel. I imagine they they would be made to match the rest of the chassis they're being welded to. 

Might not be much help but here's a full manual for the CMP reinforcement plates that go over the prep and welding procedure. It doesn't have recommended weld settings but I asked for advice on that front directly from them at the time and got the following response. Someone with more welding knowledge might be able to deduce the steel grade from the voltages mentioned? I've no idea how that works. These guys have developed the kit, have installed it on numerous cars so do know what they're doing.

Doesn't answer the certifier's question directly but if you have no luck in your search for information, maybe he'd be satisfied enough for you to follow the tried and tested procedure laid out in the manual?