C notching chassis

[dvslux]

Hey guys, a friend of mine wants a C notch done on his ute (full chassis Datsun). How far does the notch have to cover the chassis? Is it 100mm?

Origionally he wanted just a notch cut out of the chassis with a piece of pipe welded in place, which I managed to convince him out of.

[johnbrett]

Very few C-notches are done to a good standard- I fail most of them.

Even the Hobby Car technical manual fails to cover how it should be done.
If you want to see how this sort of thing should be done, look at professional steelwork, e.g. in a building frame.

In essence, the strength of a beam such as a chassis rail is in the top and bottom flanges, very little is in the side web. If the flange has a change of direction, it needs to be supported by a web-plate across the section to be still able to transmit tensile and compressive loads.

If you want to just cut a chunk out of a chassis rail- it is YOU the modifier, who need to prove that the original strength in not reduced. (and you won't be able to) Better if you ask someone to design a proper C-notch in the first place

[dvslux]

Hey John,

the initial idea of cutting a peice out of the chassis rail was nipped in the bud as soon as he told me, I flat out refused to even talk about it basically, so you dont need to worry about that part

This is the notch I will be using



He only needs a 2 inch notch so not all of this will be used, there will be a couple of internal gussets. The factory chassis is 3mm, the notch is 4mm. Once I have cut the lower parts of the notch off, so it only raises the notch 2 inches, will there still be enough coverage over the chassis to pass cert?

Cheers
Ben

[umbridge]

Sounds like you shouldn't be chopping a chassis

Ok, don't just cut off the bottom of that notch. That is a C Notch to lay a hilux chassis on the ground. The angle of the plates follows the rails, so 4 plates the same means a front and back on both sides of the rail. You understand these are lap welded to the outside of the rails, right?

Don't cut the chassis and fit what's left of the notch you chopped up!

The fish plates that you want to cut off, that line up with the rails, are designed so that a straight line of weld through both the inside and outside rail doesn't happen. I hope thats a good description. The tall sides of the chassis shouldn't be weakened by corresponding welds opposite each other.

That's a Forbidden Kustoms notch. Strip the chassis where you are going to weld. Tack the inside and outside notch plates and the top plate to the rails. Ask your mum to weld it up for you. Now you can cut the piece of chassis out of the notch, and if your mum has 4G overhead skills, maybe she can finish off the lower plate for you too.

But really, the reason I post this is that most certifiers actually hold NO CURRENT WELDING TICKETS! And the fact that I can weld 1-12mm MMAW/GMAW/GTAW f**king 6G all position! to a qualified standard, means I'm more qualified than you! to make a f**king decision about welding!

LVV should be the same as anything, if you can't pass it, you can't judge it.

[dvslux]

You sound rather angry, and this isnt a pissing contest as to who is more qualified to weld this. Its also not helping my enquiry into regulations of doing this C notch.

Yes it is a notch from one of the FK members, and yes it is designed to able to lay a hilux, or similar on the ground, but this is not needed to lay on the ground. This is static drop that needs a little more room before it hits the bumpstops. The notch only needs to be 2 inches.

Yes the overlapping section is designed to give more area to be welded onto the chassis, but this notch, even cut down is still overkill for the chassis that I want to weld it to. This chassis is about 2/3rds the size of a hilux chassis.

So it seems this forum is a complete waste of space if the only people posting in this thread are internet hero's, and nobody can actually answer my question with a legitimate answer e.g. YES or NO, change this a little here etc and you will pass cert fine.

Constructive critisism is appreciated, not arrogant comments telling me I shouldnt be doing something. Nobody on here has any idea of what I can/cant do so dont go assuming things you have no idea about please.

[dvslux]

Just to try and make it a little clearer, hopefully this picture will show you what I mean.

[Justin]

Hi guys

Providing details on how you should modify your vehicle isn't really what we're here for - we'll try and help where we can, but with modifications such as this many things need to be considered. Your best bet for getting good advice is to either talk directly to your LVV Certifier, or with someone who has experience or expertise in this type of modification.

John is correct that there are very few guidelines regarding a chassis c-notch. This is a modification that, due to the large number of variations in chassis manufacture and design, is impossible to have a 'one size fits all' technical guideline or requirement.

I'd suggest that you get in touch with a shop which has a good track record in doing this kind of modification - your certifier should be able to point you in the right direction.

Umbridge - regarding welding requirements for LVV Certifiers - there are actually some very good processes in place for LVV Certifiers to ensure that the quality of welding to modified vehicles is high. Obviously a visual inspection of a weld can't be relied on to pick up defects nomatter whether you're a welder or an LVV Certifier - however if there is either a welding certificate showing the welder is qualified, or evidence of a practical test having been passed, then there is a far higher likelihood of a good quality weld having been done. Here is a link to the document; www.lvvta.org.nz/documents/suplementary_information/LVVTA_Info_Tech_Bulletin5-Builders_welding_guide.pdf

I hope this helps

Justin