Notched chassis strong enough?

don't suppose it would hurt to add a bit more bracing if you can, so long as your welding is good as well

Id say its strong enough if your welds are good,

One thing to remember since you have now modified your monocoque its technaically needs a BIVA test

Sorry but though you should know

as colin says it looks to me that you may want to stick some gussets on the outsides of the chassis rail around the 'ramp' areas as that will be where it wants to bend.

or not - seen worse and I doubt whether it will suddenly fail in a nun/kitten interface.

stronger is usually better


edit

i would plug weld the sides of the chassis rail to the internal box section first as well

no point having this discussion but if it doesn't look like it should then its not.

now I'm trying not to knock anybody off but its not just a repair is it, vosa say replacing like for like is okay so same shape, gauge steel and construction and you are fine, are you sure this is like for like repair

sorry fella

It's the major part of the monocoque? It's not separate chassis they're welded on to the kickpanels and floor.

I think the whole thing is ridiculous, because we're talking about structure that was only put there voluntarily in the first place.

The mini didn't have front chassis legs at all but a subframe too low to do anything against another vehicle.
My Polo has rear chassis legs but the Fiesta of the time didn't have any, or anything additional in lieu. Neither have some more modern cars, 106/Saxo for example. Yet i can't touch mine or allow any perforation..

Plus if i choose to remove material from a chassis leg i know the car will offer less protection in a collision. Much like a standard 1961 Fiat 500 then (which doesn't have front seatbelts either), that has considerably less protection and yet i can choose to put myself in that seat.

I know a simple standard for monocoque bodyshells wouldn't be easy to determine, but i think it would be worth having, that is if the owner could choose to void it's safety status (euro N-cap four stars is still respectable today, but in twenty years it'll be as relevant as the simple wall test an Allegro earned for itself).

On another point about a bodyshell's status, if i put a 1986 Opel Manta 2dr saloon through an MoT with a 5p sized rust hole in the rear overhang behind the wheel, it'd fail. But the Polo 2dr saloon has a hole in this cavity from factory - for sunroof drainage. So laying in the boot of one car i'm allowed to poke my finger out for all to see, yet in another i'm not.

I see these as grey areas that almost seem whitewashed to me, and i think many of them are targeted unnecessarily.

Without getting into the BIVA argument etc lets look at it objectivley.
50% of the chassis rail has been removed. No additional strengthening added to replace this removed aspect. No way, other than crash testing, to determine if the 50% remaining is still sufficient. Worse scenario is MOT fail and remaining chassis rail cracks or bends.
I'd say you need additional reinforcement. Rather than adding metal to the chassis rails what about a strut going back to the bulkhead that attaches to the crossmember bolts ?
Official MOT tester manual says any repair to chassis must APPEAR to be as strong as the original structure. Removing 50% is therefore going to be difficult to convince a tester as the word is "appear" ie he has to use his judgment and if in doubt will fail.

Personally I'd have repaired as original and fitted lowered springs !

Paul H

No way to assess wether any strength had been lost so it would be pass and advise . Given that the iva doesn't test any materials or design then it would be a £450 coin toss as to wether it would pass