Post-crash strengthening?

Technical Area Steering & Suspension
2

Hi all

As I’ve mentioned in other threads, my car was shunted from the rear. It has been pulled on a jig and is apparently totally straight again, and apparently the heat technique means that the straightened metal shouldn’t be significantly weaker than it was before.

Nonetheless, it made me think that it may be worth giving the rear of the car some extra strength and support with a brace. I remember in ‘Wheeler Dealers’ when they restored a MK1, they showed pre-drilled holes under the car that braces just screw straight into - is this correct? If so, will this help?

I only ask because I’m concerned that the pulled section may suffer from ‘skuttle shake’ now. I wont know until I get the car back - just wanted opinions on bracing, whether its necessary/will help.

Cheers

3

The bracing your thinking of was for the rear sub-frame (Like the later MK1’s left the factory with), They go between holes near the rear wish bone bushes at the back, Two bars go forward to holes near the leading lower rear wishbone bushes, Then two more from there go forward to the floor-pan. The whole lot just stops any flexing of the rear sub-frame. Apparently this is quite a worthwhile mod for the early cars (Mine came with them fitted originally so I haven’t got any before and after experience there, Sorry)

Most of a panels strength is from its shape, Its not predominantly from the metal its self. Think about it, If heating up a panel was dangerous then we wouldn’t be allowed to weld patches in to anything structural. Like most company’s do these days, I think Dandy cars are just covering there ar$es just in case someone does it again and it causes more damage (I’m touching wood that it won’t happen as we speak [:)]). So please, Don’t worry, You’ll give yourself a stomach ulcer !

To be honest, I would avoid excessively strengthening the shell on a road car because… Well, Here’s a little picture from my past for you to look at.  http://www.fileden.com/files/2007/4/16/989771/Dead%20van.GIF

The recovery bloke said If I’d had the chrome bumper bars that everyone seems to fit to Vito’s, I would probably have ended up with significantly more than the mild whiplash I got, Cars are designed to distort in a crash so our body’s get less of a jolt.

If your still worried about the strength of an MX-5…

This bloke rolled his '5, Only stopping when the rear quarter found a telegraph pole, http://www.youtube.com/watch?v=zgqctb8rGwM

Even on race cars I don’t think the roll cage extends beyond the rear shock towers, http://www.youtube.com/watch?v=kvNylkt0uvc

This is just for reference, It seems the biggest worry we should have is flipping it, http://www.youtube.com/watch?v=kRJXFtyzcqw 

 

One little diversion on this thread. I remember watching that episode of ‘Wheeler Dealers’. One of the faults the car had was a rust hole half way up the A post. Has anyone else ever had this happen? It seems an odd place for rust to start. Might have been caused by some muppet gouging the paint when it had a windscreen fitted I suppose.

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Hey, sorry - only just realised this post had been responded to!

What an extensive reply! Thanks for that. I think I’ll do the rear brace as most later cars seem to have it as standard, and if it’s good enough for Mazda it’s good enough for me!

You’re clearly right about not excessively strengthening - the only reason my accident didn’t cause me more harm was because the car flexed and absorbed the impact. As much as I love the car, I must grudgingly place my health first!

Crazy videos… that last one in particular really made me sad. I didnt realise a car so low could be so prone to flipping - you’d think it’d slide long before that! Do we all need rollcages [:S]

Thanks again for the detailed response. As for the Wheeler Dealers rust thing, I remember thinking that was odd - could be as simple as a stonechip or other mark left untreated for too long. It was a G-reg car (like mine!) so plenty of time for any untreated paint chip to expose the metal and oxidise lots.


Cheers [y]