Hopeless chassis?

[bad_panda]

I've currently got a 4x4 and it's the first body-on-chassis vehicle I've ever owned. I always have a look underneath anything I'm interested in buying to check for rust, and this was no different. All looked ok apart from one section of the chassis which I knew would need to be cut out and welded up, but it looked straightforward enough.

I made a start at the weekend. Once I'd got the underseal, rust etc ground off I then cut out the rusted part which obviously then gave me a big hole through which I could see inside the chassis rail. It was full of rust. Not just bits and bobs but big, thick chunks. Using a very long screwdriver I raked out as much as I could from the 2-3 feet I could access and ended up with this pile that weighed probably 2/3 of a kg:

https://www.dropbox.com/s/90nw9mzog37falc/Rust%20p...

It was then that I also noticed that the chassis had actually deformed where I'd had the jack on it (the blue arrow is an undamaged/normal section, the red arrow is where it's deformed):

https://www.dropbox.com/s/nkoyeceixfltm4n/Bent%20c...

There are no other holes big enough to allow me the same sort of view/access into the rest of the chassis but having a quick feel through the pre-cut holes that are there, I can feel these big, thick chunks of loose rust wherever I investigate. I'm now concerned that the entire chassis could be seriously weakened, despite actually looking solid and pretty clean from the outside!

What do you reckon?

[paintman]

Vehicle & which end?

What's its previous history - lot of wading & any boat launching (esp into the sea) involved?

Random google: www.landroverblogger.com/land-rover-chassis-repair...

Edited by paintman on Monday 14th February 13:46

[bad_panda]

It's a Shogun and the bit of the chassis pictured is the nearside middle-rear. Re: its history, as far as I can see it's never lived on the coast and it was completely stock when I got it so is unlikely to have been doing much wading or off-roading. It certainly hasn't been very well looked after though, in terms of keeping the underneath clean and performing easy preventative anti-corrosion measures from time to time. The entire underneath is covered in rust, albeit all fairly superficial and well within my abilities to sort out. As a result it was bought fairly cheap as a rolling restoration on the understanding that the chassis was ok.

My welding is pretty decent so I'm happy to make spot repairs to the chassis as necessary, but my concern is that if the entire chassis is rusted too much inside then there's nothing to work with.
I suppose what I'm trying to work out is, has that deformation in the photo occurred due to thinning of the metal there due to internal rusting? If so, is there any easy way to go around the chassis and find any other similarly thin spots, short of cutting out loads of small inspection holes and actually physically measuring the thickness of the metal wall?

[paintman]

I don't know how thick the Shogun chassis is & I don't think there's any easy way of determining what's left in terms of thickness.
Apart from tapping the chassis with a pointy hammer & seeing if it breaks through.

As it's badly dented it may well be worth cutting that out to see what it's like.

A camera probe might help you see what the rest of the inside is like. There's plenty of probes for use with mobile phones cheap on ebay but I don't know how good they are.

And a hoover with a long hose (I've got a Henry I use for the cars & garage & abranet sanding) pushed into box sections is very good for cleaning them out.
I find taking the plastic off the end of the hose makes it easier as it reduces the diameter & if the box is a bit tight then a long length of caravan drainage hose taped in the end of the hoover hose does the trick.
Just don't get caught using the one the wife uses in the house!

[bad_panda]

I've actually been all around it whacking it fairly hard with a pointy hammer and, apart from the one place where I already knew it needed welding, it didn't make any holes or significant dents. So I suppose the chassis can't be terrible, but it's concerned me how it's been deformed by the jack.
I don't know enough about about engineering, metal strength etc to know if I'm just being paranoid or if it could just snap one day, despite looking fine from the outside and having no holes in it.

Using a camera probe is probably worth doing. I've got one so can have a look to at least see how much of those big rust chunks are in there.

I suppose if I could find out the original steel thickness I could even go around it all cutting out little inspection holes and get a micrometer on the walls to see exactly how much it's lost. I may end up doing that anyway just to be able to give the internal chassis a really thorough clean and then coat the entire inside of it with something like Dynax.
Another thought I had was to just keep jacking it up in various places and seeing where else it deforms, if anywhere.

Haha certainly won't be using the wife's Dyson though as you say. Like you I've got a poor, plucky little Henry that has to soak up all the abuse of tasks like this.

[paintman]

Did a bit of welding on the n/s sill of my Range Rover Classic back in September.
Tiny hole turned into something rather bigger when I started poking

Used Bilt Hamber Dynax S50 to do inside the sill after I'd done.
First time use & very impressed.
Masking tape over all the holes that are supposed to be there & a big sheet of cardboard (old box opened out) on the drive under the whole length as it gets everywhere!
Old paint brush to apply the overspill to anything under the car that looked as though it could do with it.

Other than the bent bit probably not a good idea to see if it dents elsewhere - or to cut more holes.

Edited by paintman on Monday 14th February 20:19

[Smint]

Ladder chassised 4x4s all end up like this if no one bothers to wash the winter salt bath off the undersides every year from new (most car owners wouldn't be remotely interested or have a clue why, more worried about a speck of dirt landing on the perfect block paving) , if anything the insides of the chassis can be worse because the spring and summer rains won't wash the salt layer off, the further north the car has lived the more salt its been exposed to.
General undersealing is all very well but who bothers about the chassis insides.

I wouldnt spend too much time trying to find other thin spots, usually its the rear half that suffers most, just weld up what you need to then decide what the future holds for you and the car.

Also not sure about Dynax seeing how much rust chunks came from inside, maybe spraying oil or oil based product inside the chassis would likely soak the existing rust better, but first i'd shove the pressure washer L shaped lance or preferably drain jetter hose if you have one down the whole length of the chassis first and see what loose rust you can blast out and hopefully any accumulated salt with it or such stuff as dynax is only going to put a coat over already chunking rust with fresh salt from this winter trapped under it all.

[bad_panda]

I've finished welding up the bit that obviously needed doing and all in all the chassis looks good, from the outside at least.

I agree re: the Dynax and the rust that's already in there. That's why I was thinking I could cut a couple of smallish but low square holes (i.e. the bottom of each hole is level with the bottom of the chassis rail) on each side then use them to give the whole inside of it a thorough blast out. Once they were welded up again I don't see how they could do any harm. It'd only be the same as me cutting out patches of rust.
Otherwise I don't think I'll be able to give it all a proper, thorough clean and get it properly dried out.

No way has this vehicle had the relatively small bit of maintenance it needed. It's just been left underneath until the time came to sell it, at which point someone then slathered the entire underneath with Waxoyl, on top of whatever rust was there. So it looked great but was akin to rolling a dog turd in icing sugar.

[dhutch]

Rust always looks worse than it is, a lot more material comes off after the oxidation process than was there before. Something like 1mm of steel is worth 6-10mm of rust?

Are you jacking on a jacking point, or with a block of wood to spread the load, or just stuffed he head of the jack into the middle of the box section?

Can you drill a 4-6mm hole and gauge thickness? That bush looks lovely....

[bad_panda]

Maybe it's not quite as bad as I thought then, bearing that in mind.

Another Shogun owner told me that the whole chassis was basically a jacking point (the rear diff housing as well), and there was no need to spread the load, so I just stuffed the head of the jack into the middle of the box section. It was a bottle jack as well, which I told them beforehand. Bad advice? "Nah don't worry, you won't bend it" is what I seem to recall...

Yeah I could drill a few holes like that. Even easier to weld up. Haha I was wondering when someone would mention that bush. They're all like that, or worse. Next job on the list after replacing the diff oil is to replace all of the bushes. As you can imagine, the handling is a bit "loose" at the moment...

[Smint]

That was poor advice particularly for a bottle jack with typically a small jacking area, my Prado chassis is in exceptional condition but when i jack up its on a solid section, ie the T section where the outrigger is welded to the main chassis, its several layers thick there, also where the cross member supporting the gearbox is bolted to the chassis, jacking here raises both wheels on one side, always with a full size trolley jack with rubber pad, no doubt your Shogun has similar obviously reinforced sections.

For the rear end i usually jack on the rear live axle, i do use the diff casting for raising both sides but if one side then on the axle tube as close as possible to the side being raised, again with something at least 4" wide.
I keep a solid flat piece of hardwood in with the vehicle jack in case of puncture to put on top of the bottle jack and spread the weight.

Edited by Smint on Tuesday 15th February 17:56

[bad_panda]

Damn, so I've needlessly damaged my chassis :-( Although trying to see some positive in it, the damage isn't proof that the chassis is so corroded inside that it's been significantly weakened, which is what I was originally worried about after being so confidently told that I couldn't bend it with a bottle jack...

Not a mistake I'll be making again.