Check your chassis rot!

[4Latas]

I came across some dangerous rot in my chassis, just underneath the engine. The chassis is made of what looks like a cheap nasty folded metal sheets, and prone to rot.

Worried I could bend the whole chassis while sharp breaking ( yes, that bad...) I took the engine and gearbox out and the doors, and tipped the whole R4 in some tyres.(If you maintain some blocks under the hubs, and piut the tyres in the water gutter in the roor, it wont damage nothing.)

I then used some mig welder and welded some serious sections of thick metal sheet 40x5x0.5 cm along the main spars.

This substancially reenforced the chassis, and made in the process a very useful "skidplate". Everything is painted black and very difficult to see that this repair took place. I think i won in terms of preservation of the chassis. The MOT man is happy as well, and his little hammer sails through it everytime. (No, i aint gonna tell him...)

I write this so you can check very carefully if your R4 is suffering from the same, in this area which we normally dont have visual acess to.

Have a nice week.

 

[barnfind]

Yes,mine was rotten here. It is quite surprising what lurks unseen in the various hidden parts of the Renault 4 floorpan and chassis setup.
Having seen some of the MOT coverups on my own floor pan (3 layers in one place) it is probably prudent for owners of unrestored cars to get underneath before winter really sets in and have a good look around.

 

[lazyduck15]

Have you guys any pictures to share as to know what to look for on my 4L? And how to fix it?

 

[4Latas]

Sorry, i didnt took any pictures. But its exactly under the engine, those chassis "spars" at each side of the engine & Gearbox.

 

[barnfind]

Here are a couple from mine. Left hand shot shows rotten bottom skin cut away from drivers side. Other shot is passenger side.

 

[alewis]

Mine went in the same place. although on mine it was just the outer skin. Once i cut that away the inner skin was fine.

 

[paulbrook]

Yup

Very familiar and it must be dealt with. I did a similar repair on Barnfind's R4; see

http://s484.photobucket.com/albums/rr206/RustyTrucks/Renault 4 Chassis Restoration/#!cpZZ4QQtppZZ16

I think Renault had a "lets see how many places we can double skin" competition when they designed the 4.

 

[Rutger-peer]

I think Renault had a "lets see how many places we can double skin" competition when they designed the 4.

Haha, they must have had something like that, otherwise you'd never come to something like that . Actually, it's got everything to do with cheap production ofcourse.

But anyway, 4Latas, this is a very common R4-problem and there's lots of examples of this on this forums! Good point though.

 

[barnfind]

Its all about keeing cost (and weight) down by having as simple a set of components as possible and using basic materials, joined together with spot welds.
The double skinned thing goes back into the early years of mono construction after the second world war. A lot of earlier post war designs seemed to have this sort of rust trap, because they were starting to use the shape of the component rather than the actual thickness of the material to produce a rigid structure. Hence the 'big box' chassis of the R4, compared with thick channel section of older generation chassis based cars.

Old Rootes Group cars, are a good example. Many of their models had all sorts of double skinned areas where, for example, inner and outer wings met, which made them extremely solid when new, but were put together with no thought of what happened to trapped moisture, and which make subsequent restoration a nightmare.

If you want to see how crispy an R4 chassis can really get, then do have a look at Paul Brook's photobucket link.