Chassis strenghening

Had a brainwave today whilst doing a little more work to my track car Rasheen and think il put my idea into practice and could be a really good cheap mod for some of you

Basically I was using a tube of expanding foam the other day and that's when this wacky thought occurred to me regarding filling all the following with the stuff
Chassis rails
Inner Sills
A & B pillars
Front & rear cross members

You could inject it into every chassis point throughout the vehicle but prior to injecting it I would spray some kind of light oil into cavities in order to water seal them.
It's light and very strong when cured and it surely has got to help with the overall structure of the chassis and if done correctly will help stop rust forming too 

Probably cost around £20 to do entire car so will see how it turns out and how it helps on track as il not be using a cage

Interesting, never thought about that.

Here is a write up about it. Looks like good results aswell if the correct foam is used.

https://grassrootsmotorsports.com/forum/grm/anyone-foam-fill-their-chassis/92620/page1/

I had a thought last week .
Was repairing a crushed chassis rail on an almera .

I cut the floor above the rail and inserted some box section and hammered the chassis rail straight .

I removed the box section and welded the floor up. .

Now my thought was if you cut the channel out above the rail from as far forward as you could to as far back then welded in the box section before welding the floor back in .. wouldn't that really help strengthen the floor/chassis/arb mounts.

Now that can only be a good thing

I might be stating the obvious here bob but probably a good idea to try to make sure you get a good even spread with the expanding foam. You don't want bits missing that you couldn't reach and end up with a stiffer chassis on one side than the other lol

Also just to add to this.. its not so much being water tight ist more the condensation it will hold in gaps, maybe really good for track cars but probably not for a restoration project/everday car

would prevent being able to treat any rust in these parts with wax oil or likes, think would in long term be something you would regret doing.

Would it set fire if you tried to weld something in the future? Not saying you wouldnt be able to remove it but might be a pain.

Yes it would .... as my friend bought a r5gt wich the sill was rot one side and had been filled with foam ... it was a fooking nightmare to cut all the shit out as it was solid ... and i still caught it a light

ROB_IOW wrote:I had a thought last week .
Was repairing a crushed chassis rail on an almera .

I cut the floor above the rail and inserted some box section and hammered  the chassis rail straight .

I removed the box section and welded the floor up. .

Now my thought was if you cut the channel out above the rail from as far forward as you could to as far back then welded in the box section before welding the floor back in .. wouldn't that really help strengthen the floor/chassis/arb mounts.

Now that can only be a good thing

I never thought about fixing rails that way rob gave me a few ideas for my car now.

Ive also thought was reinforcing the rails to prevent them from getting fooked up.

This has been done for years on boats. It works as well on one condition you get the right foam. The is waterproof and non waterproof. The non waterproof soaks up water like a sponge. Just remember if it needs welding do it all before. There is nothing worse than when you weld up a small hole and the next thing is smoke is poring out from that area. Talking from experience. The only way to stop it was to now cut it out. What started as a hole the size of a 5p ended a hole 1ft square.

Long term you would be best seem welding & strengthening chassis with plates & braces, cutting floor pan along chassis rails will make it weaker more than likely, modding rails externally or making from scratch would be good.
Foam approach is obviously much easier but it would need be good choice of foam & mixed with some bracing to make most of it, no idea how well it will help on an R !

I did this on my race car many moons ago. Drill holes along the inner sill then squirt in waxoil, then fill with expanding foam. Strengthens the whole car and even helps a bit with sound deadening.