Underbody/chassis protection

[bigegg]

I just bought a land cruiser.

The chassis is in good condition, but has surface rust.
I'm looking for a underbody "system" to keep it in good condition.
I don't expect to be doing any "off roading" in it - a few farm tracks + muddy grassed fields.

From a cursory reading of a few sites, I'm thinking:

1. Pressure wash (steam clean?) to get rid of any mud/dirt/oil.
2. Wire brush to "shiny" where possible.
3. ?spray?/brush with phosphoric acid.
4. Zinc rich primer/cold galvanising paint?
4a. Jotun 90al? After or instead of cold galvanising?
5. Some sort of epoxy hard coat?

Anything I've missed? Recommendations for particular products? Any to avoid?


I've already looked into getting a pool full of citric acid/molasses

 

[steveo3002]

dont want shiney /polished metal , wants to be rough

and dont put a hat on a hat , whatever contacts the clean steel is whats doing the job so pick one (in my opinion)

 

[bigegg]

dont want shiney /polished metal , wants to be rough

and dont put a hat on a hat , whatever contacts the clean steel is whats doing the job so pick one (in my opinion)

The "hat" in this case being the cold galvanising or the Jotun 90?

As to "shiny" - I guess I meant "clean'.
Is there a surface prep method that is better?
I have a small sand blaster that I could use, but imagine it would take ages, and make a huge mess. (Will be working on shared driveway)
Commercial?soda? blasting maybe?

 

[Wildefalcon]

Jotun. Then a decent layer of wax.

 

[MetalMonkey]

Yes sandblasting, Yes huge mess, Yes ages!

At that point you are better off taking every component off, blasting it all in a cabinet and epoxying, with a topcoat of your choice. Then blasting the remaining underbody in situ, with the same treatment before reassembling. That's basically what I do for a full restoration and it is the best but a huge ballache.

To just tidy it up, knock what scale you can off, rust treatment it. Epoxy if you can get to it, and cover liberally in underseal.

The problem is if you don't strip it all down, you won't get the epoxy in all the nooks and crannies to cover everything up completely, so rust is likely to creep back under the coating. So all you can really do is your best, and then keep topping it up with underseal.

 

[steveo3002]

yeah blasting will be best

and yes in my mind either jotun or the zinc primer (you can get zinc rich jotun too) i clean it up best i can and 2 coats of jotun , thats protected enough and you can spot any future scabs easily

 

[steveo3002]

i dont see any point in covering jotun with underseal or wax , its just a wasted step as its already protected , just if/when theres a scab years down the road you cant see it as its under the black mess and then when it does need dealing with you have to clean it all off

if the looks bother you then some satin black so it washes up clean

 

[julianf]

I've got loads of tins of that black gunk. I won't use it, as, without flawless prep, it just creates a laminate layer that will hold water in place.

I've got a car that I want to do a "quick" job on, so I think I'm going to use one of the thin sprays - one of the lanolin ones (not lanoguard, as they're all the same and I don't want to pay for a massive Facebook advertising campaign!) with the knowledge that it's not especially tough, but that it will seep to some extent.

 

[arther dailey]

just if you steam clean/wash make sure you thoroughly blow out all water collected in chassis ,my uncle took pride in his transit chassis for ever hosing it off , rotted out super quick as never drained properly.

 

[CompoSimmonite]

What about Dinitrol ?

Home

The only official authorised UK DINITROL® e-commerce website and directory listing Retailers, Online Stockists and DINITROL® appointed stockists

www.dinitroldirect.com

 

[Dcal]

Jotun 90A epoxy sticks better than Jotun zinc rich epoxy (Barrier 90) and requires less prep so that's what I would use.

For prep, best to excellent after pressure washing would be -

Grit blast.
Bristle blast mechanical prep.
Needle gun mechanical prep.
Derust with wire brushes etc then sand with 80 grit to get a nice matt finish.
Or any combination of the above depending on condition.

For Jotun 90, prep doesn't need to be perfect, however the better the prep the longer it will last.

Even the clean and sanding method will last many many years if done correctly.
A top coat won't hurt but isn't necessary and Jotun 90 can be tinted (within reason) to match what you want.

I always put a top coat on unless it's under plastic covers or the like, it doesn't take long when you're already that far in so why not?

A spray of wax or AC50 will sort out the inevitable small awkward bits where you "missed a bit" or check in a years time and redo the bits you missed with the Jotun.
If I'm putting covers back on, I'll always give the surface a thin coat of AC50 to give it the best chance.

 

[rambo]

Whatever you do, you MUST get inside the box sections.

 

[bert]

I don't think toyota use box sections, all the lc's I've seen use C channel and tubes

 

[frank horton]

u'll be glad it aint a Land Rover when the world comes to an end....

 

[rcx132]

3. ?spray?/brush with phosphoric acid

Acid is a strange thing, if you submerge metal in it will remove the rust. But if you have an acidic atmosphere due to unwashed acid it will ACCELERATE rusting at an alarming speed! Unless you're able to remove a part, and submerge it in neutraliser and wash, I wouldn't use acid.

I did my trooper using a needle gun and MBX tool to remove loose rust, and then thick Dinitrol. It's lasted a few years already.

Jotun or paint is only useful if you can get back to clean metal. It won't grip otherwise and the rust will spread under the paint.

 

[dobbslc]

I don't think toyota use box sections, all the lc's I've seen use C channel and tubes

The surf has a box chassis and that's basically a Landcruiser 90 / Prado, not sure about the later Cruisers.

 

[bert]

I have a 90 series, it's definitely a C channel on mine

 

[dobbslc]

I might have a crawl under the Surf later for a look then. I'm blxxdy sure it's a box section.

 

[rtcosic]

Another vote for Dinitrol products

 

[not done it yet]

Anything I've missed? Recommendations for particular products? Any to avoid?

Only the insides of any chassis rails.