Undercoating

[JayQQ97]

is This a Normal look for cosmoline on the rear diff housing... it gets hot and inside the wind tunnel under
i used the Black spray here IIRC
around it is WoolWax that has a fine nasty covering of dirty build

 

[tacojoel]

Idk about the black stuff, but that looks like you used a rust converter on the rear axle. Certainly doesn't look anything close to the amber cosmoline I did my trucks chassis with.
Also never apply another rust inhibitors that are lanolin based over petrol based ones. you can get a reaction like a buddy of mine did when he sprayed cosmoline rp-342 over fluid flim he'd done a week before. His taco had the drips, and had to be done completely over.

 

[JayQQ97]

that could be what happened here... sprayed black cosmoline over dirty black woolWax

rear axle areas were sandblasted to shiny silvery surface to remove crusty buildup that was forming and then primered before applying woolWax many years ago

i sprayed brakleen on there to remove the drippy fluid change that overfilled and all the primer come on off it back to silvery surface then sprayed black cosmoline on that surface

 

[tacojoel]

Use one or the other when applying these inhibitors, or take a chance your in for a mess. Petrol based cosmoline works extremely well on new/clean surfaces. The lanolin based stuff is probably better to cover already surface rust/scale. It's just going to need constant reapplying.
There's a reason bmw, and mercedes coat their chassis with cosmoline instead of a lanolin rust inhibitor.....cosmoline lasts years. Even the military uses cosmoline.

 

[JayQQ97]

woolwax HV lasts YEARS... i got 4 so far onit in a very High Wash Area
but it attracts so much dirt, so much dirty.

 

[tacojoel]

Well, I see enough dirt everyday. Don't need to attract more.

 

[JayQQ97]

need some black cosmoline to put on this Gen2 at the crappy front diff mounting area

 

[tacojoel]

Well....I assume you know where to get it, or asking ?

 

[JayQQ97]

 

[tacojoel]

It's too late for any undercoating when you see large holes rotted in your frame.

 

[JayQQ97]

Hard-On™ Permanent hard coating for truck frames and equipme

 

[tacojoel]

I'd be very skeptical of any hard shell, or rubber type coating that can chip. Once a chip happens, rust sets in, and spreads. You alway want a self healing undercoat like with a lanolin, or cosmoline type thats remains waxy. Just comes down to the area you operate in. and how often these coating need reapplying.

 

[JayQQ97]

it says it NOT rubber
IDK
don't like the hard to remove bit

 

[tacojoel]

Idk about that hard shell undercoating, but at least with cosmoline products, a rag dipped in mineral spirits will wipe that stuff right off. Heck with lanolin based coatings, a good pressure washer will blow that stuff right off.