Frame: Inside Treatment?

The BN4 is progressing slowly--now into welding new outriggers and sills. As I am taking such efforts to remove, transform and/or encapsulate visible rust I'm thinking about inside of the main frame. I'm not planning to send the chassis out for dipping, so looking for DIY solutions. The main frame has surface rust wherever the original rust proofing was not liberally applied (oil leaking) but no rust through.

What have you done, if anything, for the inside of the frame? If coated, what with? How did you apply it? Did you end up drilling extra holes in the frame? Should I just leave it alone and hope for the best?

Any ideas for what to do or not to do would be greatly appreciated.

Mike T in Minnesota.

Don't ignore it! I ended up cutting the end off my rails to address this and because my sway bar mounts had been trashed and welded in place. By doing so I discovered a massive amount of rust-dust. I vacuumed it out and wire brushed what I could. I used a combination of rust converter (phosphoric acid) and Eastwood's rust encapsulator as a first step. Other guys use waxoil or a homemade variant. If you buy a gallon of one of them it should be plenty to pour or inject in and slosh around.

ties581006 said:

... What have you done, if anything, for the inside of the frame? If coated, what with? How did you apply it? Did you end up drilling extra holes in the frame? Should I just leave it alone and hope for the best? ...

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Good question that I've pondered for years myself. When we had our BN2/100M chassis on a homemade rotisserie you could hear the sloughed-off rust when you rotated the rotisserie. This was an apparently well-maintained 'California car,' with only a little surface rust on the floorboards, about as good an original example of an older car as you will likely see. I decided with that much residue that using a typical rust-preventative would only turn the rust flakes/powder into a sludge, and to get a thorough coating of anything you'd need to cut off the ends of the chassis, somehow empty the rust residue out and then apply a rust converter/preventer. This will be a very low-usage car so I'm not losing any sleep over it.

For my BJ8, I bought an undercoating spray rig from JC Whitney and pumped LPS3 into the chassis through the small drainage holes. I use this stuff on exposed metal on the outer chassis and it seems to at least prevent new rust from forming; at the very least this made me feel better as I was doing SOMETHING about possible rusting. Some aircraft manufacturers--Piper, notably--(used to?) put linseed oil inside tubular airframes. Some--again, Piper--used zinc chromate paint on otherwise unpainted surfaces and it was very effective on preventing corrosion on aluminum (yes, aluminum corrodes, I believe it's usually of the 'exfoliating' type). I wish Austin had done something similar with Healey chassis, but no one expected these cars--or any from that time period--to be used for more than a few years before being sent to the crusher. I've used spray can rust converter products on exposed rust, and they seem to work as advertised but I haven't seen any suitable for fogging into a Healey chassis (it may be too thick, but I don't know).

Realistically, the only absolute solution is to get a new chassis from Jule, Kilmartin or Denis Welch. Of course, this is a major job and beyond most shade-tree mechanics' ability. I think the LPS3 (or equivalent) fogged into the holes in the chassis is about all you can do without major surgery on the chassis; you'd have to (at least) be prepared and able to cut the ends off the chassis and weld them back on to get complete coverage. I still don't know how you'd get existing rust residue out without tipping the chassis vertically both ways.

Good although agonizing question. In my case, I first blasted the frame/chassis to find what was bad or good prior to metal work. I had the same worries and, like Csarneson, I cut the sway bar mounts off since mine were mangled too. I then duct taped a shop vac hose to the opening and, with the vac running, I worked my way up & down the frame with an air nozzle blowing in all openings. I made a short 1/8" metal tubing "attachment' for the air nozzle to go in the larger holes so I could blow air at different angles around inside the frame. I kept a this until I heard no more grit bouncing down the frame to the vac. I was a bit surprised at how much sand had gotten inside through the various small holes when I blasted it and I think the sand would be a natural moisture holder so wanted to remove all I could.

After finishing all metal replacement work my plan is to blast again prior to prime/seal/paint since it has been 3 years since I started this project and everything has developed a slight surface rust film. After re-blasting and repeating the vac & blow-down, then I will weld in the sway bar mounts and prime/seal/paint.

The part I am still unsure of is applying some kind of sealer/rust preventive to the inside. This is where my plans get murky because I don't know what is the best approach - waxoil or equal, or some kind of paint/sealer coating. And, how to apply? Seems like the ideal would be to dip the chassis, but, like ties581006, I am a DIYer and don't have any way to dip it.

I do want to do some kind of coating/rust preventer simply because, after this much work, I want it to last along time and have found several times that things ignored have a great tendency to come back and bite me in the behind.

Looking forward to others ideas.

Dave

red57 said:

like Csarneson, I cut the sway bar mounts off since mine were mangled too. I then duct taped a shop vac hose to the opening and, with the vac running, I worked my way up & down the frame with an air nozzle blowing in all openings. I made a short 1/8" metal tubing "attachment' for the air nozzle to go in the larger holes so I could blow air at different angles around inside the frame. I kept a this until I heard no more grit bouncing down the frame to the vac.

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I literally did this exact thing. I had progressively longer hoses duct taped to my shopvac as I sucked out all the sand and rust. Blowing an air hose in the other holes helped a ton. I kept rotating the chassis on the rotisserie at the same time. I kept trying to figure how to rig up a 10foot wire brush but finally gave up.

Chris

I put Waxoil in mine as best I could. I'll let you know how it holds up in another 20 years or so.

Thanks for the ideas. It doesn't sound like there is a straightforward or great solution but I'll likely end up doing what a number of you have: Sand blast the frame, use vac and air to remove sand and loose rust and then try to get something sloshed around in there to encapsulate what remains. I have the frame on a rotisserie which could help a little.

Hopefully, can do this without cutting or drilling on the frame.

Have a great Holiday.

Thanks again.

Mike T in Minnesota (COLD)

I've had good luck with the Eastwood Products, https://www.eastwood.com/paints/rust-solutions/prevention.html. After the surface prep and cleaning, apply the internal frame coating, then coat the entire exterior frame with the zinc right primer. If your having a paint shop paint the chassis t/m the final finish color, have them apply a 2K epoxy primer over the entire exterior chassis before assembly. If your doing it all yourself, use PPG's 2K DTM Urethane as the chassis finish coat over the zinc, https://finish.ppg.com/rep_pafpainttools_files/Pghpaints/tdb/95-3300.pdf
This will cost you more then a "normal" enamel, but more less then a "Automotive" label PPG coating. Any commercial paint store that handles PPG Industrial coatings should handle this and be able to match the finish coating your using. Sprays very nice with a little reduction, even out of a cheap Harbor Freights gravity flow air spray gun.
Finally after all the finish chassis paint is done, but before assembly come back with a thorough coat of https://www.amazon.com/KBS-Coatings...ie=UTF8&qid=1482001391&sr=8-2&keywords=waxoyl in all the internal frame areas as final insurance.

I've been thinking of going to a commercial automotive rust inhibiting treatment centre (Lord! I'm having trouble believing I just wrote that!) called Rustchek here in town come summer with the Sprite and the 3000 and talk to them about what would be required for drilling and spraying the inside of the chassis. I believe that they use 3/8" dia holes, but the key item I figure would be to go over the manual with them and pay by the hour rather than flat rate to try to get all of the hollow spaces.
I hadn't thought too much detail, but like the idea of trying to vacuum out the inside of the rails etc. You can get a 'Vaccuflex' for the end of the shop vac that will accept various sizes of clear plastic tubing (designed to allow you to vacuum between the seats etc.) and I'm thinking that the air compressor coupled with this would be an approach.
I've also toyed with the idea of identifying various existing holes and jacking up a car so it tilts in the right direction, and then just pouring light motor oil inside in fairly large quantities, and crossing my fingers. Doug