Chassis stripping - media blasting or chemical?

[NitronGuy]

I am now 6 weeks into my first TR6 ownership and I now have an almost bare chassis, and an idea of the luckily limited corrosion it has. I want to take it back to bare metal but I cannot decide between media blasting (sand, glass etc.) or chemical stripping. I have no idea how the chassis' were originally protected against corrosion apart from paint, were they dipped to reach all the internal spaces or just painted externally? If I get it chemically stripped it should reach all the internal voids, but will all the dissolved waste get out effectively or be left inside? These surfaces will then be unprotected until waxed (as painting seems impossible), whereas blasting will reach only the external surfaces.

 

As I am sure that many of you will have successfully tackled this stage, what seems to be the preferred route? And what final surface finish / protection should be applied?

 

I have attached a photo of it before it was stripped further, just for your interest.

 

Thanks! Guy

[Waldi]

I removed the tectyl with a propane burner and scraper, then had it gritblasted, but not painted.

A clean chassis lets you find tiny fatgue cracks that remain undiscovered otherwise. Welding quality is better too on clean metal.

Next came inspection for cracks/corrosion and repair and reinforcing in the usual places.

Finally, i had it gritblasted again and powder coated.

[Dave McDonald]

Guy,

I'll be interested in what replies you get as I'm about to embark on a similar project.

 

That's a sophisticated looking cradle that you have the bodyshell suspended in towards the back of the garage.

 

Dave McD

[Steve T]

Had mine blasted, but if funds had allowed, I'd have had it acid dipped as then you know all the interior corrosion is stopped in its tracks. Would need waxing fairly soon after though.

[Alec Pringle]

Acid dipping a chassis isn't that difficult . . . . . .

 

Neutralising all the acid remains after dipping is another story . . . . . you can all too easily unstitch the chassis from the inside out in the long term.

 

I'd prefer to blast the outside, and soak the internals with as much anti-rust jollops as can be squirted in.

 

At the risk of stating the obvious, before any of that work your way round with a good 2 or 4lb hammer and a 1" cold chisel . . . . . anything that won't take a bit of piggy requires replacement !

 

Cheers

 

Alec

[Guest]

Blasting, crack checking and reinforcing corners and then painting or powder coating. When painting, try a type marine quality of offshore quality paint. There's a large stock of unused offshore paint products in harbors due to the low oil prices.

 

The TR chassis has survived almost 50 years without people taking care of it. The factory finish paint was 'iffy'. When you sort the chassis out with modern paints etc it will certainly be around for another 50 yrs. My car became 57 y/o last month. Chassis-wise it will last another 57 years. I won't (being 115 at that time...)

 

Be realistic about it and don't get carried away with all sorts of plans to turn the car into some sort motoring monument of the last century...

 

Menno

[NitronGuy]

Thanks for the replies. I have also been told to be careful that the acid doesn't continue its work if left in the joints, but then I have also heard that some types leave good metal alone after they have removed the rust. It sounds like blasting is a safe option, and possibly steam cleaning the box sections - this chassis is very grimy and oily as it looks like years of heavy engine and gearbox oil leaks have done a good job at preserving it, but it will certainly have got inside the box sections.

 

I do also intend to make sure the metal is sound, no point going to all this length and then skimping on a bit of chassis repair, we have a 3 tonne steel table at work for just this kind of task!

 

The body frame is a twin-octagonal system I saw in a youtube video... so far it works well and can have wheels bolted to it for moving about. It provides excellent access for blasting and painting (and under-seal removal!) and can be bolted on and off as required. I am just writing up a new blog of what I am doing with this car on Wordpress.

[Guest ntc]

Acid dip, jet wash, repair and dip it galvanize and no the add on weight is next to nowt.

[Bill Bourne]

Acid dip, jet wash, repair and dip it galvanize and no the add on weight is next to nowt.

+ 1 and use Envirostrip for the dipping - a big difference to other dipping services. Call and discuss their process and make your own judgement. You could get the body and panels done at the same time. I also bought one of those internal cameras, not an expensive one, just for looking inside the chassis, before and after waxoyling etc. I've only used it for that purpose, but well worth it for the re-assurance that everything inside has been treated.

 

Best Bill

[littlejim]

I grit blasted mine at home, section by section, inside a "plastic palace".

This OK if you are retired.

[ed_h]

I used both processes--First a methylene chloride stripper to remove the bulk of the paint. It isn't an acid, so there is no damage to the metal. The sand blasting goes much quicker if most of the paint is already gone.

 

Ed

 

[littlejim]

That grit blaster looks very familiar!

[Tim D.]

 

+1 on the marine paint.. Used a two pack epoxy paint.. hard as nails!! Decided not to go with powder coating as once the coat is breached you can rust creep under what looks like intact coat..

Cheers

Tim

[simonjrwinter]

Powder coating is great IF and only if the surface is prepped first. Wiping over with a damp rag won't cut it!

[littlejim]

I used POR-15 as chassis paint. See Dave Connit's blog

[NitronGuy]

Thanks once again for all the replies. I think I will initially clean it and blast it as this can be done locally, then inspect the level of corrosion.

 

I want to paint it with something that will not dry too shiny, I am looking for a satin finish, so I planned on using one of the small sponge rollers to give a slightly mottled surface. Bore-scope camera inspection and waxing seems to be a good idea too.

[RogerH]

Hi Guy,

you have had lots of mixed info - now you have to decide.

 

I would insert a fair number of access holes into the chassis. You need to get the gunk and camera's in there to see etc.

Make sure you have the rubber bungs before drilling. 1/2" is a handy size.

Corrosion removers come in all sorts. Many of the Acids do not attack the cleaned metal.

If any acid remains in the joint, don;t panic too much; as if it is the sort that does eat the clean metal it will fairly quickly neutralize it self - it can only do so much

Try and coat the inside with a decent paint that has a sealed surface - BondaRust Primer is good.

The coat with a quality wax. - Dinitrol sticks better than most. Waxoyl can harden ans peel off

 

For my part I would finish the chassis in a gloss paint. This will allow water and muck to wash off easier. It may also allow cracks and corrosion to be seen easier.

 

Not keen on powder coating as it leaves a brittle surface. Moisture can get under the paint and things disappear - leave you lawn mower out over winter and you will see.

I prefer old fashions chassis black paint - the cheap stuff.

 

Roger

[Sapphire72]

After scraping the gook off my frame, I wire brushed to metal, then painted with a rust inhibitor paint.

 

Used two cans of the Eastwood Green Internal Spray Coating- one for each side of the chassis. Four cans total would have been better.

The Green Stuff comes with a long spray tube & nozzle. You push the tube deep inside the frame section, then pull it out as you hold down the spray button.

 

http://www.eastwood.com/internal-frame-coating-w-spray-nozzle-qt.html

 

I also went with the red floor paint so as to be able to see any future damage more clearly.

The gloss black on the chassis was for better repelling any elements- I wasn't going for original or show characteristics- just preservation & ease of maintenance.

Edited December 15, 2016 by Sapphire72

[Richard Young]

I used Envirostrip,both for chassis, tub and body panels.Came back all etch primed.

Saves so much hassle, mess and time compared with doing it yourself and arguably a much thorough job.I have a blog on this site with some pics if you are interested.I know what you mean regarding acid left behind etc.. but they do a 4 part process,one of which is dipping again to neutralise the chemicals.Its worth having a chat with them..they are very friendly and helpful and they will go in to more detail of their process.

Regards

Richard.

 

Have sent you a PM

Edited December 15, 2016 by Richard Young

[littlejim]

Without thinking I used black paint (POR-15) on the chassis.

Tony Millward (this forum) and Alan Staniforth - "High Speed Low Cost" author, used white, so that they could spot any problem areas more easily later on.

Edited December 16, 2016 by littlejim

[Red 6]

Blast it and paint it that is all that is needed. The blasting will remove every trace of rot and if holes appear all the better, at least you know where to let in new metal.

 

I restored a 250 and 19.5 years later the chassis was as good as the day it was blasted and painted with smoothrite whereas I have looked at 9 TVR's recently and all of them had chassis rot where the powdercoating had cracked allowing water ingress. From my general experience with older (1988 and onwards) cars with powdercoated chassis the powdercoating seems to harden and flake like razor blades if you get my metaphor.

 

Everyone has their own opinion on this subject, mine is based on observation.

[pfenlon]

Red 6 IS on the money

 

acid stripping is not good, by far the best way of course is to shot blast the chassis, Alec's also spot on.

 

Then Powder coat after any repairs have been sorted.

 

As for galvanising, it takes 2 people to take it to the tank and 4 to bring it back.

 

And god forbid, if you ever have to carry out any welding, your in trouble right away.

[Guest ntc]

As for galvanising, it takes 2 people to take it to the tank and 4 to bring it back.

 

And god forbid, if you ever have to carry out any welding, your in trouble right away.

 

You need to take it to right place lad, and your second comment thats the point you will never need to.

Edited December 18, 2016 by ntc

[pfenlon]

As for galvanising, it takes 2 people to take it to the tank and 4 to bring it back.

 

And god forbid, if you ever have to carry out any welding, your in trouble right away.

 

You need to take it to right place lad, and your second comment thats the point you will never need to.

Neil, normally I would bow to your far superior knowledge.

 

But if you cannot name "The right Place", your wrong. We all know you cannot or will not "Name the right place" Do the right places have some sort of sign? aka, only 25 microns applied here.

 

Please don't mistake Microns for The Mysterons or Klingons again, or you will be on another planet.

 

apologies for this minor disagreement, now have some Cocoa and calm down.

 

On a lighter note as from next wednesday the days are getting longer………………………….

 

I have taken your advice today and used a vacuum bleeder on the Red Tomato, you were right. ( yes that did take some writing )

[Sapphire72]

cars with powdercoated chassis the powdercoating seems to harden and flake.

 

Everyone has their own opinion on this subject, mine is based on observation.

This happened on the upside floors of my TR6, and oxidation occurred under the black powder coating.

It's a mess.

 

Now, the floors will get wire-brushed to remove all that crap. Then I will paint with a rust inhibitor.

Powder coating is highly overrated.