I am completely comfortable with the process Ineos state they are using on the Grenadier frames. With that said, I kinda want them to galvanize the frames as, should I purchase, I don’t intend to do much in the way of frame alteration over the life of the vehicle - at least not if I don’t have to. Accidents, powertrain modifications, legislative requirements, etc. may alter that at any time.
I chose powdercoating for the restoration of an old Toyota 25 years ago and have not been disappointed. The vehicle has been driven year round in both the Pacific Northwest and in the Rocky Mountains where it was subject to a fair bit of road de-icer (not on the level seen in the Midwest or East). The total mileage driven since restoration is also far less than what the average driver racks up each year due to the low gearing and lack of modern vehicle safety equipment so that should be taken into account. While I do not “rock crawl” the vehicle which, by the way, will rip through any coating and straight down to bare metal in an instant, I do have thousand of miles of gravel road at speed. When driving those stretches it sounds like a xylophone in the cab as the rocks thrown up by the lugged tires skitter and bang off the frame channels and crossmembers. I have seen no significant rock chips or loss of adhesion to the coating or evidence of rust. Believe me, after the tremendous number of hours I put into the restoration, I am fanatic about getting a jump on any issues before they become problems. Highway miles mostly take their toll on forward facing exterior components like bull bars, mirrors, grills, and the like.
The process I used on the Toyota went like this - First the frame was pressure washed and sand blasted with instruction given to the sandblaster to pay special attention to the inside of the frame components. This was followed by an acid bath to completely degrease the metal. After that a heavy layer of a zinc-rich powdercoat primer was applied and then a double coat of the toughest black pc the shop had. One of their big clients was a parrot cage manufacturer which required the applied powder to be able to withstand the jaws of Macaw parrots which they told me was easily 300psi and could go up to several thousand psi. They claimed that the powdercoat held up for years. I then sprayed typical rubberized undercoating on the outside lateral and inferior (underside) face of the frame rails and the front crossmember. This is where the majority of road debris is aimed. Finally, I cavity waxed the inside of any channels and into every seam. I also coated every bolt and nut with wax upon initial assembly but have switched to heavy grease for any fasteners used to secure commonly removed items like skid plates, etc. I hose out the frame rails every couple of years and have added a bit of aerosol wax on several occasions. So far so good.
At the time I had the option of going galvy on my vehicle’s frame as there was a large galvanizing plant within ten miles of my residence. I still chose powdercoating. There are a number of issues with galvanizing and also some with PC.
The zinc/galvanizing bath was kept at 800ºF+ and a representative from the local plant admitted that they had seen "some" distortion in sand-blasted Land Rover frames after the process. At the time I didn’t know how much thinner the older LR frames were compared to my Toyota if at all. I didn’t want to risk it.
My frame was also riveted together from interlocking “C” channels and I was concerned with webbing over small gaps or seams which the plant representative also admitted was an issue they had seen. He also admitted to the difficulty in completely covering the inside of boxed frames as trapped or entrained air could prevent the coating from completely adhering in hard to reach places. Again, he mentioned boxed LR frames. There can also be an issue with PC in hard to reach places so that should be taken into account. In the end the rep still felt galvanizing was better than powder coating.
Working on a galvanized frame is hazardous. Welding or alteration with heat can create some pretty nasty gasses. Because of the material thickness you may need to heat and re-tap many threaded connections after coating. I had to do this with a lot of the weld nuts on my frame but the process was quick and painless. Sawing and grinding on galvanized components also requires respiratory protection. Not so much on powdercoated metals but better safe than sorry.
As an afterthought... a good set of mud flaps work wonders despite being vulnerable off highway. Sorry for being long-winded.
