Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Under-body Rust protection

Thanks for the replies.

A mucky job, but I’ll do myself, first preparing with a wire brush.

I’ll be giving the lanoguard a try. Fortunately, it’s for the purpose of prevention,
as it looks quite sound underneath, just some cosmetic surface corrosion.
The original waxoil is starting to show signs of failing.

The TR7 that I’ve just bought has been treated with lanoguard. It’s been on the car about a year and is still working well. Where it’s been applied thinly it’s dried to a semi gloss Sheen and isn’t tacky at all. Where’s it’s been applied more thickly it’s remained soft rather like lard, you can scrape it along with a finger. In both cases it’s remained excellent at repelling water.

It’s still working on the Traveller, although I don’t see the owner so much now he was commenting on how good it was when we last saw him back in September.

By contrast, a fellow Minor owner didn’t like it. He applied it very thickly and was disappointed with the way road dirt stuck. But then by his own admission he did apply it VERY thickly.

Without wishing to throw another option into the mix, I can highly recommend the rust proofing products from Dinitrol, actually I believe the Morgan Motor Company themselves used Dinitrol to protect their galvanised chassis’, certainly my 2012 Duratec Plus 4 chassis looks like they used Dinitrol 4941 which is a product I’m very familiar with, and DaveW confirms my suspicions when he talks about the MMC using it here:

https://www.talkmorgan.com/ubbthreads.php/topics/316342/wood-treatment

Back in 2011 I had my 1996 TVR Chimaera professionally treated with Dinitrol products by a company called Chassis Clean, the car was already 15 years old at this point but I wanted to see if I could cost effectively extend the life of the chassis before serious welding and replacement steel tube was required, at this point I should also point out the previous owner clearly had the chassis lightly Waxoyled at some point in its life before I bought the car from him.

The process used by Chassis Clean was to fully steam clean the chassis first, but importantly they then thoroughly dried it over a two day period, they were very particular about this stating the importance of not applying the Dinitrol products over a wet chassis. Despite using proper steam cleaning rather than say hot jet washing, they still went on to put the car over an inspection pit containing a fan assisted paraffin space heater like one might use to heat a large workshop, and there it sat for two days with a guy going down periodically with an airline to further drive out any trapped moisture with compressed air.

Only once Chassis Clean were completely satisfied the underside of my TVR was as dry as a bone did they apply the first coat of Dinitrol 3125 wax to the cavity areas such as the very extreme outer corners of the outriggers, 3125 has excellent creep qualities so it's used to get to places where other treatments fail to penetrate. The 3125 was followed by Dinitrol 4941 which is more like a cross between a wax and an underseal, this was comprehensively applied wherever Chassis Clean could get it and especially all the exposed high impact areas of the chassis, the whole process took a full three days.

Nine years later I decided to lift the body off the chassis to have the outriggers replaced, this is a common point of corrosion with a TVR Chimaera and by this time my outriggers were 24 years old so I figured they were due for replacement. By lifting the body off the chassis we were able to properly inspect how well the Dinitrol products had performed before mechanically de-rusting what we didn't need to replace with new steel tube, letting in the new outrigger tubes and then painting the whole chassis with two coats of 2 component Jotun epoxy mastic paint as used in the commercial marine environment.

Removing the Dinitrol to prep for paint was a royal pain in the arsh, thus proving just how well the products had hung on over those 9 years of all season driving. I would describe the results as outstanding, but caveat this by saying you can't expect any rust proofing product like this to reverse the effects of existing corrosion. The Dinitrol had certainly performed brilliantly over anything that was in good shape when the treatment was applied, although it's hard to prove I also believed it also served well to hold back the further spread of corrosion where it had already started to take hold.

A good example of how well Dinitrol helps to protect a corrosion free component was the O/S front wishbone, it was a fairly recent replacement fitted just a few years before the the rust proofing treatment was applied, to show this here it is as it arrived at Chassis Clean back in 2011 before the steam cleaning process.



And this is how it came up after the light layer of Waxoyl and road dirt was removed by the steam cleaning process, as I say it was a replacement and correctly powder coated wishbone that was only a couple of years old at this point so understandably it came up like new.



The next image shows the same wishbone after Chassis Clean had given it their two stage Dinitrol treatment.



Now we fast forward to 2020 to look at that same wishbone again after 9 years and at least 70,000 miles of all season abuse, this time we're half way through removing the above Dinitrol treatments applied almost a decade earlier.



As I've already stated removing the Dinitrol 4941 was an absolute pain, in the end diesel proved to be the most effective (and cost effective) solvent for breaking down Dinitrol 4941, but even then and after soaking the wishbone for 24 hours it was still not at all easy to remove the stuff!



Finally, here's that very same wishbone that must have been at least 13 years old by this time, it's fully cleaned here and ready to be keyed up before being brush painted with the Jotun epoxy mastic we put over the original powder coat finish.



As we can see it came up like new, thus proving just how effectively the Dinitrol products had protected the wishbone over all that time. I'm sure this new heavily marketed sheep's wool stuff is fine but for me it remains unproven, however, based on my above experience I can definitely highly recommend the excellent performing rustproofing products from Dinitrol:

https://www.dinitroldirect.com/guide/classic-car-rustproofing-guide

Does the Dinitrol application need any special prep before being sprayed onto the underside of an Aluminium wing ?

I don't think any special prep is required Keith, other than making sure the surface is clean and dry, however, it would be best to contact Dinitrol for their advice. What I can say is all these rust proofing treatments work best applied over a surface that has not yet started to corrode, the ideal time to apply therefore is when the car is new.

Ziebart is another good treatment, they've been in the game since the 60's, I remember seeing a 1968 Volvo Amazon in the early 90's that was Zeibart treated from new. A full 25 years later the condition was amazing, the Zeibart treatment had kept the chassis and panels completely rust free, further proof the 'treatment from new' approach is best.

I believe Morgan themselves used Dinitrol 4941 as their final pre-delivery underbody treatment, sprayed over the new inner surfaces of painted aluminum panels and a new galvanized chassis has to be a very good recipe, add in a stainless steel bulkhead and these later Trads should be very long lived cars indeed.

My MGB was Ziebarted from new. 43 years later and although a few areas will need some work in the coming years, the majority of the shell is in excellent condition for the age.

Even with paint finishes that claim to be OK for use directly on bare metal I would always (where possible) use a rust converter first after the loose is first removed.

A point of note is that Ziebart was always professionally applied by trained operators so it was done properly, Ziebart had maps for most common cars in the 60's & 70's to show the operator where to drill and inject the treatment. The Volvo was just one example of a number of cars we saw in the workshop that were Ziebarted from new, they always had the Ziebart sticker in the rear window and loads of little holes drilled all over the place where you could see the product oozing out.

All these cars had little or no corrosion, whereas the same model of the same age that had not been treated would typically be completely rotten, this was the early 90's when I was involved in classic car restoration so the vehicles we were seeing were in the 20-30 year old age bracket. TBH we forget how badly cars corroded back in the 60's, 70's and 80's, it wasn't until the mid 90's that we started to see manufacturers taking rustproofing seriously.

Ziebart definitely works because I saw the evidence with my own eyes, Dinitrol is also a proven product to me as it seemed to hold back the existing corrosion on my TVR outriggers, and where it was applied over the fairly new (at the time) wishbones the Dinitrol 4941 worked even better. By the time we cleaned everything up during the body off restoration the chassis was 25 years old, and it was in way better shape than I expected. Sure, the outriggers were rusty and holed in the very corners but the rest of the chassis was in great condition and the wishbones that were 13 years old at this point were like new, they'd always been protected either with a light coating of Waxoyl when fitted or covered in Dinitrol 4941 just three years later.

As such I'm super happy that Morgan chose to protect their new cars with Dinitrol 4941, I'm sure this will help to keep my 12 year old Plus 4 in great shape for many years to come, the fact Morgan also uses superformed aluminum panels over a galvanized chassis and a stainless steel bulkhead leads me to suspect my Morgan won't need to see any remedial work due to corrosion for another 40 - 50 years.

Back in the early 90's when I was in the restoration trade Morgans had a bit of a reputation as rot boxes, like Lotus Elans the chassis swap was a common job. However, it does seem by the early 2000's Morgan had clearly put a lot of thought and effort into shaking off this 'Rot Box' reputation. Galvanizing the chassis, Cuprinol dipping the ash frame and pressing bulkheads from stainless steel were all massive improvements over the previous cars, finishing the job off by spraying the whole underside of the car with Dinitrol 4941 just took it to the next level.

Well done Morgan