Modern Vespa

In the end I went with an 2K epoxy primer with anti rust / corrosion properties. I spoke to the manufacturer and they confirmed it can be left as is without a top coat permanently. It gives a really nice gloss slippery finish and gets good reviews on other restoration forums. Not sure if you get it over in the states?

https://u-pol.com/product/raptor-bed-liner-protective-coating/raptor-accessories/anti-corrosive-epoxy-primer/

Certainty not a perfect job with my first go at proper air spray gun application but it's good enough for the tunnel!

Won't epoxy come off when you weld it?

I think it was safis who used an anti-rust weld primer (I think it was copper based to take the heat, or something to that extent).

Rust in the tunnel seems to always be a pain.

Yes, it will a bit but hopefully not too much. I will clear the spot weld holes first so I can actually weld the floor in place. It will also get PU seam sealer.

Once the floor is welded in place I will do another coat of epoxy via a brush through the hole for any areas it gets burnt off. It's going to be intesresting to see how it pans out!

You could clean off the epoxy where you are spot welding and spot spray with weld through primer, then do whatever sealing you planned. The primer you used is fine and your work should last a good long time. This is where the home restorer has the advantage.

Yeah, also an option. I may try a test spot weld later today to see how the epoxy reacts.

For the record, Japtastic, this thread has put me over the hump on the decision that I'm going to replace the floorboard on the Smallstate when I do the paint & body on it.

Excellent, yeah definitely makes it easier to tackle all the rust and add protection. I would have had to do so many repairs on the old floor board it just wasn't worth saving it in the end.

Ok, well my idea was a complete fail

Epoxy primer being anywhere near welds just doesn't work. I did remove it where the spot welds were but it just melts and spits and makes a big mess. Probably a rookie mistake.

I'll try again tomorrow if I get a chance. It just means removing the epoxy for this piece and then removing it from the seam. The epoxy can stay in the main part of the tunnel and everywhere else. I'll apply weld through primer on the areas that I remove Epoxy....

Bummer. Looks like it's time to get some weld-through primer.

Yep. To be honest, it was just one of those days where nothing went right. Work related and scooter! I even managed to make a big hole in the wall while fitting the new washing machine

Oh yeah. You don't want to have any coating on the area where you are welding, within at least a 1/4 inch (maybe more) of the welds.

It will just burn off, and you'll breathe it. And it gets in the metal. You can see the color change in the mask.

It looks like maybe it's not hot enough to fuse the metal? Seems like it should still weld, just not be the cleanest welds. If there's paint, it will get bubbles.

Does your welder also do mig?

Should work to just mark with pen where the welds go, and clean those up with a wire brush or 120 grit disc.


On this one, I put Ospho on the metal, which makes it kind of chalky here, but prevents rust. It probably also gets into the welds, but is very light.

Painted the inside of the tunnel, but left the contact surface bare. I made a mess getting the spot welds out (had to repair). The dark spots are touch up welds that burned through two layers of metal

same with the mating surface here.

Yeah it was just a mess and epoxy burning straight away. I did already grind out the spot welds so it's almost certainly a no go with the way it is currently. TIG only on my welder. I find MIG harder. Those pics are super helpful and what I plan to do now. I'll get some weld through and give that a go. Shame as I wanted more protection for the seam.

I'm wondering if I can even use PU sealer on that seam as I'm going to have the same issue. May just have to seal from the outside rather than sand which the sealer between the metal?

Weld-through primer should be fine. It's designed for that.

I think it also just burns off, but the areas outside the welds wouldn't.

Then do the 3m seam sealer on the outside, so no water gets in there and sits.

Was hoping the epoxy was more tougher than that.

But it is essentially glue, which would burn pretty quick.

The epoxy around the test welds might have delaminated because of the spreading heat, especially areas with pockets of air. Just something to note, it's probably not as "sealed off" now, best go back to bare metal as much as possible.

Seam sealer is best used when you already have epoxy of filler primer already down.

My (very limited) experience is that the metal gauge is so thin, especially on the rusted, aged examples we are fixing, that heat spread is further than I'd expect.

Welding automotive gauge or new 20 ga is much quicker and requires less heat soak, but these beasts get pretty hot when welding which makes sealing beforehand near impossible.

Again, vespa vintage welding experience count of 1 here. I may have an especially rusty version and the new patch panels were pretty garbage metal.

Maybe a more experienced welder would know, but seems like the epoxy would burn off. The welder is hot enough to liquify steel.

The problem with any kind of coating is that it will get into the weld, and there will be defects.

It's possible that the epoxy prevented the electrical connection, so it didn't take?

Here's a kind of fun video about dirty welds with a master welder.

It's a combo of degraded electrical contact, contamination of the weld and the burning epoxy displacing the welding shielding gas.

I would leave the epoxy everywhere but the seam. Use the weld through on the seam. It shouldn't cause problems with your welding. Plug welds require more heat, at least with MIG. Priority is strong welds.

Much more positive day today and although challenging to weld, I'm one step further forward.

I removed all Epoxy from my patch piece and the receiving part of the frame then applied weld through primer. It was still a pain in the ass to weld as the metal on the body is really thin and even on very low amps, down to 20 in some parts, I was still melting metal like it was chocolate coming in to conact with boiling water. Quite suprising how fragile it was.

I think probably I hadn't removed quite as much rotten metal as I should have. Although I couldnt tell from the outside. I'd say at least 5-8mm of the body just melted away on contact. A pain but this bad metal dissapeared and was then replaced with good welds so not as bad as it sounds.

It's pretty rough and some tidy up to do but it's getting there. Ran out of time again!

Oh yeah, nearly forgot, do you guys recreate the factoy look spot welds somehow? For looks as well as knowing where they are? If not I started wondering how the next person that does this job (or decides to replace this part as a whole) will remove this bit if they dont know where the spot welds are... that's why I stopped grinding them flat in the pic until I checked.

I'm not sure how to duplicate the look of spot welds on that part.

Once thing that can make plug welding hard is when there is a slight gap between the 2 sheets such as a blind area that you can't clamp tight. Sometimes, with MiG, I don't drill a hole through the outer layer and burn through the top. You could also make a larger hole in the outer layer. You could also back up the weld from the inside with a piece of copper .

I didn't recreate it.

I thought about it. You could do it with a dremel and a small grinding stone. Or maybe a punch.

But it weakens the metal. So I left it.


Maybe one of these?

It's smooth, but I forgot about it!

This is what they look like on my P.

Thanks chaps, I didn't recreate them today but do have them documented in case I decide I want to. I'm stoked with how this turned out being my first fabricated part. Getting a small amount done each day! Takes longer than you think doesn't it!? Between learning new skills, work, kids etc!

That came out amazing.

What color are you going to paint it?

I noticed on your floor panel, the edge bead doesn't match exactly. Same on mine, but it's covered by the floor rail, so isn't noticeable when it's done.

Thanks! Yeah, I'm pleased as you'd be hard pressed to know it was repaired unless you knew what you were looking for. Not completely decided yet. Potentially a blue of some kind. So many other things to do first so I put that decision on the back burner for a while.

Yeah odd that, isnt it? They got everything else spot but made it a few mm too wide. It think once I roll the edge bead a bit more it will match fairly good. Good to know that the floor rail covers it, I hadn't realised that.

Fun thread to watch.

Amazing stuff so far.

That came out great. Nice work!

Lots of little bits done today in preparation for the floor to be welded in soon.

Sanding back the epoxy in the tunnel that got damaged with the welding and resprayed.

Using foam brushes with extensions to get down the tight parts of the tunnel not normally accessible.

Removing Epoxy from the new floor and replacing with weld through where it needs it.

All took time but will make a good job when it's done!


Burnt Epoxy removed ready for another coat.

Tig filler rod was a good extension with the foam brush :)

Weld through applied

Beautiful work!

One of the most ridiculous things I've done for a while and quite possibly a world first? 😂 I doubt a Vespa has ever been in a sauna before! But I really did need all the Epoxy to be dry in the morning. Dries in 20mins at 60c so that's what it got 😄 Don't tell the wife!

It's the smell that gives you away every time. Trust me on this one.

Genius! I have gotten away with a lot of things, but paint smells are the one thing the missus won't abide.

Yeah, had to open the windows wide and close the door to that room. Most of the smell had gone already as left it for a few hours after spraying/painting. Couldn't smell a thing then luckily!

I will always respect a man pushing the limits of what you can get away with in regards to the hobbies…

One of my favourites is CM throwing a broken down smallie in the back of the wife's Tesla.

Hats off to Vespa in a sauna using IR to shorten drying times.

I've thrown a lot more broken down scooters than just the smallie in the back of it. Usually, I just get hit with, "Why does my car smell like gasoline?" It's when I have to call for a rescue that it gets to be a problem.

The time I jammed my Stella in it, though, and the grep got black marks all over the headliner, though...that one cost me. Luckily, I was able to get it cleaned pretty well off with upholstery cleaner, but now every time I try to put a scooter in the back of it, she asks me if I'm going to get marks all over the ceiling.

Sometimes you just have to use a house appliance to get shit done!

I did consider getting this one, when I bought it, in the back of the Model X and although the boot is absolutely massive I didn't know if it would fit and how I'd get it in and out + the risk of fuel and oil everywhere so opted for a bike trailer instead.

You need one of these…

What's that you say about appliances?

Your next challenge to try… stuff where it's not suppose to be. Push the boundaries of being in the dog house…

Anyone done this and lived to see another day??

#TheresAPhotoForEverything

You must.