Rear Hatch Rust Repair - A detailed guide.

[gav240z]

Last night I tried out the vents to see how they look and line up..

 

They were a little loose, and I had forgotten that there is clips that go underneath the vents to fix them in place. Here is a photo of the hatch on HS30 00150, note the clips in the corners, but also the 'hand brushed' black paint (similar to the front radiator support panel) factory finish that goes under the vents. 

 

I'll be sure to replicate this when the car is repainted and the hatch for that matter.

 

Since I can't live with the patched up repair in each corner tonight I started to fabricate the lower corners. It looks trickier than it is, the left side is done and the right side is not quite finished yet.

[PB260Z]

Hi Mate

 

You are develping some solid skills.

Interesting to look at the inner surfaces of that tailgate shell, no wonder Z's are prone to rust.

These days cars are dipped to ensure every single crevice is coated, that combined with adviances in steel technology have greatly reduced the threat posed by rust.

 

Cheers

 

PB

[gav240z]

Hey Peter,

The inside of the hatch has some surface rust build up because of the sandblasting I did a while ago. I believe there is a very thin coating from factory on the inside, but obviously not enough to prevent them rusting. I will be painting on some KBS rust seal (which can be applied to a surface like that) and it tends to love binding to a rough surface like that.

 

After talking with the teacher about unpicking the entire skin we both concluded it's a lot more work and may disturb the shape around the rest of the panel (requiring more filing of already thin metal etc..) and so instead I'm going to pour down some KBS rust seal into the hatch to treat the inside area and swish it around. Since they usually don't rust up top I think this should do the trick..

 

In terms of skills, it's funny that sometimes things just suddenly start to click, working on a few items last night I felt that way. I'm less dependent on the teacher now for shaping areas and figuring things out, but sometimes I hesitate to just get started and give it a go.

 

After doing this course for a while I've discovered the basic tools you want at home are:

1. Good hammer and dolly set.

2. Body file and slapper.

3. Small folder doesn't have to be big.

4. Small roller to get nice curves.

5. Good surfaces of flat steel with some varying edges (like dollies etc..)

6. Sand Bag is another good 1.

 

With those items you can achieve a lot!

 

English wheel would be awesome, but expensive and takes up a lot of room.

[gav240z]

Minor update on the corner repairs. In some ways I feel like I've just kicked the can further up, but anyway here goes.

 

Last night the regular teacher was on holiday so I decided I'd give it a go without consulting anyone and if I made a mess of it, well I tried. I figure at some point there might not be a teacher to ask so I may as well give it a go as if I'm working in my own garage.

 

Step 1, I traced out / scribed the cut line. In fairness I made a bit of a mess of this because when I put the piece in place after cutting away the old bit I had a bit of a gap in areas. Given the complex shape of the item though I guess a bit of fettling was going to be required.

 

 

I deliberately left a bit of excess around the lips so I could trim them down afterwards, since even when you have your measurements looking good it's always possible something is out when the time comes to marry it all up.

 

 

Since the original hatch is quite thin, and a little oxidised from exposure to the elements I had a little trouble with blowing holes.

 

 

Let's just say I got a lot of practice with the oxy / acetylene last night. I persevered though and I'm somewhat happy with the way it turned out.

 

You can see the edge is now a lot better than before.

 

But the messy looking area is the existing hatch where there were pinholes due to thin metal / rust. I might just use a hole saw and punch that area out and then weld in another piece, I've patched it with the oxy but we will see how it goes once I file it down a bit.

 

This is what I mean by Can Kick, in some ways I moved the problem along to new spots. But I do think overall it's better to use filler on the flat surfaces than on an edge and it looks a lot sharper this way.

 

 

Here is a comparison with the old patched up piece.

There is a couple of spots I may need to go over again to make sure I got good penetration on the weld. I'll ask the teacher next week about this and then do the other side. Then I'll use some rust sealer on the inside of the hatch and fit the lower skin piece and weld that up also.

 

So I'm in 2 minds about all this, on the 1 hand I'm happy I managed to achieve what I did without any help and given how complicated the section is and welding it with an Oxy welder is quite a challenge. On the other hand I've sort of moved the imperfection in and away from the edges. So I wonder if it was worth it?

 

But if I nothing else my welding skills are improving and my metal working skills with it. So that's a positive.

[Brabham]

Looks Good Gav, although are you sure you don't want to go to a MIG, you will put less heat and distortion in the panel and should avoid some of the more serious warping. I did my first lower guard with an oxy and it pulled in, the second I did with a MIG and haven't looked back.  The TAFE teachers are old school though and seem to love oxy, but there is a lot of planishing to get out all the distortion created. Vent panel looks very professional. I'd blast the inside again before applying the KBS though, you will still have a textured surface from the blasting. A mix of Tectrol and fish oil may be better for running inside the hatch, I imagine the KBS is a bit on the thick side.

 

I miss TAFE

[gav240z]

Looks Good Gav, although are you sure you don't want to go to a MIG, you will put less heat and distortion in the panel and should avoid some of the more serious warping. I did my first lower guard with an oxy and it pulled in, the second I did with a MIG and haven't looked back.  The TAFE teachers are old school though and seem to love oxy, but there is a lot of planishing to get out all the distortion created. Vent panel looks very professional. I'd blast the inside again before applying the KBS though, you will still have a textured surface from the blasting. A mix of Tectrol and fish oil may be better for running inside the hatch, I imagine the KBS is a bit on the thick side.

 

I miss TAFE

 

Hey Alex,

 

Late reply, my home MIG is not at that flexible in terms of the way I can adjust wire speed and heat. I'm thinking of buying a better unit actually. The mig welders at Tafe are a lot better and I get better control but then you have excess metal to grind off. I did get a bit of warping but the nice thing about an oxy weld is the metal remains pretty pliable after the weld unlike Mig where the metal hardens up and it can be difficult to hammer / reshape.

 

I have a few early hatches now, so I may very well restore another in future if I'm still unhappy with the way it turns out after paint and prep work, I suspect it won't be a big deal but I do have OCD and take pride in doing a good job so I expect in some cases that means re-doing things .

 

I actually quite like the Oxy also, it's difficult compared to MIG but, in the case of this rear hatch in order to MIG I'd have to clean up the surface rust and that means to some extent making the metal thinner and more difficult to weld.

 

Thanks for the tips re: rust proofing. Fish oil will have to wait until AFTER paint for obvious reasons. I'm going to experiment with the KBS rust seal stuff even if it's thicker I like what I've seen so far with it.

 

Also we have been discussing this welding torch at Tafe a couple of times now.

The Cobra DHC2000 Torch (also known as a Henrob 2000)

 

It appears to use far less gas and produce a much more controllable flame and is a good cutting torch! Which looks extremely useful for thin metals.

 

Website here supplies it with parts.

http://detroittorch.com/dhc2000/

[1600dave]

seem to love oxy, but there is a lot of planishing to get out all the distortion created.

 

Yep, but at least you can easily planish an oxy weld. MIG are much harder welds, plus you need to grind the weld bead down for a good finish. Get it right with the oxy and you pretty much fuse the two bits together with very little filler rod. It may seem more difficult at first, but its a very satisfying skill to master (and not that hard to learn

 

Gav, if you are ever up in Newcastle with a spare half hour, feel free to give me a yell and drop in to try my Henrob / Dillon / DHC2000 / Cobra /whatever its called this month if you are interested. It's a much easier bit of gear to use compared to the more "normal" oxy torches. There is an Australian distributor called Amweld, good to deal with - I recently bought some extra "in-between" sized tips and a pair of their special aluminium welding glasses http://amweld.net.au/

 

Very nice job on the panel work, BTW   

Edited May 9, 2016 by 1600dave

[Brabham]

No worries Gav, a lot of it comes down to personal preference too. Don't worry if it is not 100% perfect, there will always be a skim of filler on pretty much every panel. I am a perfectionist too, but I can only get it so close before I run out of talent! I just wasn't happy with the level of distortion I was getting from oxy and found I could minimise later work by making the patch as correct as possible and keeping it as cool as possible while welding it in. Each to their own, and I am impressed by the level of skill the TAFE teachers have after oxy welding and planishing in being able to get panels pretty much perfect, something we can all aspire to. For surfaces I can access I am using POR15/KBS too, it was only things like the sills and rear hatch that I will be using the fish oil (after painting, of course ). Another thing to keep in mind is that I don't think they let you own acetylene bottles, but you can now own argon ones, so rental gets expensive.

 

Keep up the good work.  

[gav240z]

Replaced the left hand side lower corner last night. This time I was a lot more careful with my scribing and filing of the edges on both sides so that there was far less gap between the new piece and existing hatch. I also used vice grips to provide a solid clamp to get me started. It helped a lot as this time it was a far neater weld.

 

 

Progress.

 

 

 

Despite appearances the weld is a lot neater with far less distortion caused this time and hardly any grinding to be done. It should clean up nicely. I don't think it will be 100% perfect after paint, but it is the underside of the rear hatch and won't be so obvious once it's all painted and installed on the car (I hope).

 

I just noticed 1 thing I didn't take photos of is the little dimples that run along the edge where the lip is, these little dimples are visible underneath when you open the hatch and are done presumably to give more strength to the lip (since the metal is so thin), I managed to re-create these by heading the lip / edge and then hitting it with a rounded edge (like a screw driver shaft). Again not exactly like factory but close.

 

Time to start applying rust proofing and get it ready for the top skin to be installed.

[gav240z]

So small update, using the guide here provided by John.

http://www.viczcar.com/forum/topic/4564-part-1-preparing-bare-panels-priming-and-surfacing-tutorial/

 

I went down to Bunnings to get some wire brushes, nylon brushes etc.. I cleaned up the frame inside using the techniques John outlined, even though this area won't be seen I figure it's best to clean up the metal as best as possible before applying KBS rust seal.

 

The wire wheels and nylon work well as they are not too harsh and won't take much metal/material off. As you can see the lower hatch metal is a bit pitted so you want to avoid doing anything to further weaken it or make it thinner than it already is.

 

Then I hit the metal with Aquaclean, rinses it and dried, then applied RustBlast. I'll do KBS rust seal application in the morning (it's drying over night).

 

Whilst at Tafe the other night I spot welded the rear hatch lock support piece in place. Hence the copper primer.

 

The plan is to finally weld the 2 pieces together so rust proofing whilst it's apart now.

[gav240z]

Applied KBS rust seal today in the sun.

 

I poured KBS seal into the gaps and under the skin and then moved the hatch around to try and swish it around as best as possible. The stuff is quite thick and heavy and therefore not the easies to get to spread around.

 

I also treated the underside of the new skin, so hopefully that means I can get the new skin onto the hatch this week!

 

[gav240z]

Last week was a bit of a fizzer, I had intended to weld on the lower portion of the hatch but my teacher said I really needed to test fit to the car before making the final touches...

 

I was a bit annoyed since I really wanted to get this thing done and dusted, but no sense rushing it last minute and ending up with it not working out.

 

So tonight I removed the old hatch and test fitted the new hatch. Using vice grips to hold it in place.

 

Gaps look consistent most of the way around.

Minor adjustments required at each edge where it meets the 1/4 panel. Left side passenger side needs about 3-4mm adjustment.

Should be able to whack this with a hammer in a bit and fix it.

Right side needs 2mm.

Lighting is bad in the garage at night, this gap will improve once it's folded over, right now it can't sit flush because of the lip sitting half folded.

Gaps are good on this side also.

I had to scribe the lower lip (where the tail light side is).

Multiple white markers so when it's off the car I can line them up before welding it back together.

 

Lower lip isn't folded yet, which is why it looks so wide, once folded it should line up with 1/4 panel lines.

 

The part where it looks a little high here is simply because the lip won't allow it to sit lower until it's folded over the frame.

 

Otherwise fitment wise it's looking good. There are some shims that go behind the hinges for extra adjustment. I've left them off for the most part here.

 

However I will experiment better with this once I've finished welded it together and see if there is any further adjustments required.

[jeff43]

Looking good gav. Nice to see yo getting into the KBS rustseal.

 

Cheers Jeff

[Retro Z]

You can thin out the kbs rust seal with the Kbs #1 thinners they sell.

[gav240z]

You can thin out the kbs rust seal with the Kbs #1 thinners they sell.

Thanks I'll look into that, I will probably buy an air compressor and set up (rather than brush it on), I plan to use it to paint a load of stuff. The suspension components, fuel tank straps, basically anything black under the car. I'll do several coats and will likely thin it out that way.

[gav240z]

After mocking it up on the car I made some notes of how much adjustment was required for each edge.

Using a hammer and dolly I gently folded in each edge to fit to a specific arc..

 

Next after scribing the fold for the bottom lip. I started to fold the lip under for the lower portion of the hatch.

 

The outer edges were a bit longer so got trimmed with tin snips.

 

Very rough look from lower edge.

 

I trimmed the edges of the hatch and after some adjustments (lots of little detail work not shown in between) it was tach welded into place using a MIG welder.

 

Got it home tonight and just placed it on the car. I haven't tightened the fasteners on it yet. So it will pull up a little when that's done I'd imagine.

 

Poor lighting again, but you can see the lower lip now looks much more adjusted.

 

There is still about 1mm of overhang on the left hand side.. but until it's buttoned up properly will be hard to know if it requires changes etc..

 

A couple more shots for completeness...

 

The gaps at the bottom of the hatch are really close. If anyone can post a photo of how much gap they have at the bottom of their hatches that would be really helpful since I don't have my 72 240z handy for comparison.

 

I hope to have this hatch mostly finished after next week. Which is sadly the last week for the semester. But at least I'll be moving onto the next panel by then (I hope!).

[gav240z]

If anyone can post pics of this gap on their cars?

 

 

Just so I can get a feel for how much gap is normal. On my repaired hatch it's quite tight on either side. So may need to trim a mm or so at each edge..

[CBR Jeff]

Great work Gav. It's looking very nice.

Jeff

[gav240z]

Great work Gav. It's looking very nice.

Jeff

Thanks Jeff, somewhat relieved to nearly be done with it. 1 of the other blokes in the class said I must have a lot of patience because he would have thrown the towel in ages ago. I think that's a good thing.

It certainly would have been quicker to find a better hatch in hindsight, but... they are getting really hard to find now. I toyed with the idea of importing 1 from the US but to go to that effort and expense / sandblast it and find similar bog / patch work would be disappointing.

I think realistically finding these in rust free shape is pretty hard - even from a 'dry state'.

 

So adding completely new 'thicker' metal is a good thing, plus once the car is painted I can stand back and think "I made that".

 

I did get a bit of help with some of the final touches last night (nothing particularly difficult) from the teacher simply because I was kind of rushing hoping to get it done last night. But as it turns out, still not enough time.

 

If anyone can share photos of the gaps they have on their cars it would be appreciated.

[gav240z]

Spent a little time in the garage lining things up, may be a bit overly fussy.

 

Just looking at photos around the web, notice that the hatch sits a bit proud on this car and the lower edge of the hatch is slightly less thick than the 1/4 panel section. So I think even from factory they were not perfect.

 

[gav240z]

So this will likely be my last post in this thread, I think from here on it's going to be hard to document the subtle differences I'll need to make to get this hatch 100% perfect. A lot of it involves feel for high / low spots which are hard to photograph.

 

To join the original and new lower hatch skin we used a MIG welder, Oxy was a concern because it could cause distortion with the heat and since we can't hammer it from the rear this was a better idea.

 

[CBR Jeff]

Gav are you going full old school and lead wiping the join area?

I'm planing on having a go at lead wiping the joins I have manufactured on my car. If you are you can go first!!! :-)

 

Jeff

[gav240z]

The tafe teacher said we could use filler or lead join it. I originally thought I'd use bondo / plastic filler but I might do lead now that I've thought about it a bit more.

 

It's a little bit low/high around the join now and as you probably know you can only file it down so much before you thin the metal out too much.. I've done lead filling / wiping before on the 240z door.

 

Here is the post.

http://www.viczcar.com/forum/topic/3202-tutorial-door-skin-removal-for-dummies/?p=147048

 

There is a video I took the audio might not be great as it's on my mobile phone.

 

Eastwood's do a 'body solder kit' which is lead free. (excuse the 80s guitar riffs).

 

I might look at something like that, given the work you've done on your car so far I'd say you should be fine using the solder if you follow the instructions. It's not that difficult.

[gav240z]

Gav are you going full old school and lead wiping the join area?

I'm planing on having a go at lead wiping the joins I have manufactured on my car. If you are you can go first!!! :-)

 

Jeff

I had a go at this last night, I did the left hand side. Which had a larger low spot than the right side. I used my DHC 2000 Cobra Torch which came with the attachment needed for doing lead wiping.

 

It still look a bit rough because I had just started to file it down. I was going to use regular filler on the right side, but now I think I might just go the whole hog and do both sides with lead.

 

I am also thinking I'll use it on the underside for a low spot where I joined the new metal in the edges and I might use it along the fold where it joins the original metal. The new piece I made was a thicker gauge steel and if you look at the side of the hatch you can see the metal is thicker, I am thinking I'll use the lead to taper off the join so it's less obvious.

 

I really want to get this thing into epoxy primer soon though! Really want to move onto the next panel, either bonnet or rear slam panel / valance section.

 

Also attached the right side for comparison (I very slowly and carefully used a finger sander to file down the weld more level).

[RB26DETT]

FYI this is the gap on my 72 car.

Edited August 11, 2016 by RB26DETT