Mazda-Menders

That was a very productive day Nate, nice work!

Managed to get another few hours tonight, I was a little bit uncertain on how to work the alignment of the three panels at the back of the sill.

Basically there's the rear arch, the sill and the b pillar all come together, and trying to get them to fit is a bit of a head scratcher.

Hopefully the photos below make it a bit clearer, but basically it's a lot of time spent finding the spot welds and drilling them out and then a million attempts at putting the replacement panel in place, mark the cuts, remove the panel, feel uncertain, put the panel back in place, repeat...



You basically have to cut a flap in the b pillar and pull that up to allow cutting the original sill to align with the replacement panel, then fold it all back in place, mount up the arch panel and make sure they align nicely



The front is quite a bit simpler, another case of finding the spot welds and drill them out, mark the cut lines and crack on!




There's a couple of bits where the gap is bigger than 1mm so will have to do some bridge welding, otherwise it'll be tacking the butts and then stitching together.

Oh no, wait, of course it's not that simple... There's the inner rear sill...



Looks crusty in there eh? Fortunately it's not a particularly complex shape so I'll do some card templating and make up a replacement piece in 1.2/1.5mm steel, can't remember what pieces I've got tucked away...

Hoping to get back over on Thursday, the evening will probably be entirely spent on fabbing up the inner sill section, but that should mean everything is ready for final alignment checks before tacking it all together!!

Are you intending to joint the new rear panel to the original in a straight line at the top of the new panel?

Also I remember you will get some movement/ Walpage when you weld the new panel.

John&Luke wrote::text-coolphotos:
Are you intending to joint the new rear panel to the original in a straight line at the top of the new panel?

Also I remember you will get some movement/ Walpage when you weld the new panel.

Sorry J&L, which panel do you mean? The sill to the b pillar? That was going to be the plan, although if you've got some pearls of wisdom please share!

I'm planning on stitch welding but working a small (inch or so) weld one end then jumping to the other end and slowly working towards the middle, will likely give the welds a blast with the air gun every few minutes too.

Another great thread, you guys have some great skills, great tools and big balls lol..

Mine will be a lot simpler and scrambling on the floor, I do love your rotisserie simply and effective, but I doubt I'll be taking the engine out when I do mine, I could do with doing but that adds further complications

Keep up the great work, descriptive posts and photos, helps others (me) a lot

Natehd9 wrote:

John&Luke wrote::text-coolphotos:
Are you intending to joint the new rear panel to the original in a straight line at the top of the new panel?

Also I remember you will get some movement/ Walpage when you weld the new panel.

Sorry J&L, which panel do you mean? The sill to the b pillar? That was going to be the plan, although if you've got some pearls of wisdom please share!

I'm planning on stitch welding but working a small (inch or so) weld one end then jumping to the other end and slowly working towards the middle, will likely give the welds a blast with the air gun every few minutes too.

Natehd9, I was referring to the wheel arch repair panel.

J

graymattor wrote::clap:

Another great thread, you guys have some great skills, great tools and big balls lol..

Mine will be a lot simpler and scrambling on the floor, I do love your rotisserie simply and effective, but I doubt I'll be taking the engine out when I do mine, I could do with doing but that adds further complications

Keep up the great work, descriptive posts and photos, helps others (me) a lot

The rotisserie has made life a lot simpler, and I get so much less crap in my eyes now (although this is inevitable no matter what orientation you're working in sometimes!)

If you're going to be doing extensive work it might be an idea to drop the engine, there are a few ways to do it, and if you've got a second (or third!) Pair of hands it's possible (and maybe easier?) To drop the engine out of the bay rather than lift it out.

Either way, I'm glad the threads on here are inspiring you to crack on, I'd not done any bodywork before this car so it's a learning experience for me too!

[/quote]

Natehd9, I was referring to the wheel arch repair panel.

J[/quote]

AHH I'm with you now! I had originally intented on just using the bottom portion where the arch overlaps the sill, but now I have the panel I'm considering chopping the entire arch to make sure the inner arches aren't hiding anything nasty... These jobs like to grow arms and legs, and it's nice to know that there won't be a trace of tin worm for the foreseeable future.

Didn't get to spend any time on the car on Thursday as planned, but did manage to get in a further 5 hours or so yesterday.

Had a look at the inner sill rear section, it's quite a complicated piece that has multiple curves and folds so rather than leave it in situ and try to replicate, I chopped it back to clean metal






Having played about with card templating I couldn't manage to get a decent on piece with all the folds and curves so decided, as it's not a visible piece, to take a simpler route:

First I cut the flange that would make up the bottom of the inner sill and the face that connects up to the front arch/sill piece, this was then marked and bent to replicate the old piece, not the smartest move as I'll explain later.



From this point it was a case of replicating the curve of the inner sill piece, I did so by finding a hole saw which had the same radius as the bend on the old sill:




At this stage I tacked the two pieces together so I could cut the return line on the curved section:




Cut the two pieces apart and make the marked cuts, tack them back together and get this:



I could now start offering the piece up to see how it measures, and promptly forgot to keep taking photos, in short, I needed a return which required a little more measuring, cutting and tacking.

Once the piece was more or less there I thought it was a good time to clean up the area around the workpiece to make sure there was no further rust:





So the mistake I was talking about earlier, I should have put all the replacement panels together and measured up the new piece from them as one of my flanged faces needed cutting and adjusting to fit, not the end of the world, but i was making the panel without any real reference (the corresponding section had rusted away on the old piece so I was assuming what it would look like and was wrong!)
Basically if you're planning on doing this or something like it, put all the replacement panels together, get them more or less aligned and then work from that!

So after adjustment of the panel the driver's side is pretty much ready to start tacking back together!

Nice work, that’s a tricky section to fabricate. Shame a repair section isn’t available for this area. It’s my least favourite job on MX5’s.

As you say a lot of trial and error without good reference edges.

Natehd9 wrote:

Natehd9, I was referring to the wheel arch repair panel.

J[/quote]

AHH I'm with you now! I had originally intented on just using the bottom portion where the arch overlaps the sill, but now I have the panel I'm considering chopping the entire arch to make sure the inner arches aren't hiding anything nasty... These jobs like to grow arms and legs, and it's nice to know that there won't be a trace of tin worm for the foreseeable future.[/quote]

Yes agree, inner arches almost certainly rot along with the outer edge as I guess the corrosion sets itself up between the two panels.

My only advice if you decide to do the whole arch would be to cut and join the new panel with the old along a radius that follows the arch. I’ve seen a couple of examples of folk drawing around the new panel and cutting to this shape. This leave a long straight joint about three quarters of the way up the panel. I reckon this would be a bugger to weld without distortion. This then creates the problem of filling to remove any rippling etc.

Hope this makes sense. J

John&Luke wrote:Yes agree, inner arches almost certainly rot along with the outer edge as I guess the corrosion sets itself up between the two panels.

A lot of people do not realize that there are two skins ..inner and outer...and they are not sealed ,just spot welded...which is even worse on a Nb...but it does let water creep in between the none protected bare metal to start to rust very quickly... resulting in blown arches etc...so when they do seal them( when it is always to late)....they forget something else on the rear end that helps to the rot from the inside out....the boot on these roadster are all prone from leaks and natural condensation which does run down the inner and outer wings to the arch lips and sill areas to have a chew on fresh unprotected metal..the batteries don't help in this process for condensation,if there is water getting in the boot the condensation will be a lot worse., ....so the box sections,open areas...in the inner boot area all needs cavity wax skip loading in the areas to also help the holding back of the tin worm...
M-m

Got another couple of hours in last night, been sleeping badly recently and works been tough so didn't manage as much as I wanted to, but we've a bank holiday weekend of potentially rubbish weather ahead so I might make up for that!

Decided to bite the bullet with the drivers rear arch, a couple of 10mm spots looked a little interesting so rather than risk it I thought I'd make a thorough job. Having considered J&Ls advice above I cut the panel along the line of the line of the wheel arch to reveal an inner arch in pretty good nick... Nevermind!

I didn't get any photos of the 'in progress', much the same as any other panels, just a case of working round the inner and outer arch, finding the spot welds and drilling them out. What did surprise me was the sealant holding the two panels together at the flange, I assumed id missed a weld and chopped the panel out in chunks, only to find it came away with a bit of 'persuasion'

Wire brushed everything that looked a little suspect, quick coat of kurust and then either zinc rich or etch primer (depending on whether the face was being welded or not) left me with this:



There isn't any metal left to chop off on the driver's side so I can stop procrastinating and get on with some welding next time!

Also, finally got my new job sorted so looks like I've got a week at the end of June to get on with the car (assuming that life hasn't returned to something resembling normal life by then!) Here's hoping in that time I can have the driver's side done and make good progress on the passengers side!

Yep, that’s how I do mine. At least you know you have good metal behind the arch now. Are you going to joggle the edge of the original rear wing panel to accommodate the edge of the replacement arch ?

This will stiffen up the original panel and provide an overlap surface to weld. I joggle the original panel so the open edge of the joint is facing down presenting less chance of water or crud sitting in there.

Very good work on the sill section.

Looks great, coming a long really well, keep the pictures and details coming, all of which is extremely useful for when i come to start mine! (im hoping to post my build thread later today) i may look at taking a week off once i have everything i need to get going, but not so easy at the moment with doing multiple jobs with quite a few people on furlough so busy as!!

John&Luke wrote:This will stiffen up the original panel and provide an overlap surface to weld. I joggle the original panel so the open edge of the joint is facing down presenting less chance of water or crud sitting in there. .

JL, i read somewhere that joggling and overlapping the panels leaves a crevice on the inside for moisture to sit, is this right or a load of rubbish? i'm about to pull the trigger on an air Joggler, it looks a far better and easier way to get backing for a good weld and like you said strengths the area for welding so less distortion

Actually just read that again! do'h you face your internal flange down to prevent moisture sitting!