Datsun Roadster Forum-311s.org

I'm not the master metalworker Graeme is, and since i need to replace the front part of the rocker where the fenders mount I began thinking I would make fiberglass pieces, but I wanted to get feedback from you guys.



This is rotted out just where you would expect it to be. any repair to the door post/a-pillar would be done in metal, but the hoagie-roll shaped piece is what I'm thinking of reproducing in glass. It's only structural job, as far as I can tell, is to hold the bottom of the fender behind the wheel. I'm thinking of making bucks out of urethane foam, fitting them carefully, and making fiberglass neg-molds, them making glass positives, and JB welding captive nuts for the fender mounting. If it works I would have molds for folks in the same pickle.

Unothrodox? (Metal is nice if you have the skills to do it)
What you've described has lasted 25 years on my car.
I got rid of the jack holes because I hated the stock jack which had damaged my door when it tipped.

The sill or rocker panel is a very important structural element of any car but more so in one without a roof.
Agreed, the use of a separate chassis provides additional rigidity not seen in a conventional uni-body construction.
Even so, I would be very reluctant to advise anything but new metal.
From your pic. it seems to be, in my experience, a fairly minor rustout
However, the integrity of the surrounding panels would need to be checked closely to ascertain the extent of the damage.
You have already done one major time consuming job that a Shop repair would charge you for, the removal of the guard.
If you can present the repair to a Shop and not require them to remove and replace panel you have minimised the expense and should get the maximum return for your $.
All that is required now is to cut the damage out, cut the patch, and weld them in.
I would also venture to say that a reasonably skilled repairer could cut and shut that rustout in a lot less time it may take to develop a buck and make up the 'glass panel.
After fresh metal is welded in, it would be as strong if not stronger than the original.
And you will be confidant that after the appropriate corrosion proofing and painting, it will last another 40 years

I'm not the master metalworker Graeme is

Thank you for that, but all I have under my belt is experience.
Going back to the brief course I did years ago on Auto Body Repair, the very first thing our Tutor asked us was,
"Are you interested in how a car body is constructed?"
No one said they were.
He then proceeded to admonish the class severely since, he claimed,
"How can you repair something if you don't know, or care, how it was constructed in the first place!"
Mmmmm, he had a point!
So if you want to repair a rustout, you need to take note of how the panels were layered, their thickness and shape etc.
Skin repairs are simple but when you start dissecting successive spot welded structural items, it gets more complex and therefore more important to get the repair right.
I would like to think that most owners of these classics would want to do the best job possible with repairs to give the car the best chance of survival
Anyhoo, it's your car

Nissanman wrote: Skin repairs are simple but when you start dissecting successive spot welded structural items, it gets more complex and therefore more important to get the repair right.

It is just these layers at this particular point which have me flummoxed. The front portion of the rocker (sill) is sandwiched under other parts. That, and the compound curve of the piece, it seems like it will be 2 to four pieces patterned, panel-beaten, and welded together. I will re-visit your writeup.

Well it all depends if you want to re-produce the EXACT shape of that curved sill cap.
I decided that a little artistic license would be acceptable considering it will all be hidden behind the trailing edge of the guard.
So, my caps have a square leading edge and are more angular than what they replaced.

I was more interested in replacing the strength of the cap than matching the appearance.
Yes, there are layers of metal involved, but if the top side of the cap is OK, I would just cut the bottom 1/2 or 1/3 away and patch that.
That would require a closer match to the original shape.
Aftermarket sill caps have been available although I haven't seen any recently.
I just couldn't justify the cost of them
P.S.
It is great to have the EDIT function back

I agree with Graeme.

By the time you clean up the area, fill it with foam or whatever, take a proper mold from it and then produce your first piece, you'll have way more time and money into it than it would cost to have a welder / body shop apply a patch for you.

The only critical part of shaping you have is that lower flat, and the immediate contour coming up from the flat. And that's due to the imbedded nuts in the lower flat. The forward surface never even makes contact with the fender, it simply closes the rest of the rocker. As far as strength, the door pillar post is important, but a properly fashioned patch, even if it's made from 2, 3 or even 4 or more pieces, as long as the welds are done well.... is better and stronger than fiberglass.

I'm not saying that fiberglass patches or even repairs are bad, just that this is such an easy piece to fabricate, that the extra work the fiberglass would require in order to get it to adhere properly to what metal you have there, that it's just easier.

FWIW
E

Nissanman wrote: Aftermarket sill caps have been available although I haven't seen any recently.

An Aussie company has them. http://www.hrc-dat.com.au/sub1.htm They are not inexpensive, but they do look great.

"How can you repair something if you don't know, or care, how it was constructed in the first place!"

This is an excellent question, and got me wondering. Why is the rocker stamping the shape it is, with the two bullnose ends fore and aft? Was the reason for the shape of the piece structural rigidity, or ease of manufacture? As I mentioned before, the only function I can see for the rounded protrusion into the fender well is a place to hang a couple captured nuts to bolt the fender to. That and trap dirt and moisture

So does this shape have any structural function other than a fender-mount?

spl310, you don't think $325 each isn't pricey?

MTyler wrote:... Why is the rocker stamping the shape it is, with the two bullnose ends fore and aft? Was the reason for the shape of the piece structural rigidity, or ease of manufacture? As I mentioned before, the only function I can see for the rounded protrusion into the fender well is a place to hang a couple captured nuts to bolt the fender to. That and trap dirt and moisture

So does this shape have any structural function other than a fender-mount?

Heck, it gets even better than that. There is only one really good access point into the rocker panel ... the jacking point. There are a couple of weep holes for drainage, but in their wisdom the steel within wasn't totally galvanized, nor painted nor otherwise rust-proofed. Result? Over 40 years worth of dust and grime that seeps into this cavity, especially if the jacking point cover isn't put on the car.

The odd end shape that you point out really is questionable, except that as you point out, it may be that shape for ridgid strength. Even in the front of the rear fender it doesn't touch the outer skin, and leads to a very interesting catch pocket ... with the eventual problem of rust and dirt accumulating inside there.

When I was working in this area on mine, I drilled some access holes from the inside of the car to shoot POR within the holes and coat the inside of the rocker. Took a while to get all the crud out from inside there, and just as long to Marine Clean and Metal Ready but she's coated inside there.

FWIW
E

Graeme: With the edit function back, my comment regarding pieceing together the panel is out of sequence with your edit addition of the picture. LOL

alp wrote:spl310, you don't think $325 each isn't pricey?

If you re-read my statement, I said that they are NOT inexpensive. That means that they are expensive.

spl310 wrote:

alp wrote:spl310, you don't think $325 each isn't pricey?

If you re-read my statement, I said that they are NOT inexpensive. That means that they are expensive.

just for comparison. The corresponding piece for an MGB through The Roadster Factory is $29.50
The whole outer sill is 90 bucks! Oh well, if only there were a half-million roadsters made

my mistake

They are not inexpensive, but they do look great.

The whole [MGB] outer sill is 90 bucks!

Zachary!
When you see the end result of the reproduction caps and the sills proper, and you have some fabrication skills, the prices seem astronomical.
I'm not absolutely sure, but those caps are probably imported from the US, I don't think they are made in Oz
Anyhoo, unless my weakly Lotto entry comes good, I'm not likely to be purchasing either of these parts
As for the shape of the caps, I guess after a few glasses of after banquet Saki, it seemed like a good idea at the time
As Enrique mentioned, there are some awful debris traps in the factory sill design.
It will be a fact that access holes will be cut, probably in the cabin side flat panel to allow a liberal dose of Cavity Wax.
Then I'll fit some rubber plugs in them and they will be hidden beneath the carpet.
There will also be some non original drain holes incorporated in the new sill bottom edge.
Modern cars have these if you look closely.
The hole for the jack point is a one way valve for moisture and debris.
There is a famous quote from that eminent Russian Hot Rodder, Boris Kutchacokov: -
"You can seal water IN but you can't seal water OUT!"

It all gets back to studying how the car is put together, where has the design gone wrong and how can I prevent a recurrence of the problem, using stealth of course

For instance, I'm making the curved section of the cap, where the guard attaches, on a smaller radius.
This will introduce an 8-10mm gap between the inner guard surface and the sill cap, easier to flush clean than the original factory "intimate contact" design.
The trailing edge of the cap is flared out to the correct radius to mate up with the centre sill section.

I have welded two square tubing sections on the bottom of the cap.
These will be drilled and tapped to accept the guard mounting fasteners which originally screwed into captive nuts inside the sill cap.

Nissanman wrote: For instance, I'm making the curved section of the cap, where the guard attaches, on a smaller radius.
This will introduce an 8-10mm gap between the inner guard surface and the sill cap, easier to flush clean than the original factory "intimate contact" design.
The trailing edge of the cap is flared out to the correct radius to mate up with the centre sill section. I have welded two square tubing sections on the bottom of the cap. These will be drilled and tapped to accept the guard mounting fasteners which originally screwed into captive nuts inside the sill cap.

Graeme,
Thanks so much for the info and the photos. You've got me leaning towards a metal repair. I do like the airspace between the fender and the front of the sill. The square tubing mounts will allow positioning the fender properly and making the final marks for the mounting holes in registration. I was concerned about setting captive nuts and having the piece be just enough out of whack to make me cry