Rust Bucket Support Group

[EScanlon]

Number 40 is correct, if you are lucky you will only need the front end of the piece, changing the whole rocker would be rather challenging I would think. The rocker on a Z goes under both the front fender and the rear dogleg and is exposed under the door. A strange piece if you are used to working on older American cars....

Lance answered it. Their drawing can be confusing if you're not sure of what you're going to get. But Lance's description is 'spot on' as our down under friends would say.

But Lance, that is a strange piece only if you've never worked on a Uni-Body car.

As far as it being a challenge to change the whole rocker panel, it shouldn't be any harder than changing out a floor pan. Different? Yes, since part of the piece is "finish" metal (metal that ends up being part of the "finished" part of the paint job or "viewable" paint job.) But not necessarily any more difficult.

I would recommend that the front part of the rocker panel on the car be removed first, BEFORE you start cutting the new rocker panel. Then with the front open, you should be able to ascess just how bad the rest of the rocker panel is. If the rust on the rocker actually DID begin due to the detritus of the cowl drain providing a wet sponge onto the metal, then the rest of the rocker should be fine. If on the other hand, the rocker panel was also doing a good job of rusting out from the inside out, then I would recommend you remove the WHOLE rocker panel and replace with the new.

To an experienced bodyman, this type of complete panel metal replace is actually LESS complex than a cut and fill repair since there isn't any cutting/patching in the middle of a panel.

FWIW

Enrique

[LanceM]

Enrique,

It's strange to me cause at heart I'm a 4WD truck guy, replace many rockers on things with frames Not to mention way back when, before unibody became a word What I thought would be tough would be the rocker under the dogleg of the rear quarter, I'd hate to cut all of those welds and pull the quarter up to get to it if the quarter was good. Both the rocker and dogleg on mine had gone under and so cutting to get to it were necessary, but to do it to something that was still good would have been a tough choice for me... And I should add that lucky for me I was able to do all of the patching of the rocker under the dogleg, leaving me only one weld line to make nice and unseen.

[1972zed]

Thanks guys, I will be getting a professional bodyman to do this after I buy the part. No point paying for inflated parts.

[WalterMondale]

That hole on the rocker box is very common. I think that the front fender vibrates against it and wears the paint off. Once wet with water from either the cowl drain or road spray, the rust accelerates the growth of the hole.

Once I discovered and made the repairs on mine, I applied brush-on undercoat on the rocker and the inside of the fender.Then I applied a piece of "peel-n-seal" over the rocker where it may touch the inside of the fender. This I hope will minimize a new "wear-thru". I also copied EScanlon's idea about extending the cowl drain away from this area.

[EScanlon]

...I think that the front fender vibrates against it and wears the paint off. Once wet with water from either the cowl drain or road spray, the rust accelerates the growth of the hole.

...... I also copied EScanlon's idea about extending the cowl drain away from this area.

Walter:

Not to toot my own horn, but in my experience with various Z's in and out of the rust-belt, it's the buildup of cr@p behind the fender that causes the bulk of the rust-thru on the fender. That's the main reason for the extension of the cowl drain.

The cowl, being in front of the windshield and having the grill to allow fresh air into the vent, collects all sorts of debris. From dust to leaves, pine needles and just about anything that falls from the air. Then add a bit of water and it drains.....right out the hose and into the space between the fender and body.....and the rocker panel. Additionally, Datsun was very helpful in providing a stiff rubber flap that purportedly would make it easy for that cr@p to fall out. Instead, it acts as a cork and keeps it in there.

Give the detritus some time, and the organic matter will begin to decompose and exhude those compounds which will help attack the metal. These will slowly seep their way through the glob and end up between the rocker and the fender. They'll actually congeal into a jelly like acidic compound, which resists being washed out. That's why you'll usually note this type of rust through as starting real low on the fender....about where the rocker is coming into contact with the fender, and not higher up, where the cr@p is.

The rubbing that you mention although it would expose the metal to the air and other oxidants, would not necessarily contribute to the rusting process unless you leave the car sitting for long periods of time without driving it or having carefully washed out the grime behind the fender. If you do have a bunch of cr@p behind the fender to begin with, then the two will make it rust that much faster.

If you examine that rubbing, you'll note that the only way it can occur is if the body flexes. The body will obviously NOT flex at rest, only when in movement and then only when being "run through it's paces". That is, hard cornering, steering, shifting etc. Metal that is under this kind of stress, tends to get "annealed" rather than rusted. (Annealing is another method of strengthening and working metal. You heat and cool the metal. Friction will result in heat.) Take a look at your disc brakes, or the railroad ties on an active spur and you'll note that the metal takes on a dark and glossy surface. This surface will eventually rust, but not quickly nor more quickly than non-annealed metal. However, it is much quicker than unprotected metal.

FWIW

Enrique

[WalterMondale]

Enrique,

You are the MAN!