Why do doglegs rust? Can it be stopped?

[Boy from Oz]

Apologies if this has been covered before.

 

My car appears to have had at least two replacement dogleg sections on each side, meaning the panel has rusted at least three times. Has whatever causes this been identified and has any modification been known to prevent it from reoccurring? Thanks.

[hoov100]

Once the dog leg is cut out, you can cover it in POR15 or a rust inhibitor. The rust problems are mainly due to moister in the air and salt. These cars almost literally rust from the inside out, as most people who have cut up or repaired s30's have experienced this first hand.

 

Also, just welding a new panel over the old rusty one is not repairing rust, but just masking it.

Edited June 16, 2010 by hoov100

[spork]

All rust needs to be removed and then when the repairs are completed, it needs corrosion protection on the inside too! This step is often overlooked and you'll end up with more rust down the road. Some areas are hard to access, but a lot of body shops have wands that can reach into the hard to get to areas to respray the inside of panels to keep them protected. The other thing to watch for is leaves and other crud building up behind panels that will hold he moisture in. I replace floor pans in one car, and ended up with literally a 5 gallon bucket of wet sand that was packed in the frame rails...and the car had been stored in my garage for over a year before I even started the repairs. Once moisture gets in, it has a hard time getting out, so make sure there are no pin holes or missing body plugs.

[Boy from Oz]

Thank you for your responses but I am particularly interested to know the design flaw which seems to always create rusting in the dogleg.

[hoov100]

Thank you for your responses but I am particularly interested to know the design flaw which seems to always create rusting in the dogleg.

 

Theirs no design flaw. These cars where built over 30 years ago and live in very moist climates for the most part, combine that with hidden spaces between body panels with very little rust protection and you will have a car that rusts from the inside out. a Lancia is a perfect example of this.

[johnc]

IMHO, there might be a couple causes:

 

1. Road debris from the rear wheel gets thrown into the little pocket at the bottom front of the rear wheel well and rusts into the rocker panel area.

2. Water leaks into the rocker area from the screw holes on the sill, weep holes underneath, and then works its way to the back and does its damage.

[clutchdust]

I will contribute my meager opinion and please, take it for nothing more that that.

I'm no expert in Z-cars, I come here to learn from everyone else. However, I lived in Japan for a year courtesy of Uncle Scam. One thing I learned while living there is that the manufacturers just didn't put that much time or expense into chassis longevity. Part of the reason is that the climate is so humid that rust starts just about the day the car rolls off the assembly line. The other factor is Japanese regs preventing people from using the same engine in excess of 40,000 (maybe 60,000?) miles. The result is most people just replace the car at that point. The Japanese mentality has been that their automobiles are a wear item. The idea of collectibility is a much newer concept there. As such, until recently, the manufacturers just didn't put a lot of expense into anything to make it last past that 40k (or 60k) mark. To the manufacturer, what good is a pristine chassis if the motor has to be removed?

The main reason we're seeing Japanese cars from the 80's and 90's in as good a shape as they are, and comparatively better shape now than earlier cars were at the same age, is because of the large portion they are now importing stateside. We expected them to last longer and now those manufacturers are building them to last longer. But now they build them all to last longer, not just the ones they import over here.

My $.02. Your mileage may vary.

[Konish]

I will contribute my meager opinion and please, take it for nothing more that that.

I'm no expert in Z-cars, I come here to learn from everyone else. However, I lived in Japan for a year courtesy of Uncle Scam. One thing I learned while living there is that the manufacturers just didn't put that much time or expense into chassis longevity. Part of the reason is that the climate is so humid that rust starts just about the day the car rolls off the assembly line. The other factor is Japanese regs preventing people from using the same engine in excess of 40,000 (maybe 60,000?) miles. The result is most people just replace the car at that point. The Japanese mentality has been that their automobiles are a wear item. The idea of collectibility is a much newer concept there. As such, until recently, the manufacturers just didn't put a lot of expense into anything to make it last past that 40k (or 60k) mark. To the manufacturer, what good is a pristine chassis if the motor has to be removed?

The main reason we're seeing Japanese cars from the 80's and 90's in as good a shape as they are, and comparatively better shape now than earlier cars were at the same age, is because of the large portion they are now importing stateside. We expected them to last longer and now those manufacturers are building them to last longer. But now they build them all to last longer, not just the ones they import over here.

My $.02. Your mileage may vary.

 

I know I'm a necro-poster, but this info is just false. There is no mileage limit placed on cars in Japan. The real reason most folks get rid of their cars is that after the initial "new car" shaken (safety certification) it gets increasingly more and more expensive to keep cars on the road. In fact, at some point the govt mandated inspections and associated parts costs to "conform" is more than the value of the car itself. It's also the reason that used cars in Japan are basically worthless after about 8-10 years...in fact some people *pay* a dealer to de-register their old cars.

 

Having lived here in Japan for the past 4 years (plus 2 years in Sasebo about 10 years ago) with 2.5 more to go, I've been through my share of cars and have a good working knowledge of the rules/regs in registering Kana plated cars.

 

The Japanese mentality on collector cars is no more or less different than the US mentality on, for example, MOPARs during the late 80s early 90s. Hell, you couldn't give a good Duster away when I was in H.S....gas was too expensive, the cars were just "old", weren't the most desirable models in the line-up and most folks wouldn't put the money into them to restore them (right before they got collectible). You have to understand that rust prevention right up until the 80s was just not common practice anywhere (Porsche started galvanizing their shells in '78 starting with the 911SC for US models). Check out a late 70s US built car and you'll see the same rust-bucket effect.

 

Japan has always exported more cars than it uses domestically. Honda is a good example of this, and actually design cars for the US market and installs engineering fixes for their own domestic market, so corrosion resistance had nothing to do with their export numbers increasing in the 90s. Corrosion warranties started to become a "value add" in the early 80s which then prompted the industry to improve their corrosion resistance in order to keep from having to make good on rust-related warranty claims.

 

I remember as a kid the first car commercials that actually used corrosion resistance in their ad copy as a feature. Of course, "rust-proofing" cars became a standard practice for all manufacturers that wanted to stay competitive...like stock A/C, AM/FM/CD decks, power windows, carpeting etc etc. Believe it or not, there was a time when even floor mats were dealer installed optional items that cost extra and NOT included as stock equipment (and sometimes for your money you got deluxe rubber mats for your $$$) My dad's 1976 Ford Courier PU didn't have a rear bumper because it was an option he just couldn't afford at the time...a rear bumper! LOL

 

If you really want to see how freaky Japanese car dudes get, see if you can get a copy of "G-Works" magazine...these dudes will eat Ramen noodles for months to spend every freakin' dime on their rides. Seriously, car dudes in Japan are some of the finest, salt-of-the-Earth folks you'll meet anywhere...and about as crazy to boot.

Edited August 9, 2010 by Konish

[Tony D]

It's simple design. the 'flaw' is inadequate drainage.

You will see that the inner fenders on a US Specification 260 and 280Z have plastic flaps inside them to preven road debris from being flung into places it shouldn't be. The original cars had drain flaps which couldbeplugged closed by mud, or in some cases parking under the wrong kind of tree.

 

Look at the door windows: they have 'fuzzies' on US cars, the datsuns had rubber wipers. What for? To keep leaves anddebris from getting INSIDE the doors and soaking up moisture---and holding it against an untreated metal surface.

 

The issue is that drainage of water is usually adequately addressed in these cars, but the issue of debris ingress was not, and in many cases the debirs accumulation in these areas will hold moisture and rot from the inside out. it was not uncommon to see people with high pressure washers blowing up into 'drain holes' in the chassis to dislodge mud, leaves, etc...

 

If you park in a garage, people think that is what saves you from rust. Only by the factthat leaves and dust can not get deposited into these areas! I've found parking under the wrong kind of tree will do in a car FAR faster than anything else. Small leaves, in particular, like to get into these crevices, plug the drain holes, and then you're screwed.

 

As for the comments on 10 year japanese car ownership, this is also true (Konish) so many myths surround this it's not funny. But it IS true that Japanese manufacturers AT THAT TIME looked upon a car as a 10 year appliance, and didn't STRESS rust prevention. Drainage, but not prevention. Driving around on Okinawa revealed mid-panel rust as bad as anywhere in the Rust Belt back home... They got better because they HAD to get better. But in the 70's across the board, they didn't put a lot of stress on corrosion prevention. And the Z's being lightweight had thinner metal than most. Go check and compare a 76 celica fender against a 76 Fairlady and you will be amazed that you can physically measure a significant difference in metal thickness!

 

Additionally, much of the inner-fender plastic cladding used on the US cars was NOT installed on the Fairlady. My 77 S31 does not have inner fender liners like my 77 280Z. Why? Weight, and perceived domestic market expendability of a motor vehicle. Seriously, in 1987, when these cars came due for Road Tax in April, they FLOODED into the scrap yards. I watched and almost cried when I saw an ORIGINAL Fairlady 240Z (HS30) get scrapped for a slight wipe down one side. The yard paid the owner 5000 Yen. Which was all ANY car with expired road tax, and expired shaken-Sho is worth at that point. It was COMMON to simply take a perfectly running car down to the scrap yard and turn it in for scrap value, and go get a new one. it's a clutural accomodation. I ended up with a brisk business transferring cars from Japanese Friends to Servicemen because I would give 2X the price the scrap yard would (10,000 yen, like 33$ at the time) and then would have a car dealer process the transfer through LTO and sell the cars all day long for $500 and $600 with a one-year Shaken-Sho on them. For a short-timer, it was a perfect deal, and he could resell the car (at 11 or 12 years old) to another servicemeber for what he bought it for, and THEY would run it thorugh another inspection for $300. You got a car for a year for under a grand, insurance included. What a deal.

 

I digress...

[theghosttanker]

I just cut out and replaced doglegs on my shell a few months ago. When I cut them out, there was a couple inches of mud/sand/dirt/leaf debris packed tight inside. After replacing them, I used an undercoater's spray wand, which you can sneak all the way down into the bottom of the dogleg if you take out the interior trim and uncover some big access holes. I thoroughly and completely sprayed inside that whole area with Rust Bullet. Should be better, but I intend to clean out the dogleg area periodically just to make sure. IMHO, the fact that dirt can get in there and pack that whole area full IS a design flaw.

[Konish]

It's simple design. the 'flaw' is inadequate drainage.

You will see that the inner fenders on a US Specification 260 and 280Z have plastic flaps inside them to preven road debris from being flung into places it shouldn't be. The original cars had drain flaps which couldbeplugged closed by mud, or in some cases parking under the wrong kind of tree.

 

Look at the door windows: they have 'fuzzies' on US cars, the datsuns had rubber wipers. What for? To keep leaves anddebris from getting INSIDE the doors and soaking up moisture---and holding it against an untreated metal surface.

 

The issue is that drainage of water is usually adequately addressed in these cars, but the issue of debris ingress was not, and in many cases the debirs accumulation in these areas will hold moisture and rot from the inside out. it was not uncommon to see people with high pressure washers blowing up into 'drain holes' in the chassis to dislodge mud, leaves, etc...

 

If you park in a garage, people think that is what saves you from rust. Only by the factthat leaves and dust can not get deposited into these areas! I've found parking under the wrong kind of tree will do in a car FAR faster than anything else. Small leaves, in particular, like to get into these crevices, plug the drain holes, and then you're screwed.

 

As for the comments on 10 year japanese car ownership, this is also true (Konish) so many myths surround this it's not funny. But it IS true that Japanese manufacturers AT THAT TIME looked upon a car as a 10 year appliance, and didn't STRESS rust prevention. Drainage, but not prevention. Driving around on Okinawa revealed mid-panel rust as bad as anywhere in the Rust Belt back home... They got better because they HAD to get better. But in the 70's across the board, they didn't put a lot of stress on corrosion prevention. And the Z's being lightweight had thinner metal than most. Go check and compare a 76 celica fender against a 76 Fairlady and you will be amazed that you can physically measure a significant difference in metal thickness!

 

Additionally, much of the inner-fender plastic cladding used on the US cars was NOT installed on the Fairlady. My 77 S31 does not have inner fender liners like my 77 280Z. Why? Weight, and perceived domestic market expendability of a motor vehicle. Seriously, in 1987, when these cars came due for Road Tax in April, they FLOODED into the scrap yards. I watched and almost cried when I saw an ORIGINAL Fairlady 240Z (HS30) get scrapped for a slight wipe down one side. The yard paid the owner 5000 Yen. Which was all ANY car with expired road tax, and expired shaken-Sho is worth at that point. It was COMMON to simply take a perfectly running car down to the scrap yard and turn it in for scrap value, and go get a new one. it's a clutural accomodation. I ended up with a brisk business transferring cars from Japanese Friends to Servicemen because I would give 2X the price the scrap yard would (10,000 yen, like 33$ at the time) and then would have a car dealer process the transfer through LTO and sell the cars all day long for $500 and $600 with a one-year Shaken-Sho on them. For a short-timer, it was a perfect deal, and he could resell the car (at 11 or 12 years old) to another servicemeber for what he bought it for, and THEY would run it thorugh another inspection for $300. You got a car for a year for under a grand, insurance included. What a deal.

 

I digress...

 

Tony,

Great stories and good memories. I laughed out loud at the conversion rate of Y10000 being equivalent to $33 in '77. My dad served in Japan for most of his 21 years in the Navy and I always love to hear how he would take his pay in cash at the ships clerk and then convert it to Yen at the wooden table set up right next to the clerks pay table. He said he'd walk out with enough Yen to fill a wheelbarrow and he'd live LARGE for the next month...wish it was like that now...Y85 to the $1...ouch.

 

It's funny, you still see the 10 year cycle here. One year it's a ton of blue/green Mitsubishi RVRs on the road with "Y" SOFA plates and the next it's silver Nissan Cubes. This year it's red Mazda MPVs with silver accents...I own one and on Kadena, I see no kidding, 20/day. I keep thinking my wife is driving all over the base all day long...LOL.

 

Completely agree with your 5th para...the move to add corrosion resistance to cars pushed the entire automotive industry to get better (at least in this area)

[Tony D]

Yeah, we couldn't GIVE yen away when I got there, then when it changed in 88 things changed. Guys came to me with 68,000 yen in a jar one time asking if I wanted it. "Uh, dude, that's like almost $700!"

 

He sat there looking shocked. Asked him what was the matter and all shook up he said: "This is my drinking change. If this is what I had left over, how much did I [/i][/u]spend[/u][/i]???"

 

I was stationed at Kadena 84-89, watched yen go from 268 to 117. As for insisting that dirt getting into a dogleg is somehow a design 'flaw' the question is, since there ARE drainage holes, and the owner's manual says to thoroughly flush the areas...is it a design flaw, or one of shoddy upkeep and maintenance? I know plenty of Z's with no rusty doglegs which were run around off-road and were flushed religiously....

 

The leaves are the killer, they don't flush well, and is the biggest argument for using a car cover outside.