Rusty Fender Identification
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MNspiderman
Rusty Fender Identification
Just curious question: Sometimes I see spiders for sale and they have a particular bead of rust going across the lower front fender behind the wheel just on top of the rocker panel trim molding. Between the door and front tire. What is this? Is this where the air and rain enters the vent cowl under the wiper arms and then drains on the sides and as a byproduct you get a rusty lower front fender? Thats my guess because that was the situation on old 70's muscle cars that had a/c.
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leeputmanjr
Re: Rusty Fender Identification
The cowl vents drain into the engine compartment. Or, for early cars with foot-vents, into the footwells! 
I believe the line of rust you see is a bit different for early & late cars. Early cars (BS forward) seem to get it creeping up from the stainless trim - not sure how/why that area gets/holds water. Might be that the stainless trim doesn't fit tightly enough against the rubber seal, giving a small gap that holds moisture. I'm not sure how well, or differently AS series cars rusted in theis spot, but the stainless under-door trim was quite different.
Later cars (Fuel injected) had a pass-through from the wheel well into the area behind the map pockets - supposedly sealed from the elements by a plastic wheel well liner. These crack, rattle, and get removed by frustrated owners, who then get water splashing into thier front speakers, rotting out that panel from the inside. When maintained properly, the wheel well lines did a darn good job protecting the shock towers.
Most Spiders also get moisture into that area through the lower door hinges, too! That lower opening collects dirt, then moisture hits it, holds it, and rot occurs. Similar to the quarter window drains, rust is minimized if it's kept clean, horrific if not.
I believe the line of rust you see is a bit different for early & late cars. Early cars (BS forward) seem to get it creeping up from the stainless trim - not sure how/why that area gets/holds water. Might be that the stainless trim doesn't fit tightly enough against the rubber seal, giving a small gap that holds moisture. I'm not sure how well, or differently AS series cars rusted in theis spot, but the stainless under-door trim was quite different.
Later cars (Fuel injected) had a pass-through from the wheel well into the area behind the map pockets - supposedly sealed from the elements by a plastic wheel well liner. These crack, rattle, and get removed by frustrated owners, who then get water splashing into thier front speakers, rotting out that panel from the inside. When maintained properly, the wheel well lines did a darn good job protecting the shock towers.
Most Spiders also get moisture into that area through the lower door hinges, too! That lower opening collects dirt, then moisture hits it, holds it, and rot occurs. Similar to the quarter window drains, rust is minimized if it's kept clean, horrific if not.
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manoa matt
- Posts: 3442
- Joined: Thu Oct 26, 2006 4:28 pm
- Your car is a: 1978 Fiat 124 Spider 1800
- Location: Honolulu, Hawaii
Re: Rusty Fender Identification
All cars have inherent design flaws in the sheet metal that will inevitibly catch and hold water. VW busses are notorious for the nose rusting out just below the front windshield. This is due to the way the panel seams come together and not allow for drainage.
Rust in that spot on a Fiat is very common, early or late design makes no difference. The plastic wheel liner prevents the wheel from kicking up water and splashing it onto the inner surface of the fenders. Once that plastic wheel liner is gone the wheel will fling water at the rearward surface of the wheel well.
If you look closely at the rear surface in the wheel arch you will see there is a sheet metal panel that is not welded to the fender panel. It seals against the outer contour of the fender via a rubber seal. If you push on that panel you will see it move. Road water gets flung at that joint and makes its way into the area behind the wheel arch but in front of the door jamb. The fender at this location is welded along the lower edge to the structural sills and creates a "valley" where water can sit and not drain out.
Not mine, but shows the typical rust damage, third picture: http://www.guy-croft.com/viewtopic.php?f=5&t=2141
Note, this guy made a Pininfarina hardtop out of steam bent plywood, sweet!
Rust in that spot on a Fiat is very common, early or late design makes no difference. The plastic wheel liner prevents the wheel from kicking up water and splashing it onto the inner surface of the fenders. Once that plastic wheel liner is gone the wheel will fling water at the rearward surface of the wheel well.
If you look closely at the rear surface in the wheel arch you will see there is a sheet metal panel that is not welded to the fender panel. It seals against the outer contour of the fender via a rubber seal. If you push on that panel you will see it move. Road water gets flung at that joint and makes its way into the area behind the wheel arch but in front of the door jamb. The fender at this location is welded along the lower edge to the structural sills and creates a "valley" where water can sit and not drain out.
Not mine, but shows the typical rust damage, third picture: http://www.guy-croft.com/viewtopic.php?f=5&t=2141
Note, this guy made a Pininfarina hardtop out of steam bent plywood, sweet!