Refinishing Fender Underside - Worst job ever!

[pgerhardt]

I have my two rear fenders down in my shop to work on during the cold weather. The underside of fender #1 is finally ready for color. OMG what a job! Concave in two directions so that none of my power sanding tools work well, with tons of seams and inside edges - it required mostly hand work. It is a good thing I am retired. I think that if I were working in a shop and spent two weeks on the underside of one fender I would be fired!

Now I could have scuffed it up, put POR-15 on it with a protective top coat and have been done in a few days. But no, idiot that I am, I want to take this 80 year old, well used fender back to look like virgin sheet metal that's just been enameled. So it looks like each fender will require at least a month's work!

I plan on using Sherwin-Williams single stage "classic black" urethane enamel. That way I can leave the underside not color sanded (even I am not crazy enough to want to color sand and rub out the fender undersides!), but still shiny, while color sanding and rubbing out the top side to get that mirror finish we all love.

The first image below it the nasty surprise I found when I stripped the underside of this fender (Yes I removed all the old Bondo.) The second image is the fender underside almost there. As I said, It is good to be retired when taking on a project like this!

[quickchange]

Nice Job, Come too NZ for summer & i will give you a job, Free board >>

[Fred K-OR]

In doing my huckster a few years ago, I found that a cheap grinder from HF (on sale now for around $10) and a plastic "grinder" blade on it worked great to get off rust and paint. Lot easer than by hand. It left a smooth finish ready for paint. Even where things had ridges in the part, you could get most of the stuff off and then finish by hand. Yes it does take bondo off but it makes it nice and smooth so you can put it back on and use the disk to smooth the bondo. Make sure you wear mask, gets rather dusty and you don't know what kind of paint you are taking off.

[pgerhardt]

Originally Posted by quickchange

Nice Job, Come too NZ for summer & i will give you a job, Free board >>

With the way winters have been around here (our winter is your summer -right?), that is very tempting!

[pgerhardt]

Originally Posted by Fred K-OR

In doing my huckster a few years ago, I found that a cheap grinder from HF (on sale now for around $10) and a plastic "grinder" blade on it worked great to get off rust and paint. Lot easer than by hand. It left a smooth finish ready for paint. Even where things had ridges in the part, you could get most of the stuff off and then finish by hand. Yes it does take bondo off but it makes it nice and smooth so you can put it back on and use the disk to smooth the bondo. Make sure you wear mask, gets rather dusty and you don't know what kind of paint you are taking off.

I used my angle grinder with a "sandblaster" disk to strip most of the fender. It did a good job, but did not magically remove the rust pitting. I soda blasted to clean them out. But to restore the smooth finish I skim coated it with Bondo Gold, then sanded it all off except where there were pits. The problem is that the double concave shape of the fender underside makes it difficult to use either my angle grinder or Porter Cable 2474xp DA. The "longish" motor/handle hits the fender long before the disk is anyway near flat. An air powered DA might get in there, but I don't have one. All the seams and inside edges needed hand sanding anyway to keep all the lines crisp. I think the only solution is patience and time. I might get a little faster as I gain experience. We will see, as I have the top of this one and three other fenders to go!

[tbirdtbird]

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we presume you have dry fitted all the fenders before getting anywhere near painting...else there will be bad words if you have to fit them after painting!

[larrys40]

Doing the underside of the fender is mostly hand work... it's just the way it is. I would epoxy prime the metal and then use any filler you may need following. I use Mar Hyde high build urethane primer-surfacer. A friend introduced me to the Sherwin Williams 2nd dimension single stage topcoat and I have used it since... I really like how it goes on and is a high quality topcoat. I do the undersides first one day, mask them off and do the topside with underside masked so you don't have to worry about overspray on the underneath side. Both sides if refinished well will look nice. It's all about the prep and spending the time to do well.

[BRENT in 10-uh-C]

I kinda refrained from initially posting in this simply because my opinion and the O/P thought on the worst (sanding) job differ. For me it is sanding Model-A wheels.

One of the things that may be affecting this person's project is it appears he is trying to do messy work in a clean environment (the vacuum cleaner in the background), and there is an art that comes from experience on how to efficiently sand a fender. Most people's arms & hands just are not conditioned for the stamina it takes hand-blocking, and as mentioned above, even a 3" DA sander will not give satisfactory results on the underside of a fender. My only advice is to turn on a TV or radio to occupy your time while you sand in small gridded out areas. Kinda like a huge meal, ....small bites and steady chewing soon has the plate empty.

[pgerhardt]

"My only advice is to turn on a TV or radio to occupy your time while you sand in small gridded out areas. Kinda like a huge meal, ....small bites and steady chewing soon has the =plate empty."
======================

That is exactly what I did!

[pgerhardt]

Originally Posted by tbirdtbird

we presume you have dry fitted all the fenders before getting anywhere near painting...else there will be bad words if you have to fit them after painting!

It came off the car and into my shop. I hope it will go back on. If not you'l hear my "words" all the way in Dallas!

[pgerhardt]

Hea! I just realized my forum status now matches my age!

[BRENT in 10-uh-C]

Originally Posted by pgerhardt

It came off the car and into my shop. I hope it will go back on. If not you'l hear my "words" all the way in Dallas!

Just a word of warning, an improperly braced fender during sanding/bodywork can actually change shape. Just the 'whipping' action that comes from repetitive sanding motions can 'tweak' a fender.

[Tinbasher]

Nice job. This is why I go to the customer. It's the only way they can see the time involved to do these jobs. Keep at it you'll end up with a nice pair of fenders.

The Old Tinbasher

[Logan]

you'll like the classic black color. I've sprayed a mullins trailer, 3 chassis, and a speedster with sherwin williams 3rd dimension urethane enamel. I think it lays out great, and the black will sand and buff out beautifully, plus its an easy product to work with. Here are some pics of what it can look like if you get it to spray out of the gun just right. These are all before sand and buff.

[tbirdtbird]

nice work, Logan! Dave

[Logan]

Originally Posted by tbirdtbird

nice work, Logan! Dave

Thanks dave

[mshmodela]

Worst job? One summer working as a mason's laborer... Carrying hods of cement and 12" block in a hole was my worst job.