Thoughts on frame/underbody rust repair and prevention

Old February 2nd, 2009, 01:37 AM
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Thoughts on frame/underbody rust repair and prevention

Here are a few pictures of the underbody of my Cutlass. Frame is actually very solid with no areas of total rust through and most of the body panels are solid. However, I want to take care of the rust on the frame and some areas of the underbody as a preventative to stop further rusting. I am not going to do a "frame-off" as it were, just want to fix and continue to drive. I realize that sandblasting would be the best route to go, but that is years off so I am focusing on what to do now.

I'd like thoughts and opinions about exactly what should be done. I have considered POR-15, but I am leaning towards wire brushing the metal then painting with a rust "inhibitor" then painting with a decent paint or undercoating. I believe Eastwood makes some products that would work. Sound like the right way to go? This car will not be driven in inclement weather, it just sits throughout the winter and is driven in the summer. The car sat for 19 years. Have plans to replace the gas tank, so not worried about that. Any leads on products to use would be appreciated, also.

Oldschassis010.jpg
cutlass022.jpg
cutlass024.jpg
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Old February 2nd, 2009, 05:34 AM
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Por 15 is a very good product. You can use it to paint over the rust according to what they advertise. I used it on my frame but I sandblasted it first. Your frame looks pitted, which not just surface rust. If you do decide to use POR 15,I would suggest you spray it on since you are not doing a frame off.
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Old February 2nd, 2009, 06:51 AM
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Have the body mount bushings been changed throughout the life of the car, or are they the same ones? If they're the same, I'd highly recommend carefully removing the mount bolts (it's gonna be tough if they're rusted), and then jacking the body off the frame. The reason is, if your frame is that rusty underneath, there's going to be rust on top. And moisture loves to sit under those rubber bushings. Mine were about 5 min away from cleanly rotting through the top of the frame. I had to scrap my frame.

Just trying to save you major problems/issues down the road. Spending a little more time on this now will be more than worth it. In other words, if you don't know about the bushings, I'd remove 'em to be safe.
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Old February 2nd, 2009, 08:40 AM
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Have the body mount bushings been changed throughout the life of the car, or are they the same ones? If they're the same, I'd highly recommend carefully removing the mount bolts (it's gonna be tough if they're rusted), and then jacking the body off the frame. The reason is, if your frame is that rusty underneath, there's going to be rust on top. And moisture loves to sit under those rubber bushings. Mine were about 5 min away from cleanly rotting through the top of the frame. I had to scrap my frame.
I agree as well.

I recently finished the underside of my Cutlass a few months ago. I removed the gas tank, rear axle, driveshaft, exhaust system, and the rest of the rear suspension. The condition of my car was similar to yours. I had to weld a couple of patch panels in the trunk, burn and scrape undercoating off of the frame and floors (fun), grind off any loose scale (some surface rust is ok), and painted both with Eastwood rust encapsulator and extreme chassis semi-gloss black. (They both can be sprayed out of a gun or rattle can with excellent results)

If your gas tank just has some surface rust on it, and is clean on the inside, you can just boil it out, sand down any rust on the outside, and spray it with eastwood tank tone (2 cans). Hope that helps.

Darrell
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Old February 2nd, 2009, 12:09 PM
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Thanks for the comments, guys. Tom, I saw your thread about your 442 and that scared me into really getting on this frame issue instead of the 'frills' with new carpeting and interior work. I want my car to maintain a solid base so that any future work will not be wasted.

Darrell, I'd like to see bigger photos of your attached pictures, looks like damn nice work. I am leaning towards the Eastwood paint products like you used.

Again, I appreciate the advice.
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Old February 2nd, 2009, 12:49 PM
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I should warn you that wire brushing the rust will take a lot of time and it will be a pain, especially with the body on.
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Old February 2nd, 2009, 01:24 PM
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68tom,
Was your frame far from repair. My thought was to grind out the rust and weld a plate over the mount hole and redrill. Or was there more rust to make the frame unsafe?

Frankenpez,
Looks to me, you should have that frame blasted. You should spray the under body in every crack and bend and grievous you can find. POR 15 would be the easyest way.

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Old February 2nd, 2009, 01:37 PM
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Originally Posted by 64Rocket View Post
68tom,
Was your frame far from repair. My thought was to grind out the rust and weld a plate over the mount hole and redrill. Or was there more rust to make the frame unsafe?
Gene
After media blast, all issues were exposed. All in all, if it were impossible to find a frame, I guess it would have been reparable, although barely. Every body mount bushing hole would have needer to been repaired. Additionally, what looked like surface rust was actually rust all the way through on the side rails in a couple spots. Lastly, the frame had a terrible patch piece welded on and right above that section, it was cracked due to the fact the control arm supports were never reinstalled on the car. The torque just cracked the frame.

Jon, based on how deep that rust looks, if you really want to salvage the frame, I think you might simply want to drop the gas tank, remove the body bolts, and then raise the body high enough to roll the chassis out from under the body and either find a mobile sandblasting unit to come and blast the frame, or ship it off to someone. In NE, I can't see it costing more than $100 or so (most places are $75 or so). This would help on two accounts--giving you a very good idea what's going on with your frame and if good, a much easier task of painting the car. Trust me, those Eastwood or POR products add up quickly cost-wise, so it'll almost be a wash. And you'll have a rust-free frame at the end of the day that you'll be able to easily paint.

I know that you want this to be a quick thing, but I discovered early on that if you want certain things done right, you have to spend the time to do it properly. As you stated, once you get the base of the car solid, and then you can go slowly on the rest of the items. Oh, and another bonus is lifing the body that high allows you to easily work on the underside of the car.

Last edited by 68Tom; February 2nd, 2009 at 01:43 PM.
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Old February 2nd, 2009, 07:03 PM
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Darrell, I'd like to see bigger photos of your attached pictures, looks like damn nice work. I am leaning towards the Eastwood paint products like you used.
Thanks. I just need to figure out how to make them bigger.
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