I made the comment in that thread that the mid to late '79 and up frames seem to rust out a lot worse than the eary '79 and earlier frames. I've never been able to account for this, but I've sen it first hand plenty of times. I've often hyposthesized about some manufacturing process change that was specific and unique to AMC.
Today I came up with a different hypothesis. I was going through some real estate disclosures and I came across the standard "Was this house built in 1978 or prior" form. Anyone who has ever bought a house knows the form I'm talking about. It basically is there to cover the liability of lead based paint exposure that was used extensively throughout the U.S. up until 1979 when it was banned by the EPA. It got me to thinking. If the Feds banned lead based paints in homes starting in 1979, I wonder if they banned those paints in the automotive industry, too. Does anyone have first hand knowledge or a reputable first hand source of AMC paint technology from the period late '78 or early '79 and prior?
Follow me through, here: Jeep Corp uses a tried and tested lead based paint formula for decades. It's used because it is cheap and provides great corrosion resistance properties. "If it ain't broke, don't fix it." So they didn't. Then, in 1978, the Feds tell Jeep (and the rest of America) that they need to start using a different paint. They comply, but technology doesn't catch up as fast, and the new paint isn't as corrosion resistant as the old lead-based stuff. What happens? The frames and tubs used from mid or late '79 and up don't have the same quality of paint as the older stuff, so until Jeep starts galvanizing parts around '87 or so, the late CJs end up rusting out a lot faster than the older ones did. The hypothesis fits the model, but does anyone have some data to support or debunk this argument?
Older the better, but not healthier. I wheel and deal alot and see alot of good old stuff and new stuff which is in my opinion junk. As for frames, the steel was made better and stronger than what we (USA or imports) market in todays world) Great example is the same steel I bought back in 92 is stronger then the same stuff I bought last month. As for paints, I would say the same.
85' CJ7 Laredo, 383 GM, Turbo 350, NP 203. SOA, 2" frame lift, 34" TSL swampers, Dana 30 open, AMC 20 w/ detroit locker, 4:10's, 1 Piece Mosers, 35" boggers to abuse when needed.
Interesting thoughts on the lead-based paint. I suppose you could locate a cherry original frame, get some paint samples and have them tested. Do this for various years. Duplicate the paint composition, spray some steel with it and expose it to environmental testing (the salt spray tests...etc.) to test which paint is more durable/rust protective.
My gut feeling, is that the technology coupled with the frame's physical shape, environment and father time are the true culprits to any frame's degeneration. For instance, in boxed frame CJs the rear shackle hanger is prone to rot. If you look at the design, there are holes about halfway up the frame tube's side that allow mud/crud to enter and settle on the floor of the tube. The crud stays damp for long periods of time and eventually begins to corrode the frame from the inside out. Short of dipping the frame, this is a very difficult area to paint/rust proof so the result is a rotted frame in this area.
Occasionally, I read posts with questions about how to paint the inside of a frame to prevent rust. I think it's just easier to make sure crud can't accumulate. Drill drain holes and flush the inside of the frame frequently (especially after mudding) to flush mud out. That's probably the single best deterent to frame rot.
I know this post kind of tangents off from the paint composition thing but it just got me to thinking about frame rot in general..
'80 CJ5 w/AMC360, T176, D44 w/Detroit 4.56, RE 4" YJ lift and 35s..
Boxed frames rust because of dirt accumualtion inside and an inability to paint inside the frame (aside from dipping). Knowing AMC, they probably cut costs at the dipping end (if it was ever done at all).
I'd love to have a large tank of POR15 to dip my frame into!
What's left of a '79 CJ5
3 - 4" total lift
4.88 gears in a Dana 30 and off center ff Dana 44 with disc brakes
258 with TFI /T18 /D18 drive train with Saturn O.D.
33 x 12 DC Mud Country Radials
My gut feeling, is that the technology coupled with the frame's physical shape, environment and father time are the true culprits to any frame's degeneration. For instance, in boxed frame CJs the rear shackle hanger is prone to rot.
So can I infer from this that you don't think '80+ frames rot faster than '79 and earlier? I definitely agree with your above statement about the boxed part, I put that in the other thread on general production model discussion, but what I'm saying specifically is that it's been my experience that '76-'79 boxed frames, when you find them in fields or barns or whatever, seem to be in better condition than '80+ frames.
I've poked around in quite a few CJ frames (and YJ and TJ) and haven't really noticed a big difference between pre/post 1980. If anything, I'd say the older the frame, the more time for rust to set in, the worse the average rot. Now, that's coming from a fella who's only worked on Jeeps here in Newport News, Virginia, where we toss out sand on the roads in the Winter to fertilize frame rust
'80 CJ5 w/AMC360, T176, D44 w/Detroit 4.56, RE 4" YJ lift and 35s..
late 70's early 80's paint technologies where basicly two things..leads and mastics..the older paints are deffinately better then todays to a point..they did outlaw leads and yes it did spill over to cemmercial paints later in the 80's...they also lowered the Voc's..Volume of Organic Content..Thats basicly the good stuff like the pigments and different vehicles''the stuff in it that makes paint slide''..Have you ever had a bucket of paint sit for a while and you open it to see an amber like liquid on top?Thats the vehicle in paint..Todays paints are way different then even 10 years ago..And it also depends on the state,cuz every state has different Voc restrictions..There are allot of commercialy availible products availible that are very simular to POR15,but can only be purchased by a listed paint contractor..some of them are carboline,ameron''not imron'' and guardline<<nasty stuff I used at an Army Core Of Engineers site that blistered my arms all to hell the day after I got it on me..It was a nitrogen based epoxy..oh,been a union painter for over 10 years so if its a paint I most likely used it one time or another..
1980 cj7 258 weber,5'' of lift,33'' boggers,lincoln locked,lockright and a snorkle...Khaki Jeep Club member No. 1
1984 cj8 350 on 35's..the wifes
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I sent an e-mail to the EPA yesterday. Here is an excerpt from their response:
Originally Posted by the Environmental Protection Agency
The Consumer Product Safety Commission has banned the sale and use of products containing lead in amounts over 0.06 percent in 1978.
For more information on products, we would like to refer you to the Consumer Product Safety Commission (CPSC) at: 1-800-638-2772 or search their website at: <http://www.cpsc.gov>.
Testing the paint for lead, can be done by submitting samples to an accredited lab.
EPA recommends that laboratory analysis be done by laboratories recognized by EPA as proficient for paint analysis.
We've got a lab here at KU. I think I'm going to chip off a piece from my '76 (it's in fantastic shape) and take it in to get analyzed.
I have a a 79 and an 80 CJ-5 both are boxed frames. The 79 is rusted much worse, I was just under it last night putting my fingers through the bottom of the frame on the drivers side. Of course I just bought the 79 like 3 weeks ago and its been well used. The 80 I've owned since 92. Its just a matter of the previous owner IMO, if it was driven in the winter, road salt, etc.