Rear frame rails - which brand is best?

Question for you guys who have replaced rear frame rails. Which route would look the most like factory and fit the best? Buying AMD full rails and cutting off what I need, or the 48" long versions from Autobody Specialties or similar brand.

Try to find a clean original set first. If no luck AMD fit is very good. I have used parts from both companies but the AMD is a much better fit from experience. You will need to set the body on some type of jig to keep it straight.

snakeoil24 said:

Try to find a clean original set first. If no luck AMD fit is very good. I have used parts from both companies but the AMD is a much better fit from experience. You will need to set the body on some type of jig to keep it straight.

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AMD is the only way to go.I have used a great deal of their parts with little to no issues.As for the jig to replace rails not completely needed.You will be better off fitting the parts and adjusting the alignment.These cars were **** for fit and finish when new.If your measurments are less than a 1/4 of an inch off you are in factory specs!!!!!I like to fit all the parts align to my satisfaction with the panels and trim in place.

Thanks guys. I think I have found a set of originals, but if that doesn't work out I will go with AMD.

Still use a Jig to set them up you will be glad later.

I bought and installed the 48" set from Auto Body Specialties on my roadrunner. Nice heavy guage material, installed pretty good. Needed some attention back where they butt up against the rear crossmember. Flanged in fronts give some leeway as far as positioning them correctly in place. Look is fairly close to stock (besides weld tie in mid axle hump), and the price was right.

Now if you're looking for that factory matched look, OEM...... If that can't happen, AMD would be the way to go.

Good luck!

original is the best way to go by far..
imo
amd and the rest is a part of last resort...

I used originals out of a 66 Coronet for my 67. Worked like a charm and not too hard to get fit right. I have seen quite a few parts cars with very good rear rails and if you find the right guy the price would be right.

PM Dodge33, he might have a good set for you as they part lots of these things out.

hunt2elk said:

I read your book on metal replacement and was hoping that a splice wouldn't be noticable. Is it really easy to see the joint?

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LOL...Yeah, it's getting to be quite the novel eh? To be completely honest hunt2elk, the splice is noticable, from underneath the car. I wouldn't say it jumps out at you like a stop light or anything, but never the less...still visible.

I stick welded the splice from the outside of the rail and inside and did not grind down the cap for obvious structural integrity reasons. I coated the underside of the entire car so that blends the weld somewhat. If you went the route I did, that splice will be about center of the axle hump. The welds runs directly in between the two threaded holes for the axle bumpers.

I have been avoiding weighing in here, but I have to put my 2 cents in...

OEM (used) is the best and only way to go. It is great that companies like AMD etc make parts for our cars, but I am very Leary of reproduced structural parts for the following reason. It's common knowledge that in the 60-early 70's there was no HSS to be found in our unibody Mopars. So you may say... Mild steel is mild steel let them make our frame rails right? Not so fast... Mild steel used in automotive production has a yield strength of up to 30 kpsi, and depending on the manufacturers specific qualification and metals application can incorporate specific properties into the steel to make it harder/stiffer by using a specific heat treatment and/or requesting a specific carbon content for a specific part. It is not the thickness of the steel that gives a part it's strength solely.

I teach welding and structural automotive repair and have my students weld with 22 gauge and 16 gauge mild steel, these metals are very soft and ductile and yet are similar in thickness to the automotive sheet steel we have in our cars. They are in no way the same hardness as the 'mild' steel found in our frame rails. I have repaired, modified and replaced these rails (OEM) and they have specific properties. Anyone that has tried to hammer on them knows.

I would like to see proper testing done on these reproduction frame rails and structural parts. I wish to invest in a Brinnell hardness tester in the future, but I would stake my reputation on the fact that the rails we can purchase don't match the strength of the factory ones...

So what does this mean? If you use a sub-standard part you lose torsional, compressive and tensile strength. Meaning at the very least, you introduce more flex into the body. At the worst, the vehicle loses crash worthiness as the part collapses/tears easier than the OEM part. I have seen so much junk that looks good but lack's substance... I am glad to see parts for our cars reproduced, but I shudder when I see untested off shore parts being used as structure for a car that we trust as being safe... Ask any collision tech about structural bumper bars from an off shore source for late model cars.

I think we should stop and think some of this stuff through before we load up the kids for a Sunday cruise to the car show in our freshly restored Mopar...

I could be wrong... Just my two cents...