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Old 02-13-2020, 08:26 PM
blakeusa's Avatar
blakeusa blakeusa is offline
350 Buick
Join Date: Jul 21, 2005
Location: Ashford, CT
Posts: 815
71 Original Undercoating?

Was wondering if anyone has replicated the OE undercoating on your trucks.

Primarily looking at redoing my bed underside.

I know the modern urethane bed liners are a better product but was going to spray mine with epoxy then apply some type (preferably near OE) over the epoxy.

Can't tell for sure if its an asphalt/ or rubberized based product.

Any feedback or results of what you used or would recommend would be appreciated.

1971 J4000 Gladiator w/AMC 401 Restoration Project

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Old 02-16-2020, 01:11 PM
Herk's Avatar
Herk Herk is offline
350 Buick
Join Date: Jun 12, 2006
Location: Boise, ID
Posts: 1,114
My 71 just has asphalt undercoating in the rear wheel wells, and not too evenly applied. I think the front legs of the rear flares were coated with the same stuff.
There are 2 rules to success in life...
Rule #1: Don't tell people everything you know.

1971 J-4700/Buick 350 Stage 1/TH400/D20/D44/D60/Koenig PTO Winch
2005 LJ Rubicon Pretty close to stock
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Old 02-16-2020, 03:04 PM
joe joe is offline
Join Date: Apr 28, 2000
Location: PNWet, USA
Posts: 22,392
Odds are good it's an aftermarket coating. Out east it was likely Ziebart
"Don't mind me. I'm just here for the alibi"
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Old 02-17-2020, 07:28 AM
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Crankyolman Crankyolman is offline
350 Buick
Join Date: Sep 27, 2017
Location: Pacific Northwest
Posts: 818
Mine is a '72 but I don't think they did anything different in '72 than in '71. My undercoat seems to be factory, was everywhere underneath, except the frame and was even under the carpet and extends up the firewall inside the cab, which is what kept the floorboard safe for 48 years, It seems to be a rubberized coating and is thicker in the wheel well and side panels and inside the cab but was thinner under the floor of the bed. I haven't yet tried to duplicate it but somewhere I have some sort of spray on rubberized undercoating I have hopes for but haven't tried yet.
'72 J4500
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Old 02-18-2020, 12:05 PM
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tgreese tgreese is offline
Join Date: May 29, 2003
Location: Medford MA USA
Posts: 11,609
As I recall, undercoating in that era was dealer-applied. As I remember, the cars wouldn't even be painted on the underside - just plain e-coat underneath. There may be spray-on sound deadening on the interior.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
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Old 02-18-2020, 05:40 PM
Crankyolman's Avatar
Crankyolman Crankyolman is offline
350 Buick
Join Date: Sep 27, 2017
Location: Pacific Northwest
Posts: 818
Originally Posted by tgreese
As I recall, undercoating in that era was dealer-applied. As I remember, the cars wouldn't even be painted on the underside - just plain e-coat underneath. There may be spray-on sound deadening on the interior.

My truck has body color paint (copper tan) underneath the under coat, it was fully painted top and bottom, and like I said it's everywhere but on the frame and appears to have been factory applied before the body and bed were installed since the bolts and the rubber pieces between the bed and the frame were not covered in it. If a dealer applied it they did a hell of a job.

As far as inside the cab I can't tell the difference between what's under the bed and what's inside the cab. It may be dealer applied sound deadening but they would have had to pull out all the firewall insulation and some other stuff as well as do a whole lot of masking to keep it off what it isn't on.

Maybe the original dealer for my truck just went above and beyond what any other dealer may have done but to me it seems rather unlikely that it would be where it is the way it is unless it was done at the factory.
'72 J4500
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Old 03-04-2020, 06:24 PM
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rang-a-stang rang-a-stang is offline
Join Date: Oct 31, 2016
Location: Camarillo, CA/Boise, ID
Posts: 4,768
Mine is factory undercoated with rust.
79 Cherokee Chief (SOLD, goodbye old buddy)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
00 Baby Cherokee
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Old 06-09-2021, 06:21 PM
PNW69Waggy PNW69Waggy is offline
232 I6
Join Date: Oct 15, 2016
Location: Portland, Oregon
Posts: 27
My '69 is undercoated with a textured asphalt based product all over the entire frame and body mount brackets, floorpans, wheel wells, and the underside of the gas tank. They seem to have done a very good job keeping it off the suspension and drivetrain considering everything else is coated. Does that sound like a factory job or dealer/aftermarket?

The undercoat has done a great job adhering to and protecting the floorpans.... too bad they completely rusted out from the inside. However on the frame it's flaking off in sections. There is black paint under the undercoat although in many areas that's coming off too and showing some minor surface rust.

Once the rusty floor pans are replaced I plan to undercoat them again, more for NVH reasons than anything else. I'm not sure what product to use yet either and I'm wondering if I should put down catalyzed paint as well before undercoat or if 1-2 good coats of epoxy primer will be enough. If anyone has any product recommendations for undercoat let me know. I figured I'll just talk to a local paint supplier and see what they suggest. My frame, axles and suspension I just want to paint with some good, durable black 2k paint, also open to any recommendations there. Since I have compressed air I can spray both with the appropriate gun rather than using aerosols, that way I can use good 2k products where appropriate, also more cost effective for doing a larger area like an entire Wag floor or under a pickup box. Although, probably worth saying I think there are some OK aerosol undercoats out there if someone is just doing a small area.
'69 Wagoneer, Empire Blue / rust, Buick 350, TH00, Dana 20, Dana 27/44, stock & original
'91 XJ Laredo 4dr, 4.0L/AW4, 4.5" lift, 31" BFG's, etc
'02 WJ Limited, 4.7L/QD, 2.5" lift, 31" BFG's, etc

Last edited by PNW69Waggy : 06-09-2021 at 06:30 PM.
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Old 06-11-2021, 01:52 PM
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goldhammer goldhammer is offline
Join Date: Aug 08, 2004
Location: Willamette Valley, OR
Posts: 5,177
Asphalt based undercoating is probably not going to be available. Rubberized undercoating is under several labels, like Kent, SEM, and big auto parts brands like Napa.

If starting with clean metal, or can get the loose stuff off, you can hit with very coarse sanding and use some kind of user applied bed liner like Bondo, Hippo, etc brands. Won't have the durability of the hot applied and spendier applied products of the major types like pro-line, etc.
ASE Master Collision Tech
"Beast" - 81 "S" W/T, 85-360, T-18, Lock-rite,wag alloys, 31-10.50 Pro Comp MT's, Warn 8274 in a fabbed bumper/deer strainer(tested and approved)

88 XJ, 3" lift, 31-10.50's, custom bumpers and winch/tow bar mounts, Warn 9500HS, custom sliders/steps, camo paint, & headliner

Member: FSJ Prissy Restoration Assoc.
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