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bikemaniac 02-17-2013 03:27 AM

Truck bed liner (rhino, hippo, hercu, line-x etc) for frame/suspension/u-body?

I'm new to this forum and I have some questions regarding rust protection on cars. I do not do any hotrodding, however I recognize this forum as being amongst the best on the web in term of DIY projects.

I have a brand new 4x4 car with a boxed (closed) frame/chassis and the body is mounted on top by means of 12 bolts. There is no rust anywhere and I want to treat the frame + underbody + suspension with the best possible rust protection. The frame is coated with a thin, black paint.

I came across all the different types of bed liners and they look really interesting to me, however I have a hard time reading about projects where bed liners are used to protect frames, suspensions and the underbody.

Can somebody please elaborate on the use of bed liners as rust protection for frames, suspension parts and underbody? What are the advantages, disadvantages? What are the main problems when using bed liners in these areas - it looks so easy when applying the stuff using a roller or brush. Maybe some forum members have some long term experience with bed liners in these lower part areas?

The car will be used in extreme harsh weather: Lots of road salt, rain, temperatures between 20 and 90 degrees F, relative humidity typically above 80% most of the year.

Thanks in advance,


Old Fool 02-17-2013 10:29 AM

The only "cold" application bedliner I will use is SPI. The commercial "hot spray" application liners have been a good durable product but the cold application duplicolor,bondo,eastwood,etc have a reputation of failing in short time.
Barry @ SPI has developed a cold spray bedliner that tests with the best of the hot spray commercial applications.

To get the best results from either type system they need to be applied over epoxy primer. SPI epoxy is my choice for performance, ease of use and cost.

SPI Bedliner Info

OneMoreTime 02-17-2013 10:59 AM

Most new cars these days are dipped with some sort of material for corrosion resistance..I think I woudl go with something like corroseal to paint the undercarraige and then put the bedliner in the wheel wells where rocks hit the underside. Given this sort of treatment that car will probably last you way beyond the point where you are so tired of it you are ready for something different..Most of the cars I cut up for scrap are not rusted on the outside but have rusted through from the inside of the rockers and fenders where moisture and dirt has accumulated..


ogre 02-18-2013 09:40 AM

i'd think that bed liner would seal up drain holes and trap water making the rust worse.
it would also glue lines and wires where they shouldn't be glued.
i used bed liner under my fenders and cab, but i had the body blown apart and easily accessible.

i used por15 on the frame.

bikemaniac 02-19-2013 04:51 PM


Thanks for your answer. Please remember that my frame is already painted with a thin, black coat from the factory and I do not intend to sand or blast all that off, because:

POR15 will only work on bare metal or rusty metal.
Corroseal will only work on rusty metal (as far as I understand from their webpage.

I understand your concerns with sealing drain holes etc.


jcclark 02-21-2013 04:53 AM

I wouldn't use any bedliner that wasn't a 2K product.
(doesn't use an activator)

67Elcamino 02-21-2013 09:02 PM

I would not use beadliner on the frame or underside of a car. Im
Sorry but I just hate that and actually think it looms cheap. I would only use it if my underside is beat up want to cover blemishes etc... Thats right it will cover bolts, holes, lines , etc and is gunky when trying to remove bolts etc. If your frame is fairly new just use a chassis satin black on it.

If you still wanna go the bedliner way stay away from roll on types and rhino, herculiner. I would rcommend Raptor or SPI. Both sprayable 2k

69 widetrack 02-21-2013 09:44 PM

I agree with "67Elcamino"...I don't care for the stuff on frames either...I think the down side might be worse than the results your looking for. If you have a thin coating of whatever paint on it, it may be a good idea to remove it and spray it in a black Epoxy...double check but if I'm correct SPI's Dark Epoxy does have some UV protectors in may be a better way to go as Epoxy is used as a rust inhibitor.


Bryan59EC 02-22-2013 05:22 AM

I had the bottom of my 59 "Rhino-lined" along with the interior floors and smuggler's box. (Epoxy primed the frame and just but a good heavy coat of black paint on it.)

Not so much for rust prevention----but for sound deadening.
Kept all drain holes open, cause not only does the moisture need to get out, air needs to get in to help dry everything out when it can.

Again--the car was apart when this was done.

A few years ago, one of the "Big 3" used to dip the pickup/truck frames in some sort of wax.
Be interesting to try to duplicate that--I think that stuff stayed on for a long time.

However----a good cleaning and epoxy coating on the frame is probably the best route

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