15 replies to this topic

[greasemonkeyreborne 5x1g's]

I've been scratching my head on this one. Wondering what plastic the fenders/header/skins/garnishes are made of. Everyone's been saying ABS, and it seemed like a match.

After review the automotive plastics to get the CTE data, It pointed toward a blend. I was on the tail end of the GM Saturn project in the early 90's and the door skins where Pulse, an ABS/PC blend at the point in time.

Now Honda's always been the leader in technology. So I pulled out the infamous ebay book on 84-87 CRX magazine articles. Reading the first 6 articles in the book, 3 directly say the header/fenders and side trims are a "new amazing plastic alloy" called abs/PC. Some of the other articles in the book mention "Honda Polymer alloy" dubbed HP Alloy. Makes sense the US market would catch on years later

I also looked up in one of my old trade journals "Modern Plastics". And they have a really nice chart to rudimentary ID plastics. Does it flow in water? Does is melt w/ a soldering iron? What color flame? Does it stay burning? Sooty smoke? This chart is not 100% conclusive, but it appears to be in the ballpark.

And the CTE I measured between boiling water to ice bath was more in line w/ the blended material than pure ABS.

I called a local lab and I'd have to fork out $120 to do an FTIR test to get a basic composition. But I"m satisfied w/ what I've read in the magazines and from molding Saturn parts in the past. I'll save the $100 bucks and buy more parts.

Because it has high percentage of ABS, you can plastic weld quite well w/ pure ABS rods. But if you do weld, but to get a scrap fender and keep the material identical.

Oh, the articles say Polyethylene for bumpers.

D

[1985 CRX SI]

I learn something new here every day. Great work. thanks for the information.
Jeff

[RETROCRX]

For the record......where do you work now?

I used to be in Automotive with a Canadian Tier 1 called Multimatic. We did everything from IP Structures, to suspenion components, to door hinges, to full vehicle testing......we even had a 4 post shaker rig.

But since the Auto Industry took a tank I've been in Military Satellite communications equip, Steel making and now nickel smelting industries.

It's nice to see others in my field on this forum.

Rob

[firstgencrx]

I also read somewhere that the original Honda parts where an ABS, Poly-Carbonate blend. There is supposed to be an epoxy that is best to use for repair and filling cracks. I need to find that stuff. Maybe someone could put this info in the Wiki.

I would be willing to bet the after market fenders and header panels are made from just ABS.

David

[greasemonkeyreborne 5x1g's]

I did some more digging last night and found some more history:

A book called "Plastics in Automotive Industry" by James Maxell 1997 had a paragraph in page 98. "1984 CR-X used 11kg of ABS/PC plastic alloy.... .... over 40% of the body was covered in plastic.."..

So this gives me credibiltiy in facts vs a magazine article written by a non expert.

Also, more on Honda's "amazing Honda Polymer Alloy, HP-Alloy". Appears HOnda tried to keep in proprietary back in the 80's be no one else was really advanced in engineering thermoplastics (We at Dow followed the bandwagon about 6yrs after Honda did). I found about 1/2 dozen Paint prep papers by auto paint suppliers educating body shops on "how to id plastic for proper paint prep". All mentioned HP-alloy in the list of substrates. Interesting is that no other plastic was listed as a "code name". The rest were ABS, PC, Nylon,... etc

Found a 2003 article on Hondaa new plastic alloy HP/PA6. Its a Polycarbonate mixed w/ Polyamid. So in this decade, Honda canned ABS.

Again, in lie of spending $ on a test, I'm satisfied w/ this information.

I'll write up a WIKI on this as more of a history note. I think the main take away on this for is is to know what the base material is for proper paint prep. Matching the proper adhesive/epoxy to properly bond to abs/pc, and plastic weld using scrap fenders. Also, appears all thelower exterrior plastic is abs/pc beyond thebumpers.

****

I did a short stint at Dow chemical's TS&D lab working processing/extrusion/injection molding/polymer development/compression molding/ASTM testing of thermoplastics.

Did another STint at Raytheon using the background at Dow to develop/design plastic/rubber components for military programs like TWS (thermal weapon sights), Javelin missle, harpoon missile, F22 JSF, LRAS, driver's enhanced night vision - which later became the HUD forward looking flir in cadilacs. After I designed my parts, I built the mold and processed them in to tolerance. quite fun

The hardest part in all this was to get theplastic to survive from -40f to 150f (hardest were the damn orings). I give my respects to the designers on teh Challenger program. Unfortunately that ended in loss of life.

Retro, Maybe we could team up w/ the guys looking to remanufacture some of our parts? Let me know.

Dave

[greasemonkeyreborne 5x1g's]

Take a look over. I'll post to WIKI here shortly. Let me know if you have anything that should be added or is inaccurate.

Figure we'll get together collectively and post "how to repair" w/ all of you knowing solvent weld, plastic weldand glues. Not to mention the fiberglass backing technique.

Thnx

[GENONE]

Sweet information!!! thanks very much!

I know when i fix a plastic bit on the CRX using a little soldering iron, i use scrap pieces of old crx plastics to fill a gap in etc etc.
I also know that the smoke/odour which is emitted from hearing and melting this plastic is very harsh on eyes and most likely very very bad for you anyway - so stick away from the smoke.

Mike

[greasemonkeyreborne 5x1g's]

Okay,

Had a glitch w/ my inputs to WIKI. Cudos to Tom for getting that fixed asap.

I input this info in WIKI under "body and cosmetic".

enjoy

More to come once I begin plastics welding.

dave

[Jayscrx]

Okay,

Had a glitch w/ my inputs to WIKI. Cudos to Tom for getting that fixed asap.

I input this info in WIKI under "body and cosmetic".

enjoy

More to come once I begin plastics welding.

dave

I am glad that I came across this topic. I am refinishing a rear bumper cover that I got from Pick A Part. The bumper has many nicks, scrapes and small gouges. I have been to many body and paint supply houses seeking good advice on what to use to fill all the imperfections. Most of the stores say I should use Evercoat Poly filler, can't remember the exact name. They say to use a adhesion promoter then fill the imperfections and sand smooth. Then wipe down with a wax and greese remover and apply the adhesion promoter before laying the flexable primer down. Will this method work well and last along time?

Jay V

[greasemonkeyreborne 5x1g's]

Polyproplyene and ployethylene are used as bottle materials to store many hazardous chems like acids and other nasty cleaners. So I don't believe useing a solvent is a bad thing to clean the bumpers (do not use them for the abs/pc panels though). I've not yet repaired or filled voids in panels. But I'll be using a plastics welder i bought (or use a soldering iron). So I believe the best way is to sand down the area, used your old bumper and melt peices of it into the new bumper and sand it flat. That way when you get "bumped" by a car or deer later on, the gunk that got put in the void won't pop out and crack the paint. But I'm not a body expert. I'm sure a lot of guys here have use products w/ great luck.

My goal has always been long term survival (20yrs plus). So I'd rather melt the same plastic into the voids so I know it'll bond properly and won't seperate from thermal expansion/contraction over time. If you're in it for 10yrs, then it doesn't matter. Plastics were the new thing in the 80's. Now, in the 21st century, we have to sustain what we're given to work w/.

Good luck and let us know how it works out.

D

[greasemonkeyreborne 5x1g's]

Lost wiki post

[greasemonkeyreborne 5x1g's]

An update on materials to repair fenders, header, door skirts, etc.

I had done some research on pc/abs automotive panels. Dug into the Saturns of the 1990’s. There was a point in Saturns production where they switched from abs/pc to PPO. It was around 2002??? A dfw junkie had several 2 door Saturns w nice long door skins i removed for future repair use for abs/pc 2-3 years ago. i chose white and silver painted parts thinking the uv would have been reflected vs absorbed like darker colors. These older parts retained toughness. Grabbed edges w pliers to break as a test before i bought. I only bought the panels that tore, not cracked. I expect the cte to be vary similar and will make better parches than fiberglass

[greasemonkeyreborne 5x1g's]

I finally got around to patching w the Saturn door panel material.  I cut a 3x6" patch.  Sanded the patch and the CRX door rocker sill panel down to bare plastic.  
 
I precleaned w a prepaint cleaner, then a few times w IPA.
 
I used 3M 2216.  Its $200/pint.  I used it at Raytheon bonding all sorts of plastics/rubbers to each other.  Made test samples and placed them in test labs over exteme temperatures w excellent results.  We mainly used GE's Ultem plastic and silicone or EPDM rubbers for the military and avionics stuff.  I never tested it on PC/ABS blends, but if this bonding agent and process passed military qualification testing to Nuclear/biological/chemical testing from -40 to 130f, its a winner.
 
The saturn body panels tore and ripped when I bent them.  That was why i grabbed sliver and white painted panels.  Reflected UV from the lighter paints saved the plastic from UV destruction over the years in service (reflected uv away). IMO, its the best and cheapest patching material we can obtain for our cars w original Honda OEM panels.
 
The 2216 has a 90 minute working time.  Its really messy and sticky.  takes 2 weeks to cure enough for use att ambient.   must sand 220 or rougher to bare plastic.  I wiped the plastics w painters automotive cleaner before i sanded.  then used IPA after the sanding so I wouldn't be hard on the base plastic.  In this case, i used a tire jacket to hold the patch in place from underneath the car as I did not remove the sill in fear it would break apart.  I took a bunch of wood and towels and made an "oven" around the tire jack.  Placed a heater inside.  Used my fluke w a thermo probe.  Got it to 124F.   let it cook for about 2 hours to accelerate the cure time.  final touch was a quick spray w black paint.
 
 

 
 

 
Bonded Saturn patch.
 
 
 

 
Heres an OEM header I patch as a "proof of concept" using an NOS taiwanese afternarket header I bought years ago made of ABS.  This had been in service for 3 years now.  no failures or new cracks through my bonds.  Its ABS, so not a perfect ABC/PC compatible repair, but I used what I had at the time

the abs material is noticeably weaker than pc/abs, probably 1/2 strength when i was breaking parts w my hands.
 
 

 
close up of bolt tab reconstruction and underside repairs.
 
 

[greasemonkeyreborne 5x1g's]

I'll dig up the power point pages I created for the WIKI and repost here when I get the chance later on 

[greasemonkeyreborne 5x1g's]

 

Came across this on a car listed on BAT.  Good example what not to do.  Over tightened fender bolts and severely compressed the rubber.  Point of rubber washers are to allow fenders/header to float on the metal frame during body flex and thermal expansion/contraction over temperature swings.   Rubber is bulging quite a bit.