Chassis restoration - stripping grime off underside of rear cabin compartments

[Kevin S.]

Hello,

Wondering if I can get some recommendations on products that will remove years worth of grease, road grim, dirt and oils off of the underside of the fiberglass rear storage compartments on a E69 car without doing any damage to the fiberglass?

Things I have considered using but have not tried yet:
1. Paint stripper, I have both stripper for wood and a paint stripper for plastic
2. Acetone, alcohol, mineral spirts
3. DOT 3 brake fluid, also have DOT 5 synthetic brake fluid
4. Brakleen green can for cleaning brake parts, non-chlorinated
5. Simple Green, also have crud cutter and Goo Gone bug and tar remover
6. of course gasoline too

Thought I better ask someone who has had some experience with cleaning and stripping fiberglass in this area. Thank you in advance for helping to prevent me from doing something I'd regret - damaging the fiberglass.

Kind Regards.

Kevin

[Ed S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

You are going to have to do some experimenting. Regarding all the chemicals you listed. I can tell you this - I used denatured alcohol and acetone on my fiberglass - it removed paint, grease, and dirt and did zero damage. Keep in mind that these two chemicals are very volatile, meaning they evaporate rather quickly and they are not petroleum based. Acetone is really fast, alcohol not so much. Chemicals that evaporate do not penetrate the fiberglass, turpentine, paint thinner, mineral spirits and brake fluid will penetrate the fiberglass and you will never get it out. If you have to paint the other side of the fiberglass (rear storage wells) the paint will eventually bubble off. It won't hold. I would soak the residue with Simple Green or "Awesome" (available only from Dollar Tree - this stuff is cheap and amazing!), scrape lightly with a dull putty knife - or a plastic window ice scraper - then use alcohol or acetone to clean the remainder - it may take a while but it will come clean as new. Good luck.

[Kevin S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Thank you Ed,
I have better understanding of what to use and what not to use. Guessing that Brakleen non-chlorinated brake parts cleaner would fall into the same category as acetone and alcohol since it evaporates very fast. I am not familiar with "Awesome" from Dollar Tree but I'll go get some. I have lots of Simple Green so I'll get some on and let it start soaking to loosen the years worth of crud. I've got plastic scrappers. There has to be some fiberglass under there somewhere?

Thank you for the help.

Kevin

[Leif A.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Kevin,
Whatever you decide to use, stay away from gasoline...crazy dangerous. Ed has given you some good advice.

[Mark E.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

To prevent damage to the car and you, avoid any petroleum distillate. Assuming you're doing this overhead while on your back, you don't want that stuff in your face. And as Leif says, if you value your life, NEVER use gasoline as a cleaner or solvent.

I've done this project on two cars and have had good results using diluted Dawn dish soap applied with a spray bottle, a plastic bondo spreader, and Scotchbrite pads. Then refinish with a light coat of satin clear. The car will look new again without risking your health or blowing up the garage.

[Kevin S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Hey Guys,
Yep - got the "blowing up the garage" is a bad idea so it's HARD NO on gasoline as a cleaner. But, now you have a glimpse of how my mind works when unsupervised. Fortunately, still smart enough to ask for help.

For Ed, I went to Dollar Tree and bought the "Awesome" that I think you were talking about. This seemed to make sense as it is specific for cleaning and degreasing so I will give this a try.

Thanks,

Kevin

[James W.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

I use LPS PreSolve Orange Degreaser in the aerosol cans. It works excellent. Picture of my '65 after using it. I follow up with lacquer thinner to remove any stubborn paint. In the areas that aren't greasy, I use Simple Green mixed 50/50 and use the lightest weight of 3M Scotchbrite pads you can buy. Depending on wher the car is located, if in the garage, I used a pump sprayer with water and a a plastic storage tub to catch the water. This was all done in my garage.


James

[Kevin S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Hey James,
OMG the underside of your car looks so nice. I'm impressed and depressed at the same time. Wow, I have work to do. Thank you for the LPS PreSolve greaser idea. You can never have too many cleaners to pick from and I have a lot of cleaning still ahead of me.

Kevin

[Owen L.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

...have had good results using diluted Dawn dish soap applied with a spray bottle, a plastic bondo spreader, and Scotchbrite pads.

I use Simple Green mixed 50/50 and use the lightest weight of 3M Scotchbrite pads you can buy. Depending on wher the car is located, if in the garage, I used a pump sprayer with water and a a plastic storage tub to catch the water. This was all done in my garage.

Always approach a cleaning project with the solvent least likely to do damage; water is always the solvent to try first. Dish soap and Simple Green are appropriate additions to the water. Much can be done using this alone. Once you have water-soluble grime off, then look to different solvents depending on the substrate and type of grime. Most under car surfaces and finishes are impervious to denatured alcohol - except paint printing & striping on hoses. Acetone and lacquer thinner harm many plastics. etc. Always test an area prior to going whole-hog on it. If you use one of these three solvents, make sure the work area is well ventilated -- you absorb volatile solvents through your mucus membranes like your tear ducts.

As for Scotch-brite, get the kitchen scrubby with sponge. It holds more cleaning solution than the pad alone and this version of Scotch-brite won't scratch (sand) like the gray and maroon pads are intended to do. You'll probably need at least 3 to do the entire fiberglass underside.

[Thomas N.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

I like to use Simple Green in a spray bottle first to get rid of whatever it can remove, with a rag. After that I cut up small squares of ScotchBrite pads and pour some lacquer thinner in a small stainless container. I then dip the small squares of ScotchBrite into the lacquer thinner and continue scubbing until the pads break down from the thinner. It goes slow, but the surface of the fiberglass is maintained. Note, the red putty rub overspray takes a little more time to remove, but it does the job.

For safety sake, I use Gauntlet style chemical resistant gloves and the full face respirator. No worries about splashing solvent on your face, and I really like the fit of a full face mask and use it a lot for grinding and a lot of other uses.

[Kevin S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Progress update 7/14/2023

Used the Awesome grease remover and a pink scrub pad to remove the grease and oil, then I also used acetone to remove the paint overspray. Very happy with how well the LH side underside of the storage compartment turned out. Will be doing the passenger side later today and will post another picture of how that turns out. Thanks guys for all the tips and pointers.

Kevin

[James W.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Looks good!

[Thomas N.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Looks great! You found a process that works for you!

[Bob D.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

I had good luck with mineral spirits to remove undercoating from the dealer. I sprayed it on and let it set until the undercoat softened and used a plastic putty knife and plastic scrubby pad. Finished up with simple green.

Bob

[Kevin S.]

Re: Chassis restoration - stripping grime off underside of rear cabin compartments

Well alright then, here is a AFTER picture of the RH rear passenger compartment underside after using the tips and tricks that you all have been so gracious to share with me: Awesome degreaser, pink scrub pad, simple green and dawn dishwashing liquid, and some acetone at the end to get the black paint overspray off. The only thing that I have left to do is apply a very light coat of satin clear lacquer to the now clean compartment undersides. Little concerned about the red fiberglass resin layer showing and hopefully I did not clean and remove too much?

Thanks guys. Appreciate the help. I'm happy with the end result and hopefully you guys like it also...and that the end result is NCRS correct?

Kevin