c4sailor

I bought one of the drain kits and installed it and was not pleased with the outcome.

It rode too high in the V of the hatch sills and with the sealant under it I was concerned about the sealant failing and allowing water to get in underneath the grommet and into the fiberglass. So, I took out the kit and built my own. I had my weatherstrip out to be replaced - because the water acccumulation over the years had rotted it!

Here is what I did:

1. Removed the inside plastic trim from the rear surround so I could clearly see what I was doing - where to drill. The "window" for drilling is pretty narrow so measure more than twice and drill once! Also on the driver side, there are wire harnesses in the area so be extra careful.
2. Removed my inner fender liners so I could get at the underside of the body (the "second layer of fiberglass).
3. Measured back from the intersection of the back of the halo to the point that I could get a straight shot (plumb line) down from the hatch sills to the second layer of fiberglass. That distance was just over 1 inch. The second layer of fiberglass is about 3 inches below the layer of the outer body (V in the hatch sills- the gutter).
4. With an 8 inch long 1/8 inch bit, I drilled a pilot hole down through both layers of glass at the intersection of the two angles of the sills - the bottom of the gutter, the V where the water will naturally run.
5. With a similar length 5/16 inch bit I drilled out a bigger hole. I drilled this size through both layers of glass.
6. With a similar length 13/32 inch bit, I drilled it out the first (top) layer larger - "overborred" it. - note that I only "overborred" the top layer of glass because the lower layer does not need to be larger than the pipe. Trust me there is method to my madness.
7. I went to the local hobby shop (or model railroad store) and bought a foot of 5/16 OD brass tubing - it has thin walls so the ID isn't much smaller.
8. I stuck the whole length of pipe down into the hole and held it in place. - It will be easier to do this if you do it before you "overbore" the upper hole larger than 5/16 so do it after you get the 5/16 hole drilled. At 5/16, the pipe fits snuggly and you don't have to try to hold it in place.
9. Taking a sharp pencil, I ran it along the pipe to trace the angles of the inside edge of the sill and the outside edge of the sill onto the pipe. The two angles will be different - one steep (inboard) and one shallow (outboard). Assuming that your holes are not in precisely the same place on both sides of the car, the angles may be a little different so it's best to do each one as a "one-off", custom fit.
10. Using my Dremmel tool and a cutting wheel, I cut the pipe along my marks so it forms a V. You end up with a pipe with a straight cut at the bottom and a V cut at the top with one side of the V very steep and the other side quite shallow. My pipe was right at 5 inches long from the top of the V cut to the bottom.
11. Test (dry) fitted it and made sure it would stick out of the bottom layer of fiberglass by about two inches and that my cuts were at the correct angles. If correct, the top of the pipe should precisely match the sill angles and fit flush up both sides of the sills. You don't need to have the pipe stick out of the bottom layer of fiberglass by more than that or the inner fender wells will not go back in without interference. And, as a practical matter, all you need sticking out of the glass is about an inch of pipe.
12. I sanded (using a modelers file - small and narrow) the edges of the pipe to remove any burrs. I then roughed up the exterior of the pipe - for it's full length - with a larger file and lightly scuffed the body around the edge of the hole with some sand paper so that the epoxy has some "tooth" to bond on all contact surfaces.
13. I mixed up some epoxy resin - not real runny but not like a putty either. It needs to be able to flow in around the pipe to seal it in place but not so runny that it just runs down the side of the pipe and out the bottom.
14. I placed the pipe in the hole. Because the lower level hole is just 5/16, it will hold the pipe snug (so it won't slip vertically) while you epoxy the top.
15. Taking the epoxy resin, I used a pencil end stuck in the top of the pipe to keep it centered in the hole while I ran and forced the epoxy in around the pipe. I put the epoxy into the hole around the outside of the pipe so that it would fill the hole all around the pipe. I also smeared a thin layer around the top edge of the pipe to make sure I had a complete seal. The epoxy in around the pipe seals the glass and holds the pipe in place.
16. After a day to let the top part set, I took some sandpaper and lightly sanded the pipe and the fiberglass where it exits out the bottom of the second layer of glass.
17. I then used some "Car-Go Quick-Steel" Epoxy putty - like plumbers putty - and placed it all around the pipe from the bottom side under the second layer of glass and pressed it firmly up against the glass. This will seal the glass from any water or moisture coming from the wheel well.
18. Then I cleaned the **** out of my inner fender liners using "Stoners - Tarminator", - spray, wait, wipe with paper towel, rinse, repeat until the tar and crap is gone. I then prepped the inner liners - where they had grayed out - by washing them with hot soapy water, dried them, applied PPG Acyli-clean to get off any chemical residue, two light coats of Bulldog adhesion promoter and followed with three coats of spray Black "Plasti-dip" on only the area that had grayed out. After cleaning, the liners were factoy new looking from about 10 o'clock to two o'clock so they only needed paint on the lower areas at the front and rear of the tires. The Plasti-dip is slightly more dull than the factory clean surface but the difference is not noticable. And, I figured that with the rubber/plastic base in the Plasti-dip, it would resist rock and gravel damage better than normal paint.

Well, that's how I did it and I am really happy with the result. I took some pictures along the way and will update this as soon as I figure out how to get the pics online and uploaded.

Be happy to answer any questions along the way. I really think this is a cleaner solution and the one that GM should have molded into the body to begin with.

Will post pics as soon as I can. Meantime, PM me with an email address and I can email.

Hope this is helpful. :-)


Fitz
First three shots are the kit




kit profile vs. custom tube



Custom tube half way in


profile of the tube

better shot of the tube half in

tube almost all the way down

custom tube all the way in before epoxy

same different angle

expoxed in place

underside before epoxy putty applied

view from across the carr - shows bottom of the first layer of fiberglass after epoxy. note the epoxy flowed to the bottom of the first layer of glass

underside after epoxy putty applied

close up top view


While some of these look rough, be aware that they were taken with a 300 mm lens in macro mode from about 18 inches so they show every pimple. to the naked eye, the finish looks very good, I haven't yey touched it up with paint in any of the photos.

c4sailor

bump

78pacer

God, thats way too much trouble.......................but thanks for sharing, bro
Mike

Mekanic

great writeup and pics.

too much work for me, but a better solution for sure

toptechx6

Hell of a nice job I might consider if I ever remove the weatherstrips, but agree with the others who say way too much work for the gain.
I stuff a sheet of paper towel in each corner while I dry the rest of the car and the issue is handled when I remove them.

gungatim

I just use a little snot-bulb from the drug store. suck out the water and shoot it at the cat...

65Z01

Sounds like the "right way" to insall a drain in that area, congats...

samh

I like the way you think!

See3

I just blow the water out with 120 psi from my air compressor.

Weav's Vet

pianoguy

Hmmmm, we might have an old one of those laying around. Oddly, they have little resale value.

seenalot

Never had a problem with the stock drain kit. You have to take your time installing it to get it deeper into the "V"

WW7

If you install it the way they say there are no problems with it. If you would worry about water leaking around the grommet put a little silicon under it. WW

TA

You, my friend, have wayyyyy to much time on your hands

c4sailor

No, I have a 20 year old C4 that absorbs all of my time between 8 pm and 3 am and all of my money earned during the remaining hours! ;-)

Through my 30 years of experience as a sailboat owner, I learned long ago that silicone caulk does and will fail causing water to wick into the core of what ever it was meant to keep dry. On our sailboats, when mounting any hardware to the decks, we overbore any hole going through glass/balsa core, completely fill it with epoxy then drill the correct size hole through the epoxy so that the new hole has no contact with the glass or balsa. A waterproof hole!

deerra

"A waterproof hole! "

At my age, just what I need.

xCCTer

Wow. Great looking job.

Since you have so much time on your hands,

I have this new gas tank for my '71...

slicked25

I've done that before too but have been pretty consistent on using the vacuum at the carwash. It sucks it right up. But the OP has to win the most hardcore of the year job. Wow.