M1009 back glass binding

79Vette

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I have an '86 K5 with a manual tailgate window. Back in April the window bound up due to a rusted through sash and the pot metal "clutch" that couples the handle to the regulator broke.

I used that as an excuse to go through it, and cleaned and greased the regulator, replaced the rollers, replaced the flocking in the side channels, replaced the felt seals on the top of the tailgate, replaced the broken handle and clutch, replaced the sash, and replaced all the rubber seals on the shell. Spent >$600 on parts for a $2000 truck, and assumed it would be good to go...

The window never worked right with the new felt pieces, and was really tight to roll up and down. I figured the felts would wear in and take a set over time, but they didnt. Now 6 months later, my new handle broke again...

I have the regulator completely removed, and the glass still will not go up and down freely. It binds from about 30% raised to 80% raised, and will travel the first and last bit smoothly. I'm out of ideas, and about ready to go spend another $1500 on a soft top, pickup tailgate and paint and send this tailgate to the crusher... Are there any adjustments I might have missed, or a procedure for getting the side channels lined up or something? Maybe my tailgate frame is bent somehow? Any suggestions are welcome. Section 10-22 in the -20 TM covers the rear window regulator replacement, but does not provide any suggestions for alignment or troubleshooting. Any other resources I should be looking at?


EDIT:
I messed around with this again for several hours tonight. Took the glass out, checked the track alignment, cleaned and greased everything, and no change.

Tailgate frame seems to be straight. The glass is curved however, so it does not match the shape of the straight tailgate?
PXL_20211102_034117604.jpg


The window seems to be binding against the inner felt strip along the outside 4" or so of glass on each side. Is there anything that can be used to lubricate the felt seals across the top of the tailgate? Silicone, graphite, etc?
I cannot see any possible way to adjust this other than modifying the tailgate frame. It does not seem possible to bend it (too stiff in the out of plane direction), so it would be cutting/welding to open up the clearance between these felts...
PXL_20211102_040228507.jpg


Between the red lines (5.5" above the bottom of the glass to 17" up) the glass binds. Outside that it moves freely. The curvature of the glass seems more exaggerated in the center section, not sure if that matters...
PXL_20211102_035052828.jpg
 
Last edited:

cucvrus

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What do the side lower sash guides look like? Are they smooth and polished? They should be and they should have smooth corners and edges so they don't dig into the side guides. I use a rubber Trim Lok seal in the side guides. it has outlasted any replacement side guides I ever bought. The OEM ones are long discontinued and worked great. https://www.steelsoldiers.com/threads/terminus-m1009.144523/page-2#lg=post-1775427&slide=4
Check out this thread I overhauled a scrap gate and had it 100% operational with lots of real grease and hard work. I did have to spend some money on a few parts. But I used the Trim Lok in the side guides and it held up great. Good Luck. I have the trim lok if anyone wants any. I am sure we can come to terms. Be Safe and Have a Great Day.
 

79Vette

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Thanks for your reply.

What is a "lower sash guide"? Is it just the tab on the end of the sash, or is there a separate component that goes there?

The side tracks are the original parts, with the flocked lining replaced with new material from Precision.

The glass still binds with the sash entirely removed (just the glass installed by itself, with me sliding it in and out by hand). The glass seems to be getting pinched really hard between the 2 seals across the opening at the top of the tailgate, and I don't see how that would be adjusted.
 

cucvrus

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The 2 upper seals should not be preventing the smooth operation of the glass. Unless your gate has the opening bent shut. I would remove the seals and see if the tightness is coming from the side guides. I never seen replacement felts only. Were they something you added after you removed the old felt runs. Anyway that is an antiqued assembly with lots of grease and oil points in the mechanisms. the side guides and lower sash guides just need to be adjusted properly and like I mentioned the sash side tabs polished to a smooth surface. rust causes a lot of friction in the side guides. IMHO barn doors would have been the best pick. split lower doors and a swing up glass. but this is what you have so do your best. Good Luck. Something is binding. That should be like winding down a door glass. That easy.
 

79Vette

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The replacement track felt is manufactured by Precision. Part number GRP 1130 76. It is a good fit and easy to install, very similar to the original factory material, and costs $30 for both sides since you reuse the original metal tracks.

I removed the original tracks, cleaned them with a grinder and wire wheel, and installed the new lining when I rebuilt this gate back in April. The inner seal at the top of the gate was missing at that time which was causing the glass to rattle and get scratched, and ever since I replaced those seals it has not worked right.

With either the inner or outer upper seal removed the window operates smoothly, although it rattles and scratches along the metal opening in the too of the gate. With both seals installed and everything else removed (regulator, sash and guide tracks), the glass is difficult to force through the opening at the top of the gate (takes both hands and a lot of force).

I will remove both rubber seals again tonight and measure the size of the opening in the gate, from metal surface to metal surface. I'll also measure the thickness of each rubber seal. Any chance you have a M1009 tailgate you could measure to compare? Even just checking the space between the seals without removing them would be very helpful
 

cucvrus

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I even added a secondary brush seal and never had issues. Something is amiss here. I can measure opening with or without seals.
 

Lothar

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I have one of these trucks and my rear glass works great. If you want to post a pic of what you need measured, I can post the same pic of mine with its measurement for a comparison.
 

79Vette

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Well, I'm not proud of this. I dont necessarily know if it was the "correct" fix, but I took the glass and felt seals out again tonight and used a prybar to increase the size of the opening at the top of the gate by ~1/8". Its an not noticeable to the eye, and the only way to tell is to measure the opening with a scale or a caliper.

Now the glass rolls up and down smoothly like how I remember my civilian 82 K5 was, with gentle pressure on the crank handle. The felt seals now just touch the glass when its fully rolled up instead of "clamping" it, and time will tell if the inside of the tailgate will be water and dust proof or not. Maybe I'll have to come back to this in a year when the seals start to wear and try to bend the gate back, who knows. Hopefully not, since these K5 tailgates are getting hard to find anymore...
 
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