I just installed mine here is an email gmc Paul's sent me about the issue.
Hi, Kirk
In regards to our push-on door seals approximately 95 % of our customers have absolutely Zero problems with them. The other 5% about half experience minor difficulties in closing their doors initially and others have major difficulties in closing the doors initially, but they do improve within a few months’ time normally.
Many have reported that applying Armor All helps greatly in allowing them to close the doors others report they used a silicone lube on the seals to achieve the same results. Why these seals work perfectly on the majority of 67-72's yet cause difficulties on a few trucks we can't always explain. Some trucks we've discovered have had repair work to the cab or doors that wasn't always done correctly that will not present a problem until new door weather strip is installed which then highlight’s the door gap problem where the inner door meets the cab opening.
Most notorious problem is door hinge or latch adjustment, improperly installed rockers, kick panels, front or rear door pillar or sill plates installed incorrectly causing the binding ( If rocker, kick panel or floor work repair was done in past definitely check to see if the front pillar are twisted slightly many fail to brace properly for this repair and they twist in or out when the adjacent metal is cut out and repaired ). Things as minor as the weather strip lip being bent outward slightly can cause this.
If your doors not perfectly centered in the opening front to rear or top to bottom then this will lead to the door binding when closing. The door when installed should be adjusted to the inner door opening then adjustments should be made to fenders to achieve as even as possible body lines and gaps. Instead quite often folks adjust the doors to the front & rear gaps where it meets fender in front & cab in back.
In Example- If they then install door to far forward to get that perfect gap on the outside at fender & cab where door meets them then it causes binding in the front, if they adjust it rear ward then it binds in the rear. But if they adjust the door to the inner opening itself then move fender forward or back to achieve a even gap this is correct and there’s no binding.
Many previous owners will adjust either the door hinges or door latch inward when the original door seals were not sealing fully anymore and thus they need adjusted back out when new door seals are installed by a later owner of the truck.
We have also found that several customers discovered a large portion of the problem is the new door bumpers are far firmer than GM originally made them and when the door bumpers are installed with the weather strip it causes great difficulty in closing the doors, when the door bumpers are removed the doors close easily. Those customers have found that trimming the door bumper ends by approx. 1/8" allowed the doors to close as they should.
Some find the problem is they butted both ends together tightly under the door sill plates or even glued the ends together, this should never be done. GM recommends that under the door sill plate you should cut the bulbous portion of the sill at a angle on either end so that where the bulb portion meets it forms a V shape. This allows the air that is in the bulb portion of the door seal a way to escape easily. If the ends are butted tightly together then the air has nowhere to go easily causing difficulty in closing of the doors.
If you go through and examine these things I've mentioned you'll more than likely find that one of the above mentioned things will fix the difficulty you are currently incurring with these. The door seals do settle in with time allowing much easier closing of the doors within a few months of installation. This breaking in time was less of a problem when the vehicles were built new as it took 1-3 months from vehicle completion to delivery to the dealerships for sale which allowed factory seals when the trucks were new to have time to break in before the trucks were sold.
Those that have difficulties with our push-on door weather strips generally have even greater problems in closing the doors using the original style glue on door weather strips that are exactly like original GM and those that use them generally switch to this version because they allow the door to close more easily than the glue on version did because of it being a softer seal.
Some have advised they were able to eliminate the break in period by closing door and applying heat with a heat gun to quicken the process of molding to the opening by softening them with heat while compressed helping to better mold them to the current door gap.
With so many variables involved its hard to say exactly which of the above things it may be without examining the truck in person, so I tried to cover the majority of problems we know of that cause difficulty with door closing using new seals. I feel you will find upon further examination that one of the above suggestions or problem areas is causing your current difficulties.
If you find your problem to be different please let us know so that we can help others in determining theirs better.
My Very Best Regards
Paul Jr @ GMCPauls
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