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Plastic Wiper Pivots - Who would have thought???


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Just had to cry about removing them so I could patch a hole in the cowl.

 

Oh, I'm so Clever - just take the torch and get those frozen nuts off those studs.  (I was observant enough to realize the entire "stalk" sticking out was plastic so I used Heat Damn to protect it from the torch.

 

So the RHS pivot got 2 studs melted loose - I guess I'll have to burr off the nut and stud to remove.  Its too difficult to try to grab the stud head inside the cowl.

 

So the LHS pivot was better since I knew what I was up against.  However, the plastic ear/flange for the bottom stud broke off.  I don't know if I did it or it was like that.  But it did leave the 2 opposed studs which are the 2 you would want.

 

I'll probably put them back in with nuts and bolts  where I messed things up.  Maybe I'll fab some new studs and put a steel nut plate between their heads and the plastic flange.  That way the nut plate will react the stud torque, not a weak press fit in thin plastic. 

 

NOTE:  If they made the plastic 1/4" thick - a nice thick block - it might have worked just fine.  Considering how they seemed to do this in many other areas, the pivot design is disappointing.

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And then there is the rusted cowl.

 

They had a good basic design with the high plateau in the center with no vents above it and also where the heater snorkel is.

 

However, why in the world did they put that "speed bump" across the plateau right in the center?

 

If the truck is parked leaning, water that would get in there (which shouldn't) would pool and rot.  And if the lean caused the pool by the snorkel, it would soak the spot weld flange and really rot out which is exactly what happened for me.  If they had only swapped ends when they parked it, there wouldn't have been any hole.

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You can get new plastic from the help aisle at the auto parts place. They come in assorted package. You have to cut two of the opposing tabs off but then they fit like they were made for the 620. Don't forget to add a dab of grease. 

 

 

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That's the linkage bushing, the pivot is the wiper shaft assembly with the flange and 3 mounting studs - its plastic!

 

Here is a thread where they do some upgrades from a 510:  http://community.ratsun.net/topic/29741-how-to-repair-and-upgrade-620-wiper-arm-assembly/

 

There are different part numbers for models Feb 1977 and after and are probably the metal ones.  But they also say the entire system is different with a different wiper motor too.

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Its not the bushings - they are OK. 

 

I screwed up the plastic flanged housing with the pressed steel studs in them. 

 

I am confident I can get them back in and operational, but it will require a few mods like using nuts and bolts or making a "stud plate" to eliminate the weak plastic press fit for the studs.

 

Its like there are a 1000 & 1 little mods/fixes that I'm making on this poor truck.  But then it appears that no one really did any quality work on it except perhaps for the paint job which wasn't that bad, but the use of Home Depot Silicone Calking was NOT the thing to use. 

 

Frankly, I believe SikaFlex 1a is the penultimate polyurethane calking which you can only purchase at the most industrial/commercial supply houses - the places were DOT buys stuff or people building bridges, roadways, or big commercial buildings.

 

For concrete and masonry 1a uses a thick "superglue" primer that is so tenacious that you CANNOT separate the calk from the concrete with a screw driver.  PERIOD.  Can't be done.  I've tried it.

 

Learned about it from a friend who serviced commercial concrete pools.  If you need to make two pieces of concrete watertight, 1a w/primer cannot be beat.  You could even put it between sidewalk slabs to completely eliminate forever grass and weeds growing in the crack.  Just remember to use foam backer "rod" so you have a nice ligament between the pieces and not some big thick section so you get properly designed expansion joint.

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  • 2 years later...
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I broke one of those plastic base pieces on the pivot tower. Popped off the snapring, took the tower apart, cleaned with simple green and a little brass bristle brush from harbor freight $.79 cents. (Always clean your parts with a softer material than it is made of to avoid removing or scoring base material;)

 

Pounded out broken rusted splined bolts with a punch and socket. Drove in some used ones from a 730.

 

Used JB weld to glue base plate back together.

 

Then traced our the base one some sheet metal and cut it out with tin snips, and drilled out new holes in sheet metal. Jb welded it to backplate then plastic base and clamped it together for 24 hours.

 

Reassembled towers and linkage with used plastic connectors, also from 720. Snaked the whole thing back into place in one piece, bolt in place without having to stick a hand in cowl hole to hold boltbheads from spinning. When the tower is de-Gunked and re-lubed there is very little torque on the towers and the linkage and towers pivot easily. Just barely tighten it down and don't over-tighten it.

 

Another option is to rob a 76 or earlier 620 and get the wiper linkage with metal connectors, as long as they're not already rusted out.

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