Windshield wiper thread-tap grub screw modification so they don't fly off project

Stevehose

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Since I have a pending road trip and would like one less worry (the dreaded windshield wiper highway detachment syndrome) I thought I'd give a go at inserting a grub screw through the wiper arm base into the splined post to lock them on. A dicey proposition on paper and in reality.

Here's the 2mm tap & drill set and the M2 6mm grub screws:

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First I marked the position on the arm that I wanted to drill, it's on the underside so you won't notice the hole without really looking for it. I used a spring loaded punch to mark the drill bit location:

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Next up is the drill, I stopped the wipers in the full sweep up position on the windshield, marked off a little over 6mm on the bit and made sure it was square going in (it goes about 3mm into the spline, not just the wiper arm). Dicey operation #1:

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I blew out the hole with compressed air, put a little penetrating oil on the tap and started dicey procedure #2. I turned in a couple revolutions with some pressure then back out and cleaned the threads of the tap, this is critical to do and you have to go slow and add some oil each time. I did this until the tap bottomed out in the hole. The black ink mark tells me when I'm close:

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Next I blew out the debris after tapped all the way down then fitted the screw:

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And all the way in, tightened down, they are not going to fly off, and are not noticible when viewing from the front:

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Ready to roll!!!
 
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HB Chris

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Looks like you have a good spring clip, was it really that loose? Did you drill slightly into the splines for the screw to seat itself? Great tutorial.
 

Stevehose

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Looks like you have a good spring clip, was it really that loose? Did you drill slightly into the splines for the screw to seat itself? Great tutorial.
Yes the spring clips are still there, but with a little tugging the arms come right off, I've tried to tension them but I think years of fatigue prevents much tightening. Yes I drilled into the splined post so they are locked together because the screw goes about 3mm into it..
 

Stevehose

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Also it seems when the wiper is in motion for a little while, the pressure against the glass can force the arm up the spline a little, then with 80mph winds off it goes. Happened to me twice, fortunately both times it landed on the base of my windshield/hood and I was able to retrieve it.
 
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halboyles

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Excellent writeup! This is also necessary on '02s especially since the only time they go soaring off into the night is in a driving rain storm at 60 miles an hour!
 

Stevehose

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Also I have 8 leftover screws so if anyone wants a pair I'll drop them in the mail to you. EDIT: all spoken for, link is posted below for source.
 
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Belgiumbarry

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remembers me of our first !! rally.....i lost my wiper.... of course it was dark&rain . Lucky, found it on the road and could continue....
nice solution with the grub screw....we just drilled a hole and mounted a bolt/nut.
SAM_3625.JPG
 

eriknetherlands

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Nice write up, and nice solution as it is sooo stealthy.
I had a wiper fly off as well, found it on the side of the road luckily, but i do have the same worry of it happening again.

One thing that may get us an A+: vibration could possibly loosen the screw as you (I also) probably would not dare to tighten the grub screw; the pot metal of the wiper being soo soft. Having no or little pre-stress (due to compression) on the grub screw means that it is held by a low friction only.

Should it come undone by itself then i would consider a dap of loctite.
For anyone else considering this modification, i would drive the M2 tap not fully through. I would leave the last turn of the thread formed only partially: then the grub screw will lock itself due to the somewhat ill-fitting thread. It's comparable to the squashed nuts that are used in the rear axles.
 

Stevehose

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Nice write up, and nice solution as it is sooo stealthy.
I had a wiper fly off as well, found it on the side of the road luckily, but i do have the same worry of it happening again.

One thing that may get us an A+: vibration could possibly loosen the screw as you (I also) probably would not dare to tighten the grub screw; the pot metal of the wiper being soo soft. Having no or little pre-stress (due to compression) on the grub screw means that it is held by a low friction only.

Should it come undone by itself then i would consider a dap of loctite.
For anyone else considering this modification, i would drive the M2 tap not fully through. I would leave the last turn of the thread formed only partially: then the grub screw will lock itself due to the somewhat ill-fitting thread. It's comparable to the squashed nuts that are used in the rear axles.
Yes I thought about not going into the hub but I didn't want to put too much stress on the wiper arm metal either so I decided to spread the force to both. The hex wrench size needed for the screw is .9mm, I don't have one so I ordered one, I was able to get it pretty tight with a very small phillps head screwdriver. It's pretty snug, if I feel like it may work itself out after proper tightening with the hex wrench I may add some loctite.
 
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Stevehose

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Update: I received the .9mm hex tool, snugged the bolts in just until I could feel a little resistance begin, then stopped. They are now just below the surface of the wiper arm and tight enough not to strip the pot metal or work themselves out.
 

bavbob

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You always make mods that look OEM. That is perfect.

Blue Loctite? Also I would put that hex wrench into your tool kit, you never know. I say this becasue I had Enkei 3 piece wheels years ago, had a flat and did not have the damn hex wrench to take the cover off to expose the lug nuts.
 

Stevehose

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You always make mods that look OEM. That is perfect.

Blue Loctite? Also I would put that hex wrench into your tool kit, you never know. I say this becasue I had Enkei 3 piece wheels years ago, had a flat and did not have the damn hex wrench to take the cover off to expose the lug nuts.
Thanks, yes the hex wrench is in my travel kit of misc spare parts and emergency repair stuff. Still considering the loctite.
 

Wladek

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Steve, i think you should consider loctite or something similar as a barrier so that the stainless steel bolt does not enter into electrochemical corrosion with Zn-Al spline due to moisture. If the hole was chromed inside it wasn't a problem, but after threading it's just bare Zn-Al.
Or you can just use zinc plated bolt instead.

p.s. great idea anyway;)
 

Stevehose

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Steve, i think you should consider loctite or something similar as a barrier so that the stainless steel bolt does not enter into electrochemical corrosion with Zn-Al spline due to moisture. If the hole was chromed inside it wasn't a problem, but after threading it's just bare Zn-Al.
Or you can just use zinc plated bolt instead.

p.s. great idea anyway;)
Ok that does it, loctite goes on tomorrow!
 
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