740 juddering wipers

Use denatured alcohol to remove.clay bar won?t do a damn thing

^ Thanks. Don't have denatured alcohol, but I will try vinegar first and isopropyl alcohol if vinegar doesn't do the trick. If neither work, I'll pick up the denatured alcohol. Thanks again.

Ended up using non-abrasive glass cooktop cleaner. Seems to have worked. I'll see the next time it rains.

Nope. It didn't do a thing, it just left a different polish on top that wore off quickly.

I then used mineral spirits, which didn't work, followed by kerosene, which also didn't work. Made sure not to get a drop of anything on the trim or paint.

So, is denatured alcohol worth the try?

I think this thread from another site looks useful:

https://bobistheoilguy.com/forums/threads/removing-rain-x-the-final-word.279171/

tl;dr mechanical action with a light abrasive and microfiber cloths is the most reliable way as the solvents needed to take off silicones are weird. RainX, amusingly, makes a good mildly abrasive cleaner ("Xtreme Clean") which is supposedly quite effective.

Surprised the clay bar didn't remove it as that is also a mild abrasive.

Denatured alcohol is worth a shot, it's pretty handy to have around anyway. I use it to do the final clean on parts before painting.

I've used rainx on and off for years, never remember anything but a flawless experience using it.

No one so far has talked about what is causing the shudder though a couple alluded to it.

For wipers to work correctly they must be dragged, and it's the free play in the mounting of the blade and the flex in the blade itself that achieve that.

It sounds to me as though the blade holders have been crimped tight onto the blades and the blade can't move freely as it needs to.

As someone else said, if it's trying to push it, it will grip, load up, then release, and repeat - that is what the shuddering is.

Modifying something that typically works great on 60 year old cars let alone 30 year old cars seems to be a bad idea, to me.

Something is clearly wrong, perhaps the something is mods done in the past or recently during 'installation'.

Make sure the blades can move and do move, and trail behind the arm in both directions. They basically can't shudder if they're being dragged as it would mean excess flex/freeplay in the entire drive mechanism and stickiness of the blade onto the glass to create a grabbing and releasing cycle which seems pretty unlikely to me.

My 2c.

Simple minded thought here: How about squeegeeing the windshield by hand with a blade and see if there is an angle or pressure that works.

Quick update: I used rain x "x-treme clean" to remove the coating... which appeared to have come back?!

Anyway, switched back to rain-x wipers. They sometimes judder a bit. Sometimes not at all. Whatever. As long as they do the job... I've kind of given up.

Funny enough, last week I saw new-ish Mercedes, something like a 2019 with juddering wipers across an intersection when it was raining. They were juddering just like mine. Whatever the issue, I feel somewhat reassured it is not a weak wiper motor, unless they fail on new Mercs.

At this point I'm just hoping whatever is causing the problem will wear off.

Did you read my post above?

Weak wiper motor could not cause bind up and release - it wouldn't be able to overcome the binding.

Did you check the mounts to ensure they have the proper play in them and aren't crimped tight?

FreeEMSFred said:

Did you read my post above?

Weak wiper motor could not cause bind up and release - it wouldn't be able to overcome the binding.

Did you check the mounts to ensure they have the proper play in them and aren't crimped tight?

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The blades drag as they should, flipping sides as they start to move in the opposite direction. They also wipe well along the whole windshield. Maybe I should take a video, although the issue is now very subtle and at times not even noticeable with the rain-x wipers.

Here's a follow up for anyone with the same issue. I used "Rain-X X-Treme clean" to give the windshield a clean, and the juddering went away. However, it reappears about a month later, depending on the weather and wiper usage.

I just give my windshield a quick clean with the stuff after I notice the juddering start to reappear and it keeps the wipers running smooth for another month or so. I would say it delivers fairly consistent results. Just wished it was "one and done" deal.

On my Jag XJ6 i had this juddering issue as well. I discovered one of the wiper arm axels was sloppy. It was adjustable with a large chromed nut so i tightened it until the slop was gone. No more judder.
conclusion: a worn or lose wiper arm axel can be the cause of wiper judder.

Harry Tuttle said:

To amplify this, make sure that the blade is being dragged across the glass trailing the arm in both directions, not being pushed ahead of it, if that makes sense. Is the juddering in question happening in one direction only?

Those helper springs look ugly, but could be the solution to 35-year-old arms with weak springs. Where can they be had?

Click to expand...

This is usually the culprit when I have this issue. When the wipers park, they're usually with the blade pointing in one direction, and I think over time, that gets a slight twist in the main part of the wiper arm. This leaves the blade pivot at a slight angle, and if the windshield is slippery enough (being TOO clean can contribute!) then instead of the bland flipping back and forth as the arm changes direction, it ends up being dragged one direction (good) and pushed the other (bad). When being pushed is when it is going to shudder and judder and twitch.

Pull the arm back, rotate the blade 90 degrees so the angle of the arm is visible, and then give it a gentle twist, toward the direction it's being pushed. Then try it again. See if you gave it enough twist. When it's good, the blade will resume flipping back and forth as the arm changes direction again, so that it's always being dragged, never pushed.