Michael Benno

When I use my wipers on my 1988 928 S4, they stutter or skip across the windshield forward and backward. The problem is worse at the normal wipe mode, less so at intermittent mode. The blades are new OEM style Bosch.

I thought this the motor, so I tested the wipers with arms of the windscreen, and they are smooth as silk and with my hand on the arms, I could not feel any roughness in the mechanism.

On the advice of a fellow list member, I sprayed RainX on the windscreen and the problem went away for a few hours. So this tells me this a friction problem.

Any good clues on the fix? Do I need to "bend the arms" for a better angle? Are there other blades that have less friction? Is the windshield too rough (some sort of coating worn off).

I seem to remember seeing something about this in previous posts but not my searching doesn't yield any results. So sorry if this is a common issue that has been discussed already.

Suggestions appreciated.
Mike

Bertrand Daoust

Same problem here.

It was a lot better when I put new Bosch Icon's but the problem slowly got back.

I also notice that it is better when I put detail spray on the windshield!
But like you, it doesn't last much.

I would like to get rid of this little problem too!

WallyP

Sometimes the problem can be helped by a little fine-tuning...

Use pliers to squeeze the small metal tabs that wrap around the wiper blade. On the conventional-style blade, there will be six or eight pairs of these on the arched parts of the supports. You want the tabs to hold the blade with very little free play, but the rubber must be free to slide in the tabs.

If the stutter is only in one direction. you can try twisting the arm slightly to change the angle at which the blade hits the glass.

You can buy orange washer fluid that contains Rain-X. Using that when the rain starts might help.

Bertrand Daoust

Thanks Wally.

LexVan

Clay bar your windshield to deep clean all the contaminants.

Wisconsin Joe

No coating on the outside of the windshield that I'm aware of.

Cerium Oxide can be used to polish it.
It's available at glass shops, not the usual car parts places (O'Rielly & AZ had no clue what it was).

PaulD_944S2

Clean the windshield with either clay bar, or 0000 steel wool. Steel wool is probably the easiest and cheapest. Available at home improvement or hardware stores.

Use painters' masking tape to cover the rubber surround.
If you use the steel wool, rub the glass in two directions, vertically and horizontally, not circularly, until the glass feels "greasy" and then try the wipers. You don't need to press hard. DO NOT use any water or other liquids; the glass must be dry.

You may need to clean the edges of the wiper blades with isopropol alcohol to remove any residue that the wipers may have picked up from the windshield.

BTW, you can clean all of the outside glass with steel wool; really makes it clear.

The Forgotten On

I clay bar it and then wax the glass.

As crazy as it sounds it lasts a while on the front if you don't use the wipers too much (you wont need to as the water beads up and rolls off better than rainx).

It also keeps the wipers from chattering too; when you use them.

It practically lasts forever on the rear hatch glass.

a4sfed928

The root cause is slightly worn plastic bushings in the wiper linkages.
All the above suggestions will help but they are only temporary.

dr bob

Mine is completely solved after replacing the 30YO soap cake in the wipre gearcase with good grease. Cleaned and lubricated the bushings at the all the joints. Buttah smooth now.

Speedtoys

If it ever stops raining in Norcal, I'm doing this too. Been putting it off far too long, and now it's a SE Asia monsoon every 3 days...

safulop

+++++++++++++++1 !

I saw that Pacheco Creek looks like the mighty Mississippi these days!

Adk46

I hate wipers! The idea with RainX is not to use them at all - it quickly wears the coating off, and a partial presence makes everything worse until it is entirely gone. A flick of the wipers is needed occasionally at slow speeds, but that should be all.

The stuttering comes from the difference between static and dynamic friction, exacerbated by anything that promotes a low-frequency resonant vibration. The principle of ski wax for classic cross-country skiing is to increase the static friction, so you can both kick and glide - you don't want anything like that on your windshield. Downhill wax would be better, designed solely for easy glide (I"m not suggesting this).

I suppose if you wanted a nice squeaky sound, you could use the rosin you put on your violin bow.

Considering that we're talking about a(n) harmonic vibration, stiffness and damping play a big role in addition to the nature of the friction - that's where new bushings comes in. New wiper rubber does various good things, for that is where the rubber meets the ...

Speedtoys

...I picked a good year to move out of zip code 95006.


Downtown San Jose now, 19 floors up sipping Manhattans watching traffic into SJC..when its no raining, which is never i seems.

http://www.speedtoys.com/weather

Speedtoys

Looks like a good refresh of everything important would be new:

92862822103 Crank drive (new arms come with new bushings)
92862824304 Lever (wear point)
PCG62812900 x2 Arm bushes
94462812900 x 2 Arm Bushes
94462812600 Grommet
94462812700 Bush
92862871602 Grommet
92862871701 Grommet

Clean Motor/Transmission, and wiring plug.

...$250 and another system to forget about for 30yrs.