AlexStanley

Hi all,

I've just been out in the 928 and it's been raining a LOT here. I've noticed for a while that the sweep of the wipers seems to be 'jerky', in that it's not a smooth motion.

It seems to get worse when the screen is relatively dry, for example when the rain is less torrential, but it happens when there is plenty of water on the glass too so I don't think it's contaminants on the windscreen.

Any tips that I can try?

Thanks.

Rob Edwards

Pivot the wipers off the glass (so the arms are sticking up 90 degrees from the glass surface) and run the wipers. If the jerkiness goes away, your blades were sticking/skittering on the glass. If they're still jerky, you might have broken teeth on the gear in the wiper motor, or a transient contact somewhere.

AlexStanley

That's a great shout! I'll try that - thank you

atb

If I recall correctly, the juttering of the OEM wipers was caused by the portion of the wiper that holds the actual wiper blade not gripping the blade tight enough.

If you remove the blade, pinch the portion of the wiper arm that actually holds the blade, and then reinstall the blade, that should solve the problem.

Zirconocene

Rob is correct, of course. It may also be that the wiper mechanism requires some lubrication. If it's never been serviced, whatever was on the joints originally is...original. A little lithium grease might go a long way, or if you're not worried about paint in the future, you can use something like a silicone grease.

I just completely overhauled my wipers and feel confident in the electrical and mechanical bits of the system, but there's still some less-than-smooth action when the windshield is not completely wet. I attribute it to old glass with imperfections that are not particularly visible to my eye, but cause enough friction across the wiper blades to cause some drag. I may also be full of it, so there's that.

Good luck

The Forgotten On

They're pressed pretty tight against the glass so they tend to skip a little in my experience.

The only easy "fix" I have found is to either wax the glass (works like rainx on steroids) or use rainx washer fluid.

The wax or rainx act as a lubricant for the wipers and eliminate the skittering.

The washer fluid is easy because every time it starts to skip just spray some on the glass and you're good.

Speedtoys

Mine have been jerky for a few months.

Got new ones yesterday.

All fine now.

Speedtoys

Agreed, but if this "helps" the rubber is old and hard, its not 'flipping" and dragging water as it moves.

It's trying to shovel it...and it sticks and hops.

AlexStanley

Thanks all for the replies; I'm going to be spending some time looking at the wiper mechanism today as I don't know whether it's ever had any maintenance in the past..

justabout

I believe the new wiper blades have a coating (graphite?) to provide some lubricity. Rain x is a solution too.

Petza914

Replace with PIAA silicone wipers and use the treatment wipe that comes with them following the YouTube instructions. You won't believe how smooth and silent wipers can be and they'll last for years. Every year, refresh with a new treatment packets which can be purchased separately.

I have these on all 9 of my cars including both 928s.

AlexStanley

Thanks all for the help so far - for info the wiper blades are brand new (or rather a couple of months old).

I’ve now got the wiper linkage and motor out of the car - I tried Rob’s suggestion but I wasn’t happy that it was smooth with the wipers off the glass. Now I’m trying to turn the linkage from the bolt that connects the linkage to the motor and it seems quite stiff, but I have no real reference point to compare to. Using a spanner/wrench on the nut, I have to use a lot of arm force to turn the spindle clockwise (anti/counter-clockwise just unscrews the nut). Is this right or does this suggest that there could be something amiss?

Zirconocene

I think that moving the motor via the linkage is quite difficult, regardless of the overall condition.

Do you have a 12V source that can power the motor? That will give you direct feedback on how things are moving, since you'll be able to see everything now that it's out of the car.

You can start with popping off the linkages and cleaning everything up, then lubing and reassembling. while all that is off. Take pictures first, of course! Then you can bench test the motor but if it moves well with things disassembled it's likely OK and you can put everything back together.

For bench testing, my pin layout was pin 6 = ground, pins 2, 3, 5 were the various motor speeds.

Cheers

G.P.

I found in MY 87, that the stutter was coming from the sliding contacts inside the wiper motor gearbox.
This thread has some good advice- https://rennlist.com/forums/928-foru...stutter-3.html
Hope this helps

NickTucker

There is this nugget from Wally...

Fine tuning

Some good info in the rest of the thread as well.