traxtar928

Since I've owned the car, I've had issues with the wipers. They intermittently chatter on the windshield. I've gone over the glass with a clay bar, and tried different brands of wipers, but nothing fixes is. When there is a decent amount of water on the windshield, the chatter goes away.

Also, the wipers don't always stop in the right position... sometimes they stop ~1 inch too high. Quickly flicking the control stalk will blip the arms down to the correct resting position.



Lastly, the plastic grommets for the wiper arm where the knurled end of the motor rod goes through the trim do not align properly with the trim hole.

I'm worried that if I just take the wiper arm and move it down, that sometimes it will be 1" too low instead of too high... and will impact the trim and potentially scratch it.

Should I look into a new motor? I'm guessing the control circuit that knows the 'stop' position gets confused sometimes, and misses the mark. Only the passenger side has this issue.

EDIT: The passenger side misalignment is very apparent, as it's off by about 1" at times. The driver's side is only off by a fraction of an inch. I'm guessing this is due to the long arm on the passenger side.

Wisconsin Joe

I'm guessing the "only the passenger side" is about the chatter. No clue on that.

For the stopping issue, there's a series of conductor fingers and a notched conductor ring in the transmission. They dictate where the wipers stop. I'd guess you have a bit of corrosion or something on the "park circuit" bands and a simple disassembly and cleaning would help.

Thread on replacing the bearing in the motor, but it has good info on how to pull the wiper setup and a good pic of the open wiper motor & trans unit (4th pic down):

https://rennlist.com/forums/928-foru...-overhaul.html

The Forgotten On

Try waxing the windshield with carnauba wax after clay barring it. It acts like rain x when when but lasts a lot longer and lubricates the wipers pretty well.

Michael Benno

I have the same chatter problem. Some people have suggested its from play in the bushings and pivots. I plan to remove and rebuild my assembly this winter to find out more.

gazfish

On other cars I've owned the chatter had been caused by incorrect tension on the wiper arm spring.

Michael Benno

and was the solve to increase or decrease tension?

G.P.

To fix the chatter in my 87 I removed the wiper motor, cleaned and re-lubed the gearbox and cleaned the electrical contacts inside the gearbox.

gazfish

The springs had weakened with age so the new springs had more tension. The wipers used to lift off the windscreen at higher speeds as well, but I'm not sure if the same would be true with the 928 airflow.

traxtar928

I'll try removing the motor, cleaning everything, and re-installing. Thanks for input everyone.

Michael Benno

Lets us know of the results if you get to if before I do.

safulop

I thought this was normal behavior for the wipers. Mine always do that, and have always done that for the past 5+ years.

traxtar928

Sounds good. Probably won't be soon though... I have a laundry list of other parts I need to get to first.

dr bob

The lubrication in the little transmission turns to soap after the lubrication part goes away with age. R&R the motor and transmission, carefully clean all the old caked mung out of there, and replace with some handy #2 red synthetic grease before reassembly. Use a little on the bushings in the arms and the pivots. With that your wipers will be smoother and faster with no chatter.

FWIW, the window motor transmissions and the rear wiper transmission all suffer from the same malady.