b9boy

Hi

One of the growing list of jobs to tackle on my newly acquired '87 S4 is to sort the rear wiper sweep out.

I've dug around on this forum and found some info from 2011 relating to a pin in the rear hatch engaging but the thread refers back to the "correct sweep for a 928". Can someone please confirm what that sweep is? I am assuming its the red area marked on this pic (of my car)? the actual sweep at the minute is shown in yellow.










Please bare in mind mine is a RHD car......I dont know if lefties have a different sweep?

Is it possible to simply loosen my wiper arm and move it to where I want it? I dont want to mess around and break something hence asking first!!!!

Thanks

WALTSTAR

You can loosen the larger of the nuts at the pivot and re-tighten until you get the sweep centered where you want it. Just have a bucket of water to lube your window between tests. As long as the arms dont strike the hatch frame, youre OK.

Speedtoys

Losen the nut on the drive post of the rear wiper, 4-5 turns, and while holding the drive cam inside the upper hatch, adjust the wiper one-notch over. No need to lubricate anything, the stud and collar for the wiper, have teeth, and you are one tooth off

Losening the but lets the disengage upwards (its a cone) to adjust.

You should be the red box, where it wants to sit/rest off to the side.

But theres no reason you can do the yellow box, if that worked better for you.

b9boy

On reflection I'm not sure this is going to be a simple readjustment of the arm job. On checking the wiper, from where it sits in the middle of the screen, wipes left about 6 inches, then right practically to the right hand edge of the window and then back again, resting in the middle.

So, if i move the arm to the left as it's resting position surely it will just try and wipe to the left over the paintwork? Something else must need to be done to stop it wiping left at the start you would think?

If this helps, this is the 'thing' inside the hatch. Can anyone confirm if their 'thing' looks like mine (no s******ing at the back) ??

Wisconsin Joe

First off, no difference between RHD & LHD on the wiper (thank goodness).

The linkage looks fine, except that it should be against the stop when parked. ('****' on near end all the way to the right side of the pic, protrusion on the bottom all the way against the stop)

From your description, it sounds like the part of the motor that 'decides' where to park the wiper is the problem.

Do you know how that works?

There are two 'traces' with contact arms. One is always powered, the other gets power to it when the button is pushed (and the relay closes).
The one that is always powered is the 'park' one. It allows the wiper to go back where it's supposed to when the relay opens.

There is a gap in the trace for the park circuit. That's where the wiper will stop (because it stops getting power at the gap - Captain Obvious at your service )

I will guess that there is either corrosion on the trace, or maybe the trace is broken. The power is 'stopping' before the wiper gets to the proper park position.
A new wiper motor would likely fix it. If you can find someone who has a spare that would let you borrow and install it to check, that would be ideal.

Alternatively, you can probably take it apart and check the traces. I haven't done a rear wiper, but I've done the front motor. Disassembly is straight forward, reassembly is a bit 'fiddly'.

There's a thread about the front wiper motor that shows it apart:

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

Pic is the 3rd one down, just below the bottle cap. You can see the three 'fingers' that provide power through the different choices, and the plate on the gear that receives the power.

b9boy

Thanks for that above, thats super helpful. I think for what a replacement motor will cost me £60 ish, I will buy one and fit it. Fingers crossed that solves it. I'll adjust the catch as per your comments above before I fit it. Thanks again!!

Wisconsin Joe

You shouldn't have to adjust the catch.

The part on the hatch fits into the part on the car body.

The reason the wiper isn't parked up against the stop is because the motor isn't stopping in the right place, not because of any adjustment issues.

b9boy

Oh, I see. So when the new motor works out where it should park the metal protrusions etc will sit in the correct place. Got ya