Wiper motor help required

socram, Feb 10, 1:55am
I am using an adapted MG Montego wiper rack and motor and electronic delay unit box etc, but the motor now parks the blades at 90 degrees.Does anyone know what has to be changed to get it to park correctly and just do the 180 sweep and back.

Before you ask, it swings left 90 degrees, then 180, then back to park in the centre - not wrong on the splines!
skin1235, Feb 10, 3:55am
thought the park position was set by rotating the rear cover over the drive gear, or was that on the old lucas/smith ones
socram, Feb 10, 8:19pm
I think this an electronic setting somewhere.If you move the rack at all in the box, it will still go 90 left and 180 right.I need to stop it doing the 90 left first! Or, it may be some sort of wiring change.
skin1235, Feb 10, 8:43pm
okay, on the older models the wiring connected to the back plate and fed onto copper strips embedded in the back of the rack cog, these strips set the park and start positions
even in an electronic system the motor does not reverse rotation, park position is set by the rack position, and initial movement is determined by further movement of the rack, to change that first 90degree to the left you have to reconfigure the rack to park in the extreme left position
a little confused with the 90 deg left and 180 deg right, the rack only allows for 180 deg total, unless it is a rack driven rod - and any gearing on the arms can effect the amount of arc - re wiring change, some use a third brush as the second speed, and micky-ing the wiring can cause headaches getting them to work in proper sequence - not impossible - and better done on the bench than under the bonnet up behind the plenum over the top of the carbs etc with both feet off the ground and the rad cap gouging your balls, plus you just know one of the kids is going to get in the open door without you knowing it and toot the horn resulting in lacerated hands and a huge gash to the rear of the head - and a terrified child as you get yourself untangled (silently!)
smac, Feb 10, 8:51pm
It's not sweeping 90 then coming back 180 then another 90, the two 90's are simply the halves of the same 180 sweep. SO when they first move, they are finishing the sweep that they started just before they parked. SO rack and motor are out of sync by a quarter turn.

It's Friday.beer oclock, hopefully you can follow that.
bigfatmat1, Feb 10, 11:34pm
ya need to pull the arm off the shaft of the motor its a taper spline pull the wiper arms off tapered spline turn wiper motor on and off. So it parks. Line all up so all sweeping correctly. Put ya arms back on. can be a little tricky the first time ya set wipers up. good luck and dont work on them with the motor plugged in if ya want to keep ya fingers
socram, Feb 11, 12:17am
Thanks for that - all 3 are good posts.It makes sense - and I do have a spare motor I can play with on the bench first!Thanks for the finger trapping warning too - always pays to be extra careful.

The motor is installed inside the car and I need to set it all up properly before I bolt in the new (home built) dash permanently - which is now getting pretty close. Only taken 6.8 years to get to this stage.
skin1235, Feb 11, 12:58am
BFM1's fix will only work if it completes a full sweep in one direction when started - you indicate it does a half sweep left then the full sweep right and parks in the midle position

edit I checked again, BFM1 is talking the actuator arm off the motor ( or gear) - if this can be done it will work as you want, it must be refitted at the suitable extreme of directional travel

can you post a pic of the spare motor socram, theres something not adding up here
I'm trying to picture the original location and method of activation ( I recall the motor bolted to the firewall and the actuator linked to the wiper linkages inside the dash area - they were not a center park single blade so the actuator should be in the extreme left or right position, from you say it is in the middle position,
Allowing that it is not original to that body and allowing that you have mounted it to suit your application, I'd suggest you may have mounted the motor a 1/4 turn (90 deg) away from it's original horizontal or vertical position and thus the actuator is now in the middle of it's stroke not at the end
This may be adjustable or may mean remounting the motor in it's correct plane
I also think they were a lucas motor and most of the lucas were adjustable by turning the back plate
bigfatmat1, Feb 11, 1:33am
I think the problem is both the crank on the wiper motor and the position of the arms sometimes you need to take them out adjust put back in adjust put back in ect can be frustrating to line up done many in my time lol
socram, Feb 11, 2:07am
Hmm. I don't think the plane is the problem.Give me a day or two and maybe I'll have a pic of the spare, but I might just have a pic of the current one when I took the lid off!.
smac, Feb 11, 2:37am
Was that 'parked' before being dismantled! If so the arm should be at 12 oclock or 6 oclock compared to the line of the cord (or whatever you call the bit that goes off to the wipers). Where it is now it's going to behave exactly as you describe above: 90 wipe, then 180, then 90.

Edit: oh, and did I mention a quarter turn in my first post! ;)
socram, Feb 11, 3:09pm
I have no idea if it was in park in the pic!The guy who modified the motor/rack for me may have tested itfirst but without it parking, so your explanation makes a lot of sense. Thanks.
smac, Feb 11, 3:25pm
Right, so if you remove the arm, turn it on and off so it's parked, then put the arm back on at 12 or 6 depending on whether they are park left or right (possibly not in that order!).
socram, Apr 8, 9:13am
Rain-X won't pass the Wof papa! Wipers will.

Thanks smac.Sounds totally logical.