Wiper Motor Sweep

[alexb1406]

I'm sure someone will have the answer to this - I've searched the forum and googled it but can't find what I need.

I have a USA Series 3, still a LHD, and although I've put up with the problem since I've had the car I've now decided it's irritating me! The wiper motor appears to have a very short sweep - the blades park on the left, driver's side (lhd) but when switched on the right hand blade only travels about 90% to the vertical position leaving a third of the screen unswept on the right. The left hand blade travels a little further and just (but only just) overlaps the sweep of the right hand blade. Is this normal? There doesn't appear to be any slack in the linkages.

If this is not right then the next question to ask is whether this is supposed to be a reversing motor (Lucas 15W) - it only runs one way but having looked at the wiring this does appear to be correct.

Before I dismantle the motor can someone tell me what the degrees travel of the gear should be - this is the only thing I can think of that may be wrong, though having said that it doesn't look like it's been messed about with, but then it is 40 years old and every garage in Arizona has probably played with it!

Or, does anyone have any other ideas?...

[christopher storey]

I am not conversant with S3 which may be different, particularly if yours is a 2+2 with only 2 wipers, but with the 6 cylinder cars with 3 wipers , to alter the setting from LHD to RHD, you need to remove the wiper rack and transpose the two outer drive boxes by unbolting them and reattaching to the opposite end .

[PeterCrespin]

All Series 3 are twin wiper cars Chris.

Alex, there are inevitable compromises when choosing wiper arc with a conventional two-arm system. I'm assuming the wipers currently park very low on the screen, which is nice and tidy. If you rotate them one spline clockwise they will tuck in slightly less but sweep further.

I like my wipers to be as low as possible but having them so low that they strike the screen seal eventually damages the blade edge and is perhaps too much of a good thing if that's where yours go. A spline or two further round might be a better balance for you if the unwiped notch mid-screen or right side annoys you.

It is also possible the wrong arms or blades are fitted. There is a greater range of lengths and arm-end angles than people appreciate and some experimentation can improve things. The left arm end tweaked a little bit straighter would pitch the top of the blade further round and although it might sit tiny bit higher at the outer end when parked it could be enough to get rid of the notch. Same goes for fitting a fractionally longer right blade. It's a case of trial and error to see how far you can push the tweaks without the blades tangling.

[alexb1406]

Thanks for your help guys - Chris, yes this is a series 3 with twin wipers and I do not plan to convert to RHD at present, in fact I will probably never do it, mainly because I get to keep the original air-con (has a leak at present but one day I will sort it!).

Peter, I will try to play a little more with it tomorrow if I get the chance but the wipers don't park that low on the screen - I don't think they actually touch the screen rubber but I'll have another look to confirm. I am sure though that the problem is more than just moving them over a notch or two - the right hand one only goes up to the vertical position and I'm sure that can't be right. I think you can get different gears for the motors that give you wider or smaller arcs of travel depending on the car, and at the moment I suspect that may be where the problem lies, but I can't find any information as to what the correct gear is for this car.

[alexb1406]

Had a look at it again today and also spoke to Steve Hunt who quite rightly pointed out that the sweep is not controlled by the gearing - it's the length of the link attached to the motor - I should have known this, obvious when you think about it - I was getting confused with the rack type linkages that are controlled by the gear. He said the same motor is used on minis and Triumphs so he suspects someone may have put a motor in from another car. I removed the motor to have a look and the link is stamped 1.565 - this being the length in inches between the hole centres.

Does someone have a motor lying about that they could look at the link and tell me what length it is - I think this is the obvious place to start.

[MarekH]

Dear Alex,
You may be onto something there - I measure my s3 wiper motor at just under 1&11/16" - that is nearly 1/8" more throw than you report.

To make the measurement, I removed the circlip and used dividers from inside the bulkhead. Without further disassembly, there was no obvious mark stamped onto the link that I could see.

kind regards
Marek

[alexb1406]

Great! Thank you Marek! Can you confirm this measurement was taken from the centres of the two joints? - and taken straight across without taking the kink into the measurement? If so I think we've cracked it! Now I have to find one...

[MarekH]

Alex,
Come and measure the part yourself if you want to.

Stop fretting and just take your link out, put it in a vice and spread the two 90 degree bends out a bit and reassemble. Satisfy yourself that you won't foul the captive nuts on the inside of the bulkhead which hold the motor and test your wipers for sweep. Readjust if necessary.

kind regards
Marek

[alexb1406]

Of course...but why do it the easy way when you can make a meal of it?!?

Thanks Marek, that's exactly what I'll do!...em, I mean bending the link, not coming down to measure yours but thanks for the offer!

[MarekH]

If you really want to be clever, Dremel out the end to turn it into a Y-fork (or make the hole at the motor end more oval), then you will be able to set it at any desired length. You'll need to scribe it to reassemble it, were you to take it apart at a later date.
kind regards
Marek