Wiper motor sweep?

[cswagon1]

My driver's side wiper over-sweeps the windscreen by about 2 inches so I am guessing that someone
has either changed the motor or just the cog for the wrong one, unless somebody has any other explanation please.

Would any one know what I should be looking for, in degrees sweep, for a '71 van please, or be able to offer
any other advise regarding the problem.

Many thanks

Graham.

[cswagon1]

Picture for identification hopefully.

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[svenedin]

I presume the sweep of a 71 van is the same as my 69 convertible. Basically all the parallel moving wiper types are the same sweep (not split-screen or clap hands non split-screen).

To check which gearwheel is installed you need to remove the wiper motor gearbox cover. It is secured with 4BA hex head machine screws. So use a 4BA socket. Before you unscrew the cover, mark the position of the dome part with the red wire attached to it in relation to the flat part of the cover. This is important to keep the self-parking adjustment correct.

The correct gear wheel is 150 degrees as shown in my phone in the red circle

But just to confirm first, your wipers are starting from. the bottom of the screen? If they start too far up the screen the driver's side one will hit or go off the edge of the screen.

Stephen

IMG_1382.jpeg (3.02 MiB) Viewed 54187 times

[cswagon1]

Many thanks for your reply Stephen,
I have tried setting the wiper blades in different positions and if it is set to be correct to stop before it
flies off of the screen then when it comes back down it bashes against the lower part of the screen
as if it's trying to go further.
That is why I wondered if it had the wrong gear in there, but now you've told me what it should be
then I can open it up and see if that is what I have.
Thank you for that very useful bit of info. much appreciated.

Graham.

[svenedin]

Ok Graham you're welcome. There are other possibilities for your wiper behaviour. The rack could be so worn that the wiper wheel box gear wheels are slipping. The rack is basically a long coiled wire that goes through the Bundy tube from the wiper motor and then engages with a gear wheel connected to the wiper arm spindle. Try to wiggle the offending wiper arm back and forth and see if it slips. If it does, that is the problem. The other possibility is the wrong wiper wheel box.

If you do take the lid of the gearbox part of the motor, take the opportunity to clean out any hardened grease and replace with fresh grease. I found high temperature lithium bearing grease is best. Ordinary lithium grease melts in the hot engine bay and tends to leak out.

Stephen

[myoldjalopy]

At least the motor is easily accessible in this particular case - in earlier cars, like mine, it is hidden away behind the driver's glove box liner

[svenedin]

At least the motor is easily accessible in this particular case - in earlier cars, like mine, it is hidden away behind the driver's glove box liner

Absolutely and the parts are even more scarce for those older wiper motors.

It's a bit strange that the later wiper motors (Lucas DR3a) are so expensive. They were used on many cars in the 50's and 60's and are not by any means Minor specific. I think the reason is that the DR3a was an outdated type of wiper motor that happened to still be used in Minors right up until the end of Minor production. Other cars in the late 60's and early 70's were using later 2 speed wiper motors so there weren't that many DR3a made by that point.

A basic overhaul of the motor is not difficult. Basic being strip down meaning: clean out old grease, clean commutator, check and replace carbon brushes if necessary, oil motor spindle bearing, adjust spindle end-float, re-pack with grease, paint motor housing if wanted. Usually the wire going to dome part of the gearbox housing is very elderly and worth replacing (needs a fairly powerful soldering iron).

Stephen

[cswagon1]

Thank you once again for your excellent and detailed reply Stephen.
I'll take on board all of your suggestions and once this madness of next week has
abated I'll have a more in-depth look at the problem and try to find a solution.
In the meantime, if it rains too hard I'll take my old Land Rover.

Thanks again

Graham.

[svenedin]

No problem Graham. I know what you mean. I will be glad to return to peace in the New Year!

We can help you on this forum with every aspect of the wiper system wherever the problem lies. It is a tedious job if you need to get to the back of the wiper wheel boxes because the gloveboxes have to come out to access them. If the rack has to be withdrawn it's like dealing with a super greasy snake. Messy but one step at a time.

Have a great Christmas.

Stephen

[Peted7202]

What are the numbering detail on top of the box?

[svenedin]

What are the numbering detail on top of the box?

Voltage, Model number, date (month, year) and other numbers that presumably relate to model variants, possibly related to revisions and the gear wheel sweep originally fitted.

Stephen

IMG_1383.jpeg (1.88 MiB) Viewed 53491 times

[Peted7202]

I meant on cswagons box.

[Davemate]

I replaced one of my wheel boxes from a reputable supplier and the sweep was completely wrong, “had no complaints so far” was their response
After delving deeper into the issue I found that the original wheel boxes are stamped with this number and the supplier are simply wrong
Once I got a replacement box stamped with the correct number the sweep was spot on and matched the other side
I don’t know how to post a picture but this is the number of the original 72790A

I’d would check what wheel boxes you have if both of the sweeps are different from each other

[svenedin]

I replaced one of my wheel boxes from a reputable supplier and the sweep was completely wrong, “had no complaints so far” was their response
After delving deeper into the issue I found that the original wheel boxes are stamped with this number and the supplier are simply wrong
Once I got a replacement box stamped with the correct number the sweep was spot on and matched the other side
I don’t know how to post a picture but this is the number of the original 72790A

I’d would check what wheel boxes you have if both of the sweeps are different from each other

Yes I have had exactly the same problem. However my problem with incorrect replacement wheel boxes was insufficient sweep not too much. Also if the wheel boxes are different from each other it will be immediately obvious because the wipers won’t stay parallel.

Stephen

[Davemate]

Original post only said the drivers side is over sweeping hence why I suggested checking both wheel boxes are the same as I’d say that they are probably different if one side is ok. Would have thought if it was the motor then both would be out but by the same

[cswagon1]

So, I managed to spare a few minutes today to have a look at the wipers and I've been trialing the position of
the wiper arm on the spindle and I hope i have improved it to the previous position.
The passenger side sweeps the same arc, if I've measured it correctly, but as it has the full screen it doesn't hit
anything.
I've only been able to replicate rain using the washers but at least they allow the wipers to move without any
resistance. I checked for numbers on the outside case but I only have the one line which is exactly the same
as Stephen's bottom line.
I'll check their performance in the rain when I have the opportunity but for now they seem much better.
When I get chance I'll also take the top cover off and have a look at the state of the grease and check the
sweep number as well.
Once again thank you for all your help and advice, it's very much appreciated.

Graham.

[cswagon1]

IMG_0057.JPG (1.38 MiB) Viewed 53102 times

Just for reference.