Windscreen Wiper Boxes

[simmitc]

A crossover between mechanical / bodywork / and electrical, so let's see what comes out....

Standard 2-door saloon manufactured in 1968 with standard 1098cc engine. About ten years I purchased and fitted new wiper boxes (allegedly for a 1968 car). The sweep of the arms changed from covering the full width of the screen to each arm moving less than 90 degrees, leaving large areas of the screen unswept. I refitted the original boxes and the wipers went back yo normal. The gear wheel in the wiper motor is stamped with 150 degrees.

Last year I fitted a new wiper motor. The wipers worked correctly.

This year I purchased another pair of new wiper boxes, from a different trader, and again for a 1968 car. Having fitted the second pair of new boxes, the wipers are again sweeping less than 90 degrees. Having previously changed the motor and checked the gearing, it is clear that it is the new boxes that are wrong. I have refitted the old (and now very worn) boxes, and the wipers work normally again.

It's difficult to believe that all the trade is selling incorrect boxes and that no other owners have noticed, but I do have a problem with new wiper boxes.

The older boxes are stamped with part number 72790A. The new ones with 72879A 2WB and 46 08. Does anyone know where I can get new (not used) wiper boxes to match 72790A; and has anyone else experienced this problem?

[charlie_morris_minor]

i am about to take apart my wiper.. thanks dennis they arrived this morning.. so will take a note of the numbers.. will hopefully do this tomorrow after I have fitted my new trafficators..

[mike.perry]

Surely the wiper throw is controlled by the crank on the wiper motor. The wheel boxes turn according to the amount of movement of the rack which is connected to the crank. Alternatively the gear wheels in the wheel boxes are different sizes.
Have you compared them? I only have a Series MM and a later box with identifying number 126930 ? and the gear wheels are the same size but different pitch

[Kevin]

Hmm that's strange it sound like they have been set up for a splitscreen if they move under 90degrees maybe its a mix and match of some components between the different wiper motors.

[chickenjohn]

-snip-.

This year I purchased another pair of new wiper boxes, from a different trader, and again for a 1968 car. Having fitted the second pair of new boxes, the wipers are again sweeping less than 90 degrees. Having previously changed the motor and checked the gearing, it is clear that it is the new boxes that are wrong. I have refitted the old (and now very worn) boxes, and the wipers work normally again.

Yes, i have had exactly the same problem on both my Traveller and convertible- each had a siezed wiper wheel box. On replacing the siezed item with new, I was dissapointed to find the new boxes only sweep less than 90degrees as quoted above.

Poor quality modern repro parts, I'm afraid! Currently on the lookout for good 2nd hand items that I can grease up and keep going.

Modern repro parts are rubbish!

[aupickup]

see the forsales i do have some good used 1098 wheel boxes same price as the 948

[mike.perry]

Different wheel boxes must have different size cogs or they would all move the same amount for a given motor. It must be possible to compare the sizes. I would suspect the smaller the cog, the smaller the angle of sweep.

[bmcecosse]

Quite the opposite I think!

[charlie_morris_minor]

you think right roy the motor turns a wheel which has an off centre crank and it is that which should govern the sweep..

i did not manage to get around to takign the boxes apart, fitting my trafficators took longer than i thought but they work

[bmcecosse]

This is more the eccentric crank I'm used to - and a return crank too!

[frame][/frame]

[mike.perry]

You are probably right Roy, if you say something incorrect someone is bound to pick it up which at least gets people thinking. The fact remains that if the motor and crank stay the same and the wiper arc changes then the wiper gearboxes must be different. It just needs someone with a variety of wiper boxes to check the theory

[simmitc]

I've checked three different Minors now, and all have the same part number on the wiper box. All fitted and spare wiper motors have the same gearing. Clearly the new wiper boxes do not match the specification of the ones fitted to the car. One trader commented "No, they're not original, but they're MG, and the closest we can get".

I would be grateful if anyone takes their glove-box liner out, just shine a torch upwards and report the part number on the wiper box. I can then investigate further. The item that the traders are supplying must fit something, but clearly not all Minors! Thanks.

[aupickup]

part no on the 948 clap hands wiper box is 72693D

[svenedin]

Old thread revival but this issue is still going on……..

Link is to my current problems with exactly the same issue

viewtopic.php?t=75785&start=40

[simmitc]

I read the original problem but did not read all replies, so apologies if this is duplicating anything.

Yes, it is a common problem. Kit car parts suppliers seem to be selling two different boxes, neither of which gives the correct sweep. I have purchased boxes from several Minor specialists, some now out of business and some still trading. They all supplied exactly the same boxes which matched one of those available from the kit car people. When challenged, the stock answer is that (a) that is all that is available and (b) nobody else has complained.

You can get more life out of your boxes by turning the wheels through 180 degrees so that the rack operates at least partially on unworn teeth. Otherwise, second hand is the answer. You can fit new embellishers and nuts to make them look nice and shiny.

It's all to do with gear wheel circumference and the number/spacing of teeth. The problem will persist until someone makes the correct boxes again.

[svenedin]

Yes exactly that. My thread has further details. Unfortunately my wheel boxes are seized. I have discovered that at one time the spindle, gear and splined part were supplied as replacement parts. It may be possible for me to disassemble the wheel boxes to remove the corrosion that is causing them to seize.

[jeff-d]

hi, i have found a supplier that sells old but new wiper boxes on ebay they are called jolly-old-car-spares-ltd hope this helps

[taupe]

Yes exactly that. My thread has further details. Unfortunately my wheel boxes are seized. I have discovered that at one time the spindle, gear and splined part were supplied as replacement parts. It may be possible for me to disassemble the wheel boxes to remove the corrosion that is causing them to seize.

Yes I did that on my traveller wheelboxes and got them nice and free then lubed up... also replaced the spindle rubber seals at the same time

Taupe

[svenedin]

Yes exactly that. My thread has further details. Unfortunately my wheel boxes are seized. I have discovered that at one time the spindle, gear and splined part were supplied as replacement parts. It may be possible for me to disassemble the wheel boxes to remove the corrosion that is causing them to seize.

Yes I did that on my traveller wheelboxes and got them nice and free then lubed up... also replaced the spindle rubber seals at the same time

Taupe

I never worked out how to take them apart without destroying them. It seems the end of the spindle is peened over on my wheel boxes. Despite my efforts to explain the problem of the new wheel boxes to the supplier, they have not changed their website so the problem persists and others will be caught out with new wheel boxes that reduce the arc of the wipers.

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