Wiper Problem (possibly fixed)

[svenedin]

The arc of the wipers is, as expected, better with a wet screen but I am still not entirely happy with them. To get to the right hand side of the driver's side of the screen the wipers need to start from a park position that is a bit too high on the screen. I have checked and I have a 150 degree gear wheel in the motor. I don't know whether they come with a wider arc than that. The other solution is to try to find original wheel boxes (Lucas 72790A; ADA4175) in good condition. All rather annoying to find the parts supplied are not right after all the work involved in fitting them!

[svenedin]

I had the car out in the rain today. The right hand wiper does now reach the right hand side of the windscreen but only from a rather high park position. I found it slightly annoying to be able to see the wipers in their park position whilst driving. I have asked the club spares if they have any of the correct wheel boxes. I hope they do but I dread having to do the job again! At least it will be quicker this time. It will still take me several hours though.

[svenedin]

I counted the number of teeth on the old Lucas wheel box (28) versus the modern LAP wheel box (32). Given the tooth spacing has to be the same (because it has to match the rack) this is why the wheel on the new wheel box is bigger (it has more teeth). For the same lateral movement of the wiper rack (which is determined by the gearwheel in the motor) the new wheel boxes cause the wipers to describe a smaller arc. Conclusion: I will have to replace with original wheel boxes if I can find them in good condition.

[geoberni]

I counted the number of teeth on the old Lucas wheel box (28) versus the modern LAP wheel box (32). Given the tooth spacing has to be the same (because it has to match the rack) this is why the wheel on the new wheel box is bigger (it has more teeth). For the same lateral movement of the wiper rack (which is determined by the gearwheel in the motor) the new wheel boxes cause the wipers to describe a smaller arc. Conclusion: I will have to replace with original wheel boxes if I can find them in good condition.

So this seems a fundamental design error, it's not right. You got them from ESM as I recall.


So questions to be asked are:
Did you order the correct wheel boxes?
Did ESM send you the ones you ordered?
Have ESM been supplied with the right ones by their manufacturer?
Take it up with ESM, it wouldn't be the first time that they've had a supplier issue; later heater valves comes to mind.

I must admit the images you've posted of the boxes fitted do seem to match the post 63 ones on the ESM website.

[svenedin]

I counted the number of teeth on the old Lucas wheel box (28) versus the modern LAP wheel box (32). Given the tooth spacing has to be the same (because it has to match the rack) this is why the wheel on the new wheel box is bigger (it has more teeth). For the same lateral movement of the wiper rack (which is determined by the gearwheel in the motor) the new wheel boxes cause the wipers to describe a smaller arc. Conclusion: I will have to replace with original wheel boxes if I can find them in good condition.

So this seems a fundamental design error, it's not right. You got them from ESM as I recall.


So questions to be asked are:
Did you order the correct wheel boxes?
Did ESM send you the ones you ordered?
Have ESM been supplied with the right ones by their manufacturer?
Take it up with ESM, it wouldn't be the first time that they've had a supplier issue; later heater valves comes to mind.

Hello Berni

Thanks for taking the trouble to share my concerns about this. In answer to your questions:

Yes the new wheel boxes came from ESM

1) Yes I ordered the correct wheel boxes for a post October 1963 car as far as ESM are concerned
2) Yes ESM sent what I ordered
3) LAP, based in England make these parts. I have looked at a pdf written by LAP. They make 2 types of wheel box. One is coded 2WB and has 32 teeth. The other is coded 3WB and has 40 teeth. LAP say the angle is 130 degrees when used with a 2WB. This is obviously not enough. They do not make a 28 tooth box.
4) I did better than take it up with ESM. I drove a 94 mile round trip to ESM yesterday (car also needed a gearbox oil change as it is recently rebuilt). I explained the issue, showed the mechanics, showed them pictures of the wheel box internals but all they said was "we haven't seen this problem before". There was no offer of a refund or solution but they did not charge me for the gearbox oil change. I said I was going to have to do this messy and tedious job again if I can source the proper parts.

Here is what I found from LAP: http://www.lapelec.co.uk/files/products ... ations.pdf (the motor in this document is not a DR3a but the principle is the same).

Funny you should mention later heater valves because mine exploded a few weeks back........I also discussed this with ESM and they assured me that the current ones are not the exploding type.

Here is the problem in pictures. The wipers have to park this high to reach the edge. You can see in the dirt on the screen where they reach.They could maybe park one spline lower in actual fact but it still would not be how it should be.

There are old threads from 10 years ago or more about this wiper problem (missing their pictures) and it the same problem that never got addressed. I foolishly thought that it would have been resolved by now when I ordered the parts (I had read the threads before I did the job).

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IMG_8612.jpeg (2.99 MiB) Viewed 1036 times

[geoberni]

Quite a conundrum, not one I'll face as I have a '55 SII, and nobody seems to list those wheel boxes.

I did note this website this morning though: https://www.lmslichfieldltd.com/Wiper-W ... x-31-teeth
It looks like these might be NOS as they state they were "supplied for a special MOD kit for the Army, Ex Military vehicle surplus".

The company are specialists in Gov surplus motorcycles, but they have lots of other vehicle surplus stuff

[svenedin]

Yes a tricky one but for now at least I have functioning wipers. The only other thing I can think of is the pitch of the rack. The rack is basically a spiral wound wire around a braided core. I did replace the rack as well as the wheel boxes. I did not do a direct comparison of old and new except the length. It seemed sensible to me to replace both at the same time. I could compare them side by side as I have kept the old rack but I doubt this has anything to do with it.

[svenedin]

This problem has been going on for a long time and has not been resolved.

Here is exactly the same issue from a post in 2010: viewtopic.php?t=33625

[svenedin]

MMOC spares have managed to find 2x original wheel boxes. I will fit these and hopefully everything will be back to normal. These Lucas 72790a wheel boxes are now very scarce.

[svenedin]

This dull and irritating saga is now over! I spent the best part of 4 hours taking the useless new wheel boxes out and installing good original wheel boxes. A Sunday of fiddly work behind the gloveboxes and copious grease at the rack end. All of today’s faffing about would have been avoided if the parts suppliers sold the correct parts. Wipers now work absolutely perfectly with the correct arc/sweep.

Somebody asked me what size the E-clip is on the wiper motor, I forget who asked but I said I would measure which I have done. As far as I know, E-clips are sold by the size of the shaft that they fit. Allowing for measuring error I believe this is 7/32”. Assortments of Imperial E clips are available from Frost and enough to last a lifetime.

IMG_8661.jpeg (1.41 MiB) Viewed 933 times

It looks like this:

IMG_8662.jpeg (2.01 MiB) Viewed 933 times

[tomb1963]

Interestingly I discovered the same issue with the wiper arc and wheel boxes at the back of 2020.

viewtopic.php?hilit=wiper&p=664399&sid= ... b4f7ea1a26

It's now made me wary of so called replacement parts.

[svenedin]

Interestingly I discovered the same issue with the wiper arc and wheel boxes at the back of 2020.

viewtopic.php?hilit=wiper&p=664399&sid= ... b4f7ea1a26

It's now made me wary of so called replacement parts.

I wish I’d seen your thread before I put the new wheel boxes on! What irritates me is that the job took me a long time and I did it methodically and well and then I find out it’s never going to be right with those wheel boxes. Then I had to do it all over again with original wheel boxes. I wish the parts supplier had a warning in the part description. I am also now quite wary of replacement parts. It’s a minefield.

Stephen