Hi p8mog, thank you for the quick reply. Rgr ref the wiper arm fulcrum pins, that is useful info for me, thank you. Ref the judder, it might be worth doing what I tried this morning and spray on a soapy water mix while the wiper is working and see if the judder stops..if it does it points toward the blade to screen friction.. I would check to see if your wiper blade rubber is at 90 deg to the windscreen glass so its at the optimal position, if it isnt then you might need the wiper blade arm lightly bending at the wiper blade end to make this happen. This needs to be considered and undertaken carefully with specific tools. The fact that your judder is mostly on one arm/wiper suggests that the rubber blade angle presentation could be some of the issue. Its worth checking. In addition, you could consider to super clean the screen.
Dave Plus Six "Squeak" Roadster departed. 1936 BSA Empire Star Q8. 1935 BSA W7-35. 1938 BSA M20
Dave, my money is still on the spring tension under the arms is too high
One of my other classics runs on a dynamo and 50+yr old wiper motor, I treated it to new arms and the motor almost stalled due to the spring tension, put the old ones back with just new rubbers...sorted
Evening Jon, I do not disagree that the arms spring tension could be a contributing factor. Too much downward pressure of the arm onto the windscreen increases the loading and friction between glass and rubber ( stiction ).. In my cars particular case I have now found the remenant of a screen coating, plus in all three wiper arms there is a lot of arm side movement from play at the fulcrum pin, it does not look good there when the arm judders, also consider that the springs tension between the wiper arm sections is also spring loading closed the clearance and trying to hold it together.
I could now have three possible causes of judder.. A: Screen coating issues B: Too much play at the wiper arm fulcrum pin C: Possible high spring tension on the arms. I feel I can presently dismiss the rubber wiper blade angle to screen as that looks good on all three wiper blades during their operation.
I can physically see A and B. So far three CX owners report no play on their wiper arms.. so I think I should sort A first, then consider B then C. Anyway thats my thought process on this at the moment based on info so far.
Last edited by Davetherave; 28/01/2408:45 PM.
Dave Plus Six "Squeak" Roadster departed. 1936 BSA Empire Star Q8. 1935 BSA W7-35. 1938 BSA M20
MMC seemingly take delight in leaving as much wax polish on the windscreen as with the body when delivering a new car. My second long trip involved sustained heavy rain and the windscreen was very badly smeered by the end of journey. I bought a bottle of cheap vinegar based window cleaner and eventually managed to remove the surprisingly thick coating which transformed the wiper action and view through screen.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
Just out of general interest. I used a rifle trigger pull gauge to measure the Plus Six wiper arms spring force at the wiper blade. The measurement right at the end of the wiper arm at the wiper blade was consistent on all three arms at 1.5 lb ( 0.6803 Kg ). This figure was recorded just as the wiper blade started to lift from the windscreen.
Last edited by Davetherave; 29/01/2402:12 PM.
Dave Plus Six "Squeak" Roadster departed. 1936 BSA Empire Star Q8. 1935 BSA W7-35. 1938 BSA M20
MMC seemingly take delight in leaving as much wax polish on the windscreen as with the body when delivering a new car. My second long trip involved sustained heavy rain and the windscreen was very badly smeered by the end of journey. I bought a bottle of cheap vinegar based window cleaner and eventually managed to remove the surprisingly thick coating which transformed the wiper action and view through screen.
Originally Posted by Davetherave
Just out of general interest. I used a rifle trigger pull gauge to measure the Plus Six wiper arms spring force at the wiper blade. The measurement right at the end of the wiper arm at the wiper blade was consistent on all three arms at 1.5 lb ( 0.6803 Kg ). This figure was recorded just as the wiper blade started to lift from the windscreen.
Gentlemen, Your two comments, taken together, would justifiably interest a Morgan sherlock.
Dave? Have you tried a few windscreen scrubs with a vinegar-based window cleaner? At this stage, if it merely caused a change, you two are on the right track. I am going to try it on my car this summer.
gmg
P.S. We can also idly muse that different souls wash the new cars on Pickersleigh Road. Some may allow products to slop over the windscreen and others may not, which would explain why some CX cars are afflicted and others not. At least, that could be a theory. Everything has happened in the last 115 years. There are many stories.
Just to report that the latest variation of wiper arms arrived today and also the screen cleaning/polish products. So should have a chance to apply these tomorrow one step at a time and see if any improvement.
Neil A, thanks for your post ref the videos. The wiper blade rubbers are already at optimal position relative to the screen, this was tweaked some time ago, it still judders. Ref product application to coat the screen, it appears that half the internet postings say this is very bad and half say its very good.. At the moment the screen has the remenant of a coating, as this can just be seen when you squirt soapy water on and smear it across the screen. The plan is to first remove this old coating and see what happens ref judder, after that fit the new wiper arms one at a time and compare. Hopefully, one or both actions will help. Dave
Dave Plus Six "Squeak" Roadster departed. 1936 BSA Empire Star Q8. 1935 BSA W7-35. 1938 BSA M20
Just to report that the latest variation of wiper arms arrived today and also the screen cleaning/polish products. So should have a chance to apply these tomorrow one step at a time and see if any improvement..At the moment the screen has the remnant of a coating, as this can just be seen when you squirt soapy water on and smear it across the screen. The plan is to first remove this old coating and see what happens ref judder, after that fit the new wiper arms one at a time and compare. The wiper blade rubbers are already at optimal position relative to the screen, this was tweaked some time ago, it still judders. Ref product application to coat the screen, it appears that half the internet postings say this is very bad and half say its very good. Hopefully, one or both actions will help.
Good luck with that. I look forward to your findings.Very curious.
Your search findings are typical of today's internet. It is now common that most technical forums are public now. It is impossible to distinguish the definitive from the inane. Two decades ago we would NEVER dream of putting every technical musing up as the gospel. Nothing is lost by keeping messages private except high risk to enthusiasts.
As should be obvious by now, I did not receive any information we wanted about the suppliers from the Works. Their "hard times" policy of ending the once robust information flow between owners, dealers and the MMC continues, possibly unbeknownst to the current owners. Makes no sense for a tiny company but there you have it.
However, I am not without a few other resources it appears.
To whit: The label on the motor likely says: Britax PSV aka PSV Wipers Limited Unit 18 ▪ Kempton Road ▪ Keytec 7 Business Park ▪ Pershore ▪ WR10 2TA▪ United Kingdom Tel. +44 (0) 1905 350500 www.psvwipers.com
I have always found it very cute that the MMC tries to limit their technology, from wings on up, to something found within 30 minutes drive from Malvern. Adorable.
Are you nearby Malvern? Or would you prefer me to contact them? These people will ultimately be the most helpful.
It is now common that most technical forums are public now. It is impossible to distinguish the definitive from the inane. Two decades ago we would NEVER dream of putting every technical musing up as the gospel. 
Nothing is lost by keeping messages private except high risk to enthusiasts. 
Adorable.