RogerH Posted December 13, 2019 Report Share Posted December 13, 2019 Hi Folks, The 14W wiper motor is a good replacement for the TR4/4A DR3/3A. Bags of power and good speed. However my 1 1/2 year old motor had problems with the self park. It would run on for the odd sweep or two, finally not self parking. Having removed the switch (read below for the fun and games) I believe that the actuator pin on the self park micro switch had worn down a fraction. The new switch works as it should. To replace the switch one should be able to simply (Ho ho ho) slide it off the motor body. This is not possible as it abuts the plenum bulkhead. So remove the motor completely - this is easy and essential - read on. To test the switch you need to remove the motor from the body - two screws and pull the body off. You can now rotate the gear wheel (remove the drive cable) and hear the microswitch actuator pin popping in and out. Refer to the drawing below and put a meter across contacts 1 & 2 - a low Ohm range. Rotate the gear wheel and note that the reading goes open circuit when the pin is on the cam. Mine was still short circuit which is no good. Removal of the old switch - simply lift the free end (there is a little stop) and pull the switch away. Fitting the new switch should be the reverse. Well it is AFTER you have filed flats on the actuator pin support to fit the slot and removed casting flash to allow the spring clip to fit Once you have fitted the switch into the body along with the gear wheel (again) hook up the meter and rotate the gear wheel - if all is well you should get an open circuit with the pin on the cam. To fit the motor body back on the casting you need to lift the brushes out of the way. The simplest method is to use some thin string under the brush wire, lift away and tie off onto the casting body. Insert the motor and before the string is trapped forever cut it and withdraw. Takes about 1 hour and only a couple of curses. Roger Quote Link to post Share on other sites
ChrisR-4A Posted December 13, 2019 Report Share Posted December 13, 2019 Hi Roger, while talking wipers, have you tried the PIAA blade refill reference SKR52E from www.tdcautomotive.com. I recently fitted to my 4A and was surprised how much better than the rubber ones they are. Chris Quote Link to post Share on other sites
RogerH Posted December 13, 2019 Author Report Share Posted December 13, 2019 Hi Chris, haven't used them yet but am looking at them. As an aside I have just broken into the dicky switch and the simple microswitch is a change over switch - I'll have to think about this one. Roger Quote Link to post Share on other sites
RogerH Posted December 13, 2019 Author Report Share Posted December 13, 2019 Why is life so complicated. The pin under the self park cam does not simply disconnect the earth as in the DR3 (TR4/4A) but is a change over switch. I'm still trying to understand what it is changing over.!!! Anyway my plan to use a Hall effect sensor is still promising but it will have to drive a change over relay. A few wires and a following wind and It may work. The annoying thing is did my switch fail as a one in 100,000 chance or is a better solution really required. Roger Quote Link to post Share on other sites
RobH Posted December 13, 2019 Report Share Posted December 13, 2019 Could it be shorting the winding to electrically-brake the motor Roger? Quote Link to post Share on other sites
RogerH Posted December 13, 2019 Author Report Share Posted December 13, 2019 Hi Rob, yes, it certainly could be that, as it appears to be earthing one of the main wires that give the speed (probably the slow one). The armature is quite bulky and would take a little bit of stopping when the pin and cam co-incide. Roger Quote Link to post Share on other sites
mike3md Posted December 13, 2019 Report Share Posted December 13, 2019 I have been using the PIAA blades for a few years now on the 4, they are excellent. Less useful has been the Smartscreen variable intermittent wipe which had a mind of its own, and now removed after even the manufacturer couldn't solve the problem. Mike Quote Link to post Share on other sites
Lebro Posted December 13, 2019 Report Share Posted December 13, 2019 (edited) 5 hours ago, ChrisR-4A said: Hi Roger, while talking wipers, have you tried the PIAA blade refill reference SKR52E from www.tdcautomotive.com. I recently fitted to my 4A and was surprised how much better than the rubber ones they are. Chris I bought two of these recently. Cut one down to fit the drivers side of my Jeep Cherokee - much improved now get a completely clear sweep. The other one was cut down to make 2 X blades for the TR. Fitted, but not yet tried in anger. Bob. Edited December 13, 2019 by Lebro Quote Link to post Share on other sites
RogerH Posted December 18, 2019 Author Report Share Posted December 18, 2019 Hi Folks, I bit the bullet and bought another 14W motor and dash switch. I have trawled the internet and have found that the 14W motor is widely used. Guess what !!!! they ALL use different colour coding for the wiring. Many use relays to select a different speed. aaarrrrggghhhhh!!! However the regenerative breaking works very well. With no RB the gear wheel moves on another 20 -30 degrees after power off. With RB the breaking is instantaneous. The only problem I have at the moment is that the switch is upside down to work. eg the switch is down in the parked position. Yes I can turn it around BUT why is it different to the same switch number in the dash. I have noted that the wiring code in the Advanced Auto-wire site is different to that on the SVC site. Tomorrow I shall have a fiddle - watch out for the big bang. Roger Quote Link to post Share on other sites
AlanT Posted December 18, 2019 Report Share Posted December 18, 2019 (edited) Not only are all the wire colours on a 14W inconsistent, there is no part-numbering system to define the sweep angles or any other minor differences. At the same time they are all the same and all different. The plastic-plunger, operating the park-switch, is tiny and just looking for an opportunity to break. If you remove the cylinder from the gear-case, there is a ball-bearing for end thrust, that will make a break to escape and getting this back, when there is a large permanent magnet nearby, is amusing. And fixing the brushes needs a delicate operation to re-engage them. Just a few reasons I don't work on these. Edited December 18, 2019 by AlanT Quote Link to post Share on other sites
RogerH Posted December 18, 2019 Author Report Share Posted December 18, 2019 Hi Alan, you are spot on. Colour codes all over the place etc. However I have mastered the brush re-insertion. Roger Quote Link to post Share on other sites
AlanT Posted December 18, 2019 Report Share Posted December 18, 2019 Be careful with the ball-bearing Roger. Quote Link to post Share on other sites
tthomson Posted December 19, 2019 Report Share Posted December 19, 2019 On 12/13/2019 at 4:45 PM, RogerH said: Why is life so complicated. The pin under the self park cam does not simply disconnect the earth as in the DR3 (TR4/4A) but is a change over switch. I'm still trying to understand what it is changing over.!!! Anyway my plan to use a Hall effect sensor is still promising but it will have to drive a change over relay. A few wires and a following wind and It may work. The annoying thing is did my switch fail as a one in 100,000 chance or is a better solution really required. Roger Hi Roger, I spent some time working out exactly what the changeover switch does in the 14W motor. (see attached image). When the motor is switched off, it continues to turn because the power supplied on terminal 4 is connected via the changeover switch to terminal 2, which via the external wiring should connect to terminal 5 (slow speed connection). When the motor reaches it's home position, the park switch pin pushes the common connector of the changeover switch. This disconnects terminal 2 from terminal 4 and instead connects it to terminal 1 (ground). In this state, terminal 2 is still connected via the external wiring to terminal 5, and now also to terminal 1 (ground). Connecting terminals 2 and 5 shorts out the motor winding, which brings the motor to an abrupt stop from back emf. As far as I can see, connecting the coil to ground protects it from spurious voltage spikes. I have used two changeover relays to manage the external connections since to me that is the simplest way to achieve the required connections. (Others may have different ways to do this). Noting the relative ease in swapping the changeover switch, I would estimate that switch failure is not an uncommon occurrence! I hope that helps. Tony Quote Link to post Share on other sites
RogerH Posted December 20, 2019 Author Report Share Posted December 20, 2019 Hi Tony, have replied to your PM. Your above pic helps to see what is happening. Roger Quote Link to post Share on other sites
AlanT Posted December 21, 2019 Report Share Posted December 21, 2019 Earlier motors don't have this electrical-breaking feature. I doubt this is really needed. The rack-wire has quite a lot of resistance to stop the motor. The armature on a 14W will have about the same stored rotational energy as a DR3A. I'd guess they had in mind cars with longer and heavier wiper-arms and blades. However adding this feature into the switch/connector block was the cause of failure in a brand-new motor I fixed. You'll find photos of this if you look on here for the topic. Quote Link to post Share on other sites
RogerH Posted December 21, 2019 Author Report Share Posted December 21, 2019 Hi Alan, the regen braking does complicate things a little. I was wondering if it was really necessary - but it does stop well. However I've just come up with a simple electrical circuit to remove the contact pin and mechanical change over switch. I may be destined to have the only 'super duper everlasting' 14W motor. This after noon or tomorrow I shall have it running with the motor. At present I've only proved each part of the circuit. Roger Quote Link to post Share on other sites
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