JRCWeedon Posted October 13, 2016 Report Share Posted October 13, 2016 Hi All I seem to be back in the fold having bought another TR4!! As the windscreen wipers only go halfway across the screen I suspect it has the wrong gears in the motor - the thing is what is the correct one and are spares available from anyone? Regards John Quote Link to post Share on other sites
TR NIALL Posted October 13, 2016 Report Share Posted October 13, 2016 (edited) Welcome Back John,Search for Wiper Motors and you'll find plenty of stuff from AlanT he's our Wiper Expert. Edited October 13, 2016 by TR NIALL Quote Link to post Share on other sites
peejay4A Posted October 13, 2016 Report Share Posted October 13, 2016 (edited) It's possible that the wrong gear is fitted but more likely that you have wear in the rack and/or wheelboxes. It may also be that the wheelbox clamps are loose allowing the rack tube to move around. The standard gear wheel should be marked 120 degrees. Edited October 13, 2016 by peejay4A Quote Link to post Share on other sites
JRCWeedon Posted October 14, 2016 Author Report Share Posted October 14, 2016 It's possible that the wrong gear is fitted but more likely that you have wear in the rack and/or wheelboxes. It may also be that the wheelbox clamps are loose allowing the rack tube to move around. The standard gear wheel should be marked 120 degrees. Many Thanks Regards John Quote Link to post Share on other sites
AlanT Posted October 14, 2016 Report Share Posted October 14, 2016 (edited) I make these gear wheels by moving the crank-pins about. A movement of 0.005in produces a 1 degree change in sweep. Â Another way to look at this is, quite small amount of wear in the wire-rack, wheel-head gears, the rack-nipple, the crank-arm and the crank-pin can all add up to a lot of slop at the blade tip. Â Take the cover-plate off the motor, so you can see the wire-rack and nipple. Move the blades and see how far they go without the crank-arm moving. The fourth screw will have you swearing! Â 120 degree wheels are hard to find and actually a bit too much sweep really. a TR6 uses 115 degree. Â Often 100 degree degree wheel from Morris Minors get fitted. But more commonly sweep seems to be too big due to wear. Â Probably the first thing, the easiest thing is a new wire-rack. Try to get NOS and simply cut to length with a grinder. Don't be afraid to pull the wire-rack out. They slide back in quite easily with a bit of wiggling. Â Replacing the wheel-heads is AWFUL. Sometime you can find a section that is unworn. Remember only about one third of the teeth are in use. Â Ask if you want some photos. I have loads. Edited October 14, 2016 by AlanT Quote Link to post Share on other sites
stuart Posted October 14, 2016 Report Share Posted October 14, 2016 John Remove the wiper arms and mark a dot with Tippex on the top side of the knurling then pull the rack cable out and turn the wheel-box stubs 180 and refit the cable so when in place your marks are opposite where they were this will allow you to use the unworn sections of the drive cogs. Stuart. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 14, 2016 Report Share Posted October 14, 2016 Hi All I seem to be back in the fold having bought another TR4!! As the windscreen wipers only go halfway across the screen I suspect it has the wrong gears in the motor - the thing is what is the correct one and are spares available from anyone? Regards John John, What shape is the wiper motor body - square or round? Square is correct original . Round is TR6/Defender What shape are the nuts on the wheel boxes 6 or 8 sided - This will tell which wheel boxes you have fitted are there are two types with different amounts of teeth. 6 sided is correct for orig TR4 with square motor. 8 sided is correct for TR6 which has the round body wiper motor. Â Cheers Peter W Quote Link to post Share on other sites
AlanT Posted October 14, 2016 Report Share Posted October 14, 2016 Original TR4 motor looks like this   Gear looks like this:  Quote Link to post Share on other sites
JRCWeedon Posted December 6, 2016 Author Report Share Posted December 6, 2016 Hi All Apologies for the long delay between posts! I have the correct motor (square) and having taken off the cover expected to see the wrong gear wheel but no I have the 120 deg one. The wheel boxes are correct I am told by TR enterprises they do have 6 flats on the nuts. To my mind this only leaves the rack - as the wipers are only going halfway across the screen it seems unlikely to be wear/slop. Moss list the same part nos for the rack for TR4 - 6 I thought they were different. Any advice gratefully received. Regards John Quote Link to post Share on other sites
AlanT Posted December 6, 2016 Report Share Posted December 6, 2016 http://www.ebay.co.uk/itm/AUSTIN-MORRIS-MG-BL-LUCAS-WIPER-DRIVE-CABLE-RACK-LUCAS-743251-BL-RTC202-/282268605015?hash=item41b8851a57:g:RC4AAOSwYGFUy4B0 Â They are mostly the same except for length. Cut off to suit with angle grinder. Â I always look for NOS. Â How much slop at the end of the blade? Â Remember 1 degree of slop for every 0.005in wear. Quote Link to post Share on other sites
JRCWeedon Posted December 7, 2016 Author Report Share Posted December 7, 2016 http://www.ebay.co.uk/itm/AUSTIN-MORRIS-MG-BL-LUCAS-WIPER-DRIVE-CABLE-RACK-LUCAS-743251-BL-RTC202-/282268605015?hash=item41b8851a57:g:RC4AAOSwYGFUy4B0 Â They are mostly the same except for length. Cut off to suit with angle grinder. Â I always look for NOS. Â How much slop at the end of the blade? Â Remember 1 degree of slop for every 0.005in wear. Hi Alan I have got 2.5ins of slop at the wiper blade thanks for the link I will buy it as soon as I can get broadband to work!! Regards John Quote Link to post Share on other sites
AlanT Posted December 7, 2016 Report Share Posted December 7, 2016 (edited) When fitting the new rack, try to find a bit of the wheel-head gear with less wear. Only about one third gets used.  Ensure the outer rack-tubes are all tight.  This may help: http://www.ebay.co.uk/gds/What-Could-Possibly-GO-WRONG-/10000000211157905/g.html  and this:  http://www.ebay.co.uk/gds/Fitting-Instructions-/10000000208662078/g.html Edited December 7, 2016 by AlanT Quote Link to post Share on other sites
MikeF Posted December 7, 2016 Report Share Posted December 7, 2016 It's a good tip, but don't be too hopeful about recovering efficiency by turning/rotating parts. After 50 years or so it is unlikely you will be the first to do this. My wipers were so knackered I upgraded to TR6 wheel boxes and rack. The boxes are easier to fit and better designed and made, [the 4 boxes are the same as the side screen cars with their much smaller screen]. Easier to fit is true but minor as getting access is a right pig of work. I could not detect any difference between the '4 and '6 racks. Mike Quote Link to post Share on other sites
tim hunt Posted December 8, 2016 Report Share Posted December 8, 2016 The chance of finding NOS original Lucas wheel boxes is now pretty remote and if some are found they will likely command a king's ransom - here's a tip for anyone fitting replacement pattern type wheel boxes, which could save a lot of grief. AMHIK! This is a time consuming and fiddly job, definitely not one you want to repeat in short order, Before fitting to the car place the body of the new wheel box in a vice and insert the rack. Lock the wiper spindle in some way to prevent it turning and apply a high force to one end of the rack, this will simulate the high torque load should the wipers be operated on a dryish screen. This check is to ensure that under these conditions the rack and pinion remain engaged. On some pattern parts dimensional control on the manufacturing process is inadequate and it is possible for the rack to simply ride over the pinion under high loads. If this happens on test all that is needed is to dismantle the wheel box and carefully reshape the cover plate so that it holds the rack in close contact with the pinion but without it binding. Â Tim. Quote Link to post Share on other sites
AlanT Posted December 8, 2016 Report Share Posted December 8, 2016 Yes it's the rack-wires that are usually about NOS. Â The trouble with wheel-boxes is that there is a huge variety. Angle and length were both adjusted to suit body design. Â Although I have successfully "rehomed" a few it's much more difficult than motors, which are pretty much all the same. Â They are stamped with part-numbers though and the gears all pretty much the same. Quote Link to post Share on other sites
JRCWeedon Posted December 19, 2016 Author Report Share Posted December 19, 2016 Yes it's the rack-wires that are usually about NOS. Â The trouble with wheel-boxes is that there is a huge variety. Angle and length were both adjusted to suit body design. Â Although I have successfully "rehomed" a few it's much more difficult than motors, which are pretty much all the same. Â They are stamped with part-numbers though and the gears all pretty much the same. Hi Alan The saga continues! I obtained a NOS rack although it took forever to arrive installed it and it took up all the slack in the wheelboxes. Great then I discovered I still had slop at the wipers caused by (I discovered) considerable wear in the hinges of the wiper arms. Obtained some new wiper arms and they still didn't go across the screen fully ARGHHHHHHHHHHH. Then decided to recheck the gear wheel again and it was 120deg but it looked as though the teeth were worn down compared to the spare obtained on ebay.Oh well change them over and see if there was any difference and lo and behold they now work!! Thank you for everyone's input. Regards John Quote Link to post Share on other sites
AlanT Posted December 19, 2016 Report Share Posted December 19, 2016 If you have a poor plastic gear you don't need to find another 120 gear. The plastic comes off quite easily.so you can get a more common 150. These often come up NOS. I buy them just to get the plastic sometimes. Quote Link to post Share on other sites
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