Wipers

Section XXI Heater/Demister and Wipers

Following advice from NW RHOCaR members it has been decided to fit the Austin/Rover " Mini " wiper unit and a complete VW " Polo " heater unit. The Sierra unit is far too large. Both these are small compact units and are quite easy to fit into the restricted space. There is a selection of articles on the RHOCaR Web site and these are well worth a visit. Mini bits are quite hard to get hold of, so get one ASAP. Quite easy to remove, two Phillips screws and two chrome nuts. Literally a 5 minute job. Keep all the bits, including the mounting strap, mounting rubbers, 4 tapered spacers and chrome nuts, wiper arms and especially the motor plug c/w with some wire tails. See Appendix V in the Wiring section. While you are removing the wiper unit from the Mini take off the 2 plastic windscreen heater vents and the two convoluted heater pipes, again 4 self tappers, quite easy if you remove the windscreen first. Removing the Polo heater is another story !! Moss Europe can supply full spares for these Mini wiper units, as they were fitted to the MG Sprite's & Midget's as well. While you are in the yard find some good windscreen washer nozzles & pipes.

Wiper Unit Modification & Overhaul :-

As with the Sierra wiper unit the centre distance between the two wiper arms must be reduced. A lot easier with the Mini unit. As this motor assembly will be tucked away under the scuttle it is a good idea to give it a quick overhaul. First make sure it works, and then take off the flat cover followed by the spring clip and crank arm. The wiper rack will now fall clear. Keep the washers and clip in a safe place. Clean the crap off the outside and spread the internal grease around a bit on the worm & gear. Replace the crank, washer, clip and cover for the time being.

The centre distance on the Mini wiper arms is 17 1/2" (Check this) and the Robin Hood is only 8 1/2" (Check again) We therefore need to shorten the middle tube by 9" and re-form one end to the cone shape. Whatever you cut off the tube will need to be cut off the spiral rack as well, but leave this until it is all running again. These outer tubes CANNOT be bent without special tools, as they kink and reduce the internal diameter. These racks always seem very dirty so clean the spiral rack and the insides of the tubes and re-grease after cutting to the final length. Do not wash the wiper arm gear units in petrol as you cannot re-grease the spindle and you will only wash dirt into the bearings. Remove the large internal nylon gear, clean and re-grease. While you are at this stage check or replace the nylon micro-switch. Mine was faulty and caused the wiper fuse to blow every time it was switched on. The switch simply slides off the body, note the colours of the three wires. The whole lot can now be lubricated and reassembled ready to fit into the 2B. It is a good idea to check it works once again before final assembly.

It is essential that the park position is altered to the offside. With the unit dismantled this is quite simple. Just push the large nylon gear up the main spindle and re-locate rotated thro’180 degs. You may need to file the 2 nylon location dogs just a tad to give the gear a tight fit. This should give a park position on the offside rather than the nearside. The 110 ident on the crank plate indicates the full wiper arm movement of 110 degs. Other plates are available with different angles of sweep, but 110 degs is fine

Fitting the Wiper Unit into the car:-

The two gear units simply bolt into the pre-cut holes in the scuttle, with the 2 chrome nuts and tapered spacers, spindles pointing forwards, exactly as it came off the Mini. Fitting the motor was very easy, (once you know how) using the Mini fittings, fabricate a simple bracket from a piece of 25mm x 6mm St Steel flat bar and bolt the motor and bracket to the nearside chassis with a 38mm exhaust clamp. One leg of the clamp will need to be cut off so you can just get a nut on. Cut a piece of 6mm ply 75mm x 75mm & drill a large hole to clear the nut, the motor drum sits on this plate. The photographs make it all very clear. See also the Appendix II Link to AutoCAD Drawings The rubber/ply mountings and the tapered spacers electrically insulate the motor/rack assembly from the car. An earth wire does not seem essential. This unit really fits like a dream, more or less straight off the Mini, apart from shortening the middle tube.

With the park position re-set to the offside, (see above) the top ends wiper arms need to be cranked down, and shortened slightly, so that the wiper blades sits parallel to the base of the windscreen in the parked position. The wiper blades needs to be positioned on the arm, so that in the vertical part of the 110 deg sweep, the blade tips just clear the lower edge of the upper windscreen frame. The Citroen 2CV blade (Valeo V24 or Champion X26 B01 approx 10" ) is about the shortest standard wiper blade. This gives a satisfactory, but not ideal solution, as the pre-cut holes for the wiper gear units are not in an ideal location. A perfect solution would be blades moving in opposite directions with 90degs sweep. The photo’s below show a pair of fitted blades. The wiper arms were modified Mini units. See the Moss Mini catalogue page 38. Try www.wiperblades.co.uk

Windscreen Washer Unit:-

It is very hard to find a suitable location for the RHSC's supplied unit. The perfect answer has however arrived in the form of an Austin Mini Washer Bottle & Pump unit. A superb little square unit of 2 litres capacity, Moss Europe Part No. GWW935 or going cheap at your local breakers yard. This unit is a superb fit between the pedal box strut and the Polo fan unit, leaving the nearside firewall clear for the Fuses and Relays. Also away from any water. When you take the unit off the Mini get the mounting bracket at the same time. See photographs below.

Fitting the Polo Heater Unit:-

Before you start visit the NW RHOCaR Web site where you will find two excellent articles on fitting the VW Polo Heater. The heater matrix will almost certainly be the highest point in the water circuit and provides a very good point to bleed any entrained air in the cooling system. Indeed the Polo heater is fitted with a nylon air bleed screw for this purpose. If you fit the unit " upside-down " this facility is lost. Air will always move to the highest point in the circuit, and this is the main reason for poor performance and overheating. If you fit an expansion tank make sure that the inlet/outlet is fed from this point so ensuring that all entrained air rises up into the expansion tank. Providing there are no leaks, water will flow in and out of the tank, not air. See also the section on Wiring and Appendix I

Operation:-

If you dismantle the unit for cleaning, or like me you are just nosey ! You will see that the top section of the heater matrix is open, and air from this section passes, unheated, to the two large circular output pipes, one either side. This provides Cold Air Only ventilation when the blower is ON. Probably of no use in a kit car, unless global warming kicks in, or you holiday in the Gobi desert. This leave 4 other Hot/Cold Air outlets, a large rectangular one at the top, and three square ones on the underside. The internal curved flap allows air to be proportionally directed to these outlets. When used in conjunction with the 3 speed motor control and the hot water valve on the matrix, this allows full control of these 3 outlets. The first 2 circular side outlets will only deliver cold air when the fan is on, as the air does not pass through the heater matrix. You may wish to blank these 2 pipes off until later. The 3 lower square outlets are cut off, to allow fitting into the restricted space over the tunnel, and will provide heated air into the footwells when fitted with suitable ducting. See photo. The upper rectangular opening should be blanked off with a simple piece of ply, a couple of 30mm holes allow the Mini pipework to link up with the demister vents. See photo. The nearside vent is easy to fit, but the offside vent will need some trimming and sealing, as the Steering column mounting. tube is in the way. (another result of the lowered scuttle). So we now have a system that will provide cold air to the footwells, regulated hot or cold air to the footwells and forced air at the same temperature to the 2 demisters. The last two under control of the flap valve, motor and water valve. You will need to provide 3 controls. 1) A 4 position fan switch (use the Illuminated Sierra switch). 2) Flap control cable. 3) Hot Water Valve control cable. (and if you are really smart, controls to open and close the 2 cold air supply pipes.) Use the Sierra slider unit from your donor.

Incidentally blocking off the 2 side pipes should dramatically improve the efficiency of the heater, since ALL the air from the blower must now pass through the heater matrix, unable to take the unrestricted path over the open top.

Once the controls are fitted, all that remains is to wire it up, fit the water pipes and test. All the above is covered in greater depth on the NW RHOCaR site.

See also the photographs below and the AutoCAD sketch of the ply firewall. This sketch is only given as a rough guide, they will all vary slightly from build to build.

Fitting to the Car:-

The Firewall provides a very secure mounting for the VW Polo Heater Unit. The ducting section going on the inside of the firewall under the scuttle, and the motor & heater matrix unit under the bonnet. It is not possible to use the Polo mounting flange as it is at an angle, but the motor sides provide a good clamping face. A suitable aperture is cut in the 19mm ply and the unit bolted in place. The motor & heater matrix unit may need a simple support to the chassis tube, just to stop any shake and also a simple bracket at the lower rear of the ducting section inside. There is a very convenient lug here to fit a simple support to the tunnel top. Fit the Heater unit to the Firewall BEFORE assembly to the car, including the demister ducting etc. as it will be almost impossible to fit all this once the Firewall is in. See also the section on Wiring.

Heater Controls:-

I initially fitted a full set of Heater controls but these failed the SVA (due to control knob protrusion) and were taken off. They have not been re-fitted. Very few cars are seen with heater controls. Leave the water valve set to 'hot' and set the control flap in the 'demist' position. You can turn it everything off with the Fan switch anyway. see Section XXV The SVA Test. and Section XVIII Interior & Instruments

It has been suggested that a permanently fitted scuttle is not a good idea, as working inside may prove difficult. If the Dash panel comes off easily this should not be a problem, there is very little to go wrong in this area and it is only 250mm deep. Removable panels always rattle and add no structural strength.


Detail of Mini Wiper Mounting	Further Detail	The VW Polo Heater Unit

View of the Wiper Motor and Heater	Heater fitted to the inside of the Firewall	The Assembled Heater

Go to Section XXII

Back to Home Page