floppy wipers - which option?

[neil.henderson]

I've done a lot to my stag and it is now a whole lot better & more interesting to drive. But I haven't fixed the wipers - think it is time I did something
On either side of their wipe the wipers stop short of the span they should cover with the result that the driver looks through a piece of wiped glass about 4 inches wide, instead of a wipe span about a foot wide (not exact figures, but hope you can see the problem).
One stag owner suggested that I extract the wiper drive cable, rotate the wiper boxes 180 degrees & then reinstall the wiper drive cable so that it wasn't trying to drive worn parts of the wiper boxes. Logically a great idea, but didn't solve the issue unfortunately.
Could the problem be the plastic fitting on the end of the wiper drive cable & where it attaches into the wiper motor? I don't think that the wiper boxes are worn, but that might be wrong. Someone suggested that I needed to extract the splined piece that the wiper sits on at the base of the windscreen as it was slipping in its spindle - fix the issue by reinstalling with Loctite.

I'm looking for help - someone else experienced the same sort of issue & solved it?

Many Thanks Neil Henderson (Murrumbateman, Australia)

[Andrew S]

Hi Neil

The angle of the 'wipe' is determined by the wiper motor and if the wipe is too acute, then maybe its the wrong motor. Normally failure is shown by the wipers juddering or stop and starting as they wipe. If you remove the wiper arm and reposition it on the spline again to where you want the wiper to wipe on the drivers side, where does the wiper rest when it returns? It should be down as low as it can be against the lower scree. If it does not, then I would suspect the wrong motor and gearing is fitted. I believe externally the motors look the same but have different gearing and it could be from a Spitfire or TR which have smaller screens. Is there a number stamped on top of the wiper motor cover plate?

Andrew

[V Mad]

I think Andrew's answer is the most probable cause. The other would be slippage somewhere; if you stop the wipers mid screen (switch off ignition to defeat the self parking) and try to move them; they should be quite tight with no slippage.

[martin]

Hi Neil, it sounds like you may have a TR6 wiper motor, they look identical but have a shorter stroke. If you take the cover off the motor you'll see a large gear wheel with a crank attached, there MAY be an alternative mounting hole for this, closer to the gear teeth, if so, swap it over. Let us know how you get on. Cheers, Martin.

[neil.henderson]

Hi Andrew, V Mad, Andrew,
Think I need to explain some more of the symptoms. The wipers are very 'floppy' on their drives - I can move them 1-2 inches either way when the engine & wipers are off & I think this is why the wipers only wipe a small arc of the screen. If there is a lot of rain on teh windscreen (causing very low resistance between wipers & glass) then the wipers wipe almost all of their arc, but this is the only time that they do it successfully!
I think my wiper motor is original - it looks as if it hasn't been moved for a very long time!

Cheers Neil

[alistair260661]

if they are floppy that would suggest some loose mechanical connection in the system - the most likely (and the only one I can think of) being a loose fit between the wiper arm and the box drive spline (the bit poking through under the windscreen).

I'd start by having a look at each wiper - are they both floppy? - are the splines on the wiper boxes worn down?

Another Idea occurs - are the wiper boxes bolted firmly to the car (i.e. could the whole thing be rotating? - this would perhaps give the symptoms you describe...............i.e. with friction the blade stops moving and the wiper box turns instead...... - less friction (when wet) and the blade turns further............???

If it is the wiper arm slipping on the splines loctite is the solution, by it may be worth trying some sort of thin cloth over the spline (then put the wiper on) to see if tis temp repair actually solves it.

I'd have a good look at the box fixings ............

[Duncan Skye]

Hi Andrew,
Indeed, it sounds like slop in the system somewhere as the blades sweep OK in the wet. With the wipers parked vertically on the screen (switch the ignition off mid-sweep) try lifting the blades from the glass and moving the blades together and apart at the same time. If there'e wear or looseness in the mechanism, this may reveal it as being in the wiper boxes immediately below the spindles or in the spindle-to-wiper arm splined connections. Or, with the blades just lifted off the glass as before, try moving both arms from side to side together. If they do have excessive movement, this indicates slack between the wiper boxes and the wiper motor itself. Causes may be wear at any point in the system due to inadequate lubrication, or the small nuts that hold the system together have backed off. Check tightening those is not easy, but is the cheapest method if it turns out to be the cause. There's two nuts per wiper box and a larger collar nut holding the mechanism to the wiper motor.

Whilst at the motor, if you think the motor is the correct type, try disconnecting it from the operating tube and gripping the inner with a rag, try a test push & pull to check for slack. Now a caution here: You're only checking for wear, not to operate the blades very much. Pull too far and you'll pull the curly-wurly operating core out of mesh with the wheels in the wiper boxes. Do that and you may have to re-set the blades on their spindles when you put it together again.

I hope that helps with your diagnosis.

Duncan, Skye