mk1-forum.net

Hi all.
My 1966 built Morris Cooper 998 wipers go beyond the screen in both directions.
I thought the motor had an incorrect gear fitted.
It should, I think, be 120°.
After removing the motor the gear is stamped 120°.
Will a 100° gear fix the problem?
Anyone else had this?
Thanks

Has this just happened? If the rotor has 120 degrees on it, then it is correct. If NOT, what did you change to make this over-run happen. That'll be the answer. It might be that you've got the wrong wheel boxes

Hi Peter.
To be honest it's the first time I've driven it in heavy rain.
I removed the motor anf all is good. Gear stamped with 120°.
Could it really be wheeboxes, I didn't realise they could be different.

The correct wheelbox for the DR3A wiper motor is a 72728 - the number is stamped on the main body of the wheelbox.

To be really honest, I just guessed about the wheelboxes on the basis that the main drive rotor was correct. A smaller wheelbox drive spindle will give you more degrees of movement per throw of..... anyway!

Nick at MinE bitz is the wiper and wheelbox guru. Or that other wiper guru, Andrew 1967. (see for sale). There will be others of course

Thanks very much for your advice chaps.
Next job is to check the wheel box part numbers.
From what you've said that's all that can be wrong?

Are the arms and blades correct ?

The 120 sprocket is the same size as the earlier 130, I think it’s just that the drive peg is in a different place on the sprocket.

As said, check that the wheel boxes are also correct, if the arms and blades are correct .

I think the arms are correct, the blades sit well in the parked position...

Photos of the set up might help us .. one with the lid off the motor as well ..

Interesting post in a FB group where the guys wheelboxes were fitted upside down causing the wipers to hit the scuttle panel and bonnet !

Andrew1967 wrote: ↑Sun Jun 18, 2023 7:59 am Photos of the set up might help us .. one with the lid off the motor as well ..

I'll see what I can do

Andrew1967 wrote: ↑Sun Jun 18, 2023 9:44 am Interesting post in a FB group where the guys wheelboxes were fitted upside down causing the wipers to hit the scuttle panel and bonnet !

I'll check that too

Thinkin' on my feet here, if the wheelboxes were upside down it'd be a simple matter of re-positioning the wiper arms on the splines. There'd still be the same degree iof 'throw' on the arm(s)

I think you're right, only
the wheel diameter would determine the arc...

This seems fairly obvious to me. The rack and/or wheel boxes are worn out. In heavy rain, the overthrow is exaggerated.

Yes that makes sense...

If you pop the cover off the wiper motor you can check for excessive wear in the system. The arms themselves could be worn as they are two parts riveted together, unlikely though. If there is wear in the splines of the wheelboxes, the arms have a habit of flying off completely! Lifting the arms off the screen and gently moving side to side should highlight play in the rack and wheel box gears.

Peter, there is a bit of movement of the wheeboxes.
I'll try to find a pair of new ones and maybe a new rack if I can.

I think these are the correct ones?