6 replies to this topic

[eilz1999]

Hi. I have a 1980 mini 1000. I've been having starter issues and concluded that the starter motor was at fault. I ordered 9 tooth inertia starter motor from minispares. I've put the new one on and it spins but very infrequently it catches the ring gear to crank the engine. Teeth look ok as far as I can tell. I've taken the new one off again and noticed the original very old starter had 10 teeth. Would this be the reason why I am not getting consistent cranking or going to 9 teeth doesn't matter? If not, what else could be my starting issue? Solenoid is new, clean contacts and earth ok. Battery new and charged. Thanks

[mab01uk]

Ouote below is from Old Skool Minis:-
"Inertia starter motor with the correct 9 tooth pinion for all Minis up to the fitment of the pre engaged type in approx 1984/1985. DO NOT fit the 10 tooth starter motor sold by many as it can ruin the ring gear or the bendix. Other Leyland cars used the 10 tooth such as Sprite, Spitfire etc and often get fitted as they are cheaper but 9 teeth is rarer to buy but is meant for Mini 107 teeth ring gears."
https://oldskoolmini...-morris-cooper/

 

[eilz1999]

Ok, thanks. 9 seems ok then. Apart from the grime, here's a photo inside the starter hole. Based on what is shown, do the teeth on the ring gear look ok and not too worn to work with the new 9 tooth starter motor?

Attached Files

•  IMG_20241103_161638938_AE.jpg   91.9K   8 downloads

[Spider]

What you are experiencing is a consequence of that type of starter. You need to keep a very good battery up to them and maintain a very low resistance path in the electrical system to drive them properly, as per the quote from mab01UK above, the 9 tooth is the correct one.

 

We don't call them 'smash and grab' for no reason.

[ACDodd]

To clarify the 9 tooth is correct for a mini, the mk1 metro used a 10 tooth pinion until it went pre engaged. This 10 tooth pinion meshes with the 107 tooth ring gear as will the 9 tooth. The 129tooth ring gear is specific to the pre engaged starter and no combination of inertia teeth will
Mesh with this 129tooth ring.

Ac

[imack]

You really need to check the ring gear from the other side of the flywheel, this is where the wear or damage will be, not the side you see from the starter motor mounting side. The starter pinion engages from the clutch diaphragm side of the ring gear. The engine always stops in one of two positions so wear in the ring gear may be excessive in a couple of areas resulting in the pinion gear skidding over the ring gear rather than engaging with it. You should be able to check the other side of the ring gear via the starter motor hole using a suitable telescopic inspection mirror and rocking the car in gear until the full circumference of the ring gear has been inspected.

Edited by imack, 09 November 2024 - 08:32 PM.

[eilz1999]

Thank you for your replies. Turns out the bendix on new starter motor needed some assistance to go up and down. I think it was sticking at the full end of travel on the shaft and not repositioning when I needed to start the car again. I guess even new parts need to be checked before assuming they will work straight out of the box! Thanks again...one weekend job done.