The Triumph 2000 / 2500 / 2·5 Register Forum

Hi All had to take the gearbox out of my Pi to investigate poor clutch clearance problem. Not unusual I believe. Anyway one of the side issues I’ve noted is that the flywheel ring gear is badly worn.
Maybe as much as 30% of the width of the teeth worn away in 3 distinct areas. (I’ll take a photo and post it tomorrow for you interest.
What I see is that the chamfered teeth on the ring gear are to the rear of the car but the starter is a Pre-engaged type so engages from the front.
Question which side should the ring gear face? Chamfered teeth to the front or rear.

Hi All, I've added some images for your reference. Not sure what has caused this level of "wear" to the ring gear, there is no debris in the bellhousing though I know the previous owner had the gearbox out about 4,000 miles so maybe it was already like it then!
I would think that the starter was rotating BEFORE it was engaged?
Is that something that can be adjusted?
I will replace the starter motor regardless as the gear on there is also well worn.
There doesn't appear to be a receipt for a starter recon in the file but the starter does look like its been reconditioned rather than just painted.
I'll add an image of the starter later on.
Hoping to get some feedback on the ring gear orientation as I'll need to be fitting the new one tomorrow.

Hello Jake,

the ring gear orientation should match the type of starter, so chamfer facing the front of the car for a pre engaged. A pre engaged starter does not rotate until the pinion is in mesh. The wear points coincide to where the engine tends to stop. In theory that sort of wear shouldn't occur with a pre engaged starter.

Alec

Hi Alec, it makes sense on the chamfer facing the starter that kind of what I though.
I am struggling to see how the current ring gear ended up that worn though unless it was turning before it was in mesh.

Hello Jake,

yes, a bit of a conundrum?

What happens is the solenoid pulls the pinion outward and then the contacts are made to turn the motor. Do you have a spacer fitted between the motor and the back plate, which may mean the pinion is starting to turn just as it engages?
Perhaps some measuremenst of ring gear to back plate front and similar measuremenst of the starter pinion may give some clue, Although you can't know if the pinion was worn and then turned round, although why anyone would remove and refit a worn ring gear is hard to guess?

Alec