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Ring Gear

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71tr

71tr

Jedi Warrior
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How do you know if the TR6 ring gear is worn or should otherwise be replaced? If the teeth are in good condition and the starter engages is it better to leave well enough alone? Now, if you just happen to have the engine out of the car should you go ahead and have the ring gear changed-out while you lighten the flywheel and change the clutch? Finally, the factory ring-gear was installed with the chamfer towards the transmission, presumably to accomodate the early 250 style starter which engaged from the rear. It seems intuitive to install the new ring-gear with the chamfer towards the starter motor.
 
Hi,

I've asked similar questions myself.

If the ring gear is in good shape, with no chipped teeth or cracks, I'd leave it alone.

On my TR4, it was set up for the older style starter, that pulls the long pinion gear into the ring gear from behind (but not the really old style used on TR2/3, with the "hooded" pinion gear and different gearbox bell housing to accommodate it).

The reason I asked around was I plan eventually to install a modern high-torque starter that pushes the pinion into the ring gear from the front. Seemed to me the ring gear should be flopped to accommodate the new style of starter.

However, responses I got showed most people never bother changing the ring gear orientation and have no problems with the arrangement. Some also commented on the later starters that use a push-from-the-front type of pinion and noted that it was common for Triumph to continue to install the ring gear on the flywheel with the chamfers toward the rear, even though it seems "backward".

So, apparantly the chamfers on the ring gear serve little or no purpose and I personally stopped worring about it. I'll be interested to see if anyone here thinks differently. Thanks for posting the question.

Alan
 
FWIW - my TR3A has the early starter (engages from the front) but the later bolt-on flywheel (no front chamfer). Occurred because a later engine was installed by someone who didn't know or didn't bother to change the flywheel. It has given me no trouble for 20+ years.
 
Alan, until you mentioned it I never gave the starter engagement orientation a thought. I replaced my old "pull from the rear" starter with the new gear reduction type a year ago. I have had no problems at all. Gee, maybe ignorance is bliss. Now that I know about it, the starter will probably crap out next week.
 
Mark,
That is an awesome response "the starter will probably crap out next week" LOL! I'll probably leave the ring gear alone following one more close inspection of teeth condition. But looking at those chamfers facing to the rear just irks me. Its one thing to see a few teeth thru the starter access but to look at the entire ring gear out of the car...ugh! Seems like they would save much wear on the starter pinion gear if only they were facing the right direction. What were those guys in Coventry thinking?
 
Ring gears rarely slip off the flywheel. They often get shredded for a variety of reasons. Replacing the ring gear requires someone with the ability to heat the ring and chill the flywheel, setting it in place and the two temp extremes level out to "set" the ring gear. Some have resorted to tacking the gear in place but this shouldn't be necessary. If you are going to reface your flywheel and think the gear is less than great, then this is the time to change it. I installed the high-torque starter, ran it for a year with no problems, inverted it to clear new headers and about 1 in 30 starts, the starter won't mesh. I'll wait till the clutch has to go before I check out the whole gear.

Bill
 
Hello Bill,
I have succesfully removed and replaced ring gears withour resorting to heat and chill to get them together. I would be careful about heating the ring gear especially as a lot of people use a torch to do this sort of operation and may well lose the temper on the ring gear teeth.

Alec
 
Piman, since this is an interference-type fit, fitting the gear without special tools might be a challenge. Indeed the gear will soften if it is allowed to cool on it's own. Water cooling will make it brittle. Generally the cooling is done with oil spray to maintain the correct hardness level. I have seen this done with a barbeque pit to heat the ring gear. I think it best left to an accomplished mechanic who has successfully installed more than a few. Beyond my capabilities. Sounds as though you have it down.

Bill
 
Hello Bill,
yes it is an interference fit, but no special tools were used, just normal worshop hand tools. It is not easy as the diameter makes starting and keeping it square does take a little patience and care.

Alec
 
Sounds like a job for a Farrier or Blacksmith! lol /ubbthreads/images/graemlins/smile.gif
 
Hi all,

Question... Ring gears on TR6 are interference fit? TR250/5?

The reason I ask is that I believe TR3 & earlier were also. But TR3A (some? most? all?), TR4/4A ring gears were bolted on. Easy to remove and install.

On the other hand, I've got a TR4 flywheel out in the garage right now with a sheered off ring gear bolt. That's actually not a big problem, since the flywheel was replaced with an aluminum one that's drilled for the later TR4A style clutch. But I'd still like to get that one bolt out so the spare flywheel would be usable!

If Triumph went back to the interference fit ring gear for the later cars, all I can do is repeat the question someone else already asked: "What were they thinking?"

Cheers!

Alan
 
[ QUOTE ]
...I believe TR3 & earlier were also. But TR3A (some? most? all?), TR4/4A ring gears were bolted on...

[/ QUOTE ]

Some. FYI, change point was TS 50000 (April 59) when TR3As went from shrunk on to bolt on (same time they changed from front-engaged 'bomb' starter to later style rear-engaged).
 
Hello Alan,

Triumph, in common with most U.K. manufacturers shrunk the rings on. From a production point of view it is better, and in practice, is an acceptable and reliable method.

Alec
 
Last time I had problems with a bad ring gear I heated it with a torch, it came right off, and heated the new one and It went on, no problem, this isn't rocket science. I have put many thousands of miles on since.
 
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