starter and ring gear

[jayhawk]

After having the starter in and out about 6 times over 3 months, having it "rebuilt" once and found to still have problems (Geo, take a bow again) the starter problem was finally traced to 2 things-- the little disk with "teeth" (item "N" in the catalogues) and the ring gear. The gear was work all around but in particular a section about 2.5 inches wide and about 5 teeth. see attachment above

 

[MadRiver]

I had to replace my ring gear late last year -- my very grumpy starter had chewed a lot of the teeth. A rebuilt starter is on the way from the Roadster Factory and should hopefully solve my problem.

 

[Geo Hahn]

Oooh, that is ugly. Now what would cause that? The pinion on my starter is a little chewed but the ring gear looks brand new. Indeed, it would seem prudent for them to have made the ring gear of sterner stuff that the pinion but did they?

 

[jayhawk]

I've had a bunch of old cars in my years but had never one with a worn flywheel/ring gear. As I understand it, these things on old TR's are heated and "shrunk" onto the flywheel housing. Could that process (or abuse of that process) somehow "dis" temper the metal on the ring gear and soften it? Sometimes shims apparently are used with different starters (mine had none) but perhaps another starter was used before I got mine?

 

[Alan_Myers]

Hi,

I've not seen a really torn up ring gear like that either. Now that's some serious wear!

One possible reason for it is that the TR ring gear teeth are bevelled on one side, but not on the other.

The bevel can be installed toward the front of the car, or toward the rear, simply by removing and flipping over the ring gear.

The design of the starter being used with the particular ring gear determines the correct orientation of the bevels. Early TR2/3 have the "short" or "bullnose" starter, with a pinion that pushes out toward the back, engaging the leading edge of the ring gear. In this case, the leading edge of the ring gear, where the starter gear engages, should have the bevel.

With later TR3 and TR4/4A, the "long" starter positions the gear behind the ring gear and pulls it forward to engage the ring gear from behind. In this case, the bevel should be on the trailing edge of the ring gear.

I'm not sure about the 6 cylinder engine. Anyone know?

To complicate matters, many of us now have modern gear reduction starters on our TRs. These all appear to operate like the short starter (TR2/3) engaging the leading edge of the ring gear. So, anyone installing one of these in later TR3/4/4A and not flip-flopping the ring gear is now engaging the un-bevelled side. With gear reduction starters, I've been *told* it's not necessary to match them up with the bevel on the ring gear. I still wonder, though, if it wouldn't be better. Seems to me I've heard about way too many of the new starters failing pretty quickly, I'm just not sure if the ring gear bevel is a factor or not.

Yes, some TRs have pressed/shrunk-on ring gears that need moderate heating to install (not enough to remove temper, though). In particular, earliest TR2/3 used this type, and sometime later in TR250/5/6 (not sure the exact change point, apparently done as an economy move). In between, a bolt-on ring gear was used. But, both types of ring gears have the bevelled teeth on one side, plain on the other. BTW, has anyone ever heard of a the press-on ring gear slipping on the flywheel?

The upshot of all this is that maybe that's what happened here: A starter swap resulted in a mis-match between the starter gear and the bevel on the ring gear, causing problems and the heavy wear seen. I can't be certain from the photo if the bevel or non-bevel edge is the one that's chewed up so badly.

Alternatively, a starter that fails to engage fully, or stays engaged slightly, will tear up itself and, eventually, a ring gear. Depending upon whether it's a short/push starter or long/pull, shimming was used to increase or decrease engagement. But the shimming of the starter is a bit of a mystery, too. My TR4 had a single shim under the original starter. This would slightly increase engagement of the long type starter into the rear-bevelled ring gear, as original to the car. However, the shim would reduce engagement of the modern gear reduction starter now on the car.

Aside from shimming, problems in the starter could be preventing the pinion from moving it's full stroke, one way or the other or both. That might leave it partly engaged when the car is running or fail to fully engage it during starting or both.

Also, any "wobble" in the flywheel, might cause ring gear/starter problems. It's most likely that this would pretty quickly progress to a catastrophic flywheel failure, but certainly is something to check carefully: Tight and secure mounting at the crankshaft, no runout and good balance.

One common thing you touched upon is that the ring gear teeth tend to wear in one segment (just not to the extent seen in the photo!), because the engine nearly always stops in that one orientation. While it's apart, it's good practice to remove the ring gear from the flywheel and rotate it 90 or 270 degrees, to put some fresher teeth at the starter.

I would guess that a ring gear badly worn all the way around would indicate either a dragging pinion, for one of the above reasons, possibly over-engagement being a key one. A ring gear worn heavily in one area seems to me more like it would be due to under-engagement, slipping on the first few teeth when the starter gear is trying to engage.

Keep us posted!
/ubbthreads/images/graemlins/cheers.gif

 

[martx-5]

Perhaps, I can shed a little light on the matter of the ring gear getting chewed up, the flywheel bevels, and the late type gear reduction starters. I work for a national electrical re-manufacturer and have seen just about every scenario possible. The early TR3 bullet nose and the later TR3 long shaft starters both have an inertia type drive in them. When the starter starts to spin, the mass of the drive forces it to move (forward or backward depending on which starter) along a corkscrew type spline on the starter shaft. It then locks when it's all the way in the flywheel. When the engine starts, the increased speed of the flywheel forces the drive to ratchet and pushes the drive back. If the drive doesn't come out smoothly, the starter will be spinning to fast too properly engage the flywheel and chewed up teeth will result. Anytime there is a flywheel to drive meshing problem, it can almost always be traced back to a bad inertia drive, or, in some cases gummed up or defective splines on the armature shaft.

Most starters today have a solenoid that has a dual function. When the solenoid first activates, it pushes the drive out. Again on a corkscrew type spline so it is turning to more easily engage the teeth in the static flywheel. As the solenoid reaches the end of it's stroke, AFTER the drive is engaged, it closes the contacts to energize the starter motor. So, in the inertia drive starter, both flywheel engagement and starter rotation are happening at the same time, whereas with the solenoid type starter, engagement happens before starter rotation starts.

In both types of starters, the drive gears are beveled. However, it is my belief that the inertia type starter needs more help on proper engagement and flywheel beveling becomes important. With the solenoid type starter there is much less chance of poor engagement, so the bevels on the flywheel are much less of a concern. I wouldn't hesitate to put in a modern gear reduction starter in a TR with the flywheel having bevels facing the wrong way.

 

[jayhawk]

[ QUOTE ]
If the drive doesn't come out smoothly, the starter will be spinning to fast too properly engage the flywheel and chewed up teeth will result. Anytime there is a flywheel to drive meshing problem, it can almost always be traced back to a bad inertia drive, or, in some cases gummed up or defective splines on the armature shaft./quote]



Great feedback guys, thanks.
When I pulled the starter the first time and tested it on the bench, the motor would run pretty fast but would not shoot the the pinion gear out very well. After I opened it and cleaned it it worked a little better but not right. The first time it was "rebuilt" they didn't change anything in the drive mechanism. The second time they did. In between it would work sometimes and then just growl, I suppose because it would either spin fast and not engage or hit the badly worn spot. I'll ask the guys at the shop if the current ring gear is beveled. They said when I asked, that the original could not be reversed.

 

[Jim_Stevens]

To answer Alan’s question of gear reduction starter with a press-on ring gear, my ring gear is slipping, after about two years of the modern starter…. Hmmmm, 60 years with the original starter, and two with the modern. I may go back to the Lucas…. Jim

TS44067L”O”

 

[sp53]

Hi Art so the more modern starters (like my Ford truck) with the solenoid on the starters are different in the way they engage because they come out spinning? Just trying to absorb your informative post.

Steve

 

[Madflyer]

I built my 1973 TR 6 in 1993 and did not change ring gear or starter but the ring gear did have a few chipped teeth. Last year OEM starter was changed out to a new geared one. so I replaced ring gear at the same time all new. Now I have heard that these geared starters from China will not last. 1973 to 2019 how do you beat that, CHINA. My rebuilt OEM starter is ready and able.

 

[sp53]

Sorry Art, I get now, nice wright up.

steve

 

[DavidApp]

The new starters have to engage the gear before they start turning unlike the old inertia starters that relied on the spinning starter shaft to through the gear into mesh. The new starters may turn faster than the old starters and with more torque as they are gear reduced.

David

 

[sp53]

Excellent point David it took me a while to see it.
steve

 

[allen hanford]

I was told when I changed my ring gear that 400 degrees was the number to shoot for when heating the ring and that anything in excess of 600 would cause damage to the metal. I was also told to expect to have drive the the ring onto the flywheel with a hammer and a brass drift. I managed to avoid that by putting the flywheel in the freezer overnight. It went "clank" when it dropped into place. I went with a reduction starter and haven't had problems but it's only been on there a couple of months.

 

[Gliderman8]

I heated my ring gear then dropped it on and let it cool overnight. I also have a reduction starter and it's been five years with no problems at all.