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View Full Version : Starter grinding noise caused by a broken housing.



NutmegCT
03-13-2007, 04:46 PM
Just removed the noisy starter (see previous thread). Thank you Brosky for stopping by and making a diagnosis!

Take a look at what I pulled out:

Starter pieces removed. (https://www.mgexperience.net/journal/tmorehouse/1203)


The grinding noise was probably caused by the broken housing getting caught between the ring gear and the pinion gear.

Question: is there a possibility the starter doesn't match the engine? Would this have caused the break of the pinion shaft bearing end?

Pics and info are on the link. If the starter is correct I'd like to get it fixed (or replaced). But the ring gear looks pretty new for a 50 y/o engine. Is there a way to tell from the engine number and starter number if the match is correct?

How to tell what starter I should get - if the ring gear and starter don't "match" then undue pressure on the housing may have caused the break.

What to do ... what to do?

Tom

DrEntropy
03-13-2007, 04:53 PM
Can't really tell about that ring gear, but it kinda looks decidedly UN-new. Very possibly a mis-match t'wixt ring gear and starter gear. To break the housing in the manner it has done would take a great deal of force. It appears the Bendix gear was riding too shallow on the ring and has "self-machined" the ring's teeth down to a point where it was only partially engaging... Can you get a better photo of the ring gear posted?

NutmegCT
03-13-2007, 05:05 PM
Just added a slightly better pic of the ring gear.

T.

Tinster
03-13-2007, 05:06 PM
Your ring gear looks a whole lot better
than my 69TR does.

Chalk mark the ring gear, pull your plugs and slowly
rotate the ring gear by using the fan blades. Inspect
all 360 degrees for damage, broken or missing teeth.

Try to post a close-up of the teeth after you inspect
for obvious damage. You might have "machined" off
some of the tips or edges.

d

Twosheds
03-13-2007, 05:09 PM
Like the Doc says, hard to tell if the ring gear is correct from that photo.

My old TR3 racecar TS22312 had the old style "bullet-nose" starter like yours. When I tried to buy a gear reduction starter from Ted Schumacher, Ted would not sell me one until I looked at the ring gear to see if it was held onto the flywheel by screws or not. This is because some PO might have swapped the flywheel for the late style, causing a starter/ring gear mismatch. I found no screws, so Ted sold me the gear reduction starter that replaces the early starter.

So look at the ring gear with a flashlight and mirror whilst rotating the engine.

No screws = early

Screws = late.

Also look for abnormal or excessive wear.

And I'm writing this before Gin & Tonic time, so I'm pretty sure about the screws/no screws. But someone correct me in case I have it backwards.

Lycoming O-320s had the same problem, by the way!

Twosheds
03-13-2007, 05:13 PM
Just added a slightly better pic of the ring gear.

T.


Looks chewed up to me.

It's G&T time!

DrEntropy
03-13-2007, 05:14 PM
Still ~looks~ like the ramps have been knobbled down to a degree the starter gear would not engage but rather "ride" on the tops of the teeth. That'd snap the housing and bugger the starter motor.

NutmegCT
03-13-2007, 05:19 PM
Ring gear - just found in the previous owner's maintenance records that in January 2006 the ring gear was replaced, the starter repaired, and the clutch release bearing replaced.

T.

Brosky
03-13-2007, 05:22 PM
I can't tell from the angle, but it looks to me as though all of the teeth are beveled in in the same amount and I don't see a whole lot of metal in the bottom of the bell housing.

But, could the PO have removed all of the metal shavings prior to installing a possible incorrect starter?

Tom, have you called the PO to ask about this replacement?

It was my pleasure to stop by. Once I heard the noise, I knew that the drive was crashing and the starter had to come out. I'm just not sure if the wear is excessive on the teeth and I will defer to those with TR3 experience on that matter.

MGTF1250Dave
03-13-2007, 05:29 PM
Aloha Tom,

The Bomb shell or Bullet type starter has the bendix engage the ring gear from the engine side. The later type starter has the bendix engage from the gearbox side. The later style starter (also used in the TR4) requires a different bell housing to accommodate the longer bendix. From the photos of your ring gear I would say you have the correct type starter. Tinster made a good suggestion to rotate the engine and examine the entire ring gear. From what I saw in the photos it looks good to me, but you are only looking at a small section. The bigger question is what fractured the cast iron nose piece. It may have been dropped in the past and a small crack over time resulted in it breaking off. These type starters have rubber filled sleeve assembly that separates the motor shaft from the pinion. In theory, this is to that up the shock on engagement between the motor/starter pinion and ring gear. I had the rubber fail on my starter most likely due to age. I would think that yours would have failed before cracking cast iron. In any case I'm sure the starter can be rebuilt as long as parts can be found.

martx-5
03-13-2007, 05:29 PM
My experience with broken noses on starters is usually the result of a backfire while cranking.

The pics of that ring gear aren't very encouraging. The front of the teeth look flattened out, when there should be a chamfer there. The bullet nose TR3 starter engages fron the front, rather then the rear of the post TS50,000 cars.

DrEntropy
03-13-2007, 05:29 PM
Ring gear teeth should have a machined ramp on 'em and come to a definite point. Those (tho I again say: hard to "see" in the photo)seem to have been blunted kinda badly. I hope it's just a bad angle in the shots.

DrEntropy
03-13-2007, 05:34 PM
I dragged the photo into PhotoShop but the resolution is too coarse to really get a good vidi of the teeth... A mirror held to reflect the other edge of the teeth could be of some benefit.

Brosky
03-13-2007, 05:43 PM
I may have to try to stop again on Thursday when I'm in CT.

Harry, where are you???

DrEntropy
03-13-2007, 05:53 PM
You do have a point about the LACK of "sparkly stuff" in the bell-housing, Paul. I'm hopin' it's just a wonky catchlight off the teeth causin' me to mis-read the photos.

NutmegCT
03-13-2007, 05:53 PM
ring gear teeth closeup

ring gear teeth closeup 1600:1200 (https://www.mgexperience.net/journal/pictures/view/1764)

Taken at 1600:1200, but website may be reducing it.

T.

DrEntropy
03-13-2007, 05:59 PM
MUCH improved!!! I can see some "funnies" at the peak of the teeth but NOTHING to run screaming from. WHEW!!! Looks completely servicable on that section, Tom.

Do the chalk mark and rotate it thru 360 and eyeball it all the way 'round. If it looks the same as the section you photo'd, the starter gear ratio is gonna be the suspect in this mystery case.

NutmegCT
03-13-2007, 06:02 PM
I'll rotate the wheel tomorrow after my dental appointment ...

This advice is priceless guys - thank you very much! If the wheel is decent and I know whether there are screws or not, I guess the next step is to figure out which starter I need.

Tom

DrEntropy
03-13-2007, 06:05 PM
Prezactly. Once that's discerned I suspect your starter problem will be a memory.

Brosky
03-13-2007, 06:06 PM
Doctor & Tom, I think that the amount of metal in the housing is now from the starter drive gear chewing it's case apart. But there seems to be a small amount of wear on the flywheel teeth, probably caused by all of the broken parts in there.

Tom, as Dale & the good Doctor have suggested, mark the FW with chalk and do a 360 inspection, looking closely at the teeth AND the ring gear itself, to insure that there are no cracks in the actual ring. You will then determine how it is attached as well.

Good luck...

MGTF1250Dave
03-13-2007, 06:09 PM
Aloha Tom,

As the DrEntropy noted there are some dings on the ring gear teeth. I would guess the sparkling bits in some of the photos are flakes of cast iron from the broken nose piece. Abraded off as it rattle around in there. This also is probably what blunted the points on the ring gear. I concur with the Dr., the damaged shown is not fatal, but the rest should be checked to make sure some other sector is worse. A bad section of ring gear could tear up a replacement starter pinion.

DrEntropy
03-13-2007, 06:30 PM
After looking at a high-res image I'm convinced the starter gear ratio is WRONG. Some of the teeth onna ring gear are impacted DEAD-CENTER by the Bendix gear: Like someone hit 'em with a center punch. Check the ring gear well for cracks or areas looking more worn than you show in the photos. If it's no worse the rest of the way around it, and you get the proper starter for the gear it'll be FINE!

NutmegCT
03-13-2007, 07:09 PM
This is interesting - from the Moss TR2-4 catalog:

"The starter mounting shim, #549-430, is used to adjust the position of the starter pinion relative to the ring gear. With early starters, adding a shim brings the pinion further away from the ring gear, decreasing mesh. With late starters, adding a shim brings the pinion closer to the ring gear, increasing mesh. It seems that most cars were originally fitted with one shim which generally got lost or forgotten when the starter was replaced."

Moss separates early from late starter at TS50001.

Tomorrow I'll pull the plugs and do a 360 turn inspection of the flywheel to check all teeth and check if there are screws on the wheel.

I'm starting to wonder if the January 2006 flywheel replacement may have been with the *later* flywheel, but the starter was the *early* starter (or vice versa?). And thus, for just over a year the teeth have been merrily grinding away.

Tom

Brosky
03-13-2007, 07:33 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I'm starting to wonder if the January 2006 flywheel replacement may have been with the *later* flywheel, but the starter was the *early* starter (or vice versa?). And thus, for just over a year the teeth have been merrily grinding away. [/QUOTE]

Tom, you are probably correct on both counts. I'd also get several shims, "just in case."

Twosheds
03-13-2007, 09:11 PM
Tom, I have the original bullet nose starter from the race car out in the laboratory. The front bushing is gone, but the part that is broken on yours is good on mine. If you want to buy it, let me know.

Of course, you may want to go with a late starter even though it's not correct if you find that you have the late flywheel and want to keep it, and late tranny, as MGTF points out. It's easier to change starters than flywheels!

Andrew Mace
03-13-2007, 09:25 PM
Only problem with switching to a "late" starter is that, unless you also happen to have a later 3A or 4 type of gearbox, the starter won't fit inside the bellhousing unless you punch a hole on the backside to clear the Bendix. I seem to remember that this was actually written up in an old edition of the TSOA Handbook or maybe a TSOA Newsletter issue.

Twosheds
03-13-2007, 09:30 PM
Only problem with switching to a "late" starter is that, unless you also happen to have a later 3A or 4 type of gearbox, the starter won't fit inside the bellhousing unless you punch a hole on the backside to clear the Bendix. I seem to remember that this was actually written up in an old edition of the TSOA Handbook or maybe a TSOA Newsletter issue.

That's why I wrote "and late tranny"!

TRopic6
03-14-2007, 03:25 AM
Tom,
I'm a long way from my TR3A (TS44864LO) but your starter is the correct type. When the starter spins, the inertia of the pinion should make it jump forward into the ring gear. There is a lock-ring and cover at the end of the shaft that I can see in your photo. I wonder if it is supposed to keep the pinion from smacking the cast-iron shroud?

I don't know if repeated impacts from the pinion would be enough to crack it, but cast iron will sure break if you drop it. Would a too-thick washer at the commutator end move the shaft lock-ring and cover close enough to bind on the cast iron part when it's tightened down? Fit the broken piece back and see if it has clearance from the ring & cover.

I made one good early starter from two once, and one of them had a broken nose just like yours. I never thought about how it got that way though.

Jeff
Honolulu, HI
TR6 CF13816U

NutmegCT
03-14-2007, 07:59 AM
Here's what I've learned from the previous owner:

"Originally [about 3 years ago] it was too weak to throw the starter
gear far enough to the flywheel, and supposedly was part of the reason
for the [original] ring gear's demise. The starter was supposedly rebuilt but I
suspect they only turned it and put in new brushes. I started having
the same problems as before and they put in a new ring gear and then
welded some part of the starter mechanism so it wouldn't slip. It
worked great but I didn't like the fix. I know of no reason for the ring
gear wear-- no funny noises or clashing occurred that I could tell since
the last repair/replacement.

In retrospect I (and now you) might have been better off just replacing
the starter. Folks on the forum said the old ones were pretty sturdy
but I don't know if the "rebuild" or repair were ever right. "

I'm off to turn the flywheel the full 360 now. I am *really* glad the previous owner kept the maintenance records.



Tom