[practical]

I have a 1978 crawler loader, diesel engine. At two locations on the flywheel, a tooth is missing.
Reading around on the Internet suggests many have welded and filed/ground to shape new teeth successfully.
I am not sure what metal the flywheel is made of.
I have done a little welding and have both an old 220 buzz box and a 110 mig w/gas.
Questions:
- which welder to use: 220 stick or 110 mig?
- recommendations please for best rod/wire to use?
- likely wise to use heat dam compound around the weld area to control heat absorption and protect other teeth from splatter?
- what heat setting to use?
- best to drill into the broken teeth and insert hardened dowel rod stubs on which to then build up and shape weld?

I have pictures of the broken teeth to share if possible.
I see it is important to attached the negative electrode directly to the flywheel.

Many thanks for any advice.

[practical]

Speaking with various experienced persons and continuing to read up, I plan:
- 220 volt stick welder, old buzz box
- use AC 7018 rod
- warm the flywheel first with torch to approx. a couple hundred degrees
- not sure what amp setting to use?
- no need for heat dam or worry of splatter
- no real gain by pre-drilling and installing hardened dowel rod

Any additional advise, observations, corrections, etc. are appreciated.

Attached is a photo of one of the two spots with a missing tooth.

[Tom Osselton]

I've heard of drilling and tapping for set screws then build it up with braising rod it would run in better.

[MinnesotaDave]

My recommendations:

Clamp a thick piece of metal on both sides of the damaged area at the depth of the broken tooth.
(A sandwich of metal)

This will allow you to start your arc on one scrap, weld across where the tooth goes, then finish on the other scrap.
(Some call these run-on and run-off tabs)

Continue build up until the tooth is formed - give appropriate time for cooling between passes.

Then use a zip wheel to cut the scraps off leaving the tooth a little thicker than needed.

Grind and blend from there.

[sedanman]

A suggestion to get the most life out of your repaired flywheel, mark the position of the ring gear to the flywheel. Heat the ring gear up all the way around it's circumference. It won't take a lot of heat to loosen the ring on the wheel. Spin the ring to a new postion so the ondex marks are 3 to 4 inches our of alignment. All engines have a tendency to stop at a the same couple of spots depending on the number of cylinders. So the starter is always engaging on the same few sets of teeth. By re-indexing the two parts, the starter will engage on new different sets of teeth .

[Rick_H]

My recommendations:

Clamp a thick piece of metal on both sides of the damaged area at the depth of the broken tooth.
(A sandwich of metal)

This will allow you to start your arc on one scrap, weld across where the tooth goes, then finish on the other scrap.
(Some call these run-on and run-off tabs)

Continue build up until the tooth is formed - give appropriate time for cooling between passes.

Then use a zip wheel to cut the scraps off leaving the tooth a little thicker than needed.

Grind and blend from there.

That's a great idea...

[Artie F. Emm]

I like the "sandwich of metal" idea too, but from the picture I wonder if there's enough clearance to leave the outer plates, the dams or "bread" part of the sandwich, in place.

Could the dams suggested by Minnesota Dave be a dis-similar metal, maybe copper or aluminum? The idea being to prevent grinding the dams off?

[Bill Beauregard]

Is this flywheel out of the tractor? Every ring gear I've ever heard of is pressed on to the cast iron flywheel. Usually they are pressed up against a shoulder. Tapping in a rotary manner around the ring gear will slip it off. If too tight, heat the ring gear with a small tip on an acetylene torch.

I'd be very surprised if there isn't a replacement gear available from somewhere.

What model is your Cat?

Welding, I would use only as a last resort.

[practical]

Thanks for the helpful suggestions! Good ideas here.

There may indeed be sufficient room to use the recommended "sandwich, run-on and run-off" tabs. I'll examine this possibility closely.

Agree it would be very good to rotate the teeth ring on the flywheel to change the locations of repeated abuse by the starter bendix gear. I'll examine this on the machine more closely, but my initial sense was that the teeth ring is integral to the flywheel. Maybe not. Thus far I've not found anything conclusive either way on the Internet in searching parts.

The machine is a 1978 International 100E, crawler loader with a D239 Neuss motor and powershift transmission.

I rather certain that to replace the flywheel or fully remove the fly ring gear requires one to remove the engine.

[Bill Beauregard]

I have the Dresser TD7G. It is a bit larger than yours as models seem to grow with modernization. Mine is 1988 or 1989. It has a Cummins engine of the same displacement as yours. My engine manual covers the 100G. It shows the ring gear as a separate item. I have a lot of history with IH tractors, but this is my first time to have oil drip from my elbows in a crawler. ALL of the IH tractors I've ever owned had replaceable ring gear. On occasion you'll find they have four tack welds holding the gear on the flywheel. Otherwise heat the old one to remove. The new needs to be 300 F in an oven, and the flywheel in the freezer. They slip together effortlessly. I bet you need to remove the short divorced shaft from the torque converter, or clutch housing, and slip it back several inches to get at the flywheel bolts. There's a bunch of simple stuff in the way, but it's wrench work to remove the flywheel.

Bill

[Bill Beauregard]

The IH TD7E was the same tractor with a few changes as the 100E. I know a mechanic for a small family excavation contractor who's nursed two of these beasts equipped with dozer blades since he was a teenager. One has 27,000 hours on it. If you like I'll ask him about the ring gear.

They are obsessed with IH 175 loaders. They have had a dozen, now have three. There is a nice working 1968? for sale at $6800. They have a Drott 4 in 1 loader if someone wanted. These loaders turned a one trick pony into a real versatile workhorse more versatile than any dozer

[practical]

Thank you very much Sir. Doing homework on my crawler, it's clear the engine has to be removed to get at the flywheel (whether or not the ring gear on the flywheel is integral or slip-on). More description: The back of the engine has the bell housing (thankfully with a big access area where I can reach the flywheel to weld on replacement teeth). The flywheel is bolted to the crankshaft. Bolted onto the flywheel is the torque converter drive housing via a flexible drive plate w/ 8 bolts. The transmission is attached to the torque converter by a drive universal joint.

With all that, engine removal is not an option given my situation. Therefore I'm focused on the welding challenge of shaping new teeth. The helpful inputs from this forum are welcomed and give confidence of prospects for success

[Captainbeaky]

IMPORTANT NOTE...
If/when you carry out this repair...

Make sure the flywheel is earthed directly to the welder!

If you earth the machine, or the engine block, then the path that the arc has to take is likely to be through the main engine bearings.
If this happens, you will trash a main bearing through arc damage, and while it will still run, the damage to the crank will knock out a bearing in a few hours of running.
Either clamp the ground onto the flywheel ( the preferred option), or directly onto the crankshaft nut on the other end of the crankshaft - but make sure you are on the crankshaft, and not a damper pulley etc,.

In a company I used to work for, we found that the starter current was going through the main bearings, and the machines were lasting 5 hours....


Other thoughts:-
I understand that you want to do this repair at minimum cost and hassle, so it's a good idea to practice first, as you only have one chance to get it right, and a hundred chances to bugger it up... Especially when it's as tight as it appears to get to.

Try it out on a scrap ring gear first - so you can get an idea of current setting, technique, and "get your eye in" to the repair.
This will let you try out a few different methods of shielding of adjacent teeth to stop spatter, and stopping the rod touching an adjacent tooth if (when) you miss.

I would probably err on the side of a mig with loads of pre-cleaning and degreasing, and a pre-heat, but only because I'm more confident and better practiced on the mig, and I have a nicely set up mig that provides very repeatable results.
If you are more confident with an arc welder, then use that.
If you have a scrap ring gear, you can try either and see what you prefer.

Good luck.

[Bill Beauregard]

I'm still confident the ring gear can be replaced by moving the bell housing back a few inches. The flywheel can be freed from the torque converter by rotating the engine exposing one bolt at a time. Ultimately the flywheel will come out, and a new ring gear pressed on.

If you still don't believe, install a new ring gear in two pieces. Grind enough away on the inside diameter of the new one to leave room to weld to the flywheel. Preheat to 300F in the oven, & work fast. If you fully seat each half, and weld before it cools, it'll shrink to be tight on the flywheel. You'll need a minimum of four welds to hold it on. This damages only two teeth, not several in a row. I do not recommend this technique!