Idler gear remove and replace tips?

[BruceM]

I bought a replacement brass idler gear from George to replace mine as a preventative/longevity measure, and wondered if someone could offer some tips on the job?

Bruce M
Snowflake, AZ
Metro 6/1 built 2002

[SHIPCHIEF]

The shaft that the idler gear runs on is also the top stud of the right side main bearing.
Remove inspection door. Remove the crankshaft counterweight next to the gear if your engine has counterweights.
Roll engine around until you have room to get at the gear. Mark the flywheel position and note the cam position.
Remove the nut on the idler gear axle, push the shaft thru, you should be able to reach in and pull it the rest of the way thru, the gear stayed in place for me, but it could be wiggled a bit.
Rotate the flywheel ever so slightly forward while tugging lightly on the idler  gear. With very little crank movement, and no cam movement, the idler gear will come free. Note which side faces out.
Inspect the pinion gear shaft and polish any rough spots where the New Idler will run.
When installing the new gear, roll the crank back while lowering the gear into place, opposite from how you removed the old one.
Reinstall the idler shaft with the oil groove on top. Check the gear lash and end clearance on the shaft. Oil it well.
Continue reassembly.
Piece of cake, You'll be fine.
Scott E

[Joe]

A question asked and answered in pertinent detail... all in less than an hour...as someone said very recently..." I like posting with you guys, you get shit done".
SHIT is a nautical term …Ship High In Transit….
I have occasion to work an exercise with CG folks a few times a year…depending on the scenario they could function as Good Guys or OPFOR…I always like it when they are on my side…. although they do have a language all their own…. .

Joe

[BruceM]

Thanks Shipchief!
My big concern was getting a tooth off on the process.  I'll make sure I get some alignment marks on the crank and cam.  It's reassuring to know there's not "gotchas" in the process.

On my 6/1 there's no crank weights- they're on the flywheels. The idler is easy to reach. The idler shaft seems to have a threaded socket of it's own on the crankcase close to one of the main bearing studs.

[Tom]

I have an aluminum idler gear from George for my Ashwamegh 6/1. After I got it I heard it was the twins that were the problem and evidently George went to brass. Any thoughts on using it?

[SHIPCHIEF]

   I have one of those too. I plan too keep it and the iron one I removed. Maybe the iron one is OK, the failure rate was estimated at 25%. I also have a bronze (brass?) one. I guess I'll use the bronze one and keep the other two on hand. The aluminum gear looks well made and certainly fit well when I installed it.
   I'm planning on keeping a spare parts stock. Bearings, seals, gaskets, gears, etc. Who knows how long parts will be available?
   I was thinking about testing the iron gear for hardness, etc. Maybe Hotater would let me mail it to him for testing? (just a thought)
Scott E

[JohnF13]

The aluminium gears are fine, unless you have a machine that has too little lash on either the crankshaft side or the camshaft side.  In that case it will wear very quickly - I put one in a Vidhata 12/2 and it was worn out in about 400 hours.  I think the problem with (some of) the twins is that the pilot hole that goes through the crankcase for the idler gear is out by a few thousands of an inch and that causes excessive strain on the gears, which contributes to premature wear and failure.  Ally that with a poorly cast idler and failure is pretty inevitable.  I have been toying with the idea of making an offset shoulder on the idler bolt so the lash could be adjusted.  Need a "round tuit" though! 

Everyone should go inside their engine and mark the crakn and cam gear placements to make sure you can replace an idler in th event of catastrophic failure.  If that is not done, there is a pretty easy way to get correct timing within a tooth or so.

[Tom]

Worn out in 400 hours! I think I'll stick with the OEM iron gear for now.

[kyradawg]

Peace&Love , Darren

[n2toh]

The chain sounds like a good idea.

[sawmiller]

Hi Guys
My idler gear stripped out today. I have 509 hours on it . Lost about 12 teeth.

Regards
Tim

[Tom]

Hello SawMiller,

Which engine did the gear go out on?

Tom

[rgroves]

Hi Guys
My idler gear stripped out today. I have 509 hours on it . Lost about 12 teeth.

Regards
Tim

Sorry to hear that, Tim.  Word of advice.  Check the cam gear carefully.  My partner and I just finished a rebuild on an Assaway 25/2.  When the idler let go, it took the cam gear with it. Added a lot more work to the project. We replaced the idler with one of George's bronze beauties, and the lash looks good.  BTW the crankshaft gear was OK,
surprising given the amount of scrap iron we found in the sump.

Good luck with your repairs.

Russell Groves

[sawmiller]

It was my 10/1 Ashwamgeh. I had already put the bronze gear in it ,boys they are a bugger to get timed the first time. I've got another bronze gear, so i'm going to put it in today.

Regards
Tim

[kyradawg]

Peace&Love , Darren