Lister Engine Forum
Lister Engines => Listeroid Engines => Topic started by: akghound on June 06, 2006, 05:06:56 PM
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Oh NOOO!! :o I lost another idler gear in my engine; this is the second one. The engine seemed to running just fine, no indication that there was trouble brewing, then bam, it was suddenly out of time, then dead. :'( The good part is there seems to be no damage to the cam gear. I actually didn't pull it out yet, just looking from the outside.
At any rate this is a 16/1 Saytajeet (GM90) and I would like to find out if there is a brass or bronze gear available for it. Other then a small inverter and old weak batteries this is our only source of power so it is imperative that we get her going ASAP.
In fact any ideas or opinions are helpful and welcome.
Thanks, You guys rock!!
Ken Gardner
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Hi Ken
Sorry to hear about the idler i'm on my second idler myself. They are both brass .I don't think it a gear problem ,i think it's the way they set up. There are people working on the problem . they are working on an offset pinion shaft.
Regards
Tim
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George may have some some in bronze. http://www.utterpower.com/idler.htm Others may have cast.
This has become a real problem and not just on twins anymore. To the best of my knowledge its only the higher hp singles that break gears aside from the occasional 6/1 with stamped timing marks.
See this post http://listerengine.com/smf/index.php?topic=231.0
Is this the difinitive procedure for measuring backlash? How about .005? Checking every 45º or so of rotation would indicate if the idler is out of round. Mine will be going back together soon and I want to make sure its right.
Quote from: Tom on May 24, 2006, 10:18:56 pm
Guy and Kevin,
Just to confirm that we are all talking the same thing. The lash would be measured with a dial indicator on a tooth of the cam gear and the measurement would be the amount of rotation before the slop is taken up in the gear train. And if that is the case Guy's number of 5 thou would probably be an undetectable amount when just rocking the gears back and forth.
It seems like excessive lash could be contributing to the gear failure some have experienced as the gears slap against each other. It seems like I need to attend to this before I have "chunks". And seeing as Tim lost a bronze gear that is not the answer either. So what should I do? Put the aluminum one in that I have on the shelf and see how it fits?
Tom
Thanks, Geno
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they are working on an offset pinion shaft.
Regards
Tim
That sounds like it fits in the category of (If you can't make it right make it adjustable.).:)
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I know this issue has been discussed before but could you give a brief description of the typical idler gear failure and the condition of the remaining teeth if any. Thanks!
Dave
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Chain drives would be nice eh?
Doug
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how are the gears failing?
are teeth breaking off? or..
is the gear cracking in half or what?
perhaps there is a problem with the heat treat on the cast gears?
would like to hear how these are failing, i have a 25/2 ashwameh that i intend on putting into service
and Joel provided me with a bronze gear, but i would like to know what is happening to the gears
bob g
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how are the gears failing?
are teeth breaking off? or..
is the gear cracking in half or what?
perhaps there is a problem with the heat treat on the cast gears?
would like to hear how these are failing, i have a 25/2 ashwameh that i intend on putting into service
and Joel provided me with a bronze gear, but i would like to know what is happening to the gears
bob g
Also are the teeth wearing thin then failing?
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Hi Ken... Too bad about the gears... They seem to be a common point of failure on these engines.... My solution would be to replace the timing gears with a cog belt drive... to do this I would relace the cam shaft with a longer one and extend it out through the cover that the injector pump connects to... Insted of pins just braze the cam lobes to the new shaft Then remove the flywheel and install a coged type pulley on the crank... and replace the flywheel.. Fasten another to the extended cam shaft and make an idler / tensioner in beween.. A good quality belt should last for many years... I know this is more work than most folks will want to tackle.. but after it's done I think you would have a better engine...
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I have some bronze idlers here, if you need one in a hurry I can UPS one down to you tomorrow morning. That is, assuming the GM90 gears are the same as all the others.
John F.
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The timing gears and idler for the 14/1 and 16/1 GM-90 are the same as the standard 6/1 and 8/1 CS. I'll check my shelf in the morning and see what I have in stock. If I were to tool up my gear hobber would anyone be interested in steel gears with either needle bearings, ball bearings or bronze sleeve bearings for the idler pinion? I'll check and see if I have a hob of the correct pitch and pressure angle tomorrow. Once I set it up I can cut at least 6 at a time. Another option is to make them from ductile iron billet, or semi-steel, which is much more shock resistant than the cast iron of the originals.
I have a Brown & Sharpe gear tooth vernier. I'll check the working depth, circular pitch,addendum, dedendum, Pressure Angle, and Diametral Pitch tomorrow and see how they compare to a standard US made gear.
A run of offset pinion studs is also possible if it is determined that the problem is the backlash. The problem I see with the offset pinion is that it is not always possible to split the difference between the two gears. You could set one gear right on the spot with an offset but not necessarily the other gear. I personally feel that a gear made of stronger material is the best solution. Helical gears with a small angle would be the strongest and quietest solution but would be expensive and more difficult to implement. A small angle, just enough to ensure continuous mesh, would run quiet and with minimal side thrust.
Just a few thoughts,
Mike
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I vote for roller chain and sprockets. That would last forever in there. A spring-loaded tensioner would compensate for wear and if one were really motivated, a gear pump from a car could be used to pump oil better than the reciprocating pump on some of the roids. It'd be self-priming, too.
halfnuts
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I vote for roller chain and sprockets. That would last forever in there. A spring-loaded tensioner would compensate for wear and if one were really motivated, a gear pump from a car could be used to pump oil better than the reciprocating pump on some of the roids. It'd be self-priming, too.
halfnuts
If I had a listeroid by definition I would not know precisely what was different from lister, given that unknown I 100% agree that any shop time invested would be on a solution that I could guarantee 100% effective and reliable, and that would be duplex or triplex roller chain, it's a tried and proven technology that will last many many thousands of hours and be cheap and easy to replace when it eventually wears out, unlikely to be within 10,000 hours.
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Chain drive sounds very doable to me, and might be the best solution for the long haul. The chain could easily be tensioned with an offset pinion and locked in place. I think this is an idea that deserves further investigation. The crank gears are steel and the idler and cam gear is cast iron. In automotive practice the crank gear is steel mainly for wear due to the fact that the teeth are in mesh twice as much as the cam gear. The fact that the camshaft is not evenly loaded also may contribute to the gear's failures at a specific place. Multi-cylinder engines have much more evenly loaded cam drive trains. The injector cam also contributes its pulse to the gear train. All in all, the chain and sprocket setup looks good. The main task is to remove the crank sprocket and either place a pin or mill a keyway to prevent rotation of the sprocket. Either will create a stress riser. Perhaps a shrink fit would work better? The cam gear also presents its difficulties with the transfer of the governor system to a sprocket. Possibly the cam gear could be turned off of the cam/governor assembly on a lathe to the required clearance and bolted to the remainder of the cam/ governor assembly. I'll look into the feasibility of this tomorrow also.
Mike
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Yes. Make it so.
Halfnuts
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Ken, do you still have the old camshaft? Would you be interested in sending it to me for modification? I'll look at some of my other camshafts tomorrow to determine the possibility. I think I can turn the cam gear off of the hub and shrink a sprocket on it. It wouldn't hurt to have some rivets or bolts holding it also if there is room, although a good shrink fit shouldn't need it. I have a 16/2 crank that is missing the crank gear. I can mike it but its no guarantee that it is the same size as the other listeroids.
Mike
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Wow I had thought and people like it.....
Now how about replacing the tappets with GM hydrohlic valve lifters. Small block Chevy would be best since they are standard items in Chev and Holden V8s. Does any one know if the same lifter was used in any Vauxhal emngines?
Doug
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I wonder if a Mercedes gears and chain could be adapted. Their components look like heavy duty stuff!
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Could the clearances be too tight? Then when the gears warm-up and expand they just jam and bind until they break. Evidence of this would seem to be wear on the bore of the idler gear and the idler gear shaft. Correction for this would seem to be allowing for the adjustment of the position of the idler gear shaft to get the proper C/L distance between the idler shaft and crank and the idler shaft and camshaft.
Perhaps mount the idler shaft on a plate that would be allowed to swing on a pivot mechanism to give adjustment and then locked down. Les
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Ken, I have an idler gear. Send me your address and I'll get it to you by priority mail, no charge.
Mike Montieth
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Doug,
I dont think that even the engines with oil pumps have a good enought/steady enough pressure to maitain hydraulic lifters and also since there is no oil filter keeping them from plugging would be a nightmare.
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so how about some info guys???
the question has been asked as to how these gears are failing
seems like a determination of why they fail is in order, close inspection of the failed component will lead to the cause and corrective action.
how about some pictures? some close up shots of the failure?
does the gear snap in half, or lose teeth?
are the teeth torn out into the root?
is there evidence of shock loading?
is there evidence of binding?
is there evidence of spalling?
is there evidence of brinelling?
frosting?
i wanna know...
do i have to run my 25/2 as is and let it fail, so that i can find out for myself?
would seem to me, if i had a failure i would want to know what caused it, before just replaceing the gear.
there are literally dozens of reasons for gear failure, from faulty design, to faulty setup, faulty metallurgy, lubrication, shock loading, etc, etc.
ok, now i have asked again....
anyone??
enquiring minds want to know :)
bob g
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As Mike mentioned, there are other options for materials. I was thinking along the lines of Delrin or a high impact engineering plastic. They wear forever, run quiet, and might be applicable to this application.
Bob
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Yes Firebrick that thought crossed my minds about the piston oil pumps, but if someone like Mike were to get his GM 90's retofitted with a chain drive cam maybe it would be possible to also adapt the Petter Gear pump to solve both of these problems ( In fact all the Listeroid oiling problems ).
Doug
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Should one of us have enough spare time to actually tackle a chain drive, I'm wondering about the current drive gear mounted on the crankshaft. Anybody ever remove one? It looks like it might be removable by heating in an oven for a while. Wonder if anyone has ever done it.
Halfnuts
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The gears on the crank are an extremely tight shrink fit. On one i worked on a few years ago I had to crack it with a chisel to get it off. It was a customers engine and I don't remember the brand. (The gears on that engine broke because the owner was using ether to attempt to start it instead of bleeding the injector.) I heated the new gear in oil in my heat treat oven to install it. You only get one chance to slide it home, it shrinks immediately upon contact with a room temp crank. I think a sprocket with a hub could be installed the same way. I didn't see anything that would prevent using a chain drive but you'd need to be sure of the offset of the idler. The only point of interference I see is the size of chain that would clear the cam case. I'd machine the teeth off of the cam gear until I reached base metal at the root and then machine a small flange for the sprocket to seat against when it is shrunk on. You'd also want to make a mockup with gears that would slip on the cam in order to get the timing right and allow a way to mark the position to shrink the permanent gear onto the cam assembly. A length of chain would be stretched across the dummy sprockets to mark the timing. I'd have to get a piece to see but I think a # 40 chain would clear.
Mike
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bob g
The gear that failed on me was bronze it was worn on both sides to a sharp point , then four teeth broke off then just died . I now have my second one in and running.
Regards
Tim
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The nice thing about the cog belt I proposed is that it doesn't need lube and will last as long as a chain...
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bob g
The gear that failed on me was bronze it was worn on both sides to a sharp point , then four teeth broke off then just died . I now have my second one in and running.
Regards
Tim
Tim,
Thanks for the reply!
I would suspect there is a problem with the gear train....It could be one of the other gears has a incorrect form that wears out the idler...also burrs on the crank gear(lot harder gear, it will always win) could wear it out like that. Some seem to think there is a large load on the gear train and the gear can't handle it or to much backlash. I don't think so. The old ones ran for years and no problems. I would inspect the crank gear and cam gear for sharp burrs near the top of the teeth.(stone them off if you find some). We all know the Injuns run there tooling till it doesn't work well then sell it to the Listeroid Mfg.
Good luck!
Dave
Bob g what u think?
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the tdi engine has a timing belt. the mercedes has a timing chain and the cummins has a timing gear. why would anyone want to replace a gear for a chain or belt. i am sorry.. but that makes no sense.
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Ken & List, When Tim (Sawmiller) indicated his idler shaft, he said it had an 8 thou offset. Perhaps this problem is mainly one of shoddy assembly. When I looked at my friends 6-1 today, there is nothing to indicate that it is offset, ie: no line, arrow or paint stripe, do we use the location of the oiling groove as an indication? who knows. It would seem that if this offset were installed toward the crank/cam gears, it may be running to deep, causing the sharpened gear teeth and eventual failure. Hopefully Mike will check some of his idler shafts to determine if the 8 thou offset is close to a standard, and if so, in what direction the offset should favor to get as close as possible to proper mesh clearance. The drive to make a solution, though admirable, may be entirely unnecessary, as well as not being as reliable long term. I agree with Rocket and my own somewhat limited experience, gear drive should be the best, followed by chain, the belt is not a viable solution for this application as it is not durable enough (VWs need their belts replaced as do all belt driven cam drives). To sum it up, if the offset idler shaft is standard, the cause for most of the failures could very likely be incorrect assembly, which leaves us just another thing to check for when inspecting our engines before first fire. Ken, hope your up and running soon.
Regards,
Paul
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Is there a chance that the idler gear seized to the pinion? When I took this one apart I had to drive the idler out of the gear. If this is the case the crank gear would tear the teeth off of the idler. I would post pictures but coppermine and I are not getting along right now.
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Ken, do you still have the old camshaft? Would you be interested in sending it to me for modification? I'll look at some of my other camshafts tomorrow to determine the possibility. I think I can turn the cam gear off of the hub and shrink a sprocket on it. It wouldn't hurt to have some rivets or bolts holding it also if there is room, although a good shrink fit shouldn't need it. I have a 16/2 crank that is missing the crank gear. I can mike it but its no guarantee that it is the same size as the other listeroids.
Mike
I'll send one to you Monday morning if I can find you mailing address.
Ken Gardner