Chewed Up Idler

[listeroidsusa]

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

[Doug]

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   

[Tom]

I wonder if a Mercedes gears and chain could be adapted. Their components look like heavy duty stuff!

[bitsnpieces1]

  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

[listeroidsusa]

Ken, I have an idler gear. Send me your address and I'll get it to you by priority mail, no charge.

Mike Montieth

[Firebrick]

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.

[mobile_bob]

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

[rleonard]

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

[Doug]

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

[Halfnuts]

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

[listeroidsusa]

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

[sawmiller]

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

[fattywagonman]

The nice thing about the cog belt I proposed is that it doesn't need lube and will last as long as a chain...

[xyzer]

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?

[rocket]

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.