Intermediate shaft gear troubles

[440beep]

So this happened to me while driving yesterday, somehow ground the teeth off this Milodon intermediate shaft drive gear, and left me stranded luckily near the house. The shaft/gear is roughly year and half old. Anyone else have issues like this? What would cause this?

 

[Hemi Rebel]

Is that a bronze gear? If so, thats your problem. Unless you are running a billet cam

 

[440beep]

Yes, I'm running a billet roller cam.

 

[Hemi Rebel]

Where did you get the gear?

 

[440beep]

My motor builder got it from the local speed shop. I'm hoping this was a one off fluke part, and is not a common occurrence with these bronze/brass gears. Its supposed to be the Milodon intermediate shaft to be used with the Melling oil pump.

 

[Hemi Rebel]

Its not that uncommon for brass gears to wear out. Ive read that after the first one goes it conditions the gear on the cam and the 2nd one lasts longer as a result. Change the oil, replace the gear. Hope for the best

- - - Updated - - -

http://www.hotrod.com/how-to/engine/distributor-gears/

 

[Hemirunner]

Are you running a bronze gear on a bronze distributor bushing? Usually, that's the problem. It allows the bushing and/or the bottom of the gear to wear down quickly and then the centerline of the cam and the centerline of the gear are no longer in alignment. The more it wears, the more quickly it wears until you have issues. General indicator is continual timing changes. I run a stainless steel .005 shim between the two and it seems to be enough to eliminate the problem.

 

[440beep]

As a matter of fact I am running the bronze gear on the bronze distributor bushing. Ok, need to find that stainless steel bushing then.

By chance have a link for the shim you're using please?

 

[Jeremiah]

What is the oil pressure like? Idle-hot, idle-cold, etc.

 

[Hemirunner]

http://www.mcmaster.com/#97022a333/=yc0qyu

They also have them as thin as .001 thick if you really want a thin one. Similar materials don't like being rubbed together. The shim provides a dissimilar pairing and lets more oil get in there. It's not a very large diameter shim but it works.

Look at the bottom of the gear and see if it has a groove worn in it from the bushing. The bushing will most likely also need replaced as it's probably worn down.

 

[lewtot184]

bronze intermediate shaft gears are sacrificial lambs, they're supposed to to take the wear instead of the camshaft. i've seen them not last 2 weeks. too much oil pressure can hurt them and i believe burrs on the cams gear teeth shorten their life. this is why i have no interest in using a roller cam to drive on. between the wheels and the gear there is a maintenance headache.

 

[Jackpot50]

Check to see how much clearance there is between bottom of distributor shaft and where it sits in gear, too much will let gear raise up and cause gear problems as well as timing.
Those teeth look really sharp like wore out.

 

[440beep]

The oil pressure at cold idle was roughly 75-80 psi, and at hot idle it would be lower. Hot, in gear and idling the pressure would be 30-40.

The bottom of the gear does look worn compared to an spare new one I have laying around. no longer has the beveled edge and the thickness is noticeably smaller. No grooves worn in it. And I can't tell what shape the shaft bushing is in.

That bushing looks to be a real pain to get out of the motor. Have to find a really long pair of needle nose pliers to reach down there.

 

[lewtot184]

The oil pressure at cold idle was roughly 75-80 psi, and at hot idle it would be lower. Hot, in gear and idling the pressure would be 30-40.

The bottom of the gear does look worn compared to an extra new one I have laying around. no longer has the beveled edge and the thickness is noticeably smaller. No grooves worn in it. And I can't tell what shape the shaft bushing is in.

That bushing looks to be a real pain to get out of the motor. Have to find a really long pair of needle nose pliers to reach down there.

i've taken the oil pump off and used a long 3/8" drive extension to knock out the bushing from the bottom up. also check the end play on the cam (may be difficult with the tappets having a spring load on them).

 

[Hemirunner]

It's a roller cam so end play can be checked from the lifter valley using a mag base and dial indicator if you have the intake off. I have a tool that I turned on the lathe to up the oil hole to drive the bushing out. Aforementioned extension may also do the trick. I figured the bottom of the gear would be worn. Always is. Excessive clearance between the dizzy and the drive gear isn't as much of a concern as the gear mesh is designed to keep the drive gear in place under accelleration. Some guys use the shaft collars, I use an aluminum spacer and a shim between it and the top of the bronze gear.

 

[rumblefish360]

An easy repair can be the Hughesengines gear designed to be run with ANY cam that is made by Crane. There just under a hundred bucks.

 

[Hemirunner]

An easy repair can be the Hughesengines gear designed to be run with ANY cam that is made by Crane. There just under a hundred bucks.

I'll never understand why Crane didn't sell the whole gear/shaft assembly. Those are an incredible PIA to change.

 

[lewtot184]

the design of the cam/intermediate shaft gears are so that the thrust is downward. if the shaft is climbing upward then somethings going on. i do believe that once the gears are "mated" and the shaft bushing starts wearing due to excessive oil pressure, then the bronze will give up. also, some of the bushings out there have too large of an i.d. i had a machine shop that installed a new bushing that gave .010" clearance before any run time; way excessive!

 

[coloradodave]

Check out the October 2015 issue of Car Craft. Steve Magnante has an article titled Oiling Systems 101: Moving the Lube. Very interesting read about the subject of this thread...

 

[440beep]

Here's a picture of a before and after gear. The "after" gear looks like it lost quite a bit of material compared to a new gear, but will know for sure once the new Milodon gear/shaft shows up tomorrow. I'm guessing I will be asking for trouble if I don't also replace the shaft bushing..........