Milodon Cam Geardrive Oiling Mod

[Alky V6]

A mod I did to my Milodon camshaft geardrive unit. I don't have much documentation on the modification (pics), but here's the one picture I do have.
The objective of this mod was to supply a pressurized oil supply to the idler gear bearing of the geardrive unit. A small hole was drilled into the face of the engine block in a position where it would break into the main oil galley that feeds the front main bearing. The passage that is shown in the picture was milled into the back side of the geardrive mounting plate. One end of the groove sits over the hole drilled into the block. The other end of the groove has a small hole drilled through the plate that breaks out the front of the plate in a position that will spray oil right at the idler gear bearing. The size of the hole is very small. The orifice is recessed on the back side of the plate and a tiny thimble type filter is fitted into the recess over the orifice to prevent it from becoming plugged. The filter is not in place in the picture. Also not in the picture is an o-ring groove that I machined around the oil feed groove. A rubber o-ring seals the groove when the plate is bolted to the front of the block.

 

[charlief1]

Wish you had more pics of this Donnie. I've got one and would like to use it but it's on the back burner right now.

 

[oldtimer]

Don,

Did you modify the mounting of the plate at all, or did you just follow the Milodon directions. The reason I ask is, I've heard of at least one engine builder that modifies the mounting system. I'm not sure why or how he does it, but I think Busch used these Milodon gear drives quite successfully as is but I really don't know.

George

 

[turbobitt]

I like the idea of having oil to the bearing but do you think it really needs it ? I just removed mine after 3500+ street miles and find that the bearing is OK.
Allan G.

 

[Alky V6]

Don,

Did you modify the mounting of the plate at all, or did you just follow the Milodon directions. The reason I ask is, I've heard of at least one engine builder that modifies the mounting system. I'm not sure why or how he does it, but I think Busch used these Milodon gear drives quite successfully as is but I really don't know.

George

The only other modification I did to the mounting plate was to the bottom two smaller screw holes. After setting up the gearset with the backlash clearances I wanted to use, I worked the mounting holes so that there was a very tight fit installing the bolts as the plate was mounted. In other words, if all the mounting bolts were only hand tight, there would not be any free play between the mounting bolts that would allow the plate to wonder causing a change in the backlash adjustment. Kind of like what you'd have by using tight fitting shouldered mounting bolts. I saw no reason to modify the plate for any other reason.

 

[Alky V6]

I like the idea of having oil to the bearing but do you think it really needs it ? I just removed mine after 3500+ street miles and find that the bearing is OK.
Allan G.

I never ran the gearset without the lube mod. It's something I did right off the bat. In a drysump situation, I know splash lubrication can be lacking sometimes, so I did the mod just to be on the safe side.
The type of idler bearing my system uses is a simple ball bearing type. I know there used to be another optional bearing setup. A flat roller bearing style. I believe Milodon has discontinued that style. I have had to replace the ball bearing style once already over the years. I believe I replaced the idler gear along with it for simple metal fatigue reasons (preventive maintenance). It's a small block Chevy part number for those that are curious. There wasn't any pitting. Just the bearing being a little on the loose side (wobble wise) for my liking. The last time I had the engine apart, the new bearing was holding up nicely.

I look at it this way. The lube mod can only help.

One other thing. I don't know exactly why my gearset is so quiet. The backlash clearances I used? The lube mod? But, you can't tell I'm using a geardrive by listening to the engine run. Even if you plant a stethoscope right on the timing cover!!! I have heard reports from others that have used the geardrive setup that have reported varying levels of gear whine. Maybe the lube mod is helping a lot to control the gear whine that would normally be there if the lube mod had not been done? Don't know. Like I stated, I had done the lube mod from the beginning, so I don't know what the noise level might have been like for my setup without the lube mod.

 

[Alky V6]

You'll notice that the lube orifice is located in a position so that as the oil strikes the bearing, the oil would be carried up and around the top of the bearing as the idler gear rotates.

 

[dr_frankenstein]

Was this drive always under a Stage timing cover, or did you do the mods for a regular cover?

im curious if the mods are worth it on a stock cover...

A.j.

 

[Alky V6]

Was this drive always under a Stage timing cover, or did you do the mods for a regular cover?

im curious if the mods are worth it on a stock cover...

A.j.

I modified a stock cover. As you would expect from me, I performed some very extensive mods to the timing cover. I think I started another thread in this section that gave a simple overview of the timing cover mods.

Here's the link: http://www.turbobuick.com/forums/fabrication-no-solicitation/275200-front-timing-cover-ideas.html

 

[dr_frankenstein]

Thanks! thats exactly what I neede to see!

A.j.

 

[turbobitt]

I never ran the gearset without the lube mod. It's something I did right off the bat. In a drysump situation, I know splash lubrication can be lacking sometimes, so I did the mod just to be on the safe side.
The type of idler bearing my system uses is a simple ball bearing type. I know there used to be another optional bearing setup. A flat roller bearing style. I believe Milodon has discontinued that style. I have had to replace the ball bearing style once already over the years. I believe I replaced the idler gear along with it for simple metal fatigue reasons (preventive maintenance). It's a small block Chevy part number for those that are curious. There wasn't any pitting. Just the bearing being a little on the loose side (wobble wise) for my liking. The last time I had the engine apart, the new bearing was holding up nicely.

I look at it this way. The lube mod can only help.

One other thing. I don't know exactly why my gearset is so quiet. The backlash clearances I used? The lube mod? But, you can't tell I'm using a geardrive by listening to the engine run. Even if you plant a stethoscope right on the timing cover!!! I have heard reports from others that have used the geardrive setup that have reported varying levels of gear whine. Maybe the lube mod is helping a lot to control the gear whine that would normally be there if the lube mod had not been done? Don't know. Like I stated, I had done the lube mod from the beginning, so I don't know what the noise level might have been like for my setup without the lube mod.

My Milodon drive is also very quiet and can't here it also. I'm using a factory modified cover as well. I've used the Milodon drive on other make engines with similar results.
Allan G.

 

[Alky V6]

My Milodon drive is also very quiet and can't here it also. I'm using a factory modified cover as well. I've used the Milodon drive on other make engines with similar results.
Allan G.

Then I have to conclude that we're both just using the right amount of gear backlash.

When I was installing my gearset I did some research on gear meshing. There are standards for such a thing. Basically it comes down to this, you want enough backlash so that you don't end up with gears jammed or binding together at any point during the gearsets operating temperature range, and not so loose that excessive noise ends up being created. I used a different backlash figure for each of the two different meshing locations. Tighter between crank and idler, looser between idler and cam gear. The difference between the two is very little.

 

[charlief1]

Do you remember what you set the clearance at Donnie? I've got one but for the first engine I'm going chain but I want to run the gears on the 4.1 block when I get to that point.

 

[Alky V6]

Do you remember what you set the clearance at Donnie? I've got one but for the first engine I'm going chain but I want to run the gears on the 4.1 block when I get to that point.

I'll try to hunt the numbers down for you.

 

[charlief1]

Thanks Donnie. Did you use wire guages or feeler guages to set the clearance?

 

[turbogray]

interested also looking to learn

i got this from milidon
You can now proceed with the backlash adjustment. Use a single strip of newsprint (not gloss magazine paper) 1/2" wide x 6" long, and wrap the newsprint around the idler gear, between the cam gear, idler gear and crank gear. Press the mounting plate and idler gear assembly firmly by hand toward the cam and crank gears , being sure the newsprint is in place. This centers the idler gear between the other two gears as well as sets the lash between two pairs of gears all in one procedure. A dial indicator while appearing more high tech, can not accomplish all these procedures.

 

[dr_frankenstein]

interested also looking to learn

i got this from milidon
You can now proceed with the backlash adjustment. Use a single strip of newsprint (not gloss magazine paper) 1/2" wide x 6" long, and wrap the newsprint around the idler gear, between the cam gear, idler gear and crank gear. Press the mounting plate and idler gear assembly firmly by hand toward the cam and crank gears , being sure the newsprint is in place. This centers the idler gear between the other two gears as well as sets the lash between two pairs of gears all in one procedure. A dial indicator while appearing more high tech, can not accomplish all these procedures.

I have heard of this method before.... I think I will try this for my gear set the second time around. Ive used this trick for mechanical injection set-up, but first time for timing gears.

A.j.

 

[Alky V6]

Thanks Donnie. Did you use wire guages or feeler guages to set the clearance?

.005" backlash between the crank and idler. .0075" between the idler and the cam gear. I used a little more clearance on the cam to idler because I figured the large cam gear would grow more at operating temperature.
I used a dial indicator setup similar to the way you would check the backlash on a rearend gearset. Load one gear so that it can't move, then rotate the mating gear back and forth with the dial indicator setup on the load face of a gear tooth of the gear you're rotating back and forth.
A little more complicated than the paper method, but I wanted to shoot for exact backlash figures. The paper method just didn't do it for me.

Back when I was first setting up the gearset, Milodon suggested .006"-.008" backlash. A board member suggested .005".

 

[turbobitt]

I have heard of this method before.... I think I will try this for my gear set the second time around. Ive used this trick for mechanical injection set-up, but first time for timing gears.

A.j.

I used this method and verified the complete system backlash with a dial indicator. No noise with this procedure.
Allan G.

 

[Alky V6]

I used this method and verified the complete system backlash with a dial indicator. No noise with this procedure.
Allan G.

What thickness paper did you use and what backlash figures did you end up with?