Miloon Drive

[Bewy]

Nope, the taper is more than just a placebo effect. The original Direct Connection pump drives were made of 4XXX steel. A very tough steel. Presume current versions are made of the same steel. They will withstand a certain amount of twisting....& not break. I found that they would wear, & quite quickly, when used with a bronze bush. Ok with an alum bush.
The factory piece is very hard steel, similar to the steel used for drill bits. That makes it very brittle, & has no 'give'. Run a file across the factory piece; then do the same with the aftermarket piece & see the difference. The hex on the factory piece comes to a sharp, abrupt end where it meets the shaft, creating a stress riser in already brittle steel. The taper version has no abrupt, sharp stress risers.

 

[71 Sebring +]

Need a new bronze gear for my smallblock and saw Milodon has the gear and shaft, ready to go. Didn't feel like the whole hassle of removing the old gear and installing new one on my shaft.

Have some credit from Jegs, so I thought I might just buy it, but It doesn't look very sturdy.

It's Milodon #21535. Like to hear some thoughts before I pull the trigger.

I would recommend using a mellonized drive gear. I didn't even get 2000 miles out of a milodon bronze drive gear. Plugged most of my roller lifters and collapsed them. In the process of pulling motor to take apart and inspect bearings and replace as needed.

 

[71 Sebring +]

I would recommend using a mellonized drive gear. I didn't even get 2000 miles out of a milodon bronze drive gear. Plugged most of my roller lifters and collapsed them. In the process of pulling motor to take apart and inspect bearings and replace as needed.

 

[jos51700]

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Hmm. Now that's kinda odd....

 

[mopowers]

I would recommend using a mellonized drive gear. I didn't even get 2000 miles out of a milodon bronze drive gear. Plugged most of my roller lifters and collapsed them. In the process of pulling motor to take apart and inspect bearings and replace as needed.

That's shitty. Sounds like the OP has already run a bronze gear though. The instructions for the melonized gears advise against running one with a cam that has been used with a bronze gear previously. Check out post #5.

 

[Bewy]

You can see the wear on the shaft in post #28. Less than 2000 miles on it!!!! This wear is what I was referring to in post #26.

Over the years when I had Chrys cars, I had some alum shaft bushings. These will NOT wear the shaft. I do not remember what engines the alum bushings were used in. My stuff was early BB & Poly, from 1958 to about 1964.

 

[Newbomb Turk]

You can see the wear on the shaft in post #28. Less than 2000 miles on it!!!! This wear is what I was referring to in post #26.

Over the years when I had Chrys cars, I had some alum shaft bushings. These will NOT wear the shaft. I do not remember what engines the alum bushings were used in. My stuff was early BB & Poly, from 1958 to about 1964.

You used to be able the buy those aluminum bushings but I haven’t seen them in probably 20 years.

The biggest thing is sizing the bronze bushing. They started selling those bushings that were supposed to be a press in deal without sizing but after thousands of miles and who knows how many heat cycles the bores in the blocks go out of round.

If the busing isn’t sized with the proper tool thats what you get. There is no such thing as a press in bushing that doesn’t need to be sized.

 

[Bewy]

Do you know which engines used the alum bushings?

 

[aaronk785]

Every stock engine I’ve tore down had the aluminum bushing.

 

[RustyRatRod]

Miloon. Is that like Balloon?

 

[Newbomb Turk]

Do you know which engines used the alum bushings?

I don’t remember.

 

[RustyRatRod]

With the melonized gears and composite gears, I don't understand why anyone would run a bronze gear. That's archaic by today's standards.

 

[71 Sebring +]

You used to be able the buy those aluminum bushings but I haven’t seen them in probably 20 years.

The biggest thing is sizing the bronze bushing. They started selling those bushings that were supposed to be a press in deal without sizing but after thousands of miles and who knows how many heat cycles the bores in the blocks go out of round.

If the busing isn’t sized with the proper tool thats what you get. There is no such thing as a press in bushing that doesn’t need to be sized.

So are you thinking the bushing didn't get reamed to size and it was too tight of a fit causing premature failure of the bronze gear. After the fact my engine builder said he usually gets about 20,000 miles out of them. He did send me a new mellonized drive gear and set of lifters.

 

[Ironmike]

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Something definitely wrong here. Abnormal wear. Who's your engine builder?

 

[Newbomb Turk]

So are you thinking the bushing didn't get reamed to size and it was too tight of a fit causing premature failure of the bronze gear. After the fact my engine builder said he usually gets about 20,000 miles out of them. He did send me a new mellonized drive gear and set of lifters.

The hole in the block goes out of round.

They make bushing that they claim don’t need to be sized but like I said, the hole in the block gets out of round and it also shrinks with heat cycles.

Plus, there is a tolerance for the size of the hole from the factory.

If you happen to have a block that stated out on the low side of the tolerance. Then the hole gets smaller and the bushing that is said to be “prefit” gets installed. It’s got enough clearance that it slides right in, but it’s too tight to get enough oil to keep it from grabbing the shaft.

And once it starts getting fatter the shaft it keeps wearing it.

I size every bushing I install. I’ve never had one that I could not feel the sizing broach not doing its job.

 

[Bewy]

As I said earlier, the wear is caused by incompatible materials. Nothing to do about sizing. If the shaft slides down past the bush, the size is ok. You would know that straight away by inserting the shaft into the bush. There are many grades of bronze [ eg, alum bronze, phosphur bronze ]. The bronze used is a grade that will be compatible with the hardened factory shaft. The aftermarket shaft is made from a Moly steel 4XXX, which is tough, but not hardened, & it will accept some twisting from a high pressure oil pump....but not break. The factory piece is brittle & will snap like a drill bit if overloaded. I am surprised the sellers of these drives do not include, or at least offer, an alum bush with the drive.

The drive in post #28 has less than 2000 miles on it. Imagine what it would look like after 20,000 miles!

 

[Newbomb Turk]

As I said earlier, the wear is caused by incompatible materials. Nothing to do about sizing. If the shaft slides down past the bush, the size is ok. You would know that straight away by inserting the shaft into the bush. There are many grades of bronze [ eg, alum bronze, phosphur bronze ]. The bronze used is a grade that will be compatible with the hardened factory shaft. The aftermarket shaft is made from a Moly steel 4XXX, which is tough, but not hardened, & it will accept some twisting from a high pressure oil pump....but not break. The factory piece is brittle & will snap like a drill bit if overloaded. I am surprised the sellers of these drives do not include, or at least offer, an alum bush with the drive.

The drive in post #28 has less than 2000 miles on it. Imagine what it would look like after 20,000 miles!

Have you ever measured the bushing once it’s installed? They are never straight or round.

 

[Ironmike]

here's a couple shot of my gear I just pulled this morning. Don't mind the buggering up on the stem portion. That's from yanking it off the shaft.
6700 street miles and many passes, which was 4 summers for me. This summer was crap. Only did 1100 miles. excessive heat and rain.

Cam is Lunati solid roller .640/.640 259/265 @ 50.

 

[Ironmike]

Oh .....it will get replaced.

 

[PRH]

Imo, for a bronze gear these days, with 6700 miles on it……. That looks pretty good.

Yes, it should get replaced now.

 

[jbc426]

I've often wondered if cryotreating them would help to any measurable degree, but then I switched to the melonized gear.

 

[Newbomb Turk]

I've often wondered if cryotreating them would help to any measurable degree, but then I switched to the melonized gear.

Maybe. I’ve used cryo a bunch but never on bronze. It’s worth looking into.

 

[Ironmike]

That's a Comp gear, by the way. Far as Cryo goes, I've had several competition rifle barrels done and the dude I deal with told me once that Cryo is "as effective as the hardness of the material being treated". So my guess is no good for bronze.

 

[Ironmike]

Imo, for a bronze gear these days, with 6700 miles on it……. That looks pretty good.

Yes, it should get replaced now.

I'm not going to do it, but I think that gear had another summer left....................maybe.

 

[Newbomb Turk]

That's a Comp gear, by the way. Far as Cryo goes, I've had several competition rifle barrels done and the dude I deal with told me once that Cryo is "as effective as the hardness of the material being treated". So my guess is no good for bronze.

I’m guessing that would depend on if you could possibly double the life of the part it may be an option.