Keep posting you progress please.

Putting in a 540 ci 850 hp whipple motor in my Hallett 270 step.

xr drive with shower and a -2 imco lower.

going with a 30-32 inch 4 blade pending speed runs outcome.

Maybe(vif you let me :) ) over the winter I can send you my lower gears or complete lower assy to have you put your magic gears in.

The drive is a stock XR besides the -2 imco lower

Boat should have no problem runnig in the low to mid 90's

Smitty, just lunched the new Imco, 4 decent passes and a little cruising. Hopefully the gears you're sending will last a bit longer. Do you have any 1.35s for my spare drive?

Was nice talking to you again,your gears on on their way. "just a little cruising",does that mean you kept it under 140 mph:D . Was your Imco brand new from Imco or just had new parts in it,Smitty

Smitty, It was a brand new XR upper, and brand new Imco Extreme lower, with 1.26 gears. Maybe 5 hours of run time.

Smitty, the gears showed up Friday, I'll let you know how they hold up, thanks!

The first thing I would do is look at your lubricant. You say in a later post you are using 85/140. A multiviscosity oil will give you less protection in high shear situations that even a straight weight 85 oil. That's because the viscosity index improver has very low shear strength, and "replaces" some of the straight weight oil. While it makes the oil thicker at higher temperatures than a straight weight oil, it doesn't have the protective properties. The only way to fix this problem is to reduce the gear loading (lower the input torque or use larger gears), or use a lubricant with higher sliding friction strength which means higher viscosity. I would try a 140 straight weight oil. I would look into a synthetic, since it has more stability at higher temperatures, which some people are experiencing with their drives.

Good luck!

Michael

I have tried virtually every synthetic gear oil,something about synthetic gear oils and motor oils that most people don't know is alot of times the oil is actually a straight weight oil and just happens to meet the cold/hot viscosity index reading because they meet the specs for the hot oil viscosity and still flow well enough cold to meet the lower rating. My oil isn't suffering visosity "breakdown" as it usually looks like new and is not burn't )I change it very often). Anyways,From the most Exspensive top secret stuff to el cheapo royal purple,I have not found any that made a real difference in gear life,just that I lose measurable top end speed with thicker (140 weight) oil. I will be testing new additions to the current gear finish I have already had good luck with soon (after finally finishing my motor for the season I should have boat back in water tommorrow),I plan on using royal purple 75/90 for now,Smitty

Smitty, just to clarify, you can't detect "viscosity breakdown" visually. It has to be tested. Also, I wasn't referring to viscosity breakdown per se. I was referring to oil film breakdown between gear teeth in high shear situations, which is helped by higher viscosity oil. It sounds like you have already tried this. I could be wrong (and I hope I am), but you may be fighting a losing battle, with such small gears.

Michael

I think its called breneailing[sp]??? Like Dean at the Bravo shop said theres nothing you can do about it, theres only one tooth touching at a time,Thats why there trying to get a helical style gear in the foot.3 teeth sharing the load.

I haven't had my boat out yet this year (I finally finished installing motor yesterday after dynoing it a few weeks ago and breaking the 1000 hp mark) but the gear treatment I tried last year was done to my lower 1.50 ratio gears and they lasted the rest of last season,about 3 times longer than any others have,and they are still in my drive ready to get beat up on some more very soon. I was focused on lubricants being the problem but after going thru about 5 or 6 sets of gears with every kind of synthetic gear oil in past 2 seasons I started focusing more on the surface treatment and structure of the gear. I am now convinced as long as you are running a synthetic gear oil there isn't much else you can do as far as a "outstanding oil"that will make the gears live any longer from better lubrication,I might be wrong though,Smitty