Biggus

iTrader: (1)

Was hanging around a friends shop this morning while he was tearing down a pair of XR's. Both upper pinion gears were wasted, severe deep pitting on some teeth, other teeth looked new. What was odd is given the horrible shape of the pinion gears, the forward/reverse gears looked perfect. Are the XR pinion gears made in china?

onedownonetogo

The pinion gear is at a disadvantage to the driven gear at a ratio of 16 to 19 .
This is not say that the driven gear is immune to the same kind of wear . The way the gears are made , net forging of the gear teeth lends itself to bad run out of the gear teeth . With run out of both pinion and driven gears there will be tight and lose spots . Also I think the the gears are soft on the core letting the hard surface flex leading to pitting .

Mac

articfriends

iTrader: (1)

I converted my Max-worx parts based bravo drive to the XR gears when they first came out, within 2 years-50-75 hours the pinion gear was scalloped like it was too soft. I changed just the pinion gear and that was in 2003 if I remember right, here it is 2012 and at least 400 hours on that same pinion gear, not soon after changing the pinion gear I sheared the floor on a xr upper gear that Max worx had bored out to accept a special bearing, I changed just that gear (I think in 2004) and been running the same gears ever since and they still look like new (had 650 hp , 750 hp, 950 hp and currently run my 1050 hp pulleys 90% of the time). At one point they made some pretty good upper xr gears. I have sheared off 2 vert shafts, wrecked 2 upper shafts and sheared off 1 prop shaft in the past 10-11 years, also went thru 10+ sets of lower gears, go figure, Smitty

JaayTeee

I've often thought that.

Something changed around 05'

Now it seems like it a 50/50 chance that the'll pit
very early on.

Biggus

iTrader: (1)

It seems the quality is very hit or miss. Does Cryo/ISO treating help reduce/eliminate pitting?

Smitty

iTrader: (1)

Cryo treating will help to a point. Also, the setup can make a huge difference. If a shop sets it up the standard way, it won't last. A good drive builder knows what to do...

I am working on some gears that should last a while longer. I am 6-9 months away from finished product.

articfriends

iTrader: (1)

I cryoed and isoed the upper gearsthat are in my drive that have lasted so long after they had been in service for a while, it really seemed to help the lower gears last much longer, haven't seen it help at all however for guys that are blowing teeth off gears, Smitty

pqjack

since the xr are subject to a lot of hp,and therefore run probly hotter,i wonder if a thicker oil would help?..im going to run 75w110 severe gear oil (amsoil) in mine...no secret recipe here,but it might help...

1 MAIDEN AMERICA

I got 100+ hours out of my gears before they started pitting/busted. 38 Lightning, 700HP, 35P 6B Herings. Redline 75-250

JaayTeee

I've seen these things fall apart behind 500EFI's,
I'd venture that 385's might even do a number to them,
if you get one of the bad sets.


I used Amsoil in mine (XR's) and still had issues.

Might want to check with John P @ the Bravo Shop,
he's got a line of oil thats pretty good.