KAAMA

iTrader: (1)

So then, what are you saying Steve? You are finding the X slant cut gear is now better/stronger than the XR straight cut gear? Or are you only saying that the X gear is a more reliable/stronger piece than what it once originally was??? Should I switch over to the X slant cut gears next time I rebuild or what???

I have XR gears/drives at this time....so far 200hrs on the top gears, 565cid naturally aspirated with about 670lb of torque in 32' Active Thunder turning 5400-5600rpm on top, Amsoil synthetic gear lube.

I am very curious as to what you implying here if anything---looking for clarification. Thanks

RICHARD CUNY

Steve and all in decussion
I am running a older 87 baja 240that i converted to teague 620 ITS Bravo XR boat runs near 80 but i have to shorten up the drive because it is in a alpha hole and is runnung very deep causing the boat to run very high.This is my first season back to boating after coleges and weddings and all that stuff. this decussion sure makes me wonder what I am in for should i consider contacting someone in the gear trade to have new gears heat treated or just go with another stock set.
Rich

RICHARD CUNY

steve sorry I have a 5600 chip changed it from 6000 floated a valve ans shortened a manley push rod my marina said they thought 6 was just a bit high for roller hydralic.
Rich

SpeedMaster

I am not implying anything.

Our application is water ski racing, 20' boats towing skiers,
my own engines have been a 480ci 740hp 640tq and a 565ci not dyno'd, but you get the picture.
XR gears on customers and my boats about 4 hours before pitting the pinion, X gears- haven't failed or worn any yet- 6 hours on my boat and customers with about 80+ hours.

I believe, the XR's are stronger gears, BUT when you look at there rotating action they 'step' from tooth to tooth, whereas the X's have multiple teeth in contact and have a 'rolling' action.

With your boats, heavier weight and lower rpm for peak torque you probably need the XR's for the strength, but who knows what would happen, ie I am not advocating changing.
At 200 hrs, I would think that is good life. I have commercial fisherman who wear the brass shift rings in 400 odd hours.

The XR gears are Near net forged and NOT machined on the tooth surfaces, the X and standard gears ARE machined on the tooth surfaces, therefore the more consistent backlash.

I have had the gears (both styles) metallurgically tested and composition is almost identical and the base metal is good quality, they recommended the next grade 'higher'. This was done at BHP Billotin (sp?).

I have also run XR gears with Smity's treatment, they looked good, the backlash loop was closer, but ultimately did not last longer in OUR APPLICATION.
nb. This is in no way a dig or slight on what Smitty does.

Steve

SpeedMaster

What oil, brand and grade?

The only 'failures' ( not wear) I have seen with my setups is 1 boat ran 75/90 oil xxx brand, changed to 80/140 xyx oil and no more problems.

Steve

KAAMA

iTrader: (1)

KAAMA

iTrader: (1)

[QUOTE=SpeedMaster;2655711] I believe, the XR's are stronger gears, BUT when you look at there rotating action they 'step' from tooth to tooth, whereas the X's have multiple teeth in contact and have a 'rolling' action. [QUOTE]

Yes, that is the way it has been described to me by the person who builds my drives (Mr. Gadgets)

[QUOTE=SpeedMaster;2655711] With your boats, heavier weight and lower rpm for peak torque you probably need the XR's for the strength, but who knows what would happen, ie I am not advocating changing. At 200 hrs, I would think that is good life. I have commercial fisherman who wear the brass shift rings in 400 odd hours.[QUOTE]

This may be a stretch in thinking, but with my boat having TWO drives, it might be safe to say that with it being only a 32footer it is probably close to the same weight/outdrive/HP/Torque ratio/range as your ski or test boats give or take---of course different applications. Perhaps the X gear may be a better gear (???)---that's the BIG question of the day.

Your entire response was very intriguing. Thanks

RICHARD CUNY

STEVE
The last oil change was this season i used Mercury High Proformance Gear Lube + does not say what viscocity it is just Part # 92-858064k01 could this be my problem.
Rich

SpeedMaster

No, it is one of the best I have found for durability.

87 baja 240that i converted to teague 620 ITS Bravo XR boat

Double and triple check your alignment. Does this have the longer U-joint shaft? Make sure the alignment tool is 'square' and 'centred' to the bellhousing.

Mr Gadgets

Daredevil.
Let me see if I can explain.. the NXT does have a transmission in front of it.. It sort of looks like someone took an XR upper and tipped on it's side. The input shaft goes into the top of the upper and the output is taken from the bottom of it. So the XR upper input shaft is removed and the pinion gear acts like an idler gear and only transfers power in reverse. On the other side there is another gear that drives an oil pump.
So when you are in FWD the input shaft enters the transmission and is connected to the clutch shaft. The cone clutch is locked into the gear closest to the output shaft, which is (the gear) connected directly to the output shaft. What goes in, goes out.
Now in REV, the input shaft, connnected to the clutch shaft, has the cone locked into the gear closest to the input shaft, which rotates the idler gear ( pinion gear in the XR upper) and transfers motion to the gear closest to the output shaft but rotating in the opposite direction.. What goes in goes out, opposite.
The shafts in the transmission are different than the XR and I think from the pics in the manual they are not even XR gears, just the cone clutch looks the same, but it may not be either.
I hope this makes better sense. I could scan the pics in the manual and send it to you. I dont care to reproduce it on the board, may infringe on some copyrights.. Hate to tick off the Big M!!
Dick