racinfever

I've gone through 3 sets in 12months, broke starside last oct. locked up lower & twisted off prop shaft. replaced gears, shaft &prop. last month checked port side & gears worn with one tooth missing. today i broke starside lower gears again.
I am going back to 1.50s never had problem with them.
I would rather turn motors the extra 400 RPM than keep breaking Mercury's JUNK GEARS!
Any thoughts???

t500hps

Were the 1.50 older? I've heard alot of people claim the newer gears aren't as strong. If you want to stay with 1.35, a buddy has 3-4 sets of test time only or brand new gears (1.35 and 1.36 I believe). He got them in trade for some mechanical work he did and just wants to get some $$$ for his troubles.

racinfever

Though I appreciate the offer for the gears.....as I said, I believe the gears are junk and whether they are old, newer whatever...I don't think they will hold up which is why I am going back to the 1:50's. Thanks though!

I don't think the 15/17 ver 15/19 are as strong.

articfriends

iTrader: (1)

I have always heard the 1.50 gears are weaker than the 15/17 as the teeth are smaller on the 1.50's, I have never ran anything other than the 1.50's though in my own boat. How much power nd what oil are you using. I spent exstensive time testing lower gears and different processes and have found that cryo treating and isorem finishing along with a certain clearence's and specific oil makes them last considerably longer with the exception of breaking off whole teeth (which I have never done), Smitty

waconda

Are u running 5 blades? What power?
Tell us more so we can help u out.

racinfever

Iam running T 850s xr uppers with -1 Imco lowers 30 pitch bravo ones . the boat will run over 100 mph, but seldom run over 90 mph. 17/ 15 last about 50 hours run time & then 1 tooth falls out. I ran my 15/19 gears for over 100 hours with no problem. Afriend is still running them with no problem.

Mr Gadgets

My .02, if you get a good set they last for a while. If you get a bad set, they will break a tooth. Not sure if it is ratio specific. I have yet to see the lowers just snap a tooth off. Not to say they won't, I just have not seen it yet! but the XR uppers do it quite often.
Which gear breaks the tooth off, the pinion or driven? I know the pinion is much softer than the driven and they will start to pit first, then it takes out the driven gear. Merc makes a lot of money selling them.. Keeps Americans (I hope) working??
My friend with the 36' Apache has 500hrs on his SCX's. At 400hrs he found some pitting of the lower gears and swapped them side to side. Since then he has put another 100hrs on them, well that was two weeks ago.. probably more now. Uppers were still good.
Dick

racinfever

Gears are not showing sign of much wear, tooth always drops out of pinion gear.clean break. What do you think about the extra load factor with the higher ratio ?

Mr Gadgets

My opinion, not based on any real testing, is that the load with a comparable prop would be about the same. The 1.5 uses a bigger prop and you go down in pitch for the 1.34, if I hear what you are doing??? That should keep the load fairly close. But then I am no engineer.
One thing you could do is index the teeth on the gears. I have been told that one tooth can be off by quite a bit. But if that is the case, it should show up in lash measurments. Also the pinion gear can be wobbling.. I have seen them up to .003" wobble and that needs to be corrected..