crazy canuck

I'm in the process of rebuilding both my TRS drives new gears bearings .I going to get the gear teeth nitrided .My question is will the gears have to be shimmed to a diffrent spec than the merc manual, also what about back lash does that change ?

crazy canuck

scarrab30

you shouldnt have to sim any different. If i were you i would use a good synthetic gear lube. Also it would serve you well to make a drive shower. Ive done this on mine and have very good luck with the drive staying together. I run 2 700hp 540ci chevys in a old heavy scarab. Brian

24degrees

Sorry to hijack the thread but 1400hp in a 30 Scarab sounds bad a$$........got any pics?.......what speeds are you seeing?

scarrab30

24degrees, If you look at the avitar for straight jacket, thats the boat im talking about. Hes my son, idont have an avitar so he uses it for his. The boat runs a consistant 90mph with an occasional 92.We spin4blade intimidator-x 26pitch at between 5700 and 5900. The boat is in for stringers and bulkheads right now. Its a 1979 sport 300 otherwise known as the barge. Brian

crazy canuck

Not to get off my own topic but scarrab30 what is your propshaft to running surface dimension .Mine is a deep 8" ,in the process of total re-rig, moving drive line up 4" .I have a 84' scarab11 30,and own with a friend a 79' scarab 30 s type.Motors are 468cu with 250 blowers ,superchillers ,cmi dry pipes around 600hp looking for the mid to high 80's.
Mark

scarrab30

Canuck, The prop shafts are even with the keel of the boat. If i remember right i had to move the out drives up 2and three quarter inches from where they were originally. Ive got alot of pictures ,but being computer challenged i dont know how to put them up. If my son sees this he may post them. Brian

cstraub

This is what I would do to the gears:
www.metalax.com

Works wonders in the professional race circuits on ring and pinions and tranny gears for longevity and strength.

crazy canuck

Chris i checked out that web site.The metalax process seems like some type of stress relieving operation ,but doesn't most lower gear failure happen when the surface hardness of the gear let's say gets "wiped off" causing pits then the gear fails because of the stress riser that the pitting has developed .As far as i know the gears are case hardend a few thousand of an inch to have that surface hardness but also not too hard in the core of the gear to give strength.Stress relieving is a good idea, but preventing the stress riser (pitting)is the
key to gear longivity .Nitriding would help prevent the pitting but i don't know the draw backs if any that might happen .
Mark

waterbum

Has anyone looked into cryogenic freezing for these kinds of parts? Supposedly it increases surface hardness significantly. I don't think it is that expensive of a process. I looked into it when I was having my motors built, but I ended up not doing it. Would have added about $1500 to have both motors (all parts) treated. Plus I don't think the machinist would have been real thrilled about hardening all surfaces and parts before he did his work.

articfriends

I'm currently experimenting with some multi step processes,Smitty