GT750 Water pump gear - actual failure??

[speedblock]

I did a search and didn't find exactly what I was looking for, so forgive me in advance if this is somewhere obvious and I missed it.

I see many threads discussing the typical crack that develops in the plastic GT750 water pump drive gear. My friend and I have 4 buffalo motors in pieces now and each has that issue. My question is - has anyone actually had the gear fail to the point where it stops working? I have to assume the answer is yes. If so, do we have an idea how long a new gear will last before developing the dreaded crack? The motor for my project bike has a gear with what I would consider a "not too bad" crack, but I wince at spending $80 plus shipping to replace it. Then again, I don't want to dive back into it if it fails at some point down the road.

Thanks for any insight.

- Chris

[oldjapanesebikes]

I think Allen (h2okettle) has put some incredible mileage on his without it failing - not sure if I remember correctly, but around 80,000 miles (?). Others have had them fail at considerably less. Some folks have installed a large spring clamp on the boss of the gear as a repair with success and Lane (on this board and I think also the Kawasaki Triples board) had another fix. It is your call on which way you'd like to go of course. They are available up here for not much money from Suzuki - I posted some 'how to' order info and contacts in this thread previously.

[H2RICK]

Hmmmm.....let me do a little analysis on this......

You'd rather take a chance on burning up a good motor and/or being standed in Hog Wallow, Arkansas in the middle of a trip and have to rent a truck to haul the bike back home because you're worried about spending $80 for a new water pump gear ?? Am I missing something here ?? Did I misinterpret your post ??

[speedblock]

As someone who has been temporarily sidelined, but not stranded in Hog Wallow Arkansas, I now know better and figured I'd ask before I convince myself that the cracked gear is ok.

My intent is simply to see how many of us discovered the cracked gear while tearing down the motor for something else, vs. having it actually fail, disable the cooling system and be the cause of the repair.

Another $80 or so into my '75 at this point doesn't really make a difference. But does that $80 really buy peace of mind, or will the new gear crack as soon as it heats up and is stressed a little? I'm just curious.

Thanks.

-Chris

[tz375]

Speedblock raises an interesting question. How many gears do we know off that actually failed in service? Has anyone had one fail on them or do they stay cracked and never fail in this lifetime.

I replaced a few and am starting to wonder if I really need to or if I'm being overcautious. Besides, what's a little crack between friends? Answer that one with care......

[Buffalo-guy]

I had one fail while riding, so it is not an urban myth. The first thing I noticed was the tach stopped rather suddenly, and then the temp guage started going for the moon. The gear will function when the crack is on the hub, or part way on the gear center, but the second the crack reaches the perimeter, it's done, and it breaks into multiple fragments, trying their best to mess-up the rest of the works in there. As Ian said, we have had some success with preserving gears by putting a spring steel heater hose clamp on the hub, to keep pressure on it, and preventing the spline on the metal hub from twisting in the plastic part, and starting the crack in the first place. My friend, a diesel mechanic, sourced the clamp from the Kenworth parts bin, I think for 3/4" heater hose. The plyer tabs have to be broken off, after its mounted, so as not to interfere. There are most likely other ways of accomplishing this fix. Anyway, there's my two bits worth. Cheers.
Fred

[johnakay]

didn't some one on here made one or a few out of aluminium.

[oldjapanesebikes]

didn't some one on here made one or a few out of aluminium.

That was Fred (buffalo-guy) - I posted some photos for him in the Services thread at this link.

[speedblock]

Here's another way to look at this: who has disassembled their motor (either original or after replacing the gear) and found the plastic gear without any damage? Anyone?

[oldjapanesebikes]

who has disassembled their motor (either original or after replacing the gear) and found the plastic gear without any damage? Anyone?

Nope - always at least some sign of cracking.