driveshaft front rubber bumper wear'g out

[bethron1]

I have been having a problem not being able to keep the front rubber shaft bumpers from being destroyed after a few hours of use. The shaft slips forward against the PTO so there is little spline left for the shaft spline to match up to and starts wearing the PTO splines(softer metal). In my case, as soon as the bumper is chewed up, the shaft slides forward-- the shaft ceases to turn because the PTO shaft splines have been destroyed on the front side and there is no spline left, install a rubber bumper and it holds the shaft back enough into good spline territory on the PTO until again the rubber bumper is chewed up. This has been an ongoing problem.

I thought I'd solve the problem by installing 3 pennies(the thickness of 1 rubber bumper) inside the PTO where the rubber bumper would have been. It held up for a while but the forward thrust( I know, there should'nt be any there) smashed the pennies so much, the shaft slid forward again and again the engine spins and the shaft does not. There is some serious forward thrust on those pennies, no wonder the rubber bumper don't hold up. I'm replacing the PTO because I don't have any splines left for the shaft to work with but I still have the forward thrust problem on the bumpers.
Any Ideas here?????
Could it be an engine alignment problem???

 

[JPX]

Sure sounds like an engine alignment problem. Check condition of the motor mounts - if the engine is moving around it could be making your shaft flop around more.

Maybe the shaft is not the correct one (if it is not the original part)?

The shaft could even be bent.....should check that next time you change a bumper.

 

[bethron1]

rubber bumper

yeah, I know
motor is in there solid, no movement--- different shaft, but the original one did the same thing as this one. with the pump installed and no bumper, the shaft does have some forward play so the shaft is not the wrong one(too long). I'm stumped

 

[kustomkarl]

Which doo is this one...96 or 97...they should be the same but I'll look at the manual anyway. Something isn't just right...I'll post after chow time.

Karl

 

[bethron1]

rubber bumper

It's a 97 GTI

 

[bethron1]

rubber bumper

Think is isn't some serious forward thrust--take a look at these stacked pennies
(click the thumbnail to enlarge)

 

[derek]

the thrust is taken care of in the pump. this is not possible. doesn't mean it isn't happening, but it should not be possible. if the pump didn't take the thrust on the thrust bearing, it would sieze. i think your hull is soft. your pump moves forward and squishes the shaft into the motor. i have never seen it, but i can't think of another reason. it just ain't possible.

 

[derek]

ok, you have 2 skis. the GTI now has a bad pto. put the pump from the GTI into the GS. back trailer in water and fire it up. i assume the trailer will stop ski from driving into the truck bed. run it and watch the driveshaft. does it move forward when increasing the load on the motor? if it does, the pump body is the culprit. if it doesn't, something in the GTI is flexing and allowing the impeller to push the driveshaft into the pto. if it isn't a bad pump body, the hull of the GTI is probably the culprit. if that is the case, i wouldn't try to fix it. there are plenty of broken seadoos that need motors out there for free to $500, depending on how nice.

 

[bethron1]

rubber bumper

That's an interesting thought--the hull itself flexing, although I'm not totally convinced of that( but hey, anythings possible at this point), I'm leaning toward the pump itself or alignment. You know how the front tires will have a tendency to ride up on an incline such as a curb or rut in the road, well a shaft could do the same thing if the alignment was way off, walk itself into the PTO because the shaft slines have a curvature. Is engine alignment something shops can do or a factory thing. I know the TigerShark engine is shimmed for alignment.

Yes, I have the pump from the 96 GS and it's out right now after changing pump oil, question is--are they the same pump??? If the pump is the same what about the impeller and impeller pitch? Process of elimination now.

Attached pictures show the pump installed and bolted in without the seal etc., this allows me to actually see the shaft clearance to the engine shaft(remember the PTO is hollow-see thru so the rubber bumper butts up to the engine shaft)

 

[derek]

96 GS? 717 or 787? if 717 impeller is same. they used 3 part numbers for 720 impellers but all are 11-22 degree pitch. the only diff in the pumps would be if you had to remove the 3 hose nipple-pipes sticking out of the front of the 96 pump. 96 was the year they stopped using that set-up and had a plastic mount plate on rear of machine so you didn't have to mess with hoses inside hull to remove pump. otherwise, you can put an 88 pump on a 99 GTS. plus, you are only doing it for a few minutes to eliminate one or the other as the culprit.