prop shaft runout on stock bravo1, READ PLEASE
 

Heres the story guys..bought this 1990 pq 290 enticer 2 summers ago and we love it, i noticed it wants to "blowout" more than any other boat ive owned getting and coming off of plane, (havent noticed which engine yet though) I pulled the drives off when i bought it to replace worn gimbal rings and reinstalled everything new, I noticed that the port shaft splines were noticable twisted and couldn't align that drive with alignment tool, so the coupler is probably twisted also. Looks like someone has hit something with that drive in the past, my boat "guy" sais to just reinstall it and fix that maybe during a repower (no abnormal vibration felt), got the drives done and ran it all last summer without any problems, does great!! Over the winter had the props labbed by a local guy and he said one was pretty bad off, got them all fixed up and high speed balanced out good. Im running the boat earlier today and notice the port prop/hub appears like its wobbling...not real bad but the starboard it running true as an arrow, im just wondering if that shaft is slightly bent and its causing my prop blowout issue, remember..that same port side is the one with the twisted splines. IM gonna put a dial indicator on the shaft and see what kind of runout i have.....might just be the prop hub and thats all????

better see whats causing that, if not fixed now more troubles will come, could just be missing the spacer

the spacers are in, there is no play in the shaft or prop when wobbled up/down and left/right, It just appears to be wobbling slightly when in gear, at an idle on the hose, might just be the prop hub and nothing to worry about. I would think if a shaft was bent slightly at speeds, there would be a great deal of vibration and there isn't???

I recall reading somewhere that the Mercury run out tolerance on the prop shaft is .008” as checked with a dial indicator.

Last summer I bought a new XR lower from a “reputable” authorized mercury dealer. When it was new it had a visible wobble. I was told it was within mercury specs. I didn’t have 10 hours on it when it took out the entire lower. IF it were me, I would spend the money and it checked out now before you are replacing the entire lower.

I had a wobbly prop once it turned out that the hub was missing the plastic sleeve that goes inside maybe yours is missing also?

Or you have a 1.25" prop insert and a 1" shaft?

take the prop off and run the engine on the hose.If the shaft bent even the slightest amount it can be visible at the very end of the shaft. If no wobble seen on the shaft, try rotating the bronze insert in the hub four times and observe the prop for wobble.

thanks for the replys...I will run it with the prop off, never really thought about the bronze sleve, if its worn, it might cock the prop and make it wobble..i will look at this..Thanks you. i will keep everyone posted.

update:
I set up the dial indicator and found .005" runout on port and .002" on starboard. I found alot of "crud" between bronze spacer and shaft and spacer and rear of prop hub. I cleaned everything and reinstalled everything. I am using mcguard prop locks and it says to torque to 50ftlbs. I will try to look up runout specs but only .005" of runout i don't think im gonna worry with it right now, hopefully cleanning all the crud will help. I will repost when i get a chance to run it and take a look.