Rhythm and Blues

I've got my Imco Xtream SC drive pulled from my bravo transom assembly on the stb motor. I pulled the drive for a couple reasons, 1. There were no zerks in the coupler, 2. I wanted to check the gimbal bearing, bellows, O-rings, and check the motor alignment (had a small vibration that felt like it was originating from the stb side of the boat. I ran into an issue thats a little confusing not having anyone to talk to about this and having to rely on oso and what I read on the ol interweb for answers. When I checked the motor alignment the tool would only go in less than an inch, in that small amount of engagement with grease on the front of the tool the witness marks showed the motor being high in the front. So, insted of rotating the motor 180 and rechecking to verify it wasnt a coupler issue I got the motor hoist out, suspended the motor, marked the location and loosened up the front mounts. I droped the front of the motor until I could get the tool to slide in/out with 2 fingers-easy. "Now", the grease witness marks on the front of the tool shows slightly more spline on the top then the bottom, meaning front should go down. So, now I rotate the motor 180 and I only get the tool to engage about 1"..... The motors have solid mounts in the front, std bravo type bellhousing mounts in the back. Coupler issue?

Rhythm and Blues

This afternoon I returned the motor to the original position, and went through the alignment verification process again. I could fully engage the alignment tool at this point with strong witness marks on the top, 10 o'clock and 2 o'clock. I then rotated the motor 1/4 turn, alignment tool only engaged 7/16" with witness marks between 12 o'clock and 3 o'clock. I then went another 1/4 turn on the motor so 180 from 1st attempt; now tool only engages 3/8 with witness marks between 11 o'clock and 1 o'clock and finally another 1/4 turn and get 1/2" of engagement with witness marks on the top/right between 11 o'clock and 4 o'clock.. This has got to be a coupler, right?

F-2 Speedy

iTrader: (6)

Im wondering if they used the shouldered type bolts when installing the coupler, if not it could be off center

Rhythm and Blues

Guess theres only one way to find out, right? Pull the motor? Not that thats a big deal, if thats what I need to do I'm fully prepared to do so.. Pt alignment is suspect at this point as well but I'll cross that bridge when I'm all set w the stb issue...

dereknkathy

If you turn the motor and align bar gets tighter, the coupler is not centered. There are special bolts with precise shoulders that hold the coupler centered. I hang a dial indicator on the back with dial on coupler nose and check runout.

Rhythm and Blues

I kinda thought that was what this was coming to. So your saying use 2 dial indicators at the same time? One on the coupler and one where? These are the type of coupler I'm running.

dereknkathy

first, put the alignment tool in and start the engine. sometimes 5 seconds at idle will center the gimball bearing. if no better, it is not on center. with engine out, I have stand stuck to engine with indicator running along OD of area where the coupler goes in. roughly at the w of www.whatever.com on the pic. turning with a wrench and watching runout. too much on one side, loosen bolts and scootch it. if you are under .010, you are ok. this isn't as precise as bearing clearances.

vintage chromoly

iTrader: (3)

There is a factory service bulletin that deals with this coupler alignment / runout.

the jist of it is to go buy 3 3/8-16 flush head bolts (flush head bolts have a 45* cone head on them) and install the coupler with these three bolts (every other hole) and the cone heads will locate the coupler in the center of the flywheel. Install 3 grade 8 3/8-16 bolts (permanent), remove the flush head bolts and install
the 3 remaining grade 8 bolts.

Rhythm and Blues

Ok, now I understand. Is it common for the gimbal bearing not to be centered? I guess I should also verify if the correct fasteners have been used on the coupler as well. This post appears to have the correct part #s

Rhythm and Blues

Thank you, understood. Will do.