Shaft Alignment after gerabox change.

[dwsa]

Just changed the gearbox on a friends 95 SN, now I have run into a small problem. The shaft alignment is out of tolerance, the gap at the bottom of the two flanges is 040" and 000 at the top. Now, normally I would adjust the front mounts downwards to compensate, but on this boat the front mounts have only one thread left to adjust down. Raising the rear mounts I fear will cause the engine side flange to be too high. I can only think to check the strut bearing and alignment / mounting. Has anyone had a similar experience. Cheers Greg.

[dwsa]

RE: Shaft Alignment after gerabox change.

Just want to add that the new gearbox is a PCM Powerplus with 9 degree offset, and should be the same physical dimensions as the original that came out.

[dwsa]

RE: Shaft Alignment after gerabox change.

My rough calculations indicate that I need to drop the front mounts by 1/4" and I don't have space to do that. HELP PLEASE!

[WakeSlayer]

RE: Shaft Alignment after gerabox change.

Is the shaft bent? strut bent? If the owner hit the prop real hard you could have either problem.

[dwsa]

RE: Shaft Alignment after gerabox change.

The shaft is not bent, already checked that. I still need to check the strut, certainly not bent left / right, but would like to check if stut pitch has changed.

[dwsa]

RE: Shaft Alignment after gerabox change.

Can someone with a Ford 351 block in a 95 SN send a photo of their front engine mounts please, interested to see how high they sit.

[WakeSlayer]

RE: Shaft Alignment after gerabox change.

You pulled the shaft? or eyeballed it? Something is off if your motor doesn't line up. Is the entire setup original besides the trans? And is the trans exactly what came out of it?

[dwsa]

RE: Shaft Alignment after gerabox change.

I have not pulled the shaft but rotated it with the two flanges butted together, there is no adverse movement up / down /left or right. Only the flanges are seperated at the botton about 040". The entire set-up is original, I am familiar with many ski nautiques. The gearbox (PCM Powerplus) has same case as original, I understand the internals are slightly different with the Powerplus. Photos I have seen on the internet indicate the front mounts sitfairly high up the main stud with only a few threads showing above the top nut. This has me baffled! I suspect the mis-alignment was there before I installed the new box.

[WakeSlayer]

RE: Shaft Alignment after gerabox change.

Could be that is why the trans failed. Any misalignment puts huge stress on the internals. I am not a transmission guy but have read a lot about them on the other site. Maybe give Eric Lavine a call at Fantastic Finish Marine in Ohio. He is THE transmission guy.

[jaybird]

RE: Shaft Alignment after gerabox change.

Did you replace the damper plate? Did you inspect the damper plate?

[jaybird]

RE: Shaft Alignment after gerabox change.

Check for shims under the front engine mount. Some times they are shimmed and could be removed where the mount bolts on the stringer.

[WakeSlayer]

RE: Shaft Alignment after gerabox change.

I am not sure how it could be that far off from before, all things being equal.

[dwsa]

RE: Shaft Alignment after gerabox change.

I suspect the gearbox failed due to misalignment that caused the rear seal to fail and all clutches were badly burnt and even damaged the clutch housing. My friend had just had a local auto mechanic change the flywheel ring gear and gearbox was removed at that time. With the new gerabox I installed a new damper plate and a new oil cooler.
getting back to the alignment problem, there are no shims fitted, that wouold only make my problem worse. I went on to remove the propeller strut, and cleaned awa about 1 mm thick silicon off the base and re-installed clean with just a little silicon on the bolts. This very slightly improved the situation. My front mounts are adjusted to lowest possible and I tweaked the rear mounts up slightly and was able to achieve the .003" clearance, so left it like that.
Still very strange that the front mounts are on minimum, but hey, she's back in the water!! Greg

[WakeSlayer]

RE: Shaft Alignment after gerabox change.

Nice. Just keep an eye on it. Too bad the guy had an auto mechanic do the previous work. That would be the last place I would take my boat.

[jaybird]

RE: Shaft Alignment after gerabox change.

.003" is great, I believe the reccomended max gap is .004" I like to shoot for .002" myself.