2015 SJ, Cold Fusion alignment tool & driveshaft runout

[user_error]

Looking for some input here..

Assembling a 2015 SJ hull, all oem components.

I sent in a couch shaft to get shortened to SJ length. pressed into oem stator section with oem wear ring and oem 2015 nozzle.

I have been struggling with a vibration issue from the pump area recently. I have checked alignment multiple times and must be missing something along the way.

When I try to align the pump using the cold fusion alignment tool the alignment sleeve will slide into its respective area with no issues if the driveshaft is oriented at a certain position, and the tool will sometimes catch/hang up if it is rotated to another position.

I understand driveshafts can have acceptable runout tolerances, but has anyone experienced this with the cold fusion tool?

2 friends of mine with newer SJ's have zero shims on their rear pump mounting bolts. Does your 08+ ski have shims on the rear pump bolts?

I anticipate pulling the driveshaft back out of this thing and verifying the runout.

Any thoughts?

Thanks in advance

 

[john zigler]

Sounds like your shaft is not true, and straight. The tool does not lie.

I have seen OE set up's with no shims, but the alignment has been way off. I always end up adding shims. Sometimes even on the midshaft housing as well to get it to be perfect.

 

[user_error]

I understand, I'll dive deeper into this thing.

To properly measure driveshaft runout where should it be measured? I'm assuming just behind the midshaft splines and just in front of the prop threads?

 

[x2mafia]

my brand new JM shaft had crazy runout out of the box, I didnt catch it immediately, now my ski sounds like a kawi out of the water...

 

[user_error]

That's a bummer, I can't remember the tolerances off the top of my head but if you pull it out we can measure it. I'm putting a dial on mine tomorrow

 

[Snowmobiler]

My 2004 shaft that appeared to have never been removed was also a little out of whack when reinstalling with the cold fusion tool. You could get it lined up perfectly then spin the shaft a little and it would be slightly off.
As far as I know it was run for 10 years or so like that. Pump and midshaft bearings are still tight and smooth and no noticeable wear to the splines.

Pump came with no shims from factory but when reinstalling it needed shims.

 

[user_error]

That is good to know, thank you

 

[user_error]

Does anyone have a link to the yamaha service manual describing acceptable driveshaft runout?

 

[augustaf]

This was the spec. in 1995 (Yam manual), prob. still valid. It does not, however, make good sense to me, I would much rather support the shaft on v blocks at the 2 bearing surfaces and watch the spline end wobble- I mean check at the machined area just behind o ring contact area.

 

[37]

Does your 08+ ski have shims on the rear pump bolts?

My '16 doesn't but some might. The parts fiche for the 08+ specs shims if necessary.

It does not, however, make good sense to me, I would much rather support the shaft on v blocks at the 2 bearing surfaces and watch the spline end wobble- I mean check at the machined area just behind o ring contact area.

Yamaha's description is valid. If you get 0.3mm TIR at what's effectively the halfway point on the shaft, it's bad. Holding at the bearing surfaces and measuring the opposite end as you're describing would work but is more difficult and no more accurate (and possibly less accurate due to the difficulty and unnecessary force applied). Yamaha's method is how any machinist would measure it. The shaft would sit naturally between two V-blocks without any force induced besides gravity.

Even if the shaft is bent at the 25% or 75% point, you'd still see a large amount of TIR in the center using V-blocks at each end. Their spec of 0.3mm/0.010" is a very small number along that length. I suspect 0.3mm is enough to induce vibration.

For the non-machinists/non-engineers in the crowd: TIR = total indicated runout

 

[user_error]

Measuring yesterday I used 2 v-blocks similar to the picture provided above (thank you, that helps a ton) and was able to measure just less than .020" on a dial across the entire length. I think my shaft is fine (no pun intended) and will reinstall and shim accordingly.

In my original post I should have clarified, when installing and aligning with the cold fusion tool the shaft slightly catches/contacts the sleeve when oriented to certain rotation angles and not other angles. It is not aggressivly contacting and binding. I feel as if I am looking for some issue to be readily apparent and I feel the issue is not with the driveshaft after measuring it.

 

[user_error]

To further verify my method of measuring I checked a second driveshaft from an untouched yamaha sitdown model and was able to achieve similar results. This puts my mind at ease

 

[37]

Measuring yesterday I used 2 v-blocks similar to the picture provided above (thank you, that helps a ton) and was able to measure just less than .020" on a dial across the entire length.

0.020" or 0.002"? Twenty thou or two thou... big difference. Was the number the same no matter where you measured?

To further verify my method of measuring I checked a second driveshaft from an untouched yamaha sitdown model and was able to achieve similar results. This puts my mind at ease

Was the couch shaft brand new or used? It's possible both are out to some degree. Ideally your control test should be against a brand new shaft that's never been installed or run.

I've never had a good shaft 0.020"/0.50mm out. They should be dead straight. If your driveshaft has a 0.50mm whip, it very well could vibrate at high RPM.

 

[user_error]

It was twenty thou (.020"). I did not measure from bearing surface to midpoint of shaft like the picture above, I measured from bearing surface to just behind the splines. The number decreased as I moved the dial closer to the bearing surface. Honestly i haven't really messed with these dang QC instruments much so perhaps I should check it again.

The couch shaft was from a clean original low hour model. I agree new oem would be the best test piece but I don't have one at my disposal.

 

[john zigler]

IMO .020 is WAY too much. Spec above is .010 max.

 

[user_error]

The book spec of .010 is when measuring from the bearing surface to midpoint of shaft. I measured from bearing surface to just behind splines (entire shaft length) and got .020. I'll hopefully get some time this weekend to repeat the measuring process in a manner more consistent with the image provided above. Will report back, thanks for all the replies

 

[37]

I measured from bearing surface to just behind splines (entire shaft length) and got .020.

I'm guessing you're using is the same method as what @augustaf described above. If so, you're probably at 0.020" TIR in the center as well if using the method described by Yamaha. If you hold it at one end and get 0.020" versus hold it at each end and get 0.020", the results will be the same assuming equal accuracy in each fixture. But, I can't stress enough that you need to use the right method.

Worse case, take it to a local machine shop and ask them to measure the TIR on your shaft. Perhaps they can also straighten it if it is bent. It needs to be absolutely dead-nuts straight. 0.020" will vibrate without question.

While you're there, make a few jokes about your bent shaft.