753 Main Shaft

[Jimmy Jet]

Personally I'd go a std black rubber type seal any time a wet environment is involved.
Seems odd the steel type was supplied....

[hamjet41]

Thanks again Jimmy Jet; agree and was along the lines you mention also. SJ supplied the Outer Seal...I'll touch base with them.

[hamjet41]

Jetboat Gurus 

Over the weekend installed the new main shaft with the new stuff?what a learning curve but lots of fun. Installed the shaft in situ without removing engine?.other than some basic engineering ?thinking? solutions (including a piece of wood),  numerous trial and error experiences all seemed to come together surprisingly well in the end.

One wee solution that may help others (probably mentioned somewhere in another post) I used when trying to figure out how the hell to install the bearing outer race half onto the shaft whilst in the unit. Noting an even press onto the shaft was no doubt a must, I used a piece of wood (see pic) to stop the shaft sliding both forward and back, fitted the new outer race then slipped on the old outer race the other way (effectively like the inner race), also slid the old bearing sleeve and then the coupling (I read to use the coupling for the inner race press in the HJ manual so though why not for the outer race also) put the washer/nut on and slowly tightened. In the end, a success for the outer race press, gentle pry off the old race was surprisingly easy. The inner race press went as per the manual. In the end, a DIY job me thinks. 

However, I have one other question ? reinstalling the stator housings and impellors Bullet/#2/#3 was BAU. Except there now is a space on the shaft between the back of the #3 impellor and where the washer and jesus nut when tightened up against the tread stop?WTF!!! See pic

Have I missed something! Do I need another spacer (oddly the old bearing space fits!) or is it supposed to be that way!! (Remember my old shaft was not the same as the new one)

 

[JohnR]

Oh dear.  Did you compare the 2 shafts before installing.  Also have you installed the ring that the seal runs on, it goes directly behind the bearing.  The internal lip seal. 

[hamjet41]

Thanks JohnR; no bits left over, the old shaft was not long enough to accomodate the bullet, hence the need to replace. New shaft when matched against the old should be slightly longer - calculations back when I encountered the issue revealed I required approx 355mm (bullet + stator sleeve + #2 impeller + stator sleeve + #3 impeller) from step to thread vs only 347mm  on my old shaft that fitted 3 std impellers including nose cone fine. Hence the need to replace shaft to accomodate the bullet.

Will post some pics tomorrow of the two shafts matched next to each other -  new is longer as expected and thought that was standard and didn?t think anything more about it until all installed to discover the extra shaft length conundrum. And a mockup of everything installed on the new shaft.

Does anyone have a three stage shaft handy they could measure for me? Go me buggered. 

[Allen M]

Just gone back through your threads and note you have a 740 intake housing. Perhaps to avoid confusion we should be calling it a 740 unit. I?m not sure about the front to rear dimensions between a 740 housing and a 750 housing but I know the shaft sits about 25mm lower with a 740 housing so you shouldn?t assume that they are the same. Looking at your latest photo the rear of the back blade and the rear of the housing appear to be sitting in the right place. I?ve just measured a 3 stage shaft I have sitting here and it measured 410; even longer. Are your stators 120 mm wide or 107 like some of the older Explorer I think they were called stators were.
I?d check your blade hub to stator hub clearances are ok from front to back,ie not rubbing on each other and if they?re all good machine up an old chrome cutlass sleeve to the right length, bolt it up and go boating 

[Jimmy Jet]

Good advice from Allen M, if everything is lining up, add a spacer and go.
I'm pretty sure the shaft length has stayed the same from Colorado through to 773 but happy to be corrected.
Yes the Colorado had different length stators, my one, when it was a Std 3 stage, had a 107 at the front and 120 at the rear (or vice versa).

[hamjet41]

Thank you Allen. Great points (740 vs 750 intake) because with everything installed the unit spins freely (usual resistance on wear rings), clearances are fine but will pull apart again to double check (have the 120mm stator housings) then measure the shaft free of all the bits. Thanks for your measurement also.

Youve solved the mystery for me and agree throwing a machined bearing sleeve on to take up the remaining space will make no difference. Then I can dump its bum in the water 

Couple of pics FYI of shaft comparisons and new bits on shaft mock up - I dont think any bits missed (not in pic is the locating ring)

 



   

[hamjet41]

Thanks Jimmy Jet also  )

[hamjet41]

Team, closing the loop for those interested.

Couple of pics, pulled stators/impellers to again check clearances, new bullet fits perfect and correctly on wear ring (not going to chew the intake housing forward of wear ring), #2 and #3 fit perfect also, couldn't find my old chrome sleeve so cut down a bronze bushing (same ID/OD as chrome sleeve), installed and torqued up jesus nut.

To ensure nothing was bound up, turned engine over a couple of times and she spun normally (bullet is still to wear in)

Dumping bum in water this weekend to see how the bullet changes performance. 

Thanks again to all your comments/suggestions/observations