96 SpeedsterDrive Shaft fit

[Rvan]

Hi all,
My 96 Speedster was having some cavitation and a small amount of water in the hull so I decided to tackle replacing the carbon seals, wear rings, and impellers. Using this Forum (thanks!) I've learned enough to have the pumps ready to reinstall, but I am concerned with how the drive shafts fit into the new impellers (drive shafts are out). I purchased Skat Swirls with new nose boots. The new impellers turn freely and smoothly. When dry fitting the drive shafts into the impellers with the rubber bumpers installed, the drive shafts fit nice and there is just enough gap between impeller and drive shaft lip for the nose boot. After I install the nose boot and the grease the impeller and drive shaft splines, the drive shaft slides through the nose boot and into the impeller and the splines align, but it backs out a half inch from what seems to be air pressure. I'm thinking the air displaced by the incoming drive shaft cant escape the nose boot sealing against the drive shaft. I have to push with maybe 20 lbs to pressure to seat the drive shaft properly, but when I let up, even after a minute, it backs out a bit. Should I install the pumps like this and figure the pressure will escape quickly with use? Is this normal or do I have a problem?
Thanks in advance for any advise.

 

[Toolanddiemaker]

On my 95 speedster I had the same thing happen to me it's probably just the grease causing an air pocket or displacement like you said I installed both of my driveshafts like that with no issues everything pressed together fine when it hit the pto. You should be fine.

 

[Coastiejoe]

Once it rotates some it will let the air out. And to confirm, do you have the rubber bumpers on the end of the shaft?


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[Rvan]

Bumpers are on the drive shaft. Even pushing hard to seat the drive shaft the impellers turn fine. I was worried the pressure would overload the bearings, but then when running, the impellers will be exerting force forwards and counter any rearward load.
Guys, thanks for the fast reply with the big dose of peace of mind! I was pretty sure it would be fine, but being wrong can get expensive. The impellers, wear rings, and carbon seals ALL showed signs that they were a cause for cavitation. All new now; bellows too. Love the speedster and the fast, low, "slot car" ride. Hopefully the parts eliminate the cavitation and she jumps out of the water.
Thanks again for the responses!

 

[Toolanddiemaker]

yep she should jump! after I rebuilt my pumps and put new seals on,my speedster plained out right away I couldn't believe the diff it made felt like a brand new boat! When I first bought the boat it would take forever to plain you would almost have to stand up just to see! you will be happy with all the new gear.

 

[Rvan]

I mounted the pumps and after a quick dry run of a few seconds I crawled underneath and checked out the boots; sure enough they had seated properly. I used new aftermarket bellows with the new carbon seals and rings. The new bellows felt much softer than the OEM I removed and it didn't feel like it put much pressure forward. I headed to a local lake for a quick check on performance. She didn't 'jump" onto a plane, but there was a substantial improvement; maybe 5 seconds vs 10 before. There was still some cavitation. Didn't see any water coming in, but there was a little in the bilge, so back to the dock. What I didn't know was there was an old small cotton rag in the bilge and on the way to the dock it somehow was picked up by the a drive shaft and seal.
So I put the boat on the trailer and pulled the back plug and out comes water; a LOT. I look into the engine compartment and there's maybe 50 gallons in there! WHAT????
Back at home I find the rag slightly wedging the seal open. DUMB! NOTE to all: Make sure your bilge is clean and clear!
So using the "Zip-Tie behind the bellows" method I've increased the seal pressure. Going to test it again this afternoon. I'll let you know how it goes.

 

[Coastiejoe]

Considering the rag held open the seal, your performance increase is impressive. Just wait until the next test...


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[Rvan]

Took the speedster to the lake and backed it in leaving it on the trailer. Started the starboard engine and looked for leaks. Didn't take long. The seal looked fine, but the NEW aftermarket bellows had a split. Very disappointing. The port engine seals and bellows looked good. Took her home and replaced the bellows with the OEM old one that looked fine. Now to retest.