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Rob
05-10-2000, 08:59 PM
OK, I need some help. I just purchased a 14x23 Volvo Ultra SS prop from Madpoodle for my 1971 16 Ski Sporter (250B outdrive). I went down to the dock to change out the new prop for my original 15x21 aluminum prop. I bend back the tabs on the locking ring and unscrew the prop nut(cone?), slide off the old prop and slide the new one on the shaft. Now the problem: the hub on the Ultra is deeper than the hub on my OE prop, and has a flange that extends past the back of the hub. When I try to put the locking ring and prop nut back on, there are hardly any threads left, and the flange prevents me from bending the tabs back on the locking ring.

So, either this prop won't work with my outdrive, or there is an alternative system for retaining the prop on the prop shaft. I thought I read a thread a while back that talked about having to drill and tap the propshaft to accomodate the Ultra. Can anyone tell me if that is true? If so, what specifically do I have to modify and purchase to make this prop work with my outdrive? The thought of having to drill a precision hole in a stainless steel shaft with a hand drill doesn't excite my much, but pulling the outdrive off so I can put it in a drill press doesn't thrill me either. What should I do?


Signed,
Consternated in Kansas City.

Forrest
05-11-2000, 09:16 AM
Scott, it's a regular 'ol 5/16 SAE threaded stainless-steel allen-head bolt. The trouble is that I found is that you'll need to machine down you fish-line-cutter/thrust sleeve on some models like the 280 so the the prop fits with little gap between it and the zinc collar. Then use the two-piece prop/cone and then find a stainless steel allen bolt that is just a little longer than the one provided by Volvo-Penta. *YOU NEED AT LEAST 1/2" OF BOLT THREADS INTO THE PROP SHAFT AND TIGHTEN EVERYTHING VERY WELL USING RED LOCKTITE ON ALL THREADS* Else, bring SCUBA gear and make sure that your GPS had a MOB button and be sure to press it before you start cussing. If these Ultra props are not mounted corrrectly they will fall off, but only when you hit reverse. I know, someone found mine for me after it had been on the bottom of the St. Marks River for four months. Lucky for me it was in only 14 feet of water on a hard bottom.

Rob
05-15-2000, 10:47 AM
Ok, new problem:

When I put the Ultra prop on the shaft, the blades hit the steering trim tab/exhaust port. So I take out the thrust sleeve thinking that I just need to make a thinner sleeve to move the prop back on the shaft. But even with no sleeve at all and the hub of the prop dragging on the outdrive, the prop still hits the trim tab. So there must be a different trim tab you can substitute to make this work, right? Anybody else had this experience?

PaulO
05-15-2000, 11:10 AM
If you have thru-transom exhaust, you may want to look at the thread recently about a tab that is available without the exhaust port.
PaulO

Forrest
05-15-2000, 11:13 AM
Rob, Emmo has the solution to the exhaust port/trim tab problem. I'm sure that he will post the details here. Also, whatever you do, DO NOT RUN ANY PROP WITHOUT THE THRUST SLEEVE. You may need to machine down the thrust sleeve a bit though for the correct clearance of the prop to the zinc collar.

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Forrest

Rob
05-15-2000, 06:55 PM
Thanks Forrest. I think I will try and machine a new sleeve and keep my current one in case I need to go back to the original prop. I certainly need a shorter version to gain some more space on the threaded end of the shaft, but I will be sure I still have clearance between the back of the hub and the outdrive.

Emmo, I await your trim tab instructions :-)

BillG
07-24-2000, 07:46 PM
I used the original sleeve on my 250 drive with the ultra and it works just fine. The trim tab has been removed completely, I have no torque problem at all. I was running an OJ wide blade prop before and the torque was almost too much to handle. I must say this is the best prop I have ever had on the 18 in 28 years that I have had it.

Emmo
07-26-2000, 10:51 PM
When I tried Forrest's 14x24 LH (the St. Marks River model) I just removed the exhaust port/trim tab and had a rock solid hole shot. When I put the new one on, I used the trim tab hickey that I bought from W&R and it had some slippage coming out of the hole. After 2 holeshots, some of the paint was burned off the new trim tab, leaving me to believe that the tab was causing the cavitation. As soon as I get a chance, I am going to grind off some of the front of the fin on the trim tab to see if the cavitation is fixed. I also had to trim about 1/2 mm off the diameter of the line cutter to get it to work (I did it on a lathe and about ruined a cutter doing it). If I had it to do over again, I would probably have a machine shop make me a plate with no fin on it. Just make sure that it is on to stay because I shudder thinking what a loose or ejecting tab would do to that beautiful prop.


I still think UBB needs a spell checker! http://www.donzi.net/ubb/biggrin.gif
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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>

[This message has been edited by Emmo (edited 07-26-2000).]

[This message has been edited by Emmo (edited 07-26-2000).]

[This message has been edited by Emmo (edited 07-26-2000).]

Emmo
07-27-2000, 10:35 PM
I don't remember it being all that bad. Forrest drove it as much as I did with his St. Marks prop on it. Eh, Forrest?

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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>

Forrest
07-28-2000, 09:18 AM
Not too bad Emmo . . not too bad.

Rob
07-28-2000, 02:07 PM
Scott, I finally got the new trim tab and cone/screw set up in the mail a few days ago. It was on back order so it took a while to get it. I'm going to try and get the boat pulled out this weekend and drill the propshaft. Any suggestions on what type of drill bit works best on stainless? Will a standard high quality tap do the trick?

Thanks-rob

Forrest
07-28-2000, 03:39 PM
Use a new cobalt drill bit of the proper size for the tap. You may have to go to an industrial jobber to find it since it's probably some 32nd or 64th size. A new good quality tap will be fine but use some cutting oil or other recommended lubricant. Take your time and GO SLOW - don't break the drill bit or the tap off in the hole. That would really suck!

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Forrest


[This message has been edited by Forrest (edited 07-28-2000).]

BillG
07-28-2000, 04:47 PM
I used a Zirconium nitrate coated bit from Sears to drill my shaft and did it with my cordless drill. The tapping was the hard part, because as Forrest said you don't want to break the tap off in the shaft. Take it slow and easy. Good luck

Bill G

Rob
07-28-2000, 08:53 PM
Thanks for the advice guys. The nightmare of a broken bit or tap occured to me as well. I once had a tap break off in a very hard to find set of heads where I was installing screw in rocker studs. Not a pretty picture...

I will be taking it slow and easy.

Rob
07-31-2000, 07:39 AM
Drilling and tapping the propshaft went off without a hitch. Thanks to everyone for the good advice.

I like the way the new prop works. Even though there was a couple of inches increase in pitch over the stock prop, RPM's @ WOT did not change. Top speed may have, it's hard to tell without GPS. The speedo shows a small gain.

But the biggest difference is in steering torque. It is drastically reduced with the new prop. Much easier to drive now.

Rob
08-01-2000, 08:22 AM
Emmo:

My experience with the new trim fin is exactly as you described in an earlier response in this thread. There is a little slippage out of the hole, and I am seeing paint come off the new trim tab.

Did you ever experiment with grinding your new tab, and did it help?

Emmo
08-12-2000, 01:00 PM
I have been out of town working non-stop on a job and haven't had time to mess with it. I'll try it this week some time and let you know.

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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>