StellingsExtensionBoxes vs. Fountain
 

I just had a freshly-rebuilt Tyler Crockett engine unwind with 3 hours on it. Bearing failure led to #7 and #8 rods failing.
The engines were mod 500HPs linked to Fountain-installed stellings boxes linked to Bravo 1's with Imco reinforeced gears.
Tyler thinks the stellings box shafts leading to the yokes connecting the engine were too long, by about an inch, causing pressure against the flywheel and crankshaft, leading to the bearings to fail. Does this make any sense ? The engine/box/drive combo ran flawlessly for 5 seasons previous... I have no expertise here at all. Carder

I highly doubt the previous engines would have lasted if that was the case.

Previous drives/engine combo lasted 5 years, new engines last 3 hours........yeah, that makes sense :rolleyes:

I looked at your parts the other day when I was at Crocketts,the main thrust bearing ate up on one side,the rear side facing the box as if the drivline was "stacked". I don't know how your set-up could have worked for 5 years then cause problems now unless something was changed at one point. I saw your driveshaft out of the boat and Tyler told me the slip splines were bottomed out solid causing shaft to stack the crank forward although I didn't see this when it was still in your boat. If this is true it would cause your main thrust bearing to fail but how it would change since new I don't know. Have you had to replace or change anything in the driveline recently,Smitty

Smitty, I have been following your build...nice work for a guy from the "Muth." Tyler rebuilt both engines over the winter after the port failed due to bad valve springs. He recommended redoing the STBD too, since it was probably going to fail. I ran the boat about an hour, and the vertical drive shaft on the stbd. broke in half. I was not driving hard.
He replaced the upper gears and vertical shaft with Imco, since they were stronger. he is the only one to remove/ replace the engines and redo the drive. I do not know if the drives/ stellings box/ engine were re-aligned, because he didn't talk about it,... I sure hope so, but I know it takes a special tool to align with the stellings boxes. Tyler said you had similar issues with boxes? Carder

I agree...seems like something else is going on here.

So what you're saying is, the gentleman who built the motors, built the drives and installed the motors never noticed at ANY time, that the drive shafts were too long, until AFTER the motor gernaded?
I think I'd have a problem with that. I'm sure he was paid top dollar for his professional knowledge. You would expect he would have noticed a drive shaft being an inch too long. Best of luck. Hopefully it will be resolved properly.



Darrell.

I hope so to...

Carder,I installed a Stellings box last year on my single engine boat, the driveshaft that came with it was 2 feet too long (it was for a staggered engine twin or something). When I installed it I found out the local spicer dealer had varied choices in stub shafts and female yokes,I was VERY concerned with having a driveshaft stack and damage my motor so I was extra careful to find short enough yokes to ensure that this could never happen. When everything was in place I had at least 1" of extra travel before driveshaft could bottom out and thrust the crank.Tyler told me when I was at his shop that when they pulled your motor AFTER it failed that your driveshaft was bottomed out solid against the crank. Why this wasn't noticed or corrected when motor was going back in I don't know,I guess it was assumed your set-up was fine as it had been ran that way for years. Something just doesn't make sense but I do know if the driveshaft is actually bottomed out like Tyler says then the next motor could be damaged also. I will say even though Tyler has only dynoed my motors for me and never built one for me that from what I have seen at his shop they take great care to properly ensure their motors are properly assembled and he has very modern machining equipment and a very clean work area. He then goes a step further and dynoes every motor to ensure there won't be problems once installed in the boat. Now what happened from their is the real question, if there was a problem with your driveshaft length, you as the paying customer would hope or expect it would be discovered upon installation and not overlooked causing your new engine to fail. I can sorta see from Tylers view point what hes's saying too,he didn't install the extension box or build the driveshafts,they fit previously when the boat came in and they put it back together the way it came apart. I hope this turns out ok for you,I know what I would do as a business owner if I had built then installed the motor then this happened but I can't speak for him and there may be other things I'm not aware of,Smitty

Smitty, who sells the shafts in Saginaw? I told Tyler I would be happy to pick up, if it speeds things up. Carder