Major mistake. what to do. wrong crankshaft

[workaholic]

I pulled a stupid... I WAS near completion on my winter project. A full rebuild 2001 Mercury SportJet 240hp EFI serial:0E405334. I had purchased a low hour crankshaft for it during the winter. Same part number and supposidly from a jet drive. Long story short. I never bothered checking the internal splines on the one end. I just checked the other end (stator end). I know, i am a dumb*s*.

The shaft from the pump assembly that goes into the crankshaft is an 8 spline. My crankshaft is a 12 spline. After doing some research I found out that the 12 spline is for outboards and 8 spline was for jetdrives.

There is NO WAY i want to change out that crankshaft. I was thinking of removing the shaft from the pump unit and having a machine shop either making a new shaft or "fabricating a new 8 spline end and welding it on". Only problem is that we dont have the greatest machine shops around here. I would be more than willing to deal with anyone else at any location.....

Any other thoughts?

 

[wired247]

Re: Major mistake. what to do. wrong crankshaft

Check with Dutchman motorsports in Portland OR. They'll make you a new shaft for a pretty reasonable price or they can shorten yours , respline it and make an adapter to fit your crank .

Don't weld it . It WILL break under a 240 HP motor.

 

[workaholic]

Re: Major mistake. what to do. wrong crankshaft

If the 12 spline end was cut off and an 8 spline end welded on by a professional and thickened a little (there is some room to thicken it) it wouldn`t hold?

Thanks

 

[Dukedog]

Re: Major mistake. what to do. wrong crankshaft

I pulled a stupid... I WAS near completion on my winter project. A full rebuild 2001 Mercury SportJet 240hp EFI serial:0E405334. I had purchased a low hour crankshaft for it during the winter. Same part number and supposidly from a jet drive. Long story short. I never bothered checking the internal splines on the one end. I just checked the other end (stator end). I know, i am a dumb*s*.

The shaft from the pump assembly that goes into the crankshaft is an 8 spline. My crankshaft is a 12 spline. After doing some research I found out that the 12 spline is for outboards and 8 spline was for jetdrives.

There is NO WAY i want to change out that crankshaft. I was thinking of removing the shaft from the pump unit and having a machine shop either making a new shaft or "fabricating a new 8 spline end and welding it on". Only problem is that we dont have the greatest machine shops around here. I would be more than willing to deal with anyone else at any location.....

Any other thoughts?

Don't know where ya got your information or what kinda pump ya got but tha outboard crank is an 8 spline and tha pump is supposed ta be tha finer spline...........Something in tha pump was changed. Don't fabricate nothin'. Find out why tha pump shaft has been changed....

 

[wired247]

Re: Major mistake. what to do. wrong crankshaft

Your serious?

It will break.

 

[workaholic]

Re: Major mistake. what to do. wrong crankshaft

thats what I said, the crank is 8 spline and the pump shaft is the finer spline (13 spline). How about getting the splines brazed then recutting new splines, would it hold?

 

[wired247]

Re: Major mistake. what to do. wrong crankshaft

thats what I said, the crank is 8 spline and the pump shaft is the finer spline (13 spline). How about getting the splines brazed then recutting new splines, would it hold?

Maybe if it were a 60 horse. You can do whatever you want but that 240 horse jet is actually a 300 horse powerhead meaning its more like 330 HP at the powerhead before jet losses. Thats a lot of power at a lot of RPM's to run through a brazed joint. I'm not that brave.

 

[JDusza]

Re: Major mistake. what to do. wrong crankshaft

No. Naughty. Use the right parts.

 

[Dukedog]

Re: Major mistake. what to do. wrong crankshaft

The shaft from the pump assembly that goes into the crankshaft is an 8 spline. My crankshaft is a 12 spline. After doing some research I found out that the 12 spline is for outboards and 8 spline was for jetdrives.

This is what ya said. That's backwards..........No mater. Ya need ta get tha fine spline "sport jet" crank. Any Southern Engineerin' will put ya back ta square one sooner than ya probably want............jmo

That motor is basically a hot rod 2.5 ProMax. Mostly done with different reeds, ecu and tunin'. Tha seven petal "sport jet" reeds/reed cages are a real prize in tha hot rod 2.5 world..........

 

[Faztbullet]

Re: Major mistake. what to do. wrong crankshaft

You can do whatever you want but that 240 horse jet is actually a 300 horse powerhead meaning its more like 330 HP at the powerhead before jet losses

Nah....its only about 250 and rated at crank and has old style injection....

No mater. Ya need ta get tha fine spline "sport jet" crank. Any Southern enginnerin' will put ya back ta square one sooner than ya probably want

Agree 100%... you can get a reman crank for about $600.

That motor is basically a hot rod 2.5 ProMax. Mostly done with different reeds, ecu and tunin'..

And a bunch of exhaust chest relief....

 

[glenn property of pam]

Re: Major mistake. what to do. wrong crankshaft

im sure you could take the shaft out of the pump and have a new one made with a spline pattern that would work but you have to wonder why they changed the design of the crank (they wont weld it but will make a new one from scratch) No one changes a design and then pays to re-tool unless there was a good reason in the first place. Im guessing that the 8 spine was a week point during r&d so they had to increase the spine count to 13 to correct for the problem. This was proberbly a large cost to the engine manufactor so its not something that was done for looks. Find the right crank and change it out.

 

[Faztbullet]

Re: Major mistake. what to do. wrong crankshaft

m sure you could take the shaft out of the pump and have a new one made with a spline pattern

The pinion gear is made on to the shaft so remaking is out of the question........

 

[Dukedog]

Re: Major mistake. what to do. wrong crankshaft

but you have to wonder why they changed the design of the crank

Tha finer spline works better with tha loadin'/unloadin' of a tha pump.

 

[workaholic]

Re: Major mistake. what to do. wrong crankshaft

Ahh, you guys are killing me. But I know, the proper crank needs to be put it. BUT... how about what "wired" said near the beginning. Shortening the shaft, resplining and making an adapter...

 

[wired247]

Re: Major mistake. what to do. wrong crankshaft

I would really contact Dutchman motorsports. There are several companies that will shorten and respline a shaft and make an adapter for you but they have done quite a bit of axle work for me over the last 20 years when I was building racing rear ends and transmissions and their work is top notch and they will do goofy sh!t like you are asking. For what you are doing I cant think of anyone I would have do the custom work you want over them. A shortened and resplined shaft with a stub adapter will be every bit as strong as the stock shaft.

Custom Axles and Rear Ends by Dutchman Motorsports | Brake kits | Housings | Differential Components | Ford 9" | Quick Change | Dana 60

 

[Dukedog]

Re: Major mistake. what to do. wrong crankshaft

If for some reason ya try tha "adapter" type deal ya gonna need ta do some serious measurin'. Tha "adapter" thingy is gonna have a larger od. than any part of tha regular drive shaft. Ya probably gonna run inta some clearance problems................Merc use ta have a 5" extension for a drive shaft and tha female end is good 1/2" larger od than than tha norm.... jmo

A plus on changin' tha crank is that tha reg. outboard crank can be sold ta recoup a big portion of tha cost. Suck it up and just chalk it up ta "experience"..................

 

[glenn property of pam]

Re: Major mistake. what to do. wrong crankshaft

Ahh, you guys are killing me. But I know, the proper crank needs to be put it. BUT... how about what "wired" said near the beginning. Shortening the shaft, resplining and making an adapter...

contact a machine shop like wire247 said and email them the pics. They do this kind of work all day long so they will know what can and can not be done for the right price. Where i work it nothing out of the ordinary to have shafts and gears remade or adapters made for shafts then sweat fitted so they are as tough as the original the problem is going to be at what price the fix costs compaired to the cost of replacing the crank.

 

[CharlieB]

Re: Major mistake. what to do. wrong crankshaft

A plus on changin' tha crank is that tha reg. outboard crank can be sold ta recoup a big portion of tha cost. Suck it up and just chalk it up ta "experience"..................

Second this.

Do it right, the first time, or you WILL be doing it again in a very short time. 300 HP has a great potential for destroying parts. Merc shafts are prime material and hardened. I would NOT want to be the guinea pig for any custom adaptor, failure can leave you adrift, definitely NOT a good situation to put yourself in.

Just for giggles, price a shortblock and price what your motor is worth, consider selling your assy and replacing it. The price difference just may be worth saving you the time to change the crank.

Just my dime, (inflation increased the cost of opinions).

 

[workaholic]

Re: Major mistake. what to do. wrong crankshaft

took Wired247`s advice. Emailed all the specs, pics and details to Dutchman Motorsports. Hopefully they will be able to make the adapter for me for a reasonable price and quickly

If not, anyone else?

 

[wired247]

Re: Major mistake. what to do. wrong crankshaft

IF they will do it for you you won't be disappointed in their work. Ive beat the crap out of some of their axles behind 1000 HP transbrake drag cars and they hold up very well.