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Old 19-04-2006, 08:48 PM   #1
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Cutting down a 20" mid

Anyone know the score on cutting down a 20" midsection to a 15" midsection?
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Old 19-04-2006, 09:10 PM   #2
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don't be ridiculous!
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Old 19-04-2006, 09:16 PM   #3
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I'm not sure exactly but whats involved, but I reckon you'd need a bloody great saw and say "20 minutes"
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Old 19-04-2006, 09:19 PM   #4
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Re: Cutting down a 20" mid

Quote:
Originally posted by MrRob
Anyone know the score on cutting down a 20" midsection to a 15" midsection?
WTF?? Heard of cutting down a 20" shaft to a 15" but not a complete mid section??????
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Old 19-04-2006, 09:21 PM   #5
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Re: Cutting down a 20" mid

Quote:
Originally posted by MrRob
Anyone know the score on cutting down a 20" midsection to a 15" midsection?
I did it about 15 years ago, but the downshaft kept breaking on the weld which was just below the spline..The mid section itself stayed together OK, even tho' i welded it using oxy-accetylene (great skill required)

Gave up with it in the end.
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Old 19-04-2006, 09:25 PM   #6
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search around on scream and fly theres quite a bit on this topic.
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Speed costs weight so what do we cut off first
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Old 19-04-2006, 10:05 PM   #7
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Re: Re: Cutting down a 20" mid

Even if you do say so yourself!

Quote:
Originally posted by Jon Fuller
i welded it using oxy-accetylene (great skill required)
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Old 19-04-2006, 10:10 PM   #8
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I have been looking a lot on S&F about it. They cut the shafts and respline them rather than cutting a section out and reattaching the spline.
But I have not been able to find a guide on the subject.

Is it easy enough to do Jon? Problem with S&F is no one ever seems to detail whats actually involed with these things.
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Old 19-04-2006, 10:15 PM   #9
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Because if you have to ask.......
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Old 19-04-2006, 11:09 PM   #10
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Search marty powell on scream and fly!
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Old 19-04-2006, 11:11 PM   #11
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Quote:
Originally posted by MrRob
They cut the shafts and respline them
when i was involved in race cars ( Gartrac ) we used http://www.quaife.co.uk/ from sevenoaks for all our halfshaft mods, re-splining included
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Old 20-04-2006, 08:48 AM   #12
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Quote:
Originally posted by MrRob
Is it easy enough to do Jon?
I think this is probably the right time to add, that the motor in question was a 7.5hp merc twin, for use on a 12' aluminium dinghy.
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Old 20-04-2006, 09:08 AM   #13
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Quote:
Originally posted by Jon Fuller
I think this is probably the right time to add, that the motor in question was a 7.5hp merc twin, for use on a 12' aluminium dinghy.
I see!
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Old 20-04-2006, 09:08 AM   #14
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Quote:
Originally posted by Jon Fuller
I think this is probably the right time to add, that the motor in question was a 7.5hp merc twin, for use on a 12' aluminium dinghy.

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Old 23-04-2006, 08:52 AM   #15
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Find an old Hot Boat magazine ,10 years ago or so ,there was a complete artikel by John Tiger that shows you by a lot pics what to do and where to cut,and lots other things.

Remember the splines from a drive shaft are hardened for wearing out soon.
so cut it 5 inch ,respline ,and harden the metal again.
Resplining I usually pay 100€ (65 GBP)

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Old 23-04-2006, 08:21 PM   #16
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Mr Rob....

http://forums.screamandfly.com/forum...ht=cutdown+mid

http://forums.screamandfly.com/forum...ht=cutdown+mid

I'm halfway through my 15" mid project but am out of time for this season so I'll finnish it next winter.

Alan
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Old 23-04-2006, 08:39 PM   #17
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Quote:
Originally posted by Hydrostream
Mr Rob....

http://forums.screamandfly.com/forum...ht=cutdown+mid

http://forums.screamandfly.com/forum...ht=cutdown+mid

I'm halfway through my 15" mid project but am out of time for this season so I'll finnish it next winter.

Alan
Are you cutting down your mid?
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Old 23-04-2006, 10:33 PM   #18
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Rob,
Why dont ya just buy a 15" mid and gearbox???
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Old 24-04-2006, 01:30 AM   #19
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Quote:
Originally posted by MrRob
Are you cutting down your mid?
I bought a cut down tower off a member on S&F to see how it was done etc, and do the rest myself.
I will be cutting down another mid too.

You may (probably will) need to remove a section of leading edge from the top of your nosecone to allow the leg trim under the tiller and transom assembly, and run a new hose up at an angle to plumb the cooling water into the pump area.

Alan
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Old 24-04-2006, 08:03 AM   #20
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Quote:
Originally posted by Hydrostream
I bought a cut down tower off a member on S&F to see how it was done etc, and do the rest myself.
I will be cutting down another mid too.

You may (probably will) need to remove a section of leading edge from the top of your nosecone to allow the leg trim under the tiller and transom assembly, and run a new hose up at an angle to plumb the cooling water into the pump area.

Alan
I have a proper 15" trim ram so that wont be a problem
Got any pictures of your cut down you want to share?
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