"GTD" <duuuh@stoopid.net> wrote in message
news:10frq255n2d04m9vmbjb1q0t08tq76vaf6@4ax.com...
> On Wed, 17 Jan 2007 16:06:12 +1100, "Dre" <ausjules1977@hotmail.com>
> wrote:
>
>>"GTD" <duuuh@stoopid.net> wrote in message
>>news:6lkjq2djuji65921ero21m7je60vl1pnj3@4ax.com...
>>> On Sun, 14 Jan 2007 01:21:05 -0500, "\"Doc\"" <hmmmm@nahhhh.net>
>>> wrote:
>>>
>>>>Inline.....................
>>>>
>>>>"GTD" <duuuh@stoopid.net> wrote in message
>>>>news:5iliq21plm44foorkrde5alstrs8ie5qlj@4ax.com...
>>>>> My kid has an Ofna MBX Ultra with a soon-to-be-replaced force .26. I
>>>>> removed the failing 2-speed center and replaced it with a center diff.
>>>>> The problem is that the spur on the center diff is so small that even
>>>>> with a 15 or 16 tooth bell, the engine can't be moved far enough for
>>>>> decent gear mesh. I've looked for different spur gears, but could only
>>>>> find a smaller one. Anyone have an idea of how to fix this? Kinda
>>>>> wanted to avoid filing on the chassis, but I'm not finding any other
>>>>> answers. Thanks.
>>>>
>>>>The motor mount slots in the chassis can be lengthened with a dremmel so
>>>>you
>>>>can slide the motor over further. If they won't mesh up, it sounds like
>>>>you
>>>>might have the wrong spur installed?
>>>
>>> Yea, I did that, ,, but the mounts are getting awful close to the rear
>>> driveline. I've not been able to find a BIGGER spur, , just smaller. .
>>> BTW, I re-pinched the sleeve on the force .26. . .got back much of the
>>> compression, , ,and a bunch of power, , , ,, until, , , , the piston
>>> seized and the crank broke at the pin. It was WAY fat on the main
>>> needle, but it wasn't a hydraulic lock. I probably got the sleeve
>>> out-of-round, , ,but the block held it round when it was cold, , only
>>> to let it go back to out-of-round once it warmed up, causing the
>>> seize. Siezed the slug in the sleeve, broke the crank, marred the crap
>>> out of the conrod, , and knocked a hole in the block. I'd say it's a
>>> little past chewing gum and duct tape to get it working again. . good
>>> learning experience though. .
>>>
>><snip>
>>
>>Hey how did you re-pinch the sleeve??!?!?! I'm hell curious!
>>
>>Cheers Dre
>>
> First, , like all scientific endevors, , start with a few shots of
> tequilla. Next, find a couple small, narrow wormscrew type hoseclamps
> that are just big enough to go around the sleeve. Place one around the
> flange (to portion of the sleeve that seats on the top of the block),
> and tighten it a bit. You should see a marked difference in how far
> you can fit the piston up into the sleeve (the clamp is tight enough
> when the piston, being lightly pushed stops hard about 1/8 of an inch
> from TDC, which can be seen from the wear lines in the sleeve). Place
> teh second clapm just below the first, and tighten just enough that
> you see more piston'liner tightness. Then, you heat the sleeve evenly
> to 400+ degrees F (remove the piston first). I did this on the stove,
> but a heat gun will probably work just as well. Once this temp is
> obtained, quench the sleeve quickly in cold water. This will make the
> sleeve hold it's collapsed position. Re-assemble the motor and break
> it in again.
> Now is where you learn the value of those lessons we learned in school
> that told you to read all the directions BEFORE you start.. . Keep in
> mind, , Mine did not work out that well, so I would not suggest this
> to be done on any motor unless you won't mind (Or maybe even will
> enjoy) seeing it bite the big one. It is quite possible my method here
> is the dumbest thing you will read all year, , I am not a rocket
> scientist, , ,I break things often. .
> Honestly, Once I got the motor back together and running, I was a
> little too curious about seeing how much power I re-gained, and the
> idea of re-breaking it in completely eluded me. I believe that was the
> major cause of the breakage, I've heard of new engines breaking the
> rod or crankpin because of hard running when the fit is still real
> tight. I read somewhere about someone doing the re-pinch, then
> submerging the engine, with no head, in MMO and turning it for hours
> with a cordless drill. Sounds weird, , but I guess this 'could' insure
> that here was not excessive interference once the engine is powered
> up. I'll probably try that with my next one.
> L8r
Well I'll be buggered! I never even thought of doing anything like that!
I can see how it would work too, you can repair car panels with a dent in
them like this. Heat the area, then cool it quickly, this shrinks the metal
and pops the dent out.
I have a few old/stuffed engines lying around so I reckon I'll give it a try
when I'm bored one day!
Thanks for the info!
Cheers Dre