Crankcase Modification

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Kuma
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Joined: Wed Mar 10, 2021 10:41 pm

#1 Post by Kuma »

I know that there is a mod on the case that helps to prevent cracking, could someone add in an explanation and some photos? That would be really a big help.

m_mcgranahan
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#2 Post by m_mcgranahan »

Hi,

Yeah, Id like to see this as well.

Thanks

God blesss...

Mark

Kuma
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Joined: Wed Mar 10, 2021 10:41 pm

#3 Post by Kuma »


i'm posting 2 photos, one with what I think is the mod, someone that know if this is the correct area to radius, please post and agree or disagree, if wrong I'll remove.
The second is untouched, please touchup and show us where to grind or sand and please indicate how much.
[attachment=8368:case_mod_sml.jpg]

Kuma
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Joined: Wed Mar 10, 2021 10:41 pm

#4 Post by Kuma »

QUOTE (Kuma @ Apr 26 2009, 08:41 AM) <{POST_SNAPBACK}>
i'm posting 2 photos, one with what I think is the mod, someone that know if this is the correct area to radius, please post and agree or disagree, if wrong I'll remove.
The second is untouched, please touchup and show us where to grind or sand and please indicate how much.
[attachment=8368:case_mod_sml.jpg]


Here is the second untouched photo:
[attachment=8369:case_sml.jpg]

kdeal
Posts: 4
Joined: Wed Mar 10, 2021 10:41 pm

#5 Post by kdeal »

If the crank main bearing were a clock it is the area in red at 1 o'clock. Right where it comes to a point. It tends to start in that area and work it's way down the wall to the tranny and at about the imaginary line that would be where the cylinder would meet the block on a normal motor.

Kuma
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Joined: Wed Mar 10, 2021 10:41 pm

#6 Post by Kuma »

QUOTE (kdeal @ Apr 26 2009, 09:05 AM) <{POST_SNAPBACK}>
If the crank main bearing were a clock it is the area in red at 1 o'clock. Right where it comes to a point. It tends to start in that area and work it's way down the wall to the tranny and at about the imaginary line that would be where the cylinder would meet the block on a normal motor.


Then this area? would the other side be prone to cracking also, same type of point.
[attachment=8370:case_sml_mod.JPG]

kdeal
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Joined: Wed Mar 10, 2021 10:41 pm

#7 Post by kdeal »

Let Wistech or C27 reply. I would only be guessing from this point on. There is a particular case that is prone to cracking, my understanding was to relieve the area you circled. There may also be some cases where the bevel all around at the base of the sleeve is an issue and then I would imagine that whole area would need to be worked on.

cannondale27
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#8 Post by cannondale27 »

I never did any of these mods to the cases. I remember Farrar had more than one case crack from that area and it turned out to be the sleeve was made wrong. Other cracked ones I saw were down by the main bearing. Not much you can do about it other than being careful to remove and install main bearing properly.

kdeal
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Joined: Wed Mar 10, 2021 10:41 pm

#9 Post by kdeal »

Tim was mentioning a small mod for the cases known to crack. He said something about taking away the sharp edge in the area mentioned to possibly head the problem off before it started. AGAIN, this is for the ones known to have issues. They look like wet concrete (in color) on the inside of the case.

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