Topic: Turning down a 1-1/8" crankshaft question

[leman]

From everything i have read on here, most people say that if you turn down the crank on a twin to 1" so a centrifugal clutch can fit on it, the crank will snap.  Why is that?  I only ask because i also read that a few of these engines had 1" cranks on them from the factory.  Whats the difference if the factory turned the shaft down to 1" or if a machine shop does it?

[cycloneracer]

Zach Kerber has a 1 1/8" clutch.  No need to turn it down. 

if you turn it down and your making any power it will break. 

[BosRos]

we have run cranks turned down to one inch to use a noram star and haven't had a problem ,i would love to try the 1 1/8 clutch but can't justify the cost.

[leman]

Zach Kerber has a 1 1/8" clutch.  No need to turn it down. 

if you turn it down and your making any power it will break. 

Even if i find and use a factory 1" crank? 

How come you rarely hear about fully build Vanguards or Intek cranks breaking?  Those are only 1".  I know the potential for making power with those arent as great as it is with the Kohlers, but are they really that far in a league of their own in torque being produced?

we have run cranks turned down to one inch to use a noram star and haven't had a problem ,i would love to try the 1 1/8 clutch but can't justify the cost.

Thanks, im in the same boat and was also wondering if there was any success with doing this.

[cycloneracer]

If you can find a stock 1" crank you will be fine.  When you turn it down you remove the hardened case.  That is why they break. 

As for the cost of the Kerber clutch it is expensive but it is a superior clutch.   It has a special bearing on it that doesn't chew up the crank.  I have 2 full seasons on mine and it still looks new.  All the parts are hardened.  That is why it is so expensive. 

[Darkviper]

18 to 22 is 1inch. 25 up is 1 1/8

[fx28]

Like some of the above posts, the pto end of crank is hardened. Some of them are not very easy to turn down, would be better to have it ground. Turning off .060 a side as hard as it is plus add the interruption of the keyway, making it hard to get it round is why it is desirable to have it ground. Also getting the radius put back in right.
    I have done it before and had no problems, just might be easier to find a 1" crank. The commands, I believe are mostly interchangeable other than the 30HP. Just check to make sure if it uses the shim or not to be sure of end play.

Chuck

[Cromwell C4]

The 1" cranks are easy to find for the Kohlers. As chuck said, all the Kohler command v-twin cranks are interchangeable for both horizontal and vertical engines from 18-30hp, the 30hp crank just has a slightly longer stroke. I can get brand new 1" cranks pretty cheap, they are new old stock from a distributor or pull outs from brand new engines.

[leman]

Thank you for all of the responses.  I wasnt 100% positive if they were case hardened because when i lightly took a file to it, it didnt feel like it was.  But you all know what you are talking about so im sure it is.  I guess ill have to start hunting for a 1" crank.  Does anyone have a part number for it? If not, ill start searching in PartsTree

[Cromwell C4]

There are a few different pto lengths for the 1" cranks so there will be multiple part numbers. Get the shortest one possible to get more weight off the crankshaft. Send me a pm and i will get you the crank you need.

[leman]

ok that sounds good.  I will message you when im ready to buy my engine parts