yz426f crank pin removal 2000


11 replies to this topic
  • racerx143

Posted March 06, 2007 - 04:14 PM

#1

My connecting rod loves my crank pin so much they decided to get a little closer in their relationship. So close, that they have created an unholy union. Anyway, i have the crank assembly out on my work bench. I'm getting ready to take it to a friends shop with a press. Here is my question, lookin at the crank pin, i dont see how I am suppose to push it out, it doesnt look like it will clear the crankshaft in either direction.... there are machined cut out on the crank about a half inch out but not far enuf out that the pin could be pushed far enuf to allow sepearation. Obviously, it will. Im just not seeing it. I just want some imput before i start heaping tons of pressure on it. The pin is solid on one side and on the other there is this little cap thing in the middle of it. Anybody here ever split their crank apart? Which way did you push it.

  • grayracer513

Posted March 06, 2007 - 05:00 PM

#2

When the crank pin is so large that it overhangs the axles, it's usually necessary to jig the crank between the two halves and press one side off first, then the other, rather than pushing the pin through.

Are you familiar with the process of truing a pressed crank assembly?

  • racerx143

Posted March 06, 2007 - 06:33 PM

#3

Ahhhh makes sense to me. :applause: yes im a harely tech actually, ive done several of those. so obvious now, thanks for the help.

  • racerx143

Posted March 15, 2007 - 06:46 PM

#4

After getting farther into this, truing this might be beyond my ability and access to specialty tools. Anybody know of a good/reasonably priced shop that does mail ins?
Also, anybody care to explain the process? Such as - is a jig of some sort used when pressing it back together to true it? Are these fine tuned with force (brass hammer) to get into spec? Any links to aftermarket replacement crankshaft assemblies?

  • GCannon

Posted March 16, 2007 - 09:10 AM

#5

I have used a lathe as a truing jig after carful reassembly of the crank halves and new pin put the crank spindles between centers and use a dial indicator on the main bearing surfaces to check run out. To adjust clamp one (flywheel) half the crank in the vise (soft jaw) and whack the other flywheel with a brass hammer (very precise HUH) don't kill it after a few tries you will get it right on.

  • grayracer513

Posted March 16, 2007 - 09:40 AM

#6

It's generally more accurate to roll the crank on a truing stand than to use the center drillings. A truing stand consists of two vertical supports, each with a pair of bearings on parallel axes. The main bearing seats of the crank then sit on these bearings so that it rotates on the exact points that it will when installed. Dial indicators are used to detect runout. The way we used to correct an out of true assembly was to sit the crank down on a pair of lead pads and swat it with a lead mallet. Never thought of a hammer as a precision instrument, did you?

If you push the pin into one half first, drop the rod on, and then push the other half part way in place, you can stop and get the assembly basically trued up, then finish pressing it up. That will make whatever truing errors you end up with that much smaller, and it's easier to correct the errors when the pin isn't so deep in the bore.

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  • GCannon

Posted March 16, 2007 - 10:24 AM

#7

Truing stand = http://shop.thumpert...ault.asp?p=1043

Precision work with a hammer does seem silly, but it works.

  • mkporn

Posted March 16, 2007 - 10:37 AM

#8

It's generally more accurate to roll the crank on a truing stand than to use the center drillings. A truing stand consists of two vertical supports, each with a pair of bearings on parallel axes. The main bearing seats of the crank then sit on these bearings so that it rotates on the exact points that it will when installed. Dial indicators are used to detect runout. The way we used to correct an out of true assembly was to sit the crank down on a pair of lead pads and swat it with a lead mallet. Never thought of a hammer as a precision instrument, did you?

If you push the pin into one half first, drop the rod on, and then push the other half part way in place, you can stop and get the assembly basically trued up, then finish pressing it up. That will make whatever truing errors you end up with that much smaller, and it's easier to correct the errors when the pin isn't so deep in the bore.



Works great.... Here is one that I have not heard from anyone.... Use a large chisel, hammer and a V block..... Try it and see how close it is. bet you can get it within .001-.002 in just a couple of tries....:applause:

  • mkporn

Posted March 16, 2007 - 10:39 AM

#9

forgot to tell ya to put the chisel between the two halves as they rest on the v-block and give it a smack with the hammer. They will amazingly jump into place (as long as you were in the area when you pressed them back together)

  • grayracer513

Posted March 16, 2007 - 01:14 PM

#10

That will help relieve "pressed in" stresses that want to "bend" one axle off of parallel with the other. What it won't do is correct the usual problem of having the two axles parallel, but on two different axes because they are rotated out of line with each other.

  • mkporn

Posted March 16, 2007 - 02:56 PM

#11

That will help relieve "pressed in" stresses that want to "bend" one axle off of parallel with the other. What it won't do is correct the usual problem of having the two axles parallel, but on two different axes because they are rotated out of line with each other.


It will, ever try it? Done it many times and I can tell you it works like a charm... The key is the V-block.


I'll keep doing at as long it works.....:applause:

  • keith_karidis

Posted March 16, 2007 - 05:41 PM

#12

If you are not sure you want to tackle this yourself, this shop can rebuild your crank. They also offer true and welding, and balancing too.

http://www.crankworks.com

These guys do crank work too.

http://faliconcranks.com/





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