Pressing your own crankshaft

[FirstGenCTD]

I have a question for all of you that have rebuilt your own cranks. What is involved? What tools do you need to do it?

I know what some will say..."thats a precice piece and a job that should be left to professionals...blah blah blah" Well, everyone had to start somewhere. I have an old phazer motor i tore down that needs bearings, and has been sitting around for sometime since other more improtant projects came up. I do have access to a 20 ton press and probably a lathe aswell.

thanks,

matt

 

[inverted99]

No help but I will be watching this thread as well. Good question.

 

[cobbycat]

1: scribe a couple lines accross the counterweights with a straight edge.(very straight, this is critical for realignment)
2: take a couple of good clear pictures
3: get all the specs for clearances
4: make sure you have all right parts, double check
5: carefully press crank apart
6: replace parts, make sure you get the thrust washers in right
7: carefully press crank pieces back together using scribe lines for alignment, must be precise. use a feeler gauge in between the counterweight and the rod and go slow.
8: put crank in a pair of saddles and set up a dial indicator. spin crank and adjust if it isn't true.(will have to use a vice and big hammer, be really careful!)
9: if at all possible, get it ballanced.

.........and if you ***** out half way through, you can still send the pieces to your local crank repair shop. do you have an old dirtbike crank to practice on? they are easier and less $$$ if you mess it up. good luck and you can do it.

 

[FirstGenCTD]

I do have an old Yam 250 that i could tear apart and practice on i suppose, but I figured the crank i have for the phazer could be my tester.

Does it matter where the cribe marks are on the counter weights? closer to the lower rod end better, of does it matter.

And how about getting the 2 rods exactly 180deg apart?


Thanks for all the info.

 

[Comp 670]

I've done a few and my 50 ton press will barely do them..A 20 ton will be hell.

You will have to build fixtures to hold it straight and not bend it as you press.

 

[cobbycat]

I do have an old Yam 250 that i could tear apart and practice on i suppose, but I figured the crank i have for the phazer could be my tester.

Does it matter where the cribe marks are on the counter weights? closer to the lower rod end better, of does it matter.

And how about getting the 2 rods exactly 180deg apart?


Thanks for all the info.

if you scribe the lines across the counterweights(2 or 3 lines anywhere) just line them back up when you are pressing it together. one line should go across all 3 or 4 counterweights. but scribe 2 or 3 lines to be accurate. and it might be a hard go on that press.

 

[m8magicandmystery]

I've done a few and my 50 ton press will barely do them..A 20 ton will be hell.

You will have to build fixtures to hold it straight and not bend it as you press.

^^^he is right...solid square backing when pressing..did a crank without it in an old Northway 440 when i was young...20 miles and broken crank