I'm going tonight to pick up a JD JS35 with a supposed bent crank from hitting a rock.
Any quick-fixes for bent cranks?
Any quick-fixes for bent cranks?
JS35 crank bent
kevrondl
1 - 18 of 18 Posts
Joined
·
2,420 Posts
Or just do a whole re-power, new engine. Is that a Briggs on the 35?
Joined
·
395 Posts
There is a lawn mower shop here in town that straightens shafts all day long. They have had no problems.
Joined
·
5,142 Posts
O.K to straighten four cycle cranks...NOT O.K to straighten two cycle cranks.
Take the blade off and turn it over with the spark plug removed and you will know if its tweaked or not. There is a shop in town that still does it.....its a dying profession though....better hurry. Most people trash the whole machine and get new.
Take the blade off and turn it over with the spark plug removed and you will know if its tweaked or not. There is a shop in town that still does it.....its a dying profession though....better hurry. Most people trash the whole machine and get new.
Joined
·
395 Posts
Why can't 2 cycles be straightened?
Joined
·
6,564 Posts
That shop is opening the door to serious litigations if something fails with a re-straightened crank job. Almost all shops that even still has the correct tool will make the owner sign a waiver before attempting the job. I know one shop I do business with had a tech who owned a tool to do this. They did this on VERY limited basis, and made the owner sign a disclaimer form. Wouldn't think much could happen like a crank grenading, but it does and did happen in the past. I'd be leary myself. Either scrap it, replace it or short block it if it's worth the repair costs.
Joined
·
1,178 Posts
I'm with the majority here. A bent crank has been fatigued, and then to bend it back will fatigue it more. think of bending a coat hanger back-and-forth to break it. I think straightening is risky. Low probability of failure, but in my opinion not worth the risk.
Joined
·
395 Posts
A coat hanger is what, a 1/16th of an inch thick? A crankshaft is about an inch. There is no comparison. Also when you bend a coat hanger you have to bend it to about a 170 degree angle change several times to break it. If hanger was bent at the minuscule angle the shafts a bent to there is virtual no fatigue on the shaft or hanger. Now if the shaft is bent to a 90 degree angle I would say you probably shouldn't straighten it.
Joined
·
447 Posts
Upon inspecting the shaft it appears to barely be bent at all. It's almost not visible to the naked eye. If anything, the blade was mangled a bit. Is it possible that the blade was the culprit? Or will the slightest bend in the shaft still throw it off?
Joined
·
5,142 Posts
Well, you can run it with a new blade and find out....If it vibrates badly enough to numb your hands....yes, it will need to be dealt with. If its not too noticeable you can try it for awhile and see. Even the slightest bend will throw the whole engine balance out of whack and it will eventually destroy itself from the inside out.
I've had slight bends corrected on vertical shaft Briggs before and no issues since.....In fact i bent the crank on one of our trim push mowers at work, had it straightened and still using it today about 8 years later.
On two cycles you run a greater chance of a hairline crack where the flyweights meet the crank shaft when its bent back to position.....this is what an old LB mechanic told me years ago and I've followed suit since. As for personal experience, with the two cycles I just ditched the whole crank....not worth repairing.
Joined
·
2,420 Posts
Try small engine warehouse.com for a full engine re-power
1 - 18 of 18 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
