Stock Crank Strength and Stability
- Thread starter SmokeShow
- Start date
here is a link if you want a custom crank,Might cost your first born child
http://www.truetube.com/cranks.html
http://www.truetube.com/cranks.html
It's worth checking into....last time we had one made for a gasser it was under $4000 which is pretty reasonable for the amount of time and materials that are put into making one. Plus with billet if there is a problem it is very easy to weld, and when done correctly it is just as strong as original. (actually the welded and stress relieved area is stronger)
Old thread but still an obvious active problem.
Is anyone making sure the main journal bores are true and that the caps on both the mains & rods are true as well after being bored, even modified to accept high rpm shape change at the con-rod bearing journal?
Is anyone making sure the main journal bores are true and that the caps on both the mains & rods are true as well after being bored, even modified to accept high rpm shape change at the con-rod bearing journal?
My mains were actually on the very min spec for clearance, I wanna say .0028?? Don't have the build sheet in front of me but they were on the tight side before maching. What's high rpm? 4000+??
Lets hope they are not as tight after machining if you are generating higher power levels because not just increase in heat but the basic stress level on the parts. In addition to the bearings themselves being staked properly and not spinning or "piggy backing" due to lack of oil or oil flow quality.
I would say for a diesel around 3,000 and above is high rpm. As far as the shaping of the connecting rod shaping (big end), for how rigid these rods are I am not sure if operating at any rpm below 3-4,000 will change the initial form. I wonder if Ben has done this compensation for part deforming at higher rpm?
I know one engine builder sets their rods and mains at .0030 and thats for Prostock mills. Even if we set the clearance we still must make sure the crank journal is NOT out-of-round, if it is we run into problems, concentricity is key!
When a crankshaft fails, for those who have had it happen unfortunately: have you looked at the connecting rod bearings in addtion to the main bearings? I have seen a few pictures on here but I doubt I have seen them all as far as breaking points. Could be lack of material plus too sharp of a machined joint from counterwight to journal? Could be a certain vibration frequency that causes this no matter what like you guys have mentioned, the vibration dampner quality?
Since we have many breaks we must compare visually (magnifying glass etc) and compare power levels and at time of break (hopefully) see any sort of patten. If I remember right its number 2 journal? Failure analysis is VERY lengthy!
I would say for a diesel around 3,000 and above is high rpm. As far as the shaping of the connecting rod shaping (big end), for how rigid these rods are I am not sure if operating at any rpm below 3-4,000 will change the initial form. I wonder if Ben has done this compensation for part deforming at higher rpm?
I know one engine builder sets their rods and mains at .0030 and thats for Prostock mills. Even if we set the clearance we still must make sure the crank journal is NOT out-of-round, if it is we run into problems, concentricity is key!
When a crankshaft fails, for those who have had it happen unfortunately: have you looked at the connecting rod bearings in addtion to the main bearings? I have seen a few pictures on here but I doubt I have seen them all as far as breaking points. Could be lack of material plus too sharp of a machined joint from counterwight to journal? Could be a certain vibration frequency that causes this no matter what like you guys have mentioned, the vibration dampner quality?
Since we have many breaks we must compare visually (magnifying glass etc) and compare power levels and at time of break (hopefully) see any sort of patten. If I remember right its number 2 journal? Failure analysis is VERY lengthy!
Cranks break with stock and aftermarket balancers. I personally think no amount of machine work will fix the design flaw in the crank.
You're right, nothing will fix a flaw, however checking for all collateral damage leads back to the culprit will teach how to build it better.
What are the cranks made of or from and how?
What are the cranks made of or from and how?