Crankshaft endplay out-of-round

[YZFR1]

I keep getting about 0.0005"-0.001" of endplay runout.

Tried to re-torque all the mains except the thrust bearing cap, then torqued the center cap to 10lbs, pryed on the crank back and forth, turned it over and did the same thing. Then i torqued it to 20lbs and repeated the same process until putting in a final torque value of 60lbs. To make sure it sat in there, as straight as, possible.

My service manual doesn't even list the crankshaft endplay runout spec.

Has anyone had to deal with this before?

Am i just being too paranoid or does it mean i need to get a hone alighment?

Thanks for any help

 

[dsmrollerz90]

Are you talking like thrust bearing play?

 

[Red 2g GSX]

If your talking about crankshaft end play, your well inside the spec. I'm pretty sure up to 3 or 4 thousandths is ok. Half a thousandth seems kind of tight actually.

Are you sure you have the correct bearings?

 

[YZFR1]

Yeah, i was , not endplay itself but endplay out-of-round.

Just called a good machine shop, asked them how much for a line alignment, they said $150.

Then, i asked them if i'm within spec and they said, yes. Anything over 4 or 5 thou wouldn't have been.

 

[bryanwheat]

The .0005 reading probably came from not having the thrust bearing set properly. You need to loosen the thrust cap and tighten the bolts finger tight. From there you need to pry the crank towards the front of the block and the pry the cap towards the rear of the block. While keeping pressure on the crank towards the front of the block torque the bolts down. What this does is align the surfaces of the bearing so that they are flush with each other.

 

[Red 2g GSX]

Yeah, i was , not endplay itself but endplay out-of-round.

Just called a good machine shop, asked them how much for a line alignment, they said $150.

A line bore won't fix the snout of the crank being out of round. To fix that you'd have to turn the crank (which I wouldn't do on these cars).

The .0005 reading probably came from not having the thrust bearing set properly. You need to loosen the thrust cap and tighten the bolts finger tight. From there you need to pry the crank towards the front of the block and the pry the cap towards the rear of the block. While keeping pressure on the crank towards the front of the block torque the bolts down. What this does is align the surfaces of the bearing so that they are flush with each other.

That is fantastic advice!

 

[YZFR1]

So, are you guys saying that when you check crankshaft endplay than turn it around 180 degrees, you come up with exactly the same number? Not even 0.0005" off??

 

[Red 2g GSX]

So, are you guys saying that when you check crankshaft endplay than turn it around 180 degrees, you come up with exactly the same number? Not even 0.0005" off??

End play and out of round are very different things.

What exactly are you trying to measure?

 

[YZFR1]

I've already mic'ed all the crank journals and they are all within spec.

I'm talking about measuring endplay itself, turning the crank around 180 degrees and measuring the endplay again. Then see if i get a matching measurement. I get about .003" on one side and about .0035"-.004" on the other side. So it's about a .0005"-.001" of a difference between both sides. Not sure the exact way to call this measurement, so i called it an out-of-round

 

[Red 2g GSX]

I've already mic'ed all the crank journals and they are all within spec.

I'm talking about measuring endplay itself, turning the crank around 180 degrees and measuring the endplay again. Then see if i get a matching measurement. I get about .003" on one side and about .0035"-.004" on the other side. So it's about a .0005"-.001" of a difference between both sides. Not sure the exact way to call this measurement, so i called it an out-of-round

Sounds like your trying to measure crankshaft out of round, not end play. #Think of the engine sitting in the car, end play is how much the crank moves back and fourth toward the front tires.

What your trying to do is measure out of round, which you don't do on the snout of the crank, or while the crank is in the block. #You put the crank in V blocks and measure how much the center journal moves up and down as you spin it.

If your out of round is what your saying, 3.5-4 thousandths, that's way out of spec, and can only be fixed by milling the crank.

 

[twicks69]

Your measurements are within spec for crank runout. Have you checked your runout measurements at all main journals and both crank flanges? Ideally I prefer to check runout using a set of V-blocks and a fixed stand dial indicator that is accurate to 0.0001 +/-0.00005", but a cheaper one would work fine if it is at least accurate to 0.001" +/-0.0005" as you will see your runout if it is severe or not.

Normally I have seen bent cranks from over revving, too much power/boost, extreme detonation or more commonly from cutting down the counterweights and compromising the integrity of the crank.

For example, with my butchered 2.4L 7-bolt crank in my old motor it started having runout issues when I passed around 650awhp/40+PSI/8500-8600rpm range of parameters. Before that range, my mains looked great, after that, I was literally bending my crank and jump-roping my main bearings so the inner mains were severely worn while the outer mains and sides of the split thrust bearing were less worn. My crank was averaging around 0.014"-0.015" of runout and the crank was junk. Yeah, some places can salvage it, but it is not worth it in my opinion when it is that far gone. The best fix for this would be to not cut down the crank weight whatsoever as the 2.4L crank is already negative counterweight and would benefit from more counterweight being added to it.

 

[YZFR1]

Sounds like your trying to measure crankshaft out of round, not end play. #Think of the engine sitting in the car, end play is how much the crank moves back and fourth toward the front tires.

What your trying to do is measure out of round, which you don't do on the snout of the crank, or while the crank is in the block. #You put the crank in V blocks and measure how much the center journal moves up and down as you spin it.

If your out of round is what your saying, 3.5-4 thousandths, that's way out of spec, and can only be fixed by milling the crank.

Your measurements are within spec for crank runout. Have you checked your runout measurements at all main journals and both crank flanges? Ideally I prefer to check runout using a set of V-blocks and a fixed stand dial indicator that is accurate to 0.0001 +/-0.00005", but a cheaper one would work fine if it is at least accurate to 0.001" +/-0.0005" as you will see your runout if it is severe or not.

Normally I have seen bent cranks from over revving, too much power/boost, extreme detonation or more commonly from cutting down the counterweights and compromising the integrity of the crank.

For example, with my butchered 2.4L 7-bolt crank in my old motor it started having runout issues when I passed around 650awhp/40+PSI/8500-8600rpm range of parameters. Before that range, my mains looked great, after that, I was literally bending my crank and jump-roping my main bearings so the inner mains were severely worn while the outer mains and sides of the split thrust bearing were less worn. My crank was averaging around 0.014"-0.015" of runout and the crank was junk. Yeah, some places can salvage it, but it is not worth it in my opinion when it is that far gone. The best fix for this would be to not cut down the crank weight whatsoever as the 2.4L crank is already negative counterweight and would benefit from more counterweight being added to it.

Thank you!! I do have a good gauge that can measure down to .0001" and i was talking about a G4CS crank. Very interesting information.

I will definetly look into everything you said and come back if i have any more questions.

Also thanks to bryanwheat for a good post!!

 

[Red 2g GSX]

. I get about .003" on one side and about .0035"-.004" on the other side. So it's about a .0005"-.001" of a difference between both sides. )

I misread that when I said it was way out. I was reading it as you have 3-3.5 thousandths.

I would check the run out on the thrust bearing journal, not the snout of the crank.

....jump-roping my main bearings....

Could you define jump-roping a main bearings? I haven't herd that expression before.

 

[92 GSR-4]

Could you define jump-roping a main bearings? I haven't herd that expression before.

He's just giving the analogy of his crankshaft's rotation being comparable to a jump rope, meaning that his two inside journals had more wear than the outside journals because the crankshaft was basically wobbling inside the block because it was bent.

 

[twicks69]

He's just giving the analogy of his crankshaft's rotation being comparable to a jump rope, meaning that his two inside journals had more wear than the outside journals because the crankshaft was basically wobbling inside the block because it was bent.

Correct. From the forces going on in my engine, the crank was not physically strong enough to capacitate the load without deflecting due to the counterweights being cut down so much. Since it was deflecting so much, it was physically bending the crank acting like a jump rope and wearing down the inner mains very quickly. It also seperated and destroyed two crank pulleys within two weeks. The counterweight on the pulley would seperate and throw itself away. It also took out a crank angle sensor due to the extreme amount of movement. Don't get me wrong, the motor still made ridiculous power, but it was obvious that there was an issue occuring that required attention.

 

[92 GSR-4]

Tim, I'm curious if you're sure the "butcher" was the reason for your crank's failure. I've been looking at getting it done on a 6-bolt 2.4L and maybe in a 2.0 I'm about to build. The 2.4 I'm pairing with a 3076r for streetability, but the 2.0 is going to see some abuse.

 

[YZFR1]

Since, i've already had everything assembled, just did the flanges and the thrust bearing journal. Came up with almost perfect results, all within .0005"

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[Red 2g GSX]

Measuring out of round in the block isn't how your suppose to do it. It should be done on v blocks.

But how your doing it shows it isn't completely out of whack at least.

Good luck.

 

[twicks69]

Tim, I'm curious if you're sure the "butcher" was the reason for your crank's failure. I've been looking at getting it done on a 6-bolt 2.4L and maybe in a 2.0 I'm about to build. The 2.4 I'm pairing with a 3076r for streetability, but the 2.0 is going to see some abuse.

I am pretty sure the reason for the crank failure in my circumstance was from too high of piston speeds (~5500fpm is a max safe limit) is a main cause along with ALOT of boost, and alot of power. I was revving the motor to 8600-8700rpm on some days as well. 8400rpm was my "safe" limit normally.

Again, the crank wasn't bending when i was under 650AWHP, but was when I was around 750AWHP.

Taking 10# off the counterweights on a stroker crank is not a good idea for high rpm/high boost/high HP applications in my book if you want to keep your main bearings and crank in nice condition.

I changed to aluminum rods with aluminum rod bearings, ACL coated main bearings and a stock 2.4L 7-bolt crank that was uncut, and haven't had a problem yet in 3+ years. I have also been above 650AWHP the entire time, and normally have the tune set above 750AWHP for regular usage.

My crank bent, it is as simple as that. Oh well.


As for the crank measuring runout, the best way would be "unloaded" and on a set of V-blocks to really check what is going on with it not being bolted-in to the block, but I wouldn't be worried one bit with what you are seeing. As long as it rotates very smoothly and all is assembled well and lubed well, run it.

 

[YZFR1]

Yeah, i understand that

I'm within spec so i just did that for reference and reassurance

Plus, i think it is a great way to check both block and crank at the same time. After all, they are going to have to work together. Buy yeah, next time i have the crank out i might as well get some v-blocks.