Setting Crankshaft Thrust Bearings

[akotten]

I've been fighting the installation of crankshaft thrust bearings for the past day. I can't seem to get the clearance within the manuals' spec of 0.05mm-0.25mm. One side is 0.06mm and the other is under 0.04mm. I followed the method described by Ray below and can get them set where I want them, but they move back after torquing the cradle. Any suggestions? (I can't be sure of the tight side because 0.04mm is the smallest my feeler gauge goes)



"on engines with a top and bottom thrust you have to "set" the thrust. tq down the cap with the thrust washers in then crack the bolts loose. take a soft mallet and tap the crank forward and rearward. this aligns the main cap and makes the crank ride the upper and lower washers evenly. your just tapping here.. not smashing and wrecking things. then check to see if you have the propper thrust. there are many tricks to building good engines"
-Ray Pampena

[J. Fast]

Instead of tapping the crankshaft with a mallet to check for the end play turn the crank and while you're turning it push the crank back and forth to see how far it walks. Set a dial indicator with a feeler.

Your in spec where you're at. A little tight is OK

[akotten]

Instead of tapping the crankshaft with a mallet to check for the end play turn the crank and while you're turning it push the crank back and forth to see how far it walks. Set a dial indicator with a feeler.

Your in spec where you're at. A little tight is OK

I'm just concerned because I can't actually measure the one side. Also, I don't have a dial indicator available to me. I'm putting a lot of stress on this issue because the thrust bearings I removed had two showing copper and the other two looked new. This was after 1000 miles on a brand new crank, everything balanced. I didn't "set" the thrust bearings at all before though. I have thoroughly moved the crank from one side to the other and back now, so I'm guessing it should be ok this time around.

[J. Fast]

bring #1 cylinder to tdc and insert a prybar and without scoring push the crank towards the flywheel and measure each open side of each thrust bearing with your feelers and record them. Next, rotate the crank 360 and pry the opposite direction and measure the thrust on the other sides. Then, rotate the crank 90 degrees and repeat the process... Then, 90 degrees again. If the thrust measurements don't match per side as you rotate the crank and check thrust every 90° (till you have measured thru 360) the crank is warped.

[J. Fast]

I don't know why you would want to hit the crankshaft on opposing thrust ends. The crank will never move flat, it will always be rotating so measure thrust as-if the crank were moving. How I like to do it is push the crank while rotating then pull the crank. Measure each open side as you do. You don't necessarily need a dial indicator to measure thrust but it's truly a better method because you can measure thrust while the crankshaft is rotating. That's a good thing. If you're building race engines get one.

[familyMAN]

You whack each side of crank to "set thrust" which is actually setting the girdle square with block by using the crank to square it up when the main bolts are a little loose. Then measure your thrust.