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> Cam Thrust bearing too tight, I've tried 3 sets
Al Meredith
post Feb 18 2023, 05:58 PM
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The last couple of TY 4s I.ve built all have had a problem with the thrust cam Bearing. The side with the shoulders is always too tight. The cam will not spin freely . The other side , without the shoulders spins free. I 've tried three different brands and they have the same problem . The used ones have the gray finish warn but they spin fine. AL
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rick 918-S
post Feb 18 2023, 06:04 PM
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Hey nice rack! -Celette
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Never toss out T4 stuff. Never know when the used parts are better than the new ones.
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Geezer914
post Feb 18 2023, 08:09 PM
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Single thrust or double thrust? Lay a sheet of 220 wet/dry sand paper on a sheet of glass. Put a few drops of oil on it and sand off a few thousands from the shoulder until you get close to the clearance you need. Polish the end with 400-600 grit.
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Jack Standz
post Feb 19 2023, 01:21 AM
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+1 Yep, just sand it, clean it, then install it.
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930cabman
post Feb 20 2023, 10:09 AM
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What cam are you running? As you know anything NOT spinning freely is never a good thing. I would be somewhat hesitant sanding the shoulders of the new cam bearings, but also not sure where else to go. Let us know of your results
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rfinegan
post Feb 20 2023, 11:36 AM
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....don't forget the "tap a tap a" to seat the bearings after they get a light sanding
no video
1) lightly side one side of the cam thrust and try to fit in case half
2) rotate cam for bind or cam/ bearing lifting out of case
3) little sand opposite side and check fit
4) rotate come and check for bind in case 1/2 or cam /bearing lift out of case
5) once the cam is spinning and no longer lifting, use a brass or aluminum punch or wooden block and give the front of the cam 2-3 light taps to to seat the bearing.
6) repeat the 2-3 taps at the base end of the cam
7) measurements or about 0.002 is the goals for endshake of the camshaft
8) repeat above till the desired endplay in this 1/2 is achieve
9) repeat above on the other case 1/2 if using a double thrust ( a quick measure meant of the "good" thrust bearing will speed things up)
10) when assembling the case 1/2s together a final check of the end pay can be performed


If I fit another set, i would fit the back side of the thrust bearing furthest from the gear, as the face closest to the gear will get the force from the angle cut gear
I hope this helps
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rfinegan
post Feb 20 2023, 02:59 PM
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not mine, but worth a look
https://www.youtube.com/watch?v=t0d87g-iCrc&t=274s
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