Straub Trunnion Upgrade - some tight? - LS1TECH



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Straub Trunnion Upgrade - some tight?

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Old 03-19-2017, 04:13 PM   #1
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Default Straub Trunnion Upgrade - some tight?

I installed the straub trunion upgrade in my 04 rockers yesterday. About half are loose enough that I can rotate the shaft with my fingers. The other half are so tight that I have to stick a screwdriver or awl in the bolt hole to rotate them.


Anybody else experience this? Are the ones that I can move with my fingers too loose or are the ones I need a tool to move too tight? I'm kind of concerned the clearances on the tight ones that might be so tight it messes up lubrication. I did use the included break-in lube during installation.


I found on another forum that there were some suspected inconsistencies with GM's (or their vendor) manufacturing of the rocker arm and they should be honed true but haven't seen that mentioned here (and there seems to be a lot of install experience here)


I'm tempted to call Straub and buy some more bushings to redo the tight ones but wanted to get some opinions here.
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Old 03-19-2017, 04:18 PM   #2
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I had the same thing with comp trunnions. I just gave the tight bearing rockers a very slight tap as you would to push the bearing out of the rocker and they spun freely
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Old 03-19-2017, 05:30 PM   #3
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They are pushed in too far. They should rotate freely if you hold it by the trunnion. What I mean is, if you rotate the rocker up holding it by only the trunnion, the weight of the nose of the rocker should always point down. It should be that easy to rotate. If not, it'll clearance itself over time...
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Old 03-19-2017, 05:40 PM   #4
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Thanks guys - that makes sense. I pressed the bronze bushings in a tad too far and they are too tight on the shoulders of the trunnion. I might see if I can give one a gentle tap to clearance it. I have got so much money going into this engine I want to make sure everything is right on it.
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Old 03-19-2017, 06:35 PM   #5
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They all should spin very easily. I used Smith Bros, which are identical to Straub, but they said there should be a slight side to side movement as well.
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Old 03-19-2017, 11:59 PM   #6
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Never countersink them... They should be flush with the sides of the rocker arm body and use plenty of assembly lube on the trunnions/bearings and also on the push-rod tips/rocker arm cups and valve tips.
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Old 03-20-2017, 07:35 AM   #7
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Got them fixed- thanks guys. It was the same side on all of them that was pressed in too far so I just eased them back out a bit. Got my clearances back.

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Old 03-20-2017, 11:11 AM   #8
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I am pretty certain the installation instructions include a spec range for the shaft shoulders to the bushing. I used a Summit/Trickflow tool to press mine in and had no issues.

Also freezing the bushings to -40*C really helped ease the bushings into the rocker bodies.
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Old 03-20-2017, 04:18 PM   #9
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There was no clearance spec or range listed in my instructions (I reread them this afternoon). I just put some oil on the outside of the bushings before I pressed them into the rocker. They went really easy so I didn't need to freeze mine.
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