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TR2/3/3A Trunnions - Chamfered vs Flat Top

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Joel M

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I will be replacing both trunnions due to significant wear, and noticed there are two versions available for purchase - original flat top and chamfered. Do the much cheaper chamfered types function just as well as the original flat tops? Is there any reason I should spend the additional money for the flat top?

Joel
 
Glad to hear there are options now. Last time I was in the market I had to return 5 to finally get a set that even fit with less slop than the worn out trunnions I was replacing.

In answer to your question...flat would give more bearing area, so live longer in theory. Emphasis on "theory"! You must ensure they do not contact the radiused part of the vertical link stud, or that would cause a bind and point of fatigue stresses. Radiused would be an insurance that the trunnion threads would completely clear the vertical link stud radius.

In my thinking, the most important thing about trunnions is that they have minimal slop when threaded onto the vertical links. You should just barely be able to feel a motion between the 2. If there is enough to make an audible "click" as you rock them together, then that is too much. Too much play gives the forces a "running start" to hammer the link every time you hit the brakes.
 
Just make sure you are getting a reunion for a tr3 and not a tr4. Normally I would think the one with the chamfer is tr4 with 3 degrees caster.

Edit: I see Moss does carry both- given they are both repros I’d just buy the cheapest and check quality like John suggests
 
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I would have never thought to check for "slop" with new trunnions - thanks for the advice. Would you mind telling me which supplier was able to provide good units? Or does the slop vary among the same part number from the same vendor?
 
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