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cam shimming question

raisins

Well-Known Member
SH Member
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Jan 17, 2019
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I changed the bearings out in my lower cam (Bear Traxx) today. It was first time removing a cam and doing anything like that.

Everything went well except the slimmest shim stuck to the cam and I didn't see it (looked like part of the bearning). As I'm looking at the cam to press out the bearings, this little shim hits the ground and I have no idea which side it went on/fell off of.

I had 1 thick and 1 medium width shim on each side and then this slim one (0.015 inches) had to go on one side or the other since there was only one.

The bow's e-clip barely went on the axle with the thin shim installed and I had to compress the limbs together with a hand vise to get it back on (I guessed which side and thought I'd switch it later if it didn't shoot the same). So, I ended up just removing the thin shim (keeping it) and put a thick and medium shim on each side. E-clip went right back on, there's no slop in the cam, and initial shots indicate the bow is quiet and nothing has changed for POI.

Would you guys even worry about this little shim or would you call the factory and try to get information out of them? (they haven't made this bow in 5 years). I'm thinking I'll forget about it until it warms up and if my left-right with bareshafts and broadheads has changed, then I'll consider installing it on whatever side corrects that. Is it normal to have to compress limbs like that to get e-clips back on? Bearings were fully seated and slide right in (I even pushed on them a bit with the hand vise with soft ends). It stinks this happened because I was very careful not to twist or untwist my strings so that I wouldn't change my tune (I didn't take it to a local dealer because I knew every one around here would take my strings off, slop them in the corner, and then put my bow back together and twist everything up the way they saw fit which would slightly change everything)
 
I’d hang on to the shim but wouldn’t sweat it. You shouldn’t have to squeeze the limbs together to get an E clip back on.


Just curious, why did you replace the bearings and where did you buy them?
 
I’d hang on to the shim but wouldn’t sweat it. You shouldn’t have to squeeze the limbs together to get an E clip back on.


Just curious, why did you replace the bearings and where did you buy them?

Bear sent them to me for free (had to have them shipped to a dealer) after I called and explained the issue.

The side cover on one of the bearings popped off and I could see the ball bearings inside. It still shot ok, but I didn't like that and thought dirt would get in there. Since I had the cam off anyways, I replaced both the bearings of the bottom cam. It was easy to do.

After your post and speaking with some other folks that do mechanical work, I think that the thin shim was added just to take up slop in the original build and that my new bearings might have been slightly larger due to manufacturing tolerances. If 0.015" makes a difference, then I can nudge my arrow rest over a micro amount this spring and be back to perfect flight. That shim is so thin I'm with you that it just can't matter that much. It was thinner than a sheet of paper and you could flex it by accident just holding it by the edge with a semi-firm grip.
 
Can you take measurements to see if both cams are lined up equally within the the limbs on both ends? If they are the same, I wouldn't worry about it or perhaps if its a single cam, find out what the factory specifications should be. As long as there is no aggravated cam lean, the bearings seem to be working properly with no noise and added tension, your draw cycle doesn't seem to be impaired and any openings to the bearings are closed or sealed, I think you should be fine. I just wouldn't think you would want much derivation of the cam spacing between the limb tips. You may have shifted your string travel over to one side or another if there is a difference in the spacing between both limbs but I can't see a huge issue if its shooting and grouping well.
 
Don’t sweat it unless you can’t get it to tune...if it tunes, run with it.
Don’t worry about measuring to see if both cams line up...cams shouldn’t line up equally...each limb deflects differently due to the cable guard putting different stresses on different limbs, so your cams shouldn’t be equally spaced in the limb pocket...it all comes back to the tune...if it tunes, leave it alone...if it doesn’t, put it back on.
 
There's nothing to measure since it's a hybrid cam system. 2 track cam on top and 3 track on bottom. The shooting string isn't at the same point between the limbs, top vs bottom.

Even if it didn't shoot a perfect tear, I'd probably look to another adjustment (twist yoke, rest movement, etc.) To correct it. That's assuming you're confident in the fitment of the cam.
 
Thanks guys. I can't wait until it is warmer so I can really shoot this thing. If it still drops fixed blade and field points to the same spot at 40 yards and bareshafts the same then I'll call it good. The string is less than a year old, so my spring will also include checking cam timing to make sure nothing has moved around also. Probably going to buy a Bowtech Revolt and make this one my backup bow (but I am attached to it and always wanted to get a Pope and Young with it, which hasn't happened yet).

Edit: Thankfully, Bear sent me all 4 bearings. My bareshafts today are shooting low at 20 yards. If this is consistent in the spring when I'm shooting more/better, then on this bow that indicates the bottom cam is rotating ahead of the top one. I'll check timing, but I wouldn't be surprised if this has to do with the top cams bearings being 6 years old and subjected to the elements over that time and the bottom cam having brand new bearings. Part of me wanted to replace all of them once the bow was relaxed, but the bottom cam was a pain with the shims so I didn't go for more.
 
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