# Z7 Xtreme - Yoke Tuning



## Good Moses (Oct 17, 2008)

I am experiencing persistent left tears with my z7X and I am out of ideas on how to correct this. I'll spare the full details of what I have been through with this bow, but to bring you up to speed, here is a very condensed summary of what I have done:

I reviewed and documented the bow's specs when I purchased it, all good (BH and cam timing close enough to call good). I set rest to exact centershot at 13/16" and shot through paper and got bad left tears. I walkback tuned out to 45 yards to ensure centershot was where it needed to be and got a perfect vertical line at all distances, so I did not make any L/R adjustments to the rest. I then checked for idler wheel lean and saw that the idler wheel at rest and also at full draw was leaning to the left (\). Before adding or taking away any twists to either side, I documented that factory yoke twists were 4 left and 7 right. 

At this point I decided to add 1 full twist to the right yoke. After adding this twist, the string now tracks straight off the idler wheel at full draw and a straight edge runs parallel with the string at rest. I shot several times to let the string settle after this adjustment and shot through paper again. Still left tears. I decided to shoot a broadhead at 20 yards just to get an idea of how they would fly (G5 Striker 100 gr) and it impacted 2" high and right of field tip arrows. 

I feel that I need to add another 1/2 twist or so to the right yoke to take care of the this left tail whip, but I am concerned that I may over-twist the yoke if I add more twists. It is currently set at 4L and 8R, which seems like an imbalance already. 

Another issue that is floating around in the back of my mind is cam lean. Cam lean on this bow is severe compared to other bows. A straight edge run along the side of the cam will cross the string at the nock point. Does this sound normal? If this is the root of the problem, then I have no idea what to do. As far as I know you can't tune cam lean out of this bow. 

Can any of you provide a little guidance here? Have any fellow z7X owners or experienced bow tuners had to deal any of these same issues? 

28" DL
70#
CE Maxima Hunter 350
Also please note that I shot the bow approximately 300 times before starting any of these tuning procedures to allow for initial string settlement and stretch.


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## flag (Oct 4, 2009)

I have found that the 350 spine is little too weak for my 70# dxt but I would move my center shot in a little at a time till bh and field point have the same poi and I would get the up and down poi right before I messed with center shot because sometimes you fix one problem the other ones get corrected in the process. All of the z7s I have tuned the center shot was around 3/4 to 11/16 mathews gives you 13/16 as a starting point


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## Hntndad (Jan 16, 2012)

It's not cam lean. Unless that cam is bent or limb is warped (rarely the case). Set your bow back to factory specs- ata, brace and cam timing. There is a great thread on AT on tuning Mathews bows. Read it. I agree that z7s tend to center shot inside of the standard 13/16 recommendation. Mine is 11/16. Amazing how slight, and I do mean slight adjustments make a difference. Correct up/down tears first. Then horizontal. Make sure the rest is set up correctly. Arrow should lay through the Berger hole at rest. Verify you have no knock pinch if you use a d-loop. Great articles ones how to properly set up D-loops here. I like tying in a knock set above the knock and below. Most importantly make sure you shoot consistently. I have never been able to make these Mathews grips fit my thin hand. Even the newly designed z series. Had to go custom. World of difference in consistency for me. Stick with it. Small adjustments. And don't throw your bow across the yard once you do get that perfect tear and find that your broadheads aren't grouping with your fieldpoints! Good luck!


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## Good Moses (Oct 17, 2008)

flag said:


> ...I would move my center shot in a little at a time...All of the z7s I have tuned the center shot was around 3/4 to 11/16 mathews gives you 13/16 as a starting point


I just learned that I have been addressing my left tear incorrectly by adding twists to the right yoke. I was hung up with trying to correct idler wheel lean at full draw and had added to many twists to the right yoke. I backed off 1/2 twist to the right yoke and added 1/2 twist to the left yoke. These adjustments have reduced my tears to near bullet holes. I think the yoke is set to go now, so tomorrow night I am going to move the rest a tad toward the riser and see if this solves the problem. 

Thank you for your advice!


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## Good Moses (Oct 17, 2008)

Hntndad said:


> It's not cam lean. Unless that cam is bent or limb is warped (rarely the case). Set your bow back to factory specs- ata, brace and cam timing. There is a great thread on AT on tuning Mathews bows. Read it. I agree that z7s tend to center shot inside of the standard 13/16 recommendation. Mine is 11/16. Amazing how slight, and I do mean slight adjustments make a difference. Correct up/down tears first. Then horizontal. Make sure the rest is set up correctly. Arrow should lay through the Berger hole at rest. Verify you have no knock pinch if you use a d-loop. Great articles ones how to properly set up D-loops here. I like tying in a knock set above the knock and below. *Most importantly make sure you shoot consistently. I have never been able to make these Mathews grips fit my thin hand. Even the newly designed z series. Had to go custom. World of difference in consistency for me*. Stick with it. Small adjustments. *And don't throw your bow across the yard* once you do get that perfect tear and find that your broadheads aren't grouping with your fieldpoints! Good luck!


I just commented to Flag that I made a couple of adjustments to the yoke tonight. I measured specs afterwards and I am exactly in spec on ATA, BH, and timing. The rest is still sitting at 13/16" for the time being though. I am going to make some slight adjustments towards the riser tomorrow to see if that helps, especially if your bows are tuning at 11/16". 

I would love to read the thread on tuning Mathews bows, but my searches for "Z7" or "Mathews", etc., it says that there are too many search results. Not sure if I was using it correctly, but that's why I resorted to starting this thread. 

I'm good on the up/down tears. I have had to tie on 4 different d-loops to finally the height right, but it's good. 

I agree that inconsistent grip is very likely part of my problem. This is my first Mathews bow and the grip has definitely taken some getting used to. I have ordered a Focus Grip from my dealer to help with this. Do you use the Focus Grip or another brand? I have heard Torqueless are very good. May go that route if the Focus doesn't suit me. I welcome other suggestions though. 

I have been tempted to toss this thing a couple of times, but I believe this is something I can fix. Even with these annoying left tears, this thing holds some incredibly tight groups at any yardage, especially considering the short ATA (28"). 

Thank you for your suggestions. I really appreciate the guidance. I'll update you guys tomorrow after I play with the rest. Hopefully I'll have some good news to report.


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## Hntndad (Jan 16, 2012)

I commend you on your yoke adjustments! Its so easy to over adjust at first. Make small adjustment-shoot. Little more-shoot. So much easier when you have a press. Ill see if I can find that post on line about tuning Mathews bows. Its a must read. I experienced the same thing as you last spring. Paper tuned during initial set up. Shot a few hundred shots and when string settled I experienced idler wheel lean. I noticed this when my broadheads where flying right of my field tips. Regardless of how my rest was adjusted. When setting back to spec it must be done with limbs maxed out. I added 1/2 twist. Then another. Then took 1/2 out and added 1/2 to the left. Finally got perfect tears with bare shaft. Took it outside and shot a broadhead, then fieldtip. Adjusted my rest MICRO ADJUSTMENTS until p.o.I. was the same with field tips and broadheads out to 40. Ended up at 11/16ths. By the way. I like my tourqueless.. great guy to deal with.


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## Hntndad (Jan 16, 2012)

Correction-- my broadheads where left of fieldtips. Sorry for my inaccuracy. Go to the Mathews Inc. Forum and search for "the Vince tuning method" should be a couple of stickys


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## duxbux (Nov 22, 2008)

I know your pain. 

I learned to just walk away for a couple of days. 

Where are you with yoke twists now?


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## Good Moses (Oct 17, 2008)

Hntndad said:


> Its so easy to over adjust at first


You're exactly right. I believe I got off track adding twists to the right side trying to correct the idler wheel lean at full draw. After the adjustments I made last night, a straight edge placed along the side of the idler wheel no longer runs exactly parallel with the string at rest. There is a gap of about 3/8" between the straight edge and the string at the nock point. It is shooting better though, so I'm leaving it alone. 



Hntndad said:


> Go to the Mathews Inc. Forum and search for "the Vince tuning method" should be a couple of stickys


I have been all over the Mathews website with this. And I followed the L.O.S.T Arrow Tuning guide to get me this far. And getting this far is HUGE progress from where I started. 

I think part of my problem with all of this is that I have certain "Truths" in my mind about how bow tuning should work. For example, how the straight edge run off the idler wheel should run parallel with the string, how cam lean is bad, nock point must be 1/8" high, rest must be centered at 13/16", and so on. I lost sight of the fact that these are starting points and generalizations and was trying to make my bow fit into these generic molds. After I made the adjustments last night, and basically allowed my bow settle into the tune that it wants to be in - which contradict these "Truths" in some cases - things are coming together. Sometimes it takes somebody just telling you straight up, "Hey Dummy, you're doing this wrong" or "You're forgetting this..." 

Classic case of missing the forest for the trees.




duxbux said:


> I know your pain.
> 
> I learned to just walk away for a couple of days.
> 
> Where are you with yoke twists now?


duxbux, my yoke twists - after my adjustments last night - are now set at 4.5 Left and 7.5 Right. This seems to be where they want to be. I think I just need to fine tune the rest at this point. 

I forgot to add in last night's update that after my yoke adjustments and paper tuning, I went outside and shot field tips and broadheads together again just to see (approx 30 shots). The broadheads are now impacting 1" right of the field tips at 25 yards. Pretty darn close. I would probably call it good if I wasn't obsessing over this like I am.


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## Hntndad (Jan 16, 2012)

The l.o.s.t. tuning is a great read. I've read that one before and its pretty much dead on. Just remember that we all shoot a little different. That's why its worthless to have your "pro shop" dude tune your bow for you and then hand it over. Yeah great, its tuned for him! Your Mathews idler leans at rest. It is slight. Because of the offset of the cable guard. You should be able to take a shaft and place it on the inside of the idler and the insert end of the shaft will be barely off the string. Maybe 1/8 inch. When at full draw you can look up and see that the string is coming off the idler perfectly straight. * You may have more or less tourque on your bow than I do so that adjustment may or may not be the same for you. You are absolutely correct that these are all just guides. Information given to you so that you can learn the principles of tuning. You have to tune that bow to you. Unless you are a shooting machine there are no set standard adjustments. There is close though. I have accepted that I am a hunter. I've been shooting thousands of arrows for a little more than 25 years. I try to get as close to recommended set up as possible keeping in mind that I am certainly not perfect. It takes time but that is why we shoot archery and obsess over minor details. Its in our d.n.a. and we like it! If you feel that shooting perfect tears and a 1" variable at 25 yards is as good as your going to get than you have accomplished your optimal set up. As long as you are constant and accurate enough for your standards then Congrats! My Max range is 40 yards. If I can be accurate to within an inch with field tips and broadheads at that range then I am tuned. If you are not happy with your broadheads shooting 1" right then mark where your rest is currently then ever so slightly move your rest away from the riser. If your groups tighten and your hitting right with your fieldtips then great! As long as you are within +- 13/16 center shot or pretty close. If your just chasing your fieldtips across your target then its either you or you are not quite tuned well enough. Again, good enough is relative. Good luck. It will come together, just stick with it and enjoy not only the shooting but the learning of how all this works!


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## flag (Oct 4, 2009)

It doesn't matter how the idler looks at rest all that matters is at full draw. It sounds like you are getting close keep playing with rest a little very fine adjustments go a long way to get that last inch and if that don't work try rotating your nock around to a different vane I have spent hours tuning only to find out I had a few picky arrows


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## Good Moses (Oct 17, 2008)

Hntndad said:


> ...Your Mathews idler leans at rest. It is slight. Because of the offset of the cable guard. You should be able to take a shaft and place it on the inside of the idler and the insert end of the shaft will be barely off the string. Maybe 1/8 inch. ...If you feel that shooting perfect tears and a 1" variable at 25 yards is as good as your going to get than you have accomplished your optimal set up. As long as you are constant and accurate enough for your standards then Congrats!


Hntndad, 

Thanks for the follow-up. That 1" right variance that I was getting in the broadhead/field tip group was NOT acceptable. That kind of inconsistency drives me insane. And I apologize for not updating yesterday, but I got wrapped up at work and didn't have time to play with this last night.

However, I did have time tonight to mess with it and I think I have this solved. I put the bow on a (homemade) drawboard and brought it to full draw. I took an arrow and ran it down the idler wheel next to the string and noticed that the idler at full draw was still leaning juat a hair to the right side of the bow. So I pressed it and untwisted 1/2 turn from the right yoke. Put it back on the draw board and, voila, perfectly parallel. And I mean perfectly parallel. Should have taken a picture. Anyway, my previous assessments of idler wheel lean have been just eyeballing it while I have it drawn, so that caused my error in this measure. 

So I went back outside and shot broadheads with field tips and they appear to be grouping right in there together. The group in the picture is from 40 yards. The broadhead is the one with the red nock collar. Ignore that the arrows are grouped to the right - I just replaced my sight pin and I need to adjust it.

I also walkback tuned it out to 40 yards and obtained a perfect vertical line. So I am happy with the centershot. 

I have posted a picture of the paper tuning results, which I believe reveals that I have an inconsistent grip on this factory Mathews grip. The paper tears pictures are of 4 sequential shots, from 10 feet, using the same arrow. 2 are crappy left tears, 2 are bullet holes. Hopefully I will have this solved once my Focus Grip comes, but I may be buying a Torqueless anyway because I can foresee the rubber Focus driving me crazy. 



flag said:


> It doesn't matter how the idler looks at rest all that matters is at full draw. It sounds like you are getting close keep playing with rest a little very fine adjustments go a long way to get that last inch and if that don't work try rotating your nock around to a different vane I have spent hours tuning only to find out I had a few picky arrows


flag, 

You're absolutely right about the idler wheel lean at rest vs full draw. I was just being lazy and not wanting to put this in my drawboard as it is a hassle, but I did tonight. You're also right about the nocks causing problems. I am using Carbon Express shafts, which come with a horrible factory nock. I have replaced these with Gold Tip GT nocks and that helped in a major way with the paper tuning. 

Thank you guys for your help with this. I hope the Focus/Torqueless grip adds that last little bit of consistence, which it appears that I lack currently.


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