# Backing off limb bolts



## Jwaydr (Dec 13, 2007)

What happens when backing off limb bolts? I've measured ATA and found when backing off limb bolt the ATA decreases. What if any should be the corresponding tuning actions?

Thanks in advance.


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## Nevada Smith (Sep 6, 2014)

Perhaps page 12 of this manual will be helpful.


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## TMan51 (Jan 25, 2004)

Jwaydr said:


> What happens when backing off limb bolts? I've measured ATA and found when backing off limb bolt the ATA decreases.


What kind of bow are you working with? My Hoyts do not change ATA with limb bolt changes, at least over 2-3 turns.


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## ironman_gq (May 22, 2012)

sounds like you have some stretchy strings


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## gofor (Feb 4, 2013)

Yes, ATA can decrease when backing out limb bolts. Also, your draw length increases. On some bows, backing them off can also cause an increase in brace height. 

When backing of the limb bolts, the end of the limb under the bolt head pivots away from the riser. The axle end pivots the opposite direction. However, backing off the limb bolts also decreases the tension on the cables, so the limbs spring back a little. On bows that have a large range of draw weight adjustment (ex. Mission Riot), the change can be substantial in ATA, BH, and DL as well as DW.

That is why it is recommended to set ATA and max draw weight with the limb bolts all the way tight. After backing them off to the desired DW, you may have to shorten the draw length to get back to where you want it.

Go.


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## TMan51 (Jan 25, 2004)

TMan51 said:


> My Hoyts do not change ATA with limb bolt changes, at least over 2-3 turns.


I had to re-check. I backed a couple out 2 turns, and looking closely, it does change a tiny bit. About 1/16" on a Katera and a Supertec. BH was a bit less, and may have been my eye and measuring tape, pretty small.


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## Jwaydr (Dec 13, 2007)

gofor said:


> Yes, ATA can decrease when backing out limb bolts. Also, your draw length increases. On some bows, backing them off can also cause an increase in brace height.
> 
> When backing of the limb bolts, the end of the limb under the bolt head pivots away from the riser. The axle end pivots the opposite direction. However, backing off the limb bolts also decreases the tension on the cables, so the limbs spring back a little. On bows that have a large range of draw weight adjustment (ex. Mission Riot), the change can be substantial in ATA, BH, and DL as well as DW.
> 
> ...





Nevada Smith said:


> Perhaps page 12 of this manual will be helpful.



Thank you.


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## Jwaydr (Dec 13, 2007)

TMan51 said:


> I had to re-check. I backed a couple out 2 turns, and looking closely, it does change a tiny bit. About 1/16" on a Katera and a Supertec. BH was a bit less, and may have been my eye and measuring tape, pretty small.


Yes, the change is small but a change none the less and concerned it would change enough to allow doubt to enter my mind that the bow would no longer be spot on. I first tried this on an older bow I have and confirmed it would change. I was contemplating backing down my current hunting rig, just getting cold here and shoulder is protesting a bit. Since the bow is shooting fantastic I've decided not to mess with it in season.


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## carlielos (May 12, 2007)

What I'm reading here is boggling my mind, so you're all saying that by backing the limbs out your strings and cables are getting? Shorter? A good settled set of strings should not change with the amount of load thats onn them.
Honestly it defies logic, unless you're going from 80 pounds down to 50 I cannot believe the axil length would change, that would have to be one stretchy set of strings even to change 116th inch.
I pre stretch my strings at over 300lbs, that's way beyond what any modern compound bow can apply to them, if they move it's because they were not built correctly, my 2 cents!


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## Tlariat (May 11, 2008)

carlielos said:


> What I'm reading here is boggling my mind, so you're all saying that by backing the limbs out your strings and cables are getting? Shorter? A good settled set of strings should not change with the amount of load thats onn them.
> Honestly it defies logic, unless you're going from 80 pounds down to 50 I cannot believe the axil length would change, that would have to be one stretchy set of strings even to change 116th inch.
> I pre stretch my strings at over 300lbs, that's way beyond what any modern compound bow can apply to them, if they move it's because they were not built correctly, my 2 cents!


It's not the strings. Its a physical change that the limbs go through. It simply allows the axles to "rotate" towards each other.


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## carlielos (May 12, 2007)

Tlariat said:


> It's not the strings. Its a physical change that the limbs go through. It simply allows the axles to "rotate" towards each other.


 Nice theory in fantasy land, all back in the limbs off does is reduce the amount of pre load, the limbs get straighter, the only way the axil length can change is if the strings change length, there's no two ways about it. usually a brace height change occurs, that equals a change in draw length. But the axel lemgth does not change unless the strings change length.


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## SNAPTHIS (Jan 16, 2003)

The change in measurement occurs because the limb pivot is outside the limb bolt, so as you back out the limb bolt the relationship of the limb to the pivot changes the poundage, the draw length, ATA and brace height. The distance from the bolt to the pivot will be different on different bows causing the axle movement to be different on every bow. Mark


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## FS560 (May 22, 2002)

The cams, string, power cable, and control cable are a closed system. Unless the strings change length, the ATA cannot change no matter what the limb angle is.


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