# Time to retune Vectrix XL and specs are off, looking for help



## P&Y137 (Aug 6, 2004)

Had my Vectrix XL for a little over one year. I've shot it a ton and have just had my cams replaced as the bearings went out in the bottom cam. Got her all back together, and she's a little out of sorts. Wondering if I provided the info, if someone could head me down the road to getting everything back in order?

Upper cam is slightly under rotated
Draw length is 3/16" long
Draw weight is 1 pound low
ATA is 1/8" long
BH is 1/16" long
Tiller is good

Thanks.


----------



## BULLDOG25 (Jun 1, 2008)

Follow the instructions in this thread.

http://www.archerytalk.com/vb/showthread.php?t=207391

You'll need a press.


----------



## Roskoe (Apr 15, 2007)

The Mike "Javi" Cooper thread on tuning will guide you through the process about as good as it gets. But, basically, untwist the bow string about ten twists so it isn't even a part of the equation. Start with the buss cable (the one with the split yoke). Twist it until you get the ATA about 1/4" longer than specs. Adjust the control cable (the one without the split yoke) so that the reference holes are the same distance from their respective cables. At this point, the tiller should be about even with the limb bolts tightened all the way (maximum draw weight).

Then put the bow on a draw board - or if you don't have one have a buddy help you draw the bow while you check the draw stops. When the draw stop is just touching the control cable, the control cable should lay flat in the groove at the top cam. Under rotated? Either twist the buss cable or untwist the control cable. Over rotated? The opposite. Tweak this until you have it about perfect.

Finally, measure draw length. It should be long - and draw weight should be too high. Twist the bow string until the ATA is in spec. Shoot it about ten times and check again. Twist a little more. At this point, the draw weight should be about one or two pound above the rated maximum (60/70 bow should be around 71 or 72 lbs. with limbs maxed out).

Vectrix XL is one of the best bows Hoyt ever built. Tuned properly, it will shoot better than 99% of the archers who hold it (including me).


----------



## bassman409 (Jul 19, 2006)

If you would like to skip some of the steps in Javis thread then: Add 1 twist to buss cable and 4 twists to the string and remeasure your specs! Creep tune it and you should be close.


----------



## TMan51 (Jan 25, 2004)

How is the bow shooting with a planing shaft or broadhead.

Your specs are not a disaster, and string stretch over a couple weeks of shooting will likely solve most of the problem. And you (unfortunately) have some time 'til hunting season to break them in.

As a reference, all of my Hoyts shoot the best with the top cam under-rotated. The difference between "set up" and "tuning".


----------



## Roskoe (Apr 15, 2007)

Top cam under rotated is something I have not tried. I guess your setup has the buss cable twisted up pretty good and not many twists in the control cable. I have personally had the best fine tuning success, at least on my older Hoyts, by setting the cams to the exact sync/timing spec. and then loosening the top limb bolt to fine tune the tiller. Best results seem to come with the bottom limb maxed out and the top limb turned out between 1/3 and 1/2 a turn - at least for my particular form and grip.

I'm trying to visualize if we aren't doing somewhat the same thing, in terms of the draw cycle of the bow. It's giving me a headache - better sleep on it


----------



## TMan51 (Jan 25, 2004)

Under rotated is a bit of a misnomer.

When you use a draw board, or even a hook mounted to a beam, to draw your bow, it doesn't necessarily apply the same force as you do by placing your hand on the grip. A high wrist places more force on the upper limb, a low wrist places more force on the lower limb. You can compensate with tiller, or cam timing.

If you have a chronic "nock low/high" with the shaft square to the string, you can use either approach to compensate. Tiller is easiest if you don't have a press to adjust cam timing.


----------



## dpattarcher (Mar 7, 2009)

Before you start buy a set of strings and cables that do not stretch. If you do not this will only be the first of you're endless tuning sessions.


----------



## archerm3 (Jan 4, 2007)

Cam timing can give you some awful headaches, and you CAN NOT adjust it with tiller. The only thing tiller can do is adjust the angle of the riser to the string, and similarly adjust your nocking point up and down, either intentionally or unintentionally. As far as the cams are concerned, the limbs flex to equalize tension, and the angle shift on the limb is not enough to affect it's spring rate. There is only one force on a limb that causes it to bend and it acts along the line drawn from axle to axle. That line is always the same relative to the string and cables as long as timing stays the same. The angle of that line to the limb matters not.


----------



## Roskoe (Apr 15, 2007)

Tiller tuning, when your cams are set to proper sync and timing, can give you a better nock travel - in terms of a level plane. Yes, I have a press - but the cams are something I like to adjust to proper factory specs. Tiller tuning is where I have found the best "tweak" occurs.


----------

