weight adjustment on Hoyt GM

[geoffretired]

A friend at the club has a Hoyt GM.
The book shows how to adjust the limb weight, but it doesn't seem to work.
Deep inside the limb pocket is a little box into which fits the end of the limb.The box is fitted rigidly to a rod so the whole assembly can slide from front to back of the pocket, altering the weight. What we cannot see is what could prevent the limb from pushing the box away to the lightest setting. The adjustment device on the string side of the riser is a two part job. A stainless steel hollow screw with a threaded grub screw up the inside. The book says undo the stainless screw one turn and turn the grub screw in the direction required, then lock up the stainless one to keep things in position. All that seems to do is push the box away to the lightest setting. There seems to be no way of pulling the box to the heaviest setting and keeping it there.
What are we missing?
Thanks

[worthipa]

I seem to remember you turn it one way to increase the poundage and the other to decrease it then lock it down with the grub screw.

More info here:

http://www.archery-interchange.com/f...adjusting.html

[geoffretired]

Thanks for that worthipa. I think the adjuster is the part that stays inside the limb pocket; we've been adjusting the grub screw which is just part of the locking mechanism.

[worthipa]

Originally Posted by geoffretired

Thanks for that worthipa. I think the adjuster is the part that stays inside the limb pocket; we've been adjusting the grub screw which is just part of the locking mechanism.

Ah, quite so!

Looking further into this I see there's a section, with useful pictures, in the Hoyt 2006 Recurve manual, available as a PDF file from the download section of the Hoyt website.

[Random_guy]

i seem to remember that the older GM's had a system where the was a 'hollow' locking screw with a smaller hole in the middle through which you could get to the main adjustment bolt. In that case you had to use a larger allen key to unlock the mechanism a bit, then a smaller one that you threaded through the hole in the top screw to adjust the weight.

On my one which was in the last generation to be made, there was a grub screw with the same thread as the mechanism that had to be removed completely (don't lose it whatever you do!!!) and then you alter the 'little box's' position by turning the second screw that was hiding beneath the first. The limb bolt was actually threaded which meant that it slowly moved as you turned the screw, *BUT* also meant that, on mine, the thread could strip, allowing it to slowly grind back to the lowest setting whilst you were shooting!

[geoffretired]

Thanks again worthipa and thanks Random Guy.
So it is the screw running through the little box inside the limb pocket. At present this GM is in its original setting which is minimum weight. The screw seems tight and we assumed it wasn't meant to turn. With your help, we can get on now and set the weight and tiller settings.
Cheers.

[TonyF]

There is a locking screw which needs to be completely removed which then gives access to the adjusting screw. Just remember to tighten the locking screw fully when the adjustment is complete

[geoffretired]

Thanks TonyF

[deg]

i) remove the locking grub screw (and DO NOT lose it: stick it over a piece of adhesive tape)

ii) with the same tool, screw the threaded bar that keeps the box where the limb butt seats. The bar will start to enter in the box and will eventually touch the riser. ONLY at this time the box will start to move toward you.

The threaded bar may (and will) have some degree of free movement along its axis. The trick here is to PUSH slightly with the tool while screwing the bar. This will help to keep the bar in contact with the riser.

The real box movement to consider is the one it makes when the bar touches the riser; in the other case the box will move toward the back of the riser.

See if these figures may help:

1)
the space (...) marked with -v- should not be here!

-v-
[...<\\\[BOX]\\\\[ .... ]
------------------- -^-

the space marked with -^- will be closed by the grub screw [GS] BUT the box can move forward.

2)

[<\\\[BOX]\\\\[.[GS]...]

the limb will push THIS ( <----- ) way; the box is not going to move: the bar is constrained by the riser.

At the end the limb butt box will not move forward because the bar touches the riser and will not move backward because of the grub screw.

Hope this helps

[geoffretired]

Hi Deg,
Thanks for all the detail. That should be a great help. Cheers.