# Hoyt pro series tiller bolt (Failure)



## Chinese Tea (Mar 17, 2010)

I noticed that both of these washers on the back of the limb bolt head had fallen off during California Collegiate Championships this weekend. Worse yet, one of them became lodged in between the black part of the bolt head and the actual limb fork, causing a nasty circular indentation in the washer. 

To me this looks like an adhesion problem as you can also see a piece of the glue still stuck to the washer in one of the photos.

I'd never heard of this issue before and was curious to know if this has happened to others or if this is an isolated incident.


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## calbowdude (Feb 13, 2005)

No issues yet, but I haven't shot in really hot weather with those bolts. I will keep an eye on this over the summer.


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## limbwalker (Sep 26, 2003)

Nothing a little glue won't fix.


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## Neo888 (Feb 4, 2009)

Had the same issue, super glue made wonders to it. Just make sure to clean the surface from the original glue-like something before.


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## icehaven (Nov 30, 2010)

so i started using the pro limb bolts today, and i looked at the washers after I shot. there's clearly two points of high stress/pressure (namely where the limb fork hits the washer). I'm wondering if this might have contributed to your failure. these washers were fresh out of the package. The red arrows point to the darker areas that were caused by the limb pressure. (the pictures are of the same bolt)


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## Chinese Tea (Mar 17, 2010)

Since starting the thread I've taken apart my limb bolts. The washers are held against the black aluminum bolt heads with double sided sticky tape. The 'pressure points' that I was seeing was areas where the washer was bending upwards away from the tape due to compression of the tape from the limb fork. 

i.e. White = the washer is bending away from the bolt head and exposing the sticky tape to air. If you press down really hard you'll see it turn dark again.

Over time, the washer bends upwards and lifts all across the bolt head and I believe exposure to the air then weakens the adhesive capability of the tape. In my case they ended up falling off.

I ended up getting a pair of replacement washers from LAS/Hoyt and tried attaching one with the sticky tape and one pair with loctite super glue. The one with the sticky tape ended up lifting out again this weekend.

In case one wants to take apart the limb bolts:
1. Use the tip of a knife to pry off the 'pro series' tin plate off of the front of the bolt. It's just attached with sticky tape.
2. You'll see two holes and a recess. The recess faces outwards away from the bolt. Insert a pair of needle nosed pliers into the two holes and twist them counter clockwise to unscrew the plug.
3. Now the stainless bolt and the black aluminum head can separate.

I did this because some glue got stuck inside and I wanted to remove it.

Ps. I think the compressible sticky tape was a bad choice of material.


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## Norman2 (Aug 4, 2012)

Hi, I use delrin washers under my limb bolts and glued them down with Loctite super glue and have had no problems
with them. The ones I use are thicker than yours so they do not bend. I only used them to protect my limbs. See Photo.
Regards
Norman


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## Chinese Tea (Mar 17, 2010)

Norman2 - Love the idea!

I've decided to RMA my limb bolts after I noticed this while disassembling them:









The red arrows are pointing to an uneven circle where the head of the inside stainless steel bolt seems to be slowly eating into the aluminum (is it aluminum?) cap.









The circle appears to be parts where the black anodizing has rubbed off and the material under it shows wear. Under a magnifying glass, I can see indentations where I believe the edge of the SS bolt leaves an impression.


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## DK Lieu (Apr 6, 2011)

Aron and Alan... The stress spots that I see in your photos are not what I would expect to see for a design like this. Are you sure everything was assembled correctly? The edge of the limb at the U-slot should extend well beyond the center-line of the bolt when the limb is fully seated. If not, the limbs may not be seated properly or the limb bolts may be wound out too far. From Alan's photo, the stress points seem to be right at the center line of the bolt. Try fitting the U-slot on the limb bolt only (outside of the riser). Does the bolt go completely into the U-slot and without much effort? If not, the varnish on the inside of the U-slot may be causing the limb to hang-up on the bolt before it is fully seated.


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## Chinese Tea (Mar 17, 2010)

Dennis - 

The edge of my limb fork fully covered the shank of the bolt, so well past the thickest part of the fork, but did not bottom out in the U groove. I was getting a positive click from the detente and the steel barrel was firmly in the alignment dowel. Limbs went in pretty easily.

Even so, I did notice that the face of my limbs (W&W XQ1) are not perfectly flat, and there seemed to be a very slight curve to it. Therefore in all positions in and out I was never able to get 100% contact with the area of the pivoting limb bolt that's on top of the limb.


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## DK Lieu (Apr 6, 2011)

Chinese Tea said:


> Dennis -
> 
> The edge of my limb fork fully covered the shank of the bolt, so well past the thickest part of the fork, but did not bottom out in the U groove. I was getting a positive click from the detente and the steel barrel was firmly in the alignment dowel. Limbs went in pretty easily.
> 
> ...


Ahh... That's the problem. The contact point of the limb on the underside of the bolt head must be beyond the centerline of the bolt for the floating head design to work properly. If not, the head gets cocked in the wrong direction. The curve in the seating area of the limb certainly doesn't help. Might that curve have been caused by wear of the limb on the solid limb bolts, or is that a natural part of the W&W design? It seems that the limbs are fully seated. Ideally, the limb and the underside of the bolt head should be flat against each other to evenly distribute the contact pressure. Winding the bolts inward will probably help. I'm not sure if it is viable to sand down the limb in that area until it is flat.


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## HikerDave (Jan 1, 2011)

DK Lieu said:


> Ahh... That's the problem. The contact point of the limb on the underside of the bolt head must be beyond the centerline of the bolt for the floating head design to work properly. If not, the head gets cocked in the wrong direction. The curve in the seating area of the limb certainly doesn't help. Might that curve have been caused by wear of the limb on the solid limb bolts, or is that a natural part of the W&W design? It seems that the limbs are fully seated. Ideally, the limb and the underside of the bolt head should be flat against each other to evenly distribute the contact pressure. Winding the bolts inward will probably help. I'm not sure if it is viable to sand down the limb in that area until it is flat.


The contact point has to be even beyond the centerline. The virtual pivot point of the floating head is going to be at the center of the sphere well above the top of the limb bolt. Because the force applied to the limb bolt by the limb is at an angle, especially when the tiller bolts are backed out all the way, the initial contact line has to be well past the center or the bolt just flops back the wrong way. I'll bet that the new Hoyt Grand Prix limbs have a bit more material at the limb butt than the Win and Win limbs pictured.

The solution to this problem is simple. Use the old-style fixed limb bolts if your limb bolts are backed out all the way.


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## icehaven (Nov 30, 2010)

HikerDave said:


> The contact point has to be even beyond the centerline. The virtual pivot point of the floating head is going to be at the center of the sphere well above the top of the limb bolt. Because the force applied to the limb bolt by the limb is at an angle, especially when the tiller bolts are backed out all the way, the initial contact line has to be well past the center or the bolt just flops back the wrong way. I'll bet that the new Hoyt Grand Prix limbs have a bit more material at the limb butt than the Win and Win limbs pictured.
> 
> The solution to this problem is simple. Use the old-style fixed limb bolts if your limb bolts are backed out all the way.


That solution sounds about right to me. I can confirm that the limbs are seated properly. but my bolts are backed out about 5 turns each. so it is certainly beyond optimal.


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## icehaven (Nov 30, 2010)

just a quick thought. i remember the pro-limb bolts were on the formula risers originally (and now only on some of the formulas).

do formula limbs rest at a different angle on the limb bolt? this might be a reason why they don't work so well on ILF


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## Chinese Tea (Mar 17, 2010)

DK Lieu said:


> Ahh... That's the problem. The contact point of the limb on the underside of the bolt head must be beyond the centerline of the bolt for the floating head design to work properly. If not, the head gets cocked in the wrong direction. The curve in the seating area of the limb certainly doesn't help. *Might that curve have been caused by wear of the limb on the solid limb bolts, or is that a natural part of the W&W design?* It seems that the limbs are fully seated. Ideally, the limb and the underside of the bolt head should be flat against each other to evenly distribute the contact pressure. Winding the bolts inward will probably help. I'm not sure if it is viable to sand down the limb in that area until it is flat.


There's definitely a slight curve due to wear by solid limb bolts. Therefore perhaps the pivoting limb bolts are best used with new limbs without this kind of wear. There is also a slight curve to the face of the limb. I'm not sure if this is just W&W design or if it's even intentional. 

Laying an arrow (straightest thing I can find) against the face of the limb butt, there is no completely flat surface or place with two points of contact.








Click for full sized image (largish).

The limb pictured is W&W XQ-1 (flat version).

It would be nice to know if other brand's limbs are like this or if this is true for all W&W limbs.


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## autolisp (Nov 19, 2012)

Hello everyone.

I just found this thread and I am glad I did. Why. Well yesterday an archer next to me on the line asked if I had a loose spring in my longrod! As it was annoying him whenever I loosed an arrow! I said there are no springs in my longrod and my bow always made that 'twang' noise. In another post I have been trying to find the 'brace height' that would 'silence this bow' (Hoyt GMX 25" riser with Kaya K3 limbs). Whilst driving home I was pondering the problem and had wondered if the bottom of the limbs were 'jumping against the underside of the limb bolts with vibration. Having read this thread I have I think discovered the reason for the 'noisy bow'. When inspecting the limb bolts I noticed the bottom of the limbs were in contact with the underside of the 'head' only at a point just past the centerline of the bolt (just like Chinese Tea's problem/diagram). This showed that the 'floating head of the bolt' was not flush with of the contact face of the limb. However. It became flush when I adjusted the bolt to only three complete turns out from bottom, previously it had been five. So it would appear that that my £500.00p Hoyt riser with the 'advanced tiller bolt design' is not as adjustable as I was lead to believe! It's not the fault of the retailer but the manufacturer! International limb fitting should be 'International fittings' irrespective of the manufacturer. I may have a solution if someone from 'Hoyt' reads this. Is it possible to make a 'plate/washer' that could fit under the limbolt head and extend the end of the limbs to give the correct fit at any number of turns out from bottom? I would expect them to supplied 'free of charge' to us customers that purchased the equipment in good faith. I will not be holding my breath though.

Dennis


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## >--gt--> (Jul 1, 2002)

Hoyt does not advertise its risers as compatible with anything other than Hoyt limbs. Your assumption that Kaya limbs would be fully compatible is incorrect.


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## hoytshooter15 (Aug 13, 2012)

Hmmm.... fascinating... I will have to watch out for this on my bolts....


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## Dacer (Jun 10, 2013)

My SF carbon limbs actually sit better on my pro series bolts better than my G3's... But those are much old limbs compared to the 6 month old SF carbons.


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## HikerDave (Jan 1, 2011)

autolisp said:


> Hello everyone.
> 
> I just found this thread and I am glad I did. Why. Well yesterday an archer next to me on the line asked if I had a loose spring in my longrod! As it was annoying him whenever I loosed an arrow! I said there are no springs in my longrod and my bow always made that 'twang' noise. In another post I have been trying to find the 'brace height' that would 'silence this bow' (Hoyt GMX 25" riser with Kaya K3 limbs). Whilst driving home I was pondering the problem and had wondered if the bottom of the limbs were 'jumping against the underside of the limb bolts with vibration. Having read this thread I have I think discovered the reason for the 'noisy bow'. When inspecting the limb bolts I noticed the bottom of the limbs were in contact with the underside of the 'head' only at a point just past the centerline of the bolt (just like Chinese Tea's problem/diagram). This showed that the 'floating head of the bolt' was not flush with of the contact face of the limb. However. It became flush when I adjusted the bolt to only three complete turns out from bottom, previously it had been five. So it would appear that that my £500.00p Hoyt riser with the 'advanced tiller bolt design' is not as adjustable as I was lead to believe! It's not the fault of the retailer but the manufacturer! International limb fitting should be 'International fittings' irrespective of the manufacturer. I may have a solution if someone from 'Hoyt' reads this. Is it possible to make a 'plate/washer' that could fit under the limbolt head and extend the end of the limbs to give the correct fit at any number of turns out from bottom? I would expect them to supplied 'free of charge' to us customers that purchased the equipment in good faith. I will not be holding my breath though.
> 
> Dennis


You can buy the non-floating limb bolts from Alternative Services.

I had a similar problem with my Border Hex6 BB2 limbs on my 27 inch Formula HPX, so I just swapped limb bolts with my daughter's Formula Excel riser. Problem solved. I could turn down my draw weight and she got an upgrade -- one third of the way to a Formula Excel Pro. Since my limbs were made Border has adjusted their limb tips to add additional material at the limb but to improve their compatibility with the floating limb bolts -- Hoyt may not care whether their equipment is compatible with other manufacturers, but the other manufacturers definitely want to be compatible with Hoyt. Think of Hoyt as a metaphorical 800 lb gorilla.


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## autolisp (Nov 19, 2012)

>--gt--> said:


> Hoyt does not advertise its risers as compatible with anything other than Hoyt limbs. Your assumption that Kaya limbs would be fully compatible is incorrect.


Whilst I appreciate this. My comment was that 'International Fittings should fit any International fitting correctly regardless of the manufacturer'!

Dennis


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## John_K (Oct 30, 2011)

autolisp said:


> Whilst I appreciate this. My comment was that 'International Fittings should fit any International fitting correctly regardless of the manufacturer'!
> 
> Dennis


The problem is that there isn't a published International Limb Fit standard. All that happened was that other manufacturers copied the Hoyt limb fitting, which results in variations in limb pocket tolerances, pivot points, geometry etc. This was further complicated when Hoyt tweaked the pocket design, as was their prerogative.

It would be fantastic for archers around the world if there were such a published standard, but there isn't. So we have to accept that sometimes you won't get a clean fit, and then you have to look at doing some DIY or getting a skilled bowyer or tinkerer to help.


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## autolisp (Nov 19, 2012)

Following my suggested solution yesterday regarding getting full surface contact between floating head and limb surfaces. This morning I went into my workshop/garage armed with my GMX. I measured the differences to the distance from the edge of the 'floating' head to the head of the bolt holding the 'plunger' that fits the pivot point. One one limb with the bolt turned in fully to 'bottom' and on the other with the bolt turned out '5' turns from 'bottom'. I got a value which I rounded to 4mm. I then chose a piece of 1mm thick stainless steel and made a 'shim' that is shown in the images. I made it 4mm longer than the limb length measured from the end of the limb (which contacts the surface of the limb bolt) to the outside of the head of the bolt that holds the plunger + about 10mm. This 4mm extension when the shim is fitted to the limb extends the upper 'contacting surface' by that amount. A hole was drilled to allow fixing using the 'plunger bolt head', that fixed the position of the shim to get this extension. The other end was slotted to allow fitting around the bolt body and under the floating head. I attached the shim using double sided carpet tape + the securing bolt. I have attached 3 images. One of them shows the limb bolt head tilted at an angle at 5 turns out, meaning that there is only contact between the underside of the floating head and the '*edge'* of the limb bottom. The other 2 images show the same limb with the limb bolt 5 turns out but with the 'shim' in place. I hope you can see the floating head surface making full face contact with the surface of the shim and consequently the limb underneath. I have tested the bow this afternoon, shooting about 5 dozen arrows. There has been no change in the surface contact after use. So I am confident that the floating head limb bolt is now functioning as it was designed to do.

I do not have any 'Hoyt' limbs, but if they were manufactured to fit the previous design of limb bolt, I fail to see how they, or any other manufactured limbs, could possibly work (being shorter than required) as intended except when the limb bolt is turned in to the 'midway position', that is 3 turns out from bottom or less on my GMX riser! 

Well. I hope you found this of interest.

Dennis


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## bobnikon (Jun 10, 2012)

>--gt--> said:


> Hoyt does not advertise its risers as compatible with anything other than Hoyt limbs. Your assumption that Kaya limbs would be fully compatible is incorrect.


So why is it that Hoyt limbs aren't fully compatible with Hoyt risers and limb bolts then. I have the same "fitment" issues that were mentioned above, and I have had to file and sand the inside of the groove on 2 sets of Hoyt limbs to fit comfortably on the floating head bolt shaft...???


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