View Full Version : Draw weight question

03-24-2008, 12:38 AM
I have my limb bolts on my 08 Moab 50lb-60lb cranked all the way down, I used a scale to draw it and it shows I am pulling 55lbs. I hooked up a dumbell to the scale and its accurate. Anyone have this problem and how did you fix it?

03-24-2008, 07:07 AM
You need to check the brace height and A2A of the bow to see how close it is to specs. If the brace height is low and the A2A is long then it's possible to twist the rigging to put more preload on the limbs.

Depending on how close your draw length is determines what all you twist. If the draw is a hair short then you can twist up just the cable to bring the weight up some. This will also increase the draw length a bit.

If you just twist the string the weight will go down and draw length will decrease.

If the draw length is fine where it is then you need to twist both the string and cable. Because the string is approximately twice the length of the cable you need to add twice the amount of twists in the string. A good way to reference this is to draw a line on the side of the cam where it passes through the limb fork (both sides of the limb on the same side of the cam). Use this for cam rotation orientation to maintain the present draw length.

Hope this helps. Drop back and let us know how you make out.

03-25-2008, 09:53 AM
My 70 pound Bengal came with 5L limbs. Ordered my scale & heavier limbs at the same time, with the intention of making an 80 pounder out of it. With the 6L limbs, it just now pulls 70 pounds.

Might just be they build them a little on the light side & figure most folks won't notice or complain. Probably healthier to shoot lighter bows.

03-25-2008, 10:21 AM
"L" will bottom lower than peak. Therefore, you're initial bow probably bottommed at around 67-68. You're limbs (6H) will give you a peak of 75, probably bottoming at 72-73. Your scale could be off.

1 # in the deflection code will change peak by 5lbs. You're 5L limbs were designed for a peak of 70. Therefore, your 6L limbs will be designed for a peak of 75, not 80.

"L" designation will bottom 2-3 lbs. lower than peak.
"M" designation will bottom within a pound of peak.
"H" designation will bottom 2-3 lbs. above peak.

My Slayer has a limb deflection code of 4H. 2H will give me a 50lb bow, 7H will peak at 75, bottom at 77-78, etc...

03-25-2008, 10:28 AM
I'll have to print a copy of that. Mornin' Fly.

03-25-2008, 10:35 AM
See if I can get you banging your head on the brick wall this morning.

With my new 6L limbs, & the 29" module on & flexed about a 1/16th or 1/8th inch under rated A2A, it maxed at 73#.

I put the 30" module in place to see what changed, if anything. It now maxes at 70 even.

Pretty sure the new scale is accurate. It measures my old bows at the poundages they were known to be.

03-25-2008, 10:41 AM
Think my sinuses are full of that sand I buried my head in the other day.

I'm at 70 with 6L's, so 6M should put it at 75 & 6H's would go to 80?

03-25-2008, 02:17 PM
Higha Diana,

Got no idea on the mods. Got me stumped. Our brick wall is covered with snow, so I will find an icicle to suck. :D

70 even with 6L means you will be around 73 with a 6M, and 76 with a 6H. Makes no sense since the peaks come in #5 lb increments, maybe your string or cables are out of specs. Check em.

At the poundages you aspire to, everything is screwed up, including those that shoot them:D

03-25-2008, 07:28 PM

Forget about Darrenhood. I've been trying to talk some sense into that lad for so long I gave up. I personally think he should just get a pair of 10H limbs and be done with it. And we already went through the weight range he's get with 6H limbs. He should have gotten 7H so he could get his 80#.

Darren, if you're reading this, and I know you are, don't do it. I was just kidding. I don't even know if the riser would handle all the draw weight with 10H limbs.

03-25-2008, 08:36 PM
Ok I twisted, I measured everything and its all in spec..................I am still pulling 55 pounds! Am I being too anal here?

03-26-2008, 08:47 AM
That's the best news yet, they make 10H limbs?!!!

Babooze, you can gain or loose a little, like a pound, by playing with the string & cable. The 5 pound difference is in the limbs.

I still don't understand why they don't just build a 60 pound bow "AT" 60 pounds & if someone orders one & can't draw it, they'll order a 50 pounder next time.

My old mathews were the same way, 2 identical 70 pound bows that pulled 66 pounds. I could flex the limbs till they broke, but they weren't going to pull 70.

I didn't figure out my Martin was under till I ordered 80 pound limbs & after putting it together with the stiffer limbs, it just then reached 70 pounds.

You maybe could turn it into a warrantee issue & not pay for the limbs like I did.

I bought a 70 pound bow (that wouldn't do it) with the intention of turning it into an 80#. You bought a 60 pounder with the intention of it realy pulling 60 pounds. Sounds like free limbs should be in the mail already.

03-26-2008, 08:53 AM
Morning Bfisher & Flytier.

03-26-2008, 10:49 AM
Ok I twisted, I measured everything and its all in spec..................I am still pulling 55 pounds! Am I being too anal here?

Do you have the draw length right where you like it? If so then mark the side of the cam where it passes through the limb forks. Use a pencil. This is a reference mark for cam rotation to orient it for your draw length.

Now, put about 5 twists in the cable. Then put about 10 twists in the string and see if that mark lines up pretty close. My twisting the rigging you will put more prestress on the limbs and the draw weight should go up. The A2A and brace height might change a little, but these are just approximate measurements anyway.

If the weight goes up to where you want it then measure everything again and write it down and file it for future reference. If not then I think you need a trip to your dealer to see if he can order heavier limbs. If that's not in the cards then call Jake or Joel at Martin customer service and see what they can do for you.

Let us know what's happening.


03-26-2008, 09:03 PM
Diana, you need to make your own bow. Use a solid chunck of steel for the riser, with truck shox for limbs, no letoff. Then, you wouldn't have to bother us on the mtech forum.

Is there more sand around?

03-27-2008, 10:36 AM
I was told by my archery tech that bows perform best when draw weight is maxed out. Any thoughts on this?

03-27-2008, 11:57 AM
I was told by my archery tech that bows perform best when draw weight is maxed out. Any thoughts on this?

True, but it's not as much as it's made out to be. As you drop weight off the limbs the bow's percentage of efficiency goes down a tad, but it's not significant enough to matter.

For instance, say you have a bow set at 70# (maxed) and it's efficiency is 80%. Ifyou are not comfortable at that weight and drop to 65# the bows efficiency might only be 77% or 78%.

Or another scenerio: A 60# bow maxed produces a speed of 280 fps with a given arrow. The same bow with 70# limbs backed off to 60#, shooting the same arrow might only propel that arrow at 275-276 fps. Again, not enough to worry about.

However, when maxed out the rigging is tighter so the bow will shoot more quiet, too. Most bows will max a couple pounds over their marked weight--say 63# for a 60 #er. So if you want to shoot 65# you're better off to buy the 60#, put a couple extra twists in the cables and you get a better performing bow all round. Just be sure before you part with the money that it will go that high in the beginning. Or just live with it and shoot at 63#. No animal will be able to tell the difference.

However, if you plan on keeping the bow for a long time, like 10 years. Then you're better off to get the 70# unit and shoot it at 65#. Limb can and do lose a little over a long time. Maybe two pounds or so in ten years.

Hope this all helps.

03-27-2008, 12:36 PM
Thanks for the reply and the help. My bow is a 70 # and is set at 72 # and is very comfortable and smooth. I was just wondering if my bow would be ok with this set up. The bow shoots like a dream and deadly accurate, 2 inch group of 5 arrows at 40 yds. and little to no vibration now that I put on a new plastic cable guard from Martin and I had my string leeches served in.

03-30-2008, 10:11 PM
my bow is marked 5h, it is pulling right at 70 pounds. A2A is 32 3/4"