That is an excellent question!

 

What make and series of crossbow? With this information,
one may be able to offer some help. Even a picture.
As for 110 pound or 135 pound draw weight limbs, either is
very low in regards to a crossbow.

Wishing you all the best.
Take care.

 

What make and series of crossbow? With this information,
one may be able to offer some help. Even a picture.
As for 110 pound or 135 pound draw weight limbs, either is
very low in regards to a crossbow.

Wishing you all the best.
Take care.

Hi Bunny Rabbit,

Bow in question is a Scorpyd Tremor.

 

I am figuring a Scorpyd. I would go with the 135 pounders n slightly detune

 

I would have no choice.. PA’s minimum draw weight is 125#. I’d probably go with the 135s anyway. Keep 2 sets of s/c, one for whatever you want the slower speed for, and another for hunting.

 

Option 2: detune 135, you can then go faster if you want, which you can't do with the 110 limbs without overstressing them.
IMO big mistake to go for every possible inch per second from any bow. I always detune bows I WANT TO KEEP by 10% of their rated (advertised) speed. If I get speed sickness, I'll just buy a faster bow.

 

I did a bit of internet searching on the Scorpyd Tremor crossbow.
It is available using a 370 grain arrow-point combination as either 420
feet per second or 470 feet per second. There was no mention of the
draw weights, but I did find it uses a medium let off cam. My opinion
here is where the lower draw weights come into play that you mention.

In this case either crossbow would still have a lot of stress on the bow
string, limbs etc. but with the medium let off cam either will be easier to
cock. If there is no or very little difference in price, I would go for the
135 and back the cams off a bit to lower the draw weight which would be
easier on the crossbow. Using heavier arrow-point combinations will also
be easier on the crossbow.

Either crossbow, with the cams backed off a bit and then using heavier
arrow-point combinations, one still will have a fast shooting crossbow.

As a rule for every 10 grains over the manufactures advertised arrow-
point combination weight, one will lose 3 feet per second in speed.

Any modifications in regards to timing, string or cable change out or
adjustment, this crossbow requires a press.

Wishing you all the best with what ever you choose.
Take care.

 

Been detuning my bows for years either buying a shorter/less poundage Excalibur or backing the poundage off on my mission bows.
While this is not bulletproof it does help with longevity in the areas you speak of.

Im setting here debating adding 25 grs to my insert. After shooting today just finished shooting 70 yds. The bow is shooting so good I’m wondering if the 388 gr arrow is in a sweet spot for this bow. My mind tells me do it. But my eyes say did you not just see that lol.

There’s always something lol. But over the years not pushing a bow to its max has been my hallmark. I have run them wide open but seldom it left me with a smile for very long.

 

Option 2 and detune.

 

On the Scorpyd website it says 420 or 480 . I would order 480 only because it don't say 500.

 

110#
Thats a lay up

 

No brainer IMO 135#

 

135.

 

m

 

A.) 110lbs and standard strings & cables.
I do try to color within the lines.

 

Detune,then if for some lucky reason you get to go for BIG game,you got the game.

 

I believe Duke said overkill is underrated. Hard to argue.

 

It's not going to be easy to detune a Tremor. You'll change the ATA, which in turn changes the cam rotation to the flat section of the cam. This flat section will have to be perfect in the rotation. You don't want to over rotate bringing the string away from the cam in the flat. It would be better to come up short than over rotate.

These Gen-8 and Gen-9 cams are bow specific. ATA and power stroke specific together, to be more exact. Unless someone has already figured this out, you're in for a lot of head scratchin'! Not to mention trial and error string and cable changes.

If you want a low pounder, get the low pounder. The lower poundage limbs are actually more efficient (pound for pound) as you move up in arrow weight, because there is also less limb weight. Weight of cams is also a key factor to consider.

Trying to detune a Tremor or DS LT is going to be a lot more involved than you think, IMO.

Examples in 1 FPS loss for arrow weight increase. These are the ones that I charted. I have several more low poundage limbs (115#, 125# 135#) stashed for my later years.

Average FPS loss per increased arrow weight in range indicated.

60# Ventilator
1 FPS for every 3.14 grains, 360 - 451 grain arrows.
360 gr @ 308 FPS
385 gr @ 300 FPS
400 gr @ 294 FPS
404 gr @ 293 FPS
411 gr @ 291 FPS
426 gr @ 286 FPS
429 gr @ 284 FPS
436 gr @ 282 FPS
451 gr @ 279 FPS

100# Ventilator
1 FPS for every 2.8 grains, 400 - 428 grain arrows.
400 gr @ 350 FPS
428 gr @ 340 FPS

150# Ventilator
1 FPS for every 2.5 grains, 400 - 458 grain arrows.
400 gr @ 400 FPS

165# RDT
1 FPS for every 2.3 grains, 400 - 458 grain arrows.
400 gr @ 425 FPS

175# Ventilator Extreme
1 FPS for every 2.38 grains, 400 - 480 grain arrows.
401 gr @ 440 FPS
404 gr @ 438 FPS
411 gr @ 434 FPS
426 gr @ 428 FPS
429 gr @ 426 FPS
436 gr @ 423 FPS
451 gr @ 419 FPS

180# Nemesis
1 FPS for every 2.27 grains, 400 - 450 grain arrows.
400.4 gr @ 467 FPS
450 gr @ 445 FPS

I haven't charted either of my Deathstalkers, 130# and 150# Grim Reaper.

You might be able to get a limb deflection in 135ish to 145ish, which would put you in the 115# to 125# range. You just have to ask if those limb deflections are currently available.

Just some information for you to chew on.

 

I wouldn’t think a detuned bow would shoot efficiently as originally intended but maybe they will.

When I had my 150# limbs on my Ventilator, I think it shot 384/386 fps. It was a bear to cock and nearly impossible with the short sled and my long arms.

So I ordered some 125# limbs from Wyvern - it was much easier to cock and still shot 372 fps. Big deal for 12 feet.

 

Great point, TP.....thanks much for real-world data speeds....

 

Vent,

Unbelievable detail....had not thought about several of the issues you mention. Especially, the "sensitivity" involved with only slight deviation in cam rotation!
Will be doing alot of chewin' on your comments...
Really appreciate your advice!

 

Option 2 with heavier arrow

 

Exit

 

Lordy Lordy ... just use the 135lb limbs as is. Don't act like a purse swinger. 😂 135lb limbs are so unstressed already that they'd last a thousand years! Why start jerking around with odd length strings that will void your warrantee for no good reason? To me that's gambling to lose, not gambling to win. If you have some misguided desire to slow a good crossbow down just put a stupid heavy arrow in the 135lb crossbow. I think Moon Longstring can make you up some 754gr Easton FMJ's ...lol I'd go with the 135's every single time. Like Vice Lombardi said: "a good big man will beat a good small man every time." Remember: "If a little bit is good, a lot is better."

 

Back in my vertical compound days, I was under the impression the bow shot the best at the maximum poundage listed - not the least on a 60-70 pound bow for example.

I would think it wouldn’t be any different for crossbows but maybe it is.

 

Bow engineers ... make strings & cables a certain length for good reason would be my guess. Strings, cables, limbs, cams are all a system. Changing the dimensions of any of them could very well effect all the others in a way you are clueless to realize. Why would they make 110lb limbs if they could just change string length to get 135lb limbs to act the same way? It's like putting different size tires on your truck thinking you know more than the Ford engineers.

 

What I think is being missed. A 150# set of limbs on a bow made to shoot let’s say 350 fps. Is still stressed as much as a 200# set of limbs on a bow made to shoot 400fps. Only when you take the 200# limbs and detune the bow to shoot 350fps or the same as the bow built to shoot 350fps stressed. Have you gained anything pertaining to durability.

A great example would be the Excalibur 405. It was problematic shooting 405 fps. But with the rail cut down as Excalibur did(or detuned) making the 350 a very dependable bow. That had the same limbs same everything but just detuned by shorting the draw.

Mission gives another great example. The mxb 320 at least mine shot 333 fps with a 401 gr arrow. And was a 4 cylinder working hard to run its speed limit.
But the mxb 400 that will shoot a 401 gr arrow 413 fps is a v8 being very lazy. With the limbs backed off shooting/run 333 fps.

The question is will you be happy and is this what you want.

 

It is always best to ramp up with a stronger build then detune if you are looking to increase the lifespan of something.
I was talking with a crossbow company about durability a few years back. At the time of the conversation they had 4 models. I was told they have never had one of their two lightest limb bows come back for limb failures. He also said the second fastest was rare to see a failure. So 99.99% of their limb failures was their heaviest limb bow.
He went on to say that even with their heaviest limb bow they detune it to about 80% of its ability so they still don't see a lot of failures

 

Tp and Rt,
I think you are both correct. A 60# limbed vertical bow just felt better shooting at max weight than a 70# limbed bow detuned to 60#. But, I suspect that the latter was less stressed and would last longer.

I rarely have limb problems and run my xbows about 10-15’/sec slower than rated. Only my Excals (400BD and M405s ) had limb failures but a significant contributor was the sharp, too tight riser pockets plus the hard edge where the limbs exited the riser.