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gibson 787
07-04-2010, 01:43 PM
Hi all,

A few weeks ago I pulled my 09 Moab with M2 cam out of mothballs. I havn't shot it for a while and decided to change the factory string and cable with some H&M replacements.

Replacements came on Friday and I changed them over this week end. Got ATA at precisely 32 1/2", brace height was 1/4" short, but that didn't concern me as the cam rotation was good at 1/2" from edge of cam to where the string came off. Maxed out, it was 71#.

I took it down to 67# and had it ready to shoot. Drew back and found the let off seemed to be too low, or was I just imagining it as I hadn't shot it in over a year. It was shooting well, very quiet, virtually no shock and without any tuning the arrows were flying like darts, but the valley and let off just didn't feel right.

Took it back inside and found the let off was holding at 20# when it should have been 13.5# Next 30 minutes I spent altering draw stop and changing DL modules with absolutely no luck. I know the specs indicate 80% and 65% optional let off, but I know nothing about the 65% scenario as I thought it was achievable via the draw stop? I do know however, that 20# is not far off 65% of 67# DW

Any ideas guys or gals, cos I'm stumped!

gibson 787
07-04-2010, 05:40 PM
Looks like no-one wants to go near this one!

Destroyer
07-04-2010, 08:53 PM
I'm game Dave! The let off in % is just what the manufacturer quotes (you know this probably ;)). My tera for example is suppose to be 80% but the effective let off is about 77%. Yours works out at about 70%.

Draw length can alter this, especially the way it alters the power stroke. If your brace height is off that means something is not right. The actual draw length might be right but power stroke might be different.

What I would do is get the bow back to the original specs, both ata and brace height. String should be 90" and cable 34.5". Is the split yoke in the cable the same length as the original?

Its hard to figure out without actually doing it. :)

gibson 787
07-04-2010, 10:47 PM
I'm game Dave! The let off in % is just what the manufacturer quotes (you know this probably ). My tera for example is suppose to be 80% but the effective let off is about 77%. Yours works out at about 70%.

Draw length can alter this, especially the way it alters the power stroke. If your brace height is off that means something is not right. The actual draw length might be right but power stroke might be different.

What I would do is get the bow back to the original specs, both ata and brace height. String should be 90" and cable 34.5". Is the split yoke in the cable the same length as the original? My custom cable wasn't which I think might shorten the effective length by having a more acute angle. Try to lengthen the cable & shorten the string.

Its hard to figure out without actually doing it.

Good to find a man with courage!

Thanks for the input mate, but I'm not sure the BH being out, well, it's a little under 1/4", would cause the problem. As stated, I've tried a DL mod each side of my 29", which on my draw board is spot on. As well as moving the DS to crazy positions without success.

Problem is I can't really remember wheather it felt like this before, I think I can recall reading somewhere that there are DL mods that bring the let off down to 65%. I wonder if I have those little suckers? thought someone may be able to shed some light on this.

The bottom line is, it's all in spec apart from 3/16" short in BH and the cam is correctly rotated according to one of Bfishers past threads. Anyway booger it, I'll shoot it the way it is, I don't mind holding 20# instead of 13.4#, I have the DStops on the Hog and Alien set under 80%.

Thanks again mate.

Destroyer
07-04-2010, 11:39 PM
As well as moving the DS to crazy positions without success.

Does the DS reduce let off? Whats the reading without the DS, the same?


I think I can recall reading somewhere that there are DL mods that bring the let off down to 65%. I wonder if I have those little suckers?

The mod would have / in the number eg. f/-7 instead of f-7 wouldn't it?


it's all in spec apart from 3/16" short in BH

Couldn't handle that, I would have to change it. :D

gibson 787
07-04-2010, 11:53 PM
Does the DS reduce let off? Whats the reading without the DS, the same?

DS reduces let off in the normal manner if I move it forward and if I move it back so that it is innefective, I still have it at 20#

The mod would have / in the number eg. f/-7 instead of f-7 wouldn't it?

Mods look normal, as per F 7

Couldn't handle that, I would have to change it.

No dramas with me there, the hogs BH is 3/8" under.

Thanks again mate, not worth getting me Reg Grundies in a knot!