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View Full Version : Nitrous "c" to "b" cam swap



rjd
10-01-2010, 09:14 PM
Well got the new string/cable installed. Switched from the "c" cams to "b" cams. ATA and brace are in spec. But I gained over 10 # of draw weight . Is this normal. We backed limb bolts out till we had it back down to the
60# 's which is what the limbs are supposed to be.

Just wondering if this is common. Did I do the right thing by leaving them backed out?

Montalaar
10-01-2010, 11:03 PM
Depending on the limb angle this is normal. We do not know all the facts but switching between the cam sizes will affect draw weight. A smaller cam will produce a higher draw weight.

rjd
10-02-2010, 02:40 AM
Thanks Montlar. Will it be okay to use at 70#? Not that I will but occassional it might be interesting to try.

Montalaar
10-02-2010, 02:43 AM
What is your limb deflection code?

I'd say that it is safe. At least if you have a deflectionnumber of 1 or higher.

KStigall
10-05-2010, 06:11 AM
Well got the new string/cable installed. Switched from the "c" cams to "b" cams. ATA and brace are in spec. But I gained over 10 # of draw weight . Is this normal. We backed limb bolts out till we had it back down to the
60# 's which is what the limbs are supposed to be.

Just wondering if this is common. Did I do the right thing by leaving them backed out?

You should be fine if you are using the specs for the bow with a "B" cam. The "B" cam is significantly smaller so the draw weight goes up about 12 lbs. You can shoot it at 70 lbs. Using the "B" cam the limbs aren't deflecting any more than with the "C" cam. You have decreased leverage with the smaller "B" cam so it's harder for you to bend the limbs hence the increased draw weight.

What model bow is it? I may have the limb chart.

copterdoc
10-06-2010, 04:57 PM
Your B cams should only be about 5# higher than C's on the same set of limbs.

ATA should be the same, but the BH with B cams should be about 3/8" to 1/2" shorter with B cams, than it is with C's.

I'm guessing that your DL is about 1/2" longer than it should be, at the module setting it is at.

Montalaar
10-06-2010, 10:52 PM
Your B cams should only be about 5# higher than C's on the same set of limbs.

ATA should be the same, but the BH with B cams should be about 3/8" to 1/2" shorter with B cams, than it is with C's.

I'm guessing that your DL is about 1/2" longer than it should be, at the module setting it is at.

That is the problem. We do not know for sure, copterdoc.

Some say 10#, you and Barry alsways estimate 5# and when changing the Cams on my Razors i lost 0#. Or gained...

copterdoc
10-07-2010, 05:56 AM
People can't wrap their minds aroud the simple concept of cam timing.

Advancing the cams, ALWAYS reduces draw weight and draw length. Depending on cam goemetry, it can also change the brace height.

Retarding the cams, ALWAYS increases draw weight and draw length. Depending on cam goemetry, it can also change the brace height.

With NOS cams, the ATA is always going to be 1.5" shorter than the cable length.

With NOS B cams, the string needs to be 13.5" longer than the cables. With NOS C cams, the string needs to be 19" longer than the cables.

That will give you the "correct" cam timing and draw length setting.

The difference between the C and B cams is exactly 5#, regardless of riser geometry, limb deflection, length, or angle.

Spiker
10-07-2010, 07:13 AM
People can't wrap their minds aroud the simple concept of cam timing.

Advancing the cams, ALWAYS reduces draw weight and draw length. Depending on cam goemetry, it can also change the brace height.

Retarding the cams, ALWAYS increases draw weight and draw length. Depending on cam goemetry, it can also change the brace height.

With NOS cams, the ATA is always going to be 1.5" shorter than the cable length.

With NOS B cams, the string needs to be 13.5" longer than the cables. With NOS C cams, the string needs to be 19" longer than the cables.

That will give you the "correct" cam timing and draw length setting.

The difference between the C and B cams is exactly 5#, regardless of riser geometry, limb deflection, length, or angle.

I used these rules on the last bow I switched over to NOS cams and it came out right on the money.

Montalaar
10-07-2010, 07:14 AM
I can not agree.

When searching for the right specs for my bow i found out that the C cam needs a string that is 5" longer than the B cam but does not need a longer cable. You can verify this by looking into the spec charts. Although sometimes the cables on a C cam are .5 inches longer in most cases they are not.

I know that you are very skilled and have soo much knowledge about the NOS cams but i am pretty sure regarding my information.



If the difference is 5#. How is it possible that there is so much variance? ;)

copterdoc
10-07-2010, 07:21 AM
I used these rules on the last bow I switched over to NOS cams and it came out right on the money.
The cam/limb charts are great for referance only!

They are full of errors, and frequently fail to account for DL and BH differences between 13" and 14" limbs among other things.

I have played with the NOS cams since they first came out. I have done just about every conceivable riser, limb and cam configuration.

NOS cams, are my "babies" and I absolutely love them.

copterdoc
10-07-2010, 07:28 AM
I can not agree.

When searching for the right specs for my bow i found out that the C cam needs a string that is 5" longer than the B cam but does not need a longer cable.
Again, the ATA is ALWAYS 1.5" shorter than the cable length!

That applies to A, B, and C size NOS cams. The only thing that changes, is the string length.

Each "downsize" also reduces the brace height, because the damping lobe positions the string further away from the axle.

Montalaar
10-07-2010, 07:35 AM
C'mon Copterdoc, never wanted to offend you. o0

copterdoc
10-07-2010, 07:39 AM
I'm not offended!

rjd
10-09-2010, 09:04 PM
Sorry guys have been busy . The bow is '06 Slayer, left hand switched from the "c" ,s to the "b"'s. Wasn't comfortableshooting it . The draw lenght always seemed long no matter what we tried. Needed around a 27.5 " draw. Talked to a few people here and elsewhere and this seemed to be the route to try. Picking it up hopefully this weekend.