Cam timing, cam lean and yoke tuning

The cams on a compound bow work as one system. Cam timing, also called synchronization, is whether they turn together: on a bow with two cams, both should roll over and reach their draw stops at the same moment. Cam lean is whether each cam stands straight. A cam that tips to one side moves the string off a straight path.

Both come down to string and cable lengths. A cable that is slightly long or short changes how far one cam turns compared with the other. The cable guard holds the cables to one side so the fletching can pass, and that sideways pull grows as the bow is drawn, which tips the cams and twists the limb tips. A small amount of lean is normal: a cam often leans slightly at full draw. The draw cycle explorer shows how the cams rotate and wrap the string and cables through the draw.

Why it matters

• The back wall. On most two-cam bows each cam has a draw stop, a peg or post that hits a cable or the limb and ends the draw. If one cam reaches its stop first, the wall you pull against comes from that stop alone while the other cam is still short of its own.
• Nock travel. The nock should come forward in a straight, level line. Cams that are out of time push it up or down, which makes arrows porpoise. If you can’t correct a high or low paper tear, have a pro shop check the timing.
• Tears that won’t fix. A vertical tear that returns after rest and nock-point moves points to timing. A horizontal tear, or a broadhead offset, that the rest can only close by moving well away from the bow’s centershot points to lean.

What there is to time depends on the cam system. Check your owner’s manual for which one your bow uses and what the maker calls each cable.

Before any timing check, both cams must be on matching draw length settings. Never draw a bow with mismatched or missing modules, module screws or draw stop pegs.

New strings and cables settle and stretch over the first shots and keep creeping slowly after that. Cycle a new bow 10 to 20 times to settle the string. Extreme heat can stretch strings and cables and change timing. Check timing and tune after the first 250 shots. The cables rarely stretch by exactly the same amount, which is how a bow that left the factory in time drifts out of time.

Longer cables let the limbs relax. Axle-to-axle length grows and brace height drops; an axle-to-axle that is too long is the most common out-of-spec condition. Draw length and draw weight move with them. Check the specs before timing, because fixing them changes timing anyway.

What to measure

• Axle-to-axle length: from the center of one axle to the center of the other, with the limb bolts bottomed out.
• Brace height: from the deepest part of the grip to the string.
• Draw weight: peak weight on a bow scale with the limb bolts bottomed out. It should reach the bow’s rated maximum.
• Draw length: by the ATA definition, the distance at full draw from the nocking point to the pivot point of the grip, plus 1-3/4″. A draw board with a scale measures it.
• String and cable lengths: measured off the bow on a jig, under the tension the bow maker specifies. This is pro shop work.

What brings them back

Twists, made in a press. Twisting a cable shortens it: axle-to-axle length goes down, brace height and draw weight go up. Untwisting does the reverse. Twists in the string have much smaller effects. Most corrections start with the cables. Every change also moves timing, so the timing check comes after the specs are right, not before.

At rest: timing marks

Most cams carry marks that show where a cable should sit with the bow at rest. Bowtech cams have two small dots near the edge of the cam, and the cable should sit roughly centered between them, viewed from the module side. Mathews cams have small holes that the cable should cross at about the same spot on both cams. Older Hoyt cams used a pair of performance marks with the cable between them. Marks that disagree tell you the cams are out of time. Marks that agree tell you they are close, not that the draw stops meet together.

At full draw: the draw stops

This is the check that counts. On a draw board, hook the board to your D-loop and crank slowly. Stop just before full draw and watch both cams as you crank the last bit: the two stops should touch their cables or limbs at the same moment. A draw board lets you stop and look as long as you need.

Without a draw board, draw slowly while a helper watches both stops from the side. That finds a large error, but small differences are hard to see at the speed a person can draw and hold.

Single cams

Check the cam’s timing mark at rest against the position the manual shows. With one cam there are no stops to compare. At full draw, look at the idler wheel: the string should come off it in a straight line.

Timing is corrected by changing the length of one cable relative to the other. Twisting a cable shortens it. To bring the cams into time, add twists to the cable at the cam that reaches its stop first, or take twists out of the cable at the other cam. On Hoyt’s HBX cams, for example, if the bottom cam’s stop touches first, take the control cable off its peg on the bottom cam and add a twist; if the top touches first, do the same at the top cam. The same rule applies to buss and power cables.

• Work in half or full twists and recheck the stops after each one.
• Every twist needs the bow in a press, because the cable end has to come off its post.
• Expect side effects. Cable twists change draw weight and axle-to-axle length and can shift draw length slightly. They can also move the nock point up or down, so time the cams before you tie in the final nock point, and recheck nock height afterward.
• Some bows, including models from Bowtech, Elite and Darton, have built-in timing adjusters turned with a hex key. Not every model in those lineups has one: the current Bowtech Alliance needs a press for timing, and the job should be done by a dealer. Your manual says which you have.

When to leave it to a pro shop

If you don’t own a press that fits your bow, the job goes to a shop. The same goes for timing that is off by more than a few twists: it is rare to need more than three full twists in a cable, so a bigger error suggests a wrong cable length, a cable that has come off its track, or a different problem. New strings and cables are also shop work. Your bow’s manual may ask that a dealer do timing and any job that needs a press.

Lay a straight arrow flat against the side of the cam body, not the module, so it runs past the cam toward the string. If the cam stands straight, the arrow runs parallel to the string. If it angles off to one side, the cam leans. Check both cams.

At rest and at full draw

The sideways pull from the cable guard grows as the bow is drawn, so a cam can look straight at rest and lean at full draw, or the reverse. The full-draw reading is the one that matters, because that is where the shot starts. On a draw board, hold the arrow against the cam at full draw and compare it with the string. Without one, a helper standing behind you at full draw can see a large lean but not a small one.

A little lean is normal. The question is whether it is enough that the rest has to move well away from centershot to get clean arrow flight. If the rest is near the manufacturer’s centershot and the arrow flies well, leave the cams alone.

Gauges and lasers

A straight arrow is enough to see real lean. Clip-on gauges, such as Last Chance Archery’s Universal Tuning Gauge, and laser tools that sit on the rest and project a line along the string and cams make small amounts easier to read and to repeat from one session to the next.

The fix depends on how the bow is built. Bows with a classic split yoke are tuned by twisting the yoke legs. Many current bows have a yoke that can’t be tuned leg by leg, or none at all, and move the cam sideways with spacers or a built-in adjuster instead. The manual tells you which system you have. The directions below are for right-handed bows; for a left-handed bow, use the manual.

Split yokes

A split yoke is a cable that divides into two legs near one cam, one leg on each side. Twisting a leg shortens it. To correct lean, add twists to one leg and take the same number out of the other. That keeps the cable’s overall length, so timing and draw weight don’t change. Start with the top yoke, which has the larger effect because it is closer to the arrow, and only move to the bottom yoke if the top one isn’t enough. Work one or two twists at a time and reshoot after each change.

Don’t go past six twists on a side. If you reach that limit, stop and look for another cause: arrow spine, fletching contact, rest position or form.

Cam spacers and shims

On bows without a tunable yoke, the cam is moved sideways on its axle by swapping spacers of different thicknesses from one side of the cam to the other. Mathews’ Top Hats on models such as the Halon and Triax, Hoyt’s HBX cam spacers and the spacer systems on PSE and Prime bows work this way. Spacer tuning works like yoke tuning. The axle has to come out, so the bow goes in a press.

On a right-handed bow, the cams move the same way as the tear and the rest moves the opposite way. A nock-left tear calls for shifting the cams left, or moving the rest right, toward the riser. A nock-right tear calls for shifting the cams right, or moving the rest left, away from the riser. For broadheads, shift the cams left when broadheads hit right of the field points, and right when they hit left. Move one step at a time and reshoot after each.

Adjusters that don’t need a press

• Mathews Limb Shift, introduced on the 2025 Lift X: turning a wrench adjusts the width of the limb channel while the cam stays in place, with no bow press.
• Elite S.E.T.: an adjustment screw on each limb pocket changes the angle of the pocket’s pivot, which changes cam lean and the cam’s sideways position. It takes a 5/32″ hex key and gives up to 3 degrees each way.
• Bowtech DeadLock: loosen the lock screws, turn the tuning screw to move the cam left or right, and lock it again. Hashmarks on the axle housing show the zero position.
• Hoyt XTS, on the RX-10 and Alpha AX-3: a fine adjustment at the limb pockets for vertical and horizontal tears. On these bows, use cam spacers for tears over 1″ and XTS for the rest.

Your bow’s manual shows which way to turn for which result. Note the starting setting before you change anything, adjust top and bottom the way the manual says, and move in small steps.

Cable guards and roller guards

Some bows, modern Elites among them, let you move the roller guard in or out. That changes the sideways pull on the cables and can move a tear or fix vane contact. Stay inside the range the manual gives. Too much cable guard offset on a short bow can make a cable track off the cam.

Paper

Cams that are out of time are one of the most common causes of high and low tears, so check timing before you move the rest for a vertical tear. Left and right tears that only close with the rest well off centershot are the lean signature. In that case, set the rest at about 13/16″ centershot and use the bow’s own left-right tuning to clean up the tear. The paper tuning guide covers each tear pattern.

Bare shafts

Bare shafts that hit high or low of the fletched group are worth a timing check before you move the rest. Bare shafts that stay left or right after small rest moves point to lean. The bare-shaft tuning guide covers how to read them.

Broadheads

A broadhead group that drifts left or right of the field points, when the rest has already moved more than about 1/8″ from centershot, is a cam problem, not a rest problem. The broadhead tuning guide covers every impact pattern. A walkback tune after the cams are set confirms the rest’s final position.

Order

Specs → timing → lean → paper → bare shaft → walkback → broadheads.

The compound bow tuning guide walks through the whole sequence.

• Never adjust a string, cable or yoke on a bow that isn’t in a press. Taking a cable end off its post or peg on a braced bow releases the full tension of the limbs. Never remove a control cable peg unless the string is relaxed in a press.
• Use a press that fits the bow. It should be a limb-tip press: one that contacts the bow at the limb tips near the cams, compresses it straight inward and clears the cams. Never put force on the riser. Your bow’s manual may list compatible presses or rule out portable presses for beyond-parallel bows. Some presses need brand-specific fingers, such as Last Chance Archery’s set for Mathews limbs.
• Never draw a bow with missing parts. Check that the modules, module screws and draw stop pegs are all in place and matched.
• Check the warranty. Damage from improper press use, and changes beyond factory specs or the adjustments in the manual, can void a bow’s warranty.

If any step here is new to you, a pro shop can time the cams and set the lean in one visit. Everything after that, from paper tuning to broadheads, you can do yourself.

How do I know if my cams are out of time?

The reliable check is at full draw: on a draw board, or with a helper watching, both draw stops should touch their cables or limbs at the same moment. Signs that should send you to check are a vertical paper tear that comes back after you move the rest or nock point, bare shafts that hit high or low of fletched arrows, and cables that sit in different places against the cams' timing marks at rest.

Can I check cam timing without a draw board?

Roughly. Read the timing marks at rest, then draw slowly while a helper watches both draw stops from the side. That finds a large error. A draw board lets you stop just short of full draw and see small differences that a helper can't.

Do single-cam bows need timing?

There is no second cam to synchronize, but the cam still has to sit at the right rotation at rest, which most single cams show with a timing mark. String and cable stretch moves it, and it is corrected with twists in a press. At full draw the string should leave the idler wheel in a straight line; if it doesn't, the yoke at the idler needs tuning.

Do binary cams go out of time?

Less than twin cams. Binary cables run from one cam to the other, so each cam's rotation is tied to the other's and nock travel usually stays level. Uneven cable stretch can still put them out of time, so check them the same way: timing marks at rest, draw stops at full draw.

Which yoke leg do I twist to fix a nock-left tear?

On a right-handed bow, add twists to the left leg of the top yoke and take the same number out of the right leg. For a nock-right tear, do the opposite. For broadheads hitting right of field points, add to the left leg; for broadheads hitting left, add to the right leg. Work one or two twists at a time, top yoke first, with the bow in a press.

Does twisting a yoke change draw weight or timing?

Not if you twist one leg and untwist the other by the same amount. The cable's overall length stays the same, so timing, draw length and draw weight stay where they were. Twisting only one leg shortens the cable and changes all three.

Can I fix cam lean without a bow press?

Only on bows built for it. Mathews Limb Shift, Elite S.E.T., Bowtech DeadLock and Hoyt's XTS system adjust with a hand tool and no press. Yoke twists, spacer swaps such as Mathews Top Hats and Hoyt HBX spacers, and any string or cable twist need a press.

How often should I check timing and specs?

After the first 250 shots on new strings and cables, before each season, after the bow has been stored somewhere hot, and whenever a clean tune starts to drift. Measure axle-to-axle length and brace height first. If they have moved, timing probably has too.

Should I fix timing or cam lean first?

Timing, once the specs are right. Timing is set by cable length, and a timing change can change how the cams sit. A lean correction made with equal and opposite yoke twists keeps cable length the same, so it doesn't undo the timing. The order is specs, timing, lean, then paper tuning.

When should I take the bow to a pro shop?

When you don't own a press that fits your bow, when timing or specs are off by more than a few twists, after new strings and cables, when a string or cable has come off a cam, or when you want to keep warranty work simple. Your bow's manual may ask that a dealer handle press work and timing.

Cam timing

Whether two cams turn together. Timed cams reach their draw stops at the same moment. Also called synchronization.

Draw stop

A peg or post on a cam that hits a cable or the limb at full draw and ends the draw.

Timing marks

Dots, lines or holes on a cam that show where a cable should sit with the bow at rest.

Cam lean

Side-to-side tilt of a cam, mostly from the cable guard holding the cables to one side. Checked at full draw.

Split yoke

A cable that divides into two legs near one cam, one on each side. Twisting one leg and untwisting the other corrects lean.

Control / buss cable

The cables that link the cams or tie a cam to the opposite limb. Their lengths set timing. Names differ by maker.

Binary cam

Two matched cams whose cables run from one cam to the other instead of to the axles.

Hybrid cam

A power cam and a control cam of different shapes, linked by a control cable. Also called cam-and-a-half.

Limb-tip press

A bow press that holds the limbs near the cams and pushes them straight inward.

Axle-to-axle

Distance between the centers of the two axles. Grows as strings and cables stretch.