Skip to Content

Rock Climbing : Articles : General : How To Rebolt, by Chris McNamara

How To Rebolt, by Chris McNamara

Submitted by admin on 2001-11-02 | Last Modified on 2010-02-26

Rating: 12345   Go Login to rate this article.   Votes: 0 | Comments: 0 | Views: 7564

How To Rebolt

by Chris McNamara, ASCA President

Great weather in the Valley. You're making good time up Zodiac. Just after noon on the second day you pull into the Mark of Zorro belay. You're amazed to find there are 14 bolts pounded into the rock. But on close inspection they all look a bit sketchy. So, just to be safe, you haul out your hand drill and put in another one. So now there are 15 bolts.


Not on your life. Until recently there were actually 15 bolts at the Mark of Zorro belay on Zodiac. Until 1997 most other belays on Zodiac had at least six bolts. Most of the bolts, and the hangers too, were disasters waiting to happen. Is this ridiculous?


That's one of the reasons that with a group of other climbers I established the American Safe Climbing Association in the fall of 1997. During the summer Erik Sloan, Jason Smith and I had set out to replace anchors in Yosemite - but 250 bolts and over a thousand dollars later we realized we couldn't do it alone, and that a group effort was needed. It's not a new idea. In Europe, especially in France, the replacement of old bolts is seen as so essential to the sport that people are paid to do it. Ours is a volunteer effort, a non-profit enterprise dedicated to making climbing safer and encouraging other climbers to do the same.

Before getting well into this effort I had heard rumors that it wasn't possible to re-use old holes. That's not true. It is not only possible, but it makes the drilling go much faster; enlarging holes is easier than drilling new ones.

Basic Removal Procedure

Most climbers cringe when they clip into a rusty quarter incher and with good reason. They know that these bolts were weak to begin with and over time have become even weaker. Yet what most people don't know is that replacing them is a simple process.

To remove most bolts drive a thin piton under the hanger repeatedly from as many different direction as possible (#4 Lost Arrow is usually the only pin you will need although there are cases where you must start with a knife blade and work your way up).

Once the bolt has popped out as much as it can (about a 1/2" from the wall) slide a crowbar under the hanger and pull. For stubborn bolts alternate positions with the crowbar to avoid bending the bolt in one direction. For those especially stubborn bolts avoid the urge to "bounce" the crowbar pack and forth. This weakens the head of the bolt and will eventually cause the bolt to shear. Instead of bouncing, plant your feet on the wall and pull harder or get two people pulling on the crowbar. The problem with crowbars is that they exert an angled force on the bolt which frequently causes the bolts to break. Using a "tuning fork," you get much lower breakage rates, and have to carry far less weight.

"Tuning forks" are made simply by grinding out the center of a #3 or #4 Lost Arrow. The resulting tool (which resembles a tuning fork) is driven under the hanger and can often remove the bolt without needing a crowbar. It can be made at home or ordered through the ASCA, which has them professionally milled to retain strength lost when the metal is heated in home milling.

There is one strict rule to replacing bolts: once you have begun pulling a bolt, do not stop until the bolt pulls out or breaks. Leaving a bolt that you have started pulling is creating a deadly situation for the next climber. If the bolt does break do your best to camouflage the hole with epoxy. Many types will work but hand-mixed epoxies such as "RepairItQuik" (available at Home Depot and many hardware stores) are the most convenient. Once the hole is filled with epoxy, work in some rock dust on the surface to camouflage it.

Candidates for Rebolting

Rawl Drive (AKA button head) The Rawl Drive accounts for about 90% of all the dicey bolts out there. Found with either a button or threaded head, this compression bolt has a shaft split wider than the bolt hole. It compresses when driven into the rock. Rawl drives pull cleanly most of the time using the basic removal procure, though occasionally the nut on the threaded version will strip off the stud. This may be prevented by tightening the nut before pulling. If the nut does strip, hit the stud back and forth until it snaps, then patch the hole with epoxy. In some cases the bolt will simply snap off during pulling, fairly common with thread-heads, and not unheard of with button heads. In such cases, a new hole is again required, and the remnants of the old bolt is usually flush with the surface. If you have a 1/4" punch, the remnant can be driven deeper, but often these bolts are left as they are.

Torque Bolts

Torque bolts have a hex or Allen head and a threaded bottom that screws into a lead expansion cone. They are only strong if precisely tightened with a torque wrench, but because most climbers do not use a torque wrench you should consider them all bad. Often the lead cone of Diamond Tapers will pull with the bolt (never try to unscrew the bolt before pulling). However, even with a hand drill a 1/4" lead cone that didn't pull is easy to drill through. The 3/8" Diamond Tapers can not be easily drilled through because the lead catches the drill bit with every hit; however, the cone is more likely to pull with the larger bolts.

Star Dryvins, Zamac nail-ins Zamac nail-ins and 1/4" star drives represent the bleakest of the bleak. They both use a short nail that is driven in, expanding a thin surrounding sleeve. By using the basic removal technique listed above, the Star Dryvins and Zamac nail-ins slide out easily. The problem is that unless you have a brain surgeon's touch with the crowbar, the bolts usually leave their sleeves behind in the hole. If needle-nose pliers won't pull out the sleeve, you will have to fill in the hole with epoxy and drill a new one elsewhere. Larger 3/8" Star Dryvins, popular in the 1950s, are often quite strong in shear, but very weak in pull-out. Regardless, they are nearly always coupled with a terrible hanger.

Pulling these bolts can be difficult, requiring tenacity and tricky work with knifeblade pitons and a crowbar. Once the whole assemblage is slightly out of the rock, use the knifeblade to carefully tap the sheath and hanger back in to the rock, then use the crowbar to pull JUST the nail. The rest will then come out, often requiring needle-nose pliers to remove the sheath. Sometimes the sheath, especially if lead, can not be removed.

Self Drill Bolts

They are recognizable with their large machine nuts. In hard rock they are particularly easy to spot because they are usually botched - only going in the rock halfway. You may be able to yard these with a crow bar but usually you just have to unscrew the hex nut and fill in the hole.

Machine heads

A machine head is a 5/16" coarse-threaded hex nut that is pounded into a 1/4" or 9/32" hole and is generally found on aid climbs. These bolts can be strong but their strength depends on the precise fit and mashing of the threads as they are driven in. In addition, because only the first ascensionist knows how deep they were drilled, they are hardly reliable. Some 5/16" machine heads have been rated to 3000 lb., others have fallen out in climbers' hands. When removing them you will occasionally be able to unscrew a machine head back out of the rock, but most times you have to hit it back and forth until it snaps.

Aluminum Dowels

Made of 1/4" aluminum rod stock that is slid into the hole. In theory you could just pull them in and out with you fingers. Indeed, during the early ascent of many Yosemite walls such as the PO this was the case.

Unfortunately, over time dowels become embedded. With no head the crowbar usually can't latch on to them so the dowel must be snapped and patched with epoxy.

Rebolting Technique

Once pulled, not all bad bolts should be replaced. If the rock is hollow, or there is a fracture within 6 inches or there is another bolt closer than 5 inches to the bolt you are replacing, do not replace it! The bolt should not have been put there in the first place and the bolt hole should be filled with epoxy.

Drilling The New Hole

A hand drill is essentially a chisel. Between each hammer blow you turn the drill 1/4 to an 1/8 of a revolution, making sure to strike the drill between - not during - revolutions. Once you have begun enlarging the hole, loosen your grip on the drill, letting it rebound slightly with each hit. This bouncing effect speeds up the drilling by displacing rock dust in the hole, which would otherwise cause the bit to bind. If the bit does bind, immediately stop hammering and gently wiggle the drill with your hand until it loosens. If you find the bit binding frequently, make the hammer blows more quick and light. Generally when expanding 1/4" holes, constant small tapping and more rapid turning of the drill allows quick expansion of the hole without drill binding.

Every 50 hits or so, stop hammering and blow the rock dust out with a blow tube. Once the hole is done alternate using the blow tube and a test tube brush until the hole is clean.

What to Place

Anytime you drill a hole you have the opportunity to place a bomber bolt that will last for decades. Yet some climbers squander this opportunity by placing whatever was cheapest at the hardware store. Before you start replacing bolts, be sure you have the right hardware. Always use stainless equipment even in the driest climates.

Rawl 5 Piece

The Rawl five piece has been a standard for many years and with good reason. It is among the strongest bolt available for hard to medium-soft rock and is removable, which will be convenient when they need to be replaced in 30 years or so. They do require a very clean hole, however. Although great in solid sandstone, in softer rock such as the canyonlands rock dust may jam the threads, causing the bolt to spin in place without tightening. The Hilti HSL is similar to the Rawl bolt in design and strength but is hard to come by. Do not overtighten the bolts, as the head can shear off, or worse, be at the point where it is about to shear. Get a torque wrench, and use it on practice rocks to learn how tight is proper.


Fixe and makes the strongest wedge bolt available in the US. In the longer sizes this bolt has two expansion clips, making it a good choice for medium strength rock. Wedge bolts rely on a small clip sliding onto a cone, and in soft rock the clips may not catch, instead carving small grooves back out as the bolt is tightened. Wedge bolt available at hardware stores have the same design as the Fixe bolt but are nowhere near as strong. Even worse, their strength levels tend to be erratic, so you never really know what you are getting. Again, always tighten to the specified torque, as excessive tightening can cause failure.

Petzl Long Life (hard rock only)

The Petzl long life is an ideal bolt with two problems – price, and difficulty in obtaining the 12mm drill bits. At $8.60 retail (hanger included) it is no wonder that these bolts have yet to gain popularity in the U.S. Still, if you can get your hands on them, their short length (2") makes them the only 1/2"-range bolt feasible to place by hand. Do NOT use a 1/2" bit (12.7mm), as the hole will be too large for the Long Life bolt. One such bolt, originally held in by epoxy, was removed with fingers alone on Rixon's Pinnacle in Yosemite Valley.


Place a glue-in properly and it is the strongest, longest-lasting bolt available. But if the hole diameter is slightly off or you don't use the proper amount of glue, they can be incredibly weak. Unless you are willing to spend the great effort required to learn how to place glue-ins properly, stick to the other recommended bolts.


All commercial hangers that are stainless steel and rated to at least 5000 pounds are recommended. All homemade hangers and cold shuts, on the other hand, are completely unreliable and should never be placed on climbing routes.

The 12 mm Petzl Coeur is the only hanger that can accommodate 1/2 inch bolts (besides the 5-Piece bolts; 1/2" 5-piece fit 3/8" holes on hangers).


Even in dry climates, climbers should use stainless steel bolts and hangers. It is also important not to pair stainless with non-stainless metals (i.e. stainless hangers with non-stainless bolts, etc.) in wet areas. This miss-match accelerates corrosion and can be avoided by painting hangers with numerous coats of primer or by using Fixe or Metolius pre-painted hangers. Better yet, always use stainless steel bolts AND pre-camouflaged hangers appropriate for your area (plain stainless steel is camouflaged for most good granite).

While non-stainless bolts will last for some time in dry climates, much rusting occurs even in desert locations like Owens River Gorge, where those maintaining anchors observe significant rusting inside the bolt hole on routes only a few years old.

Rebolting Responsibility

Bolts causes an impact in the wilderness. Land managers would like the world to believe that this impact is equivalent to scribbling graffiti across the rock. Climbers know that this is not true and that the impact of climbing on bolted routes is far less than the impact caused by hikers, campers, horses and other wilderness users. Nonetheless, with the heavy fire that fixed anchors have come under recently, climbers must respond by making an effort to leave as little trace as possible, especially when bolting. If the bolt is going to be visible from the ground, be sure to paint all hangers a color that matches the surrounding rock and replace gnarled masses of webbing with rap rings and chains. The new regulations at Joshua Tree National Park require use of fully camouflaged bolts and hangers everywhere, and this is a good rule of thumb to follow regardless of where you are and if non-climbers could ever see the bolts.

Do not undertake rebolting anywhere without consulting other rebolters and responsible, experienced members of the local climbing community. Make every effort to contact the first ascent team to check the original state of the route with them; many classic routes have excess bolts not from the original ascent. Just because it is a rusty 1/4" bolt does not mean that it wasn’t placed in 1975 years after the first ascent. See the ASCA rebolting policy for further things to think about when undertaking the restoration of a route.

  • 24" crow bar, or "tuning fork" plus funkness device
  • thick knife blade (optional)
  • lost arrow
  • beater biners and sling to clip to old bolt during pulling
  • blow tube (2 feet of 1/4 flexible plastic tubing)
  • test tube brush
  • 1/4" nuts plus old beater 1/4" hole hanger
  • hammer
  • new bolts and hangers appropriate for the situation
  • container for old bolts
  • safety glasses
  • epoxy (RepairItQuik tubes from Home Depot, $3 tube will patch 50+ holes)
  • needle nose pliers



image, access, FS fixed anchors ban, etc - replacing bolts inexorably tied to access

Local ethics/rebolting practices - don't rebolt without checking with locals first - contacting first ascensionists- especially on routes where bolts may have been added Should the bolt be there? Many bolts should be eliminated not replaced, What to replace with - get the right gear, talk to local rebolters, use camoflaged gear - common sense - don't bolt when crowded - hammering the wall is annoying to others once you start pulling a bolt, you MUST replace - never leave a route worse than before do you need to move the bolt? Reasons why - poor rock, poor placement, bad hole, etc - camouflaged hangers, bolt heads? Required in J Tree, do it everywhere. SS is camo for Yos.


Situational safety - rappelling to bad bolts - climb nearby routes, etc - try not to need to clip the old mank! Leading the routes - Zippers, Screamers - replacing anchor while on lead in case it blows eye protection - mandatory - helmets - good idea, especially for anyone below rebolter(s) - dropped bolts dangerous! earplugs - good idea for long rebolting sessions, ringing is high-pitched Spotting bad bolts Pulling types of bolts techniques broken bolts expanding old holes - when you need new hole (excessive cratering, too sharply mis-angled original hole, too near other bolts or holes, bad rock, etc) when to hang on old to place new (rare); hooks for stabilizing on pendulum rappels patching old holes - also patch pre-existing old holes, which are common


Anchor positions, rap anchor types/setups, rock type & anchor type drilling hole - light, quick taps when expanding old hole, frequent cleaning with blow tube depth gauging - don't push it when hand-drilling until very experienced cleaning!! blow tube, nylon tube brush, repeat placing bolt & hanger, tightening - over-tightening of Rawls rampant, not too tight cleaning surrounding rock - forget, may stain rock/kill lichen.

Keeping track

Bolts labeled in bags on climb, group them in pockets or bags/remember somehow exactly what new bolts were placed, where easiest with log - use notebook any additional info you think is relevant Communicate to ASCA and other local rebolters.


Twitter  Facebook  StumbleUpon  Delicious  Digg  Reddit  Technorati

Add a Comment