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If I Had A Hammer

If I Had A Hammer
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There’s a science to the use of hammers when fixing or building cars. You’ll have an easier, safer and more satisfying experience if you know some of the science behind the types of hammers used in auto repair work.


Hammers come in many models, sizes and weights. Different types of hammers come in handy for different jobs. Expensive Stanley, Snap-On, Craftsman, Channellock, Mac Tool, Nupla or S-K hammers cost more for a reason. We’ve bought fiberglass-handled hammers at Harbor Freight that work fine in our home shop. However, we prefer the better brands of hammers when they have staked-in-place wooden handles. A flying hammer head can hurt!

The best hammers will have handles made of hickory. The heads on regular top quality hammers will be drop forged rather than cast steel. Hammer heads have different weights. You’ll find ball peen hammers weighing from 2 oz. to 48 oz. For automotive work, the most common weight range will be 8 oz. to 16 oz. Special hammers with plastic, brass, wooden or rawhide heads (or tips) also come in handy. Another tool that finds lots of automotive use is a rubber mallet.


The ball peen hammer is a style used in lots of automotive work.

Most hammers used in auto repair are machinist hammers. These include the ball peen hammer, cross peen hammer and straight peen hammer. The peen is the shaped end of the hammer’s head. On the other end you have the post (cylindrical tip) and the face (flat circular end). The peen can be used to shape metal. The word peen actually means “shaped for denting or chipping.” The ball peen can be used to hammer a bolt head or nut until the metal swells and actually prevents it from jarring loose. Straight peen and cross peen hammers can swage (cold shape) metal. They’re used by welders to chip off excess slag.



Eastwood sells this small metal shaping hammer and anvil set.

When striking a car part (not sheet metal) with a hammer, you should try to hit the part square on. The face of the hammer should be as parallel as possible to the surface you’re hitting it with. This protects the hammer and keeps you from chipping or deforming what you’re striking. Heavy blows are rarely needed. They will damage the tool or destroy the part. Avoid “banging” or  “whamming” a part. Proper hammering has a bouncy, rhythmic character to it. Instead of a “whang” you hear a “ka-bang-ka-bang, ka-bang-ka-bang, ka-bang-ka-bang” until the bearing seats or the tie rod comes loose.


Rod builders use a  hammer and seal installer tool for many jobs.

When hammering to properly seat a seal, a bearing race or a slip-in bearing, you have to tap all around the part to get it to seat evenly. Tapping on just one side will have the opposite effect. Bearing driver kits with a knurled handle that screws into flat discs of different sizes can help in seating parts evenly. If the part is seating over another part, it may be impractical to use such disc-type drivers, but a socket or piece of pipe of the right size and shape will do the job if you remember to tap lightly all around and remain patient.


A block of wood helps soften hammer blows to avoid damaging parts.

The use of two fair-sized hammers with almost the same-size heads to break a heavily rusted part loose is a technique that works. Use one hammer to tap the other into the part, again and again, with a repeated, regular rhythm. Almost without fail, after a few minutes, the corroded part will break loose.

If a heavy blow is ever required, the trick is to hold the hammer near the end of the handle. Start swinging the tool with your forearm stretched nearly straight upwards and bring the face of the hammer down hard on the object. Most of the time, however, you’ll want to try light blows—at least at first. To achieve this, move your grip about halfway up the hammer handle and don’t raise your forearm as high. Light blows come more from the wrist than the full arm. Do not hammer with your hand any closer to the head of the hammer. This will cause you to hit the object at an angle and may pinch your hand or numb it.


A wooden mallet is another option that helps deliver soft, firm blows.

When using a hammer to strike a second tool like an impact screwdriver, a bushing driver, punch or chisel, the hammer should have a face that is at least ½-in. larger in diameter than the head of the tool that you are hitting with it. The use of a hammer and impact screwdriver is often required to loosen steel screws holding aluminum parts in place, such as side covers on a motorcycle engine.


New hammer by Hammer Works Mfg. is called a Soft Grip Zinc Composite Bearing and Race Punch. Brass and aluminum end cartridges are optional.

A nice thing to have around your shop is an assortment of different size wooden dowels and wooden blocks that can be used together with a hammer to do various jobs. We gently flattened the bottom of a bent up old Hydra-Matic transmission pan by hammering on a soft wooden block held against the bottom of the pan that was moved just a little between moderate blows. Doing this with only the face of a hammer would cause dents or hammer through the pan.


Another new tool that Hammer Works Mfg. Brought to the 201 SEMA New Products Showcase is this Zinc Composite Dead Blow Hammer model J4.8.

We purchased dozens of lightweight specialty hammers designed for a variety of jobs on eBay. They included jewelry making and shoe repair hammers. We have found a couple of uses for them in automotive mechanical repairs. And although we don’t do a lot of heavy hitting, for those rare occasions they’re needed, we also added some large hammers and sledgehammers to our toolbox.