Crank Hold Bracket HOW-TO

NOTE: I have received interest in this. I am willing to make these brackets for you based on my 1.6 template. If you are interested in purchasing one, jeff [at] jefflane [dot] org (E-MAIL ME). Otherwise, these instructions should be enough to get you through fabricating a bracket for your car. If you have any questions at all about these instructions, please jeff [at] jefflane [dot] org (E-MAIL ME)

Someone recently read my writeup about changing the Timing Belt (see Timing Belt Blues and wrote to ask about the bracket I fabricated to hold the crankshaft in place while I broke the crank sprocket bolt and when I torqued it back down after changing the timing belt and water pump. This will be a brief tutorial on fabricating one yourself. It doesn't take any metal working skills, just some common sense and some manual dexterity, and a sharpie.

Let me caveat this. This does not require any real mechanical ability... just basic hand tools and some steel stock, and the ability to draw around a template with a sharpie.

Also, this works on late 91 to 93 NAs with the long nose crank 1.6L motors. I do not know if it will fit on an early 1.6L and I do not know if it will fit on a 1.8 or a 2.0 or later engine. I DO know that you can use the instructions here to build one that will fit your Miata in most cases. This bracket also assumes that you have A/C in the 1.6L location (lower right if you are facing the motor). If you don't have A/C, you may not have the pivot mount that the A/C compressor mounts to. Same goes if your A/C is in a different location. Lastly, read everything once or twice before you start. ALWAYS WEAR EYE PROTECTION. Trust me, it really really hurts when you get a hot metal splinter in your eye. I never do this kinda stuff without eye protection (I wear full sealing goggles instead of sunglasses or similar products). Also, remember that this requires grinding and cutting steel. Steel gets hot when you grind and cut it. Let it cool down between cuts and grinds, or you'll burn your fingers. Lastly, this tutorial is here for you to use, or not use. By using this, you agree to not hold me responsible in any way, legally or civilly for any injuries or damage to yourself, your car, your home, loved ones, pets, children, neighbors, stray animals and so forth.

You will need the following tools:

• Ruler
• C Clamps
• Drill (Power, unless you have a professional cordless)
• Titanium Drill Bits
• Hand-held Angle Grinder
• Metal Cutting Disk
• Metal Grinding Disk
• Sharpie
• Razor knife
• Cardboard (cereal boxes are great for this)
• Eye protection (grinders throw a lot of metal flakes around)

The ruler I use is a 12 inch steel ruler. That's pretty useful for small projects where I need a solid straight edge, it's thin and light, and also gives small right angles for when I need to mark a 90 deg. angle.

The C-Clamps are for holding the steel stock while you are drilling and cutting. You cant really do this in a vice. I clamped mine to the wooden steps on my deck except for when drilling. When drilling the holes, I clamped the steel plate to a spare piece of 2x4 I had in my shed.

Ultimately, a drill press is the way to go, but I don't have a garage or a shop, so no drill press. To drill, I did the best I could from above. The important thing to do is get GOOD drill bits. You're drilling steel, not soft metal or wood. So get the good ones. I used Bosch Titanium speed bore bits (the kind with the small head on the end that drills pilot holes). These bits tore through the steel and left very little lip to grind off afterwards. They also ran through pretty fast without the heat-up that you would get from cheaper bits.

Also, unless you have a professional grade cordless drill, use a corded power drill, or a press preferably. The cheaper cordless drills don't have the speed or torque to drill steel. Besides, a good power drill is always a useful thing to have around.

The Angle Grinder I used is a small hand held one I picked up for something like 15 bucks at Harbour Freight. You can get similar cheap ones from Northern Tools, Walmart, K-mart and other such places. It doesn't have to be fancy... it just has to work. I used two disks for this, one was a cutting disk (1/8th inch thick) that was rated for cutting steel. The other was a common grinding wheel that I used to shape the corners and round off the edges so I could avoid slicing my hands on sharp burrs.

Beyond that, I needed a sharpie to draw everything out, a razor knife (box cutter or X-acto knife) to cut the cardboard, and the cardboard. The cardboard I got by cutting up an empty cereal box. That cardboard is strong enough for template making, but thin enough to cut easily while holding it against the motor. It also stands up well when you are cutting holes in it for bolts.

The only other thing I needed was steel stock to make the bracket from. I went to Lowe's Home Improvement and picked up a piece of 3" x 3' steel weld stock. I got the 1/8th inch thick stock because it was thin and relatively light, but still strong enough that it wouldn't twist under pressure once I started torquing the crank sprocket bolt down.

The part from Lowe's is: Weld Steel Flat 1/8" X 3" - 3 FT HILL# 11665

This can probably be done with Aluminum stock too, but I was afraid the aluminum stock would not be strong enough.

So here is a picture of the bracket itself. Click on this image to open a much larger version in a new browser window.

Width = 3" (I did not need to shave any width off the steel stock)
Length = 4 1/4"
H1 = 3" center to center
H2 = approx 3 5/16"
H3 = 1 1/2"
P1 = 1 5/8"
P2 = 3/4"

I am reluctant to give the actual dimensions here. This was custom made by me to fit a 1.6L as would be seen in a late 91-93 NA. I don't know if this will match exactly on the early 1.6L, nor do I know if it will match exactly on a 1.8L or later engine. BUT you can easily make a template from the general outline and then adjust it as necessary to fit your engine before you cut the steel.

The Width and Length should be fairly obvious. As I said, the width is 3 inches. I got 3 inch stock to avoid having to shave the width any. 4 inches would have been too big, I think, and 2 inch stock would have been way too small. 3 worked out just right. The H lines are measured from center of hole to center of hole. If you have your crankshaft sitting at TDC by the TCD marks, your for pulley bolts should line up like this:

1 2
SB
4 3

H1 runs from the #2 pulley bolt to the A/C compressor Pivot Bolt
H2 runs from the A/C Pivot bolt to the #3 pulley bolt
H3 runs from the #3 pulley bolt to the #2 pulley bolt

I was also a little reluctant to put in P1 and P2. That rounded cutout is there to fit around the inner raised area on my crank pulley. I am not sure that all crank pulleys (early 1.6L and 1.8L) will have that round raised area in the center of the pulley or not. Again, that is what templates are for.

So now, how do you go about making this little thing? Well, hopefully, by now you have followed the TB change guide found in the Miata.net garage. If not, you need to follow that guide until you get to where you are ready to break the crank sprocket bolt loose. Take a break from all that and follow these steps. (By the way, this assumes that the crank pulley is still attached to the sprocket, so if you took it off, you need to put it back on and tighten down pulley bolts 1 and 4.)

1: Cut the cardboard to roughly 3" x 4 1/2"

2: Remove Crank Pulley bolts 2 and 3

3: Remove A/C pivot bolt. This is found on the lower left side of the A/C compressor, it's a long bolt that has a nut on the back side. You'll need a wrench and a socket wrench to remove this.

4: Hold cardboard against crank pulley. Slide it around until one end completely covers pulley bolts 2 and 3. Once you have that, hold it in place and punch a hole with the X-acto knife or a nail or something in the cardboard into the A/C pivot bolt hole. Now take the cardboard template and make the hole you just punched wide enough for the A/C pivot bolt to slide into.

5: Hold the cardboard back against the pulley and put the A/C pivot bolt through the hole in the template to hold it in place. Line the template back up and using the sharpie, try to draw an arc that will be just slightly wider than the inner raised area of the pulley (this is how I made the P1 and P2 area in the image). Then remove the pivot bolt and cut out the rounded area you just drew using the knife. You may have to do this several times until you get it right. It's better to cut too little than too much when making a template. I cut mine out so it was as close to the raised circle as I could get it.

6: Put the template back in, put the pivot bolt back in and line the template back up with the crank pulley so that the P area is in the right place. Now the cardboard should sit flat against the pulley AND should also cover up the #2 and #3 pulley bolt holes. Take your nail or knife and punch holes for the pulley bolt holes, remove the template and widen those holes in the template as you did for the pivot bolt hole.

7: Remember the old adage, measure twice cut once. At this point, you should have a workable template. I STRONGLY suggest you now put the template back, and make sure the pivot bolt and pulley bolt holes line up. IN fact, I would install the template completely at this point. Put the pivot bolt through it's hole and insert it into the A/C pivot. Line the template up so it fits flat against the pulley and put the pulley bolts in and hand tighten them. Now you should have it fully installed and it should be flat (there may be a slight bend as the pulley stick out a little farther than the A/C pivot does).

If you do not have this, you need to start over with the template and try again, or adjust the template you have until it is correct. Making the template is the hardest part. After that, it's all cutting and shaping.

8: Once you have a good template, place it against the steel stock. the width of your template should match the width of the steel. Line up one end (I did the end with the P area) against the end of the stock, and use your sharpie to outline it, and draw the holes and the P area.

**WARNING** Grinding and cutting steel will cause the steel stock to heat up. It won't get red hot, but you can burn your fingers. So use clamps, and let the steel cool down for a minute or two after grinding, cutting or drilling. If you get burned, it's your own danged fault!

9: Now the fun begins. I started with the grinding. It's easier, IMO to clamp down a small piece of steel to a 2x4 and drill it than it is to clamp down a big piece. So the first thing to do is to put the grinding disk on the grinder, put your glasses on and go to town. Round off the corners and grind out the P area indentation. The P area will take some time, so go slowly, be patient and it will work out fine.

10: Now put the cutting wheel onto the grinder. This is a lot like using a saw, and in fact, that is exactly what you are doing. But remember that hand held angle grinders suffer from a gyroscope effect, so they kick or pull a lot when held sideways. Be mindful of this as a safety precaution.

11: The first cut I made was the angled cut you see in the picture. I started that cut on the outside and cut in and up from the bottom of the bracket toward the end with the Pivot hole in it. The picture makes it look a little more obvious, so use that for reference.

12: The next cut I made was from the other side of the stock down until it met the angled cut I made. Once I made this cut, I had my little 3" x 4" bracket.

13: Now put the grinding wheel back on, clamp the bracket down and grind the corners and edges smooth. This will help keep you from slicing your fingers open later.

14: Once you have it smoothed out, it's time to drill the holes. The pivot bolt hole needs a 3/8" bit. You may want to even go just a hair wider, but mine is 3/8" and works well. The pulley bolt holes should each be 5/16". Here's a tip: Before you drill the holes, hold a bolt against the bit to make sure the bit is wider than the bolt threads. You do NOT want any threads sticking out beyond the bit. So drill your holes and use the grinder to gently grind any burrs or edges from around the holes.

15: Now it's time to test fit again. Hold your new bracket against the motor and put the A/C pivot bolt in. Make sure it lines up and sits flat against the pulley. You may need to grind out the P area some more to get a good fit, just don't grind down so much that you cut into the pulley bolt hole. Put the pulley bolts in and tighten them down. Tighten the Pivot bolt back down and you should see the bracket bend slightly toward the A/C compressor

If it fits and everything tightens down nicely, you are now ready to put the breaker bar onto the crank sprocket bolt and break her loose. Later, when it's time to put the crank sprocket back on and torque the bolt down, this bracket will keep the crankshaft firmly in place and will easily handle the torque required on the sprocket bolt.

That is about it. Hopefully, you have now constructed a bracket that you can use the next time you change a timing belt on your Miata, OR be the envy of your club and loan it out to club members when THEY change their timing belts. Now sit back, have a tasty adult beverage, and then return to the TB guide and finish up your work. There's a lot of Zoom Zoom to do!