7

The torque spec for my Tacoma says that cylinder head bolts should be torqued (in a specific sequence) to 27 ft/lbs initially and then again each should be turned another 180 degrees in the same sequence.

I know how to use a torque wrench to set torque to a specific ft/lbs but I don't know how to measure the angle turned by ratcheting. How do I make sure that a certain number of clicks on a ratchet equates a certain angle?

As a bonus question, can you explain why Toyota would spec the second round of torquing in angles and not ft/lbs ? I think ft/lbs would be a cleaner spec.

7

90° = quarter turn. 180° = half turn. It's alright if you are off a few degrees.

I typically start with the breaker bar perpendicular (straight out) and do quarter turns, or have it straight off to the left. Just keep yourself parallel or perpendicular to where you start.

DO NOT USE A TORQUE WRENCH. It's bad for the torque wrench to turn after its clicked. Use a breaker bar.

These bolts are "torque to yield." They stretch out, which is why they should not be reused.

If you want to be precise you can use a Torque Angle Gauge.

  • but how do you measure that you went half turn when each pull you are moving rotationally only maybe 10-15 deg and that is not precise otherwise you could count ? keep in mind, the bolts are already on high torque, I can't just take a breaker bar and spin it freely 180... – amphibient Aug 7 '15 at 15:14
  • I will only turn it in increments of 45* or 90*. You can also paint a line on your socket, so you can see where it starts and needs to stop. – rpmerf Aug 7 '15 at 15:21
  • can't really paint a line cause the bolts are set really deep inside holes in cylinder heads – amphibient Aug 7 '15 at 15:22
  • 3
    Just looked it up on Amazon. Torque Angle Gauge. Put it between the socket and extension or extension and breaker bar. There's an arm on the gauge you put against something so it will not rotate. set it to 0. tighten the bolt down. – rpmerf Aug 7 '15 at 15:26
4

I'm going to buck the other two answers and tell you

DO IT RIGHT OR DON'T DO IT.

It is very important to torque your head bolts correctly. The actual preferred method for attaining the proper torque is by figuring out the fastener stretch, not by using a torque wrench. When torquing, you are applying a clamping load on the object you are torquing. You can get this at its most accurate by measuring the stretch of the fastener by using a dial indicator. It's by far easier to torque the fastener down using a torque wrench and in most applications, this is an adequate method of doing things.

In your case it seems you are using torque-to-yield (T2Y) fasteners. These are (as @rpmerf pointed out) single use fasteners only (NOTE: If I could make this text blink, I would to emphasize the point). These must be replaced once you have broken them free (this would blink as well). If you don't, your head gasket will fail. The head gasket is the typical place for these types of fasteners. The reason these fasteners are only good for one go around is they are designed to go up to that "fail point", but not beyond. They start to fail by giving a bit or stretching. These are specific built fasteners by the manufacturer. They have done the stretch engineering for you. By applying the last degree turn, you are stretching the bolt to the tolerance they have engineered into the bolt. If you go past this point, you are only courting death for your engine. If you don't go far enough, you'll have a weak point in your torque chain which could allow for warpage in the part you are trying to affix ... especially true for a head.

As rpmerf stated, get the torque angle gauge:

enter image description here

  • I just got the thing at Autozone. What is the little dial on the side and the angular tool used for ? The dial is not for calibrating, I tried. It's just to tighten a screw that holds maybe the tool in a hole but I'm not sure – amphibient Aug 8 '15 at 0:17
  • There should be a hole to put the angle tool onto the device. The other end goes against something solid (like the head) so the dial will stay stable. When everything is in place, zero the dial, then you can tighten to your desired degree. – Pᴀᴜʟsᴛᴇʀ2 Aug 8 '15 at 0:22
  • Ok. On another note, I believe my head bolts are reusable. I talked with a Toyota mechanic who told me so – amphibient Aug 8 '15 at 0:24
  • New head bolts are cheap insurance. – Pᴀᴜʟsᴛᴇʀ2 Aug 8 '15 at 0:25
  • I understand but also too many people have a zero risk bias and this may be just one of those CYA kind of things by the manufacturer. My bolts looked in real good shape – amphibient Aug 8 '15 at 0:28
3

Torque the bolt to the required torque. Then mark the head of the bolt with a marker or pen. This way you can visually check the angle. This is commonly used to ensure bolts are torqued during assembly.

2

If you don't have access to a torque angle gauge (as rpmerf recommends) or space is tight, here is one possible way estimate the angle with a ratchet:

  • Find a ratchet that fits
  • Without any socket on the ratchet, rotate the square drive head 180° by hand while counting the number of clicks felt.

    [My own 1/2"-drive ratchet clicks 36 times in a 180° sweep, so 5° per click]

  • Install the socket and place the ratchet over the bolt and turn it in the opposite direction to simulate the maximum possible sweep. The idea here is to determine the number of clicks in a single pass.

    If the ratchet clicks less than two times per pass, the error is going to be too high to be able to rely on this method. Don't use it. Do not proceed.

    [If the sweep angle per pass is 15°, that'd be 2-3 clicks]

  • If there are 2+ clicks per pass, calculate the number of passes needed to reach the total clicks in 180° and execute accordingly.

    [Assuming 36 clicks and 3 clicks per sweep, you're looking at 12 passes]


Caveat

This approach can have high error associated with it. In the example above, one could be off by as much as 90°. The more clicks per sweep, the better the results will be with this approach.

1

i measured degree by using nail polish and white paper I painted two places on my socket, (the end of the socket is square), i first applied red nail polish down the length of the socket at corner of the square, then another down the length of the socket at the next corner of the square, then applied a small sliver of paper in the middle of each red line, then aligned the paper with the corners of the socket then added clear nail polish then need to tighten to 32 lbs then reverse one turn on all the bolts, then tighten to 22 lbs then 42 lbs then 62 lbs, what i found on head bolt torque on 1999 ford 3.0 Vulcan engine,

  • I used to find that if I put the ratchet handle or T bar handle at 12 O'Clock or 3 whatever, then I could easily do 90 degrees or 45 degrees or 180 etc... – Solar Mike Aug 25 at 7:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.