torque wrench vs blue thread lock (1 Viewer)

[gomez268]

Have a question.

I am planning on changing out the diff fluid on the cruiser and had looked at buying or renting a torque wrench but from looking at reviews unless your willing to spend over $200 on one, they are not reliable or accurate.

So I was wondering if instead of torquing the differentials fill and drain bolts, would it be ok to use blue thread lock on it and get the same result?

Or do I need to spend the money on a torque wrench or digital torque adapter?

 

[linuxgod]

A 5-80# torque wrench shouldn’t be that expensive, which should be all you need for this job. A good 20-250# is probably $200 but a lighter duty one should be less

I have a 10-150# and a 20-250# wrench. Both were inexpensive ($40 and $60, IIRC) on Amazon. They seem to be fairly accurate within a few %, as measured against each other. I know wrenches are more accurate in the middle of their range though.

Most shops don’t seem to use torque wrenches, just air impact or hand tools, unless they’re doing something specific like torquing head bolts. So unless your wrench is way off the end result is still probably better than many shops.

 

[TonyP]

No, thread locker isn't a sub for a proper torque. Two very different things going on there.

If you're on a budget you can get an old school beam style torque wrench for $30. Cheap click style torque wrenches are just as bad (if not worse due to a false sense of security) than doing it by feel.

 

[KLF]

Call your dealership and ask them what type of torque wrench they use on drain plugs. I bet you'll get a blank stare...

You guys are overthinking this.

 

[linuxgod]

Call your dealership and ask them what type of torque wrench they use on drain plugs. I bet you'll get a blank stare...

You guys are overthinking this.

Yep that was my point. An inexpensive torque wrench is IMO a perfectly reasonable option for many uses, including the OP's use for drain plugs. Others may disagree but I can say for certain that I'm really bad at determining proper torque and have stripped threads more than once.

Side notes to the OP:

• Loctite blue or red threadlocker is a secondary method for holding bolts and should not be your primary method.
• Use a threadlocker when you need to ensure a bolt won't come loose (like a suspension bolt) but you don't need to use it everywhere
• Don't use a threadlocker when it will come in contact with oil or lubricated parts unless recommended by the vehicle manufacturer. I would not use loctite blue on diff drain plugs because:
  • You may contaminate the diff oil with a chemical that is designed to harden
  • You may make the bolts unnecessarily hard to remove and/or may strip them when removing. For instance if the torque spec is 20ft/lb but you use a threadlocker with 50ft/lb of holding strength, you now need to use 2.5x the force to loosen the bolt. If the bolt is not designed for that, you may break or strip it
  • Most threadlockers (except loctite 243, IIRC) will degrade when exposed to oil

 

[TeCKis300]

It's a drain plug. It's not that critical in the grand scheme of things. Most experienced mechanics, including myself as a hobbiest with some good wrenching experience, don't bother with torque wrenches on these parts.

That said, it takes time to calibrate and get a feel for what torque should feel like. Every beginner wrencher has likely broken a bolt by over-torquing. That's where a basic, even clicking type torque wrench will help as a point of reference. Absolute accuracy is not that important. A good ballpark is all that it takes as there's engineering margin in these things. And steel parts/bolts are more resilient than aluminum (i.e. spark plugs in the head)

 

[anthracite]

It uses a crush washer to seal the diff so using thread locker on top of that is just adding more to the equation that can go wrong next time you need to drain the fluid. Just install the drain plug nice and snug and make sure the copper crush washer is completely compressed. Torquing to spec isn't as important on these type of plugs as say your wheel lug nuts, diff nuts, engine parts, etc.

Steve

 

[OregonLC]

One thing I've learned over the years is that less is more when it comes to torquing any drain plug, especially the allen keyed ones. You don't want to fight them next time. The threads are already lubricated and it's easy to over torque. Snug them up lightly but don't put your shoulder into it. And don't use the force it took to remove them as a reference. Odds are the wrench before you gave it a good heave.

Also, make sure you don't double-gasket on the re-install. That crush washer sometimes will adhere. Get it off and a fresh one on.

 

[hankinid]

It uses a crush washer to seal the diff so using thread locker on top of that is just adding more to the equation that can go wrong next time you need to drain the fluid. Just install the drain plug nice and snug and make sure the copper crush washer is completely compressed. Torquing to spec isn't as important on these type of plugs as say your wheel lug nuts, diff nuts, engine parts, etc.

Steve

Start with new washers for both drain and fill plugs...cheap.

The only copper washer I've seen is on the front diff drain plug. Remainder of washers on diff's and xfer case are aluminum. Transfer case uses flat washers and the diff's crush type. I use a torque wrench, it's a 3/8 drive with micrometer setting via the handle. $50 from local pawnbroker...local snap-on guy verified torque dead-on with his torque tester. Beam wrenches are fine, but click-type are better imo as you preset your desired torque, instead of having to see and read a scale while you're under the truck.

hth

Steve

 

[tominboise]

I often times use a short handled ratchet to install drain plugs and a long handled one to remove them.

Don't put blue lock tite on the drain plugs.

 

[UCrazyKid]

https://www.amazon.com/TEKTON-24330...wrench+3/8&dpPl=1&dpID=31mPL8dosvL&ref=plSrch

Done.

 

[TonyP]

The Tekton is what I have for my in-vehicle tool kit. No idea how accurate it is. I could probably bring it into work and test it against the torque wrenches we have that are tested via PMEL every year for accuracy.

 

[linuxgod]

I'd be curious as well. If I ever rebuild another engine I'll buy a CDI or Snap-on, but it's hard to not try the $35 options.

I have the 10-150# Tekton (https://www.amazon.com/dp/B00C5ZL0RU/ref=psdc_559968_t1_B00FMPKAD0) and at least for lug nuts it seems to be pretty close. That's just comparing to a 20-250# wrench by EPAuto, so it's possible both are similarly off, of course. The 20-250 is in my truck right now as I needed something that went to 250# when I put my new trailer hitch together.

Best cheap way to test the accuracy is to put it in a vise, hang a (precisely) 20# weight off the handle, and then do all the calculations. Or try a low, middle, and high setting against a known calibrated one, if you have one handy.

 

[pribilof]

I have several Tekton ones and have been happy with their performance

 

[OregonLC]

FWIW, at one time we had a fleet of inexpensive torque wrenches (Stanley maybe?). We sent them out annually for calibration. Never once did they come back out of calibration even after been left in Knaack boxes out in the weather for months.

 

[TonyP]

Our Snap-on torque wrenches have been known to come back needing adjustment.

 

[linuxgod]

FWIW all wrenches need adjustment from time to time, even the expensive ones.

 

[John E Davies]

DUPLICATE!

 

[John E Davies]

IMHO even a cheap Harbor Freight torque wrench, when used in the middle 2/3 of its range, and if NEVER dropped to a hard floor, is more accurate than guessing. Even a very skilled mechanic cannot reliably and repeatedly get close to the specs by hand. If he tells you differently, he is lying.

In A&P school they set up a bunch of different sized fasteners and wrenches and invited everyone in my class to hand tighten them to the specified torque, then try again using the torque wrenches. Of the 20 guys who tried only a couple got really close by hand. It was eye opening - most of them way over-tightened the fasteners. Very few under-tightened. This is why stripped threads happen.

If I were caught not using a torque wrench on a critical aircraft part, I would have been in serious trouble, if not fired. If it were a really important fastener, it was policy to have a second tech double check the wrench setting and also check the fastener with the tool, before it was safetied.

Just buy two cheap 3/8 and 1/2 inch drive ones and use them always. The size I use most is 20 to 150 ft pounds, 1/2" drive. It is perfect for lug nuts and most chassis fasteners. If you have a motorcycle, get a 20-200 INCH pound 1/4" drive one. If you will have to do really heavy wrenching, rent a 3/4 dr monster for a few hours.

John Davies
Spokane WA

 

[TonyP]

If you've ever had to drill out a snapped fastener or re-tap a stripped hole, or god forbid try to drill out a snapped tap, you'll know it's far easier to just take the extra 10 seconds to set and use a damn torque wrench.