CV Axle Nut Torque Question

[ARCHINSTL]

Well, the torque value on these axle nuts is 137 foot-pounds, whether OE or GSP.
My 3/8" wrench goes to 100 foot-pounds.
Go to shop to have torqued after my tightening to "100+"?
I've looked at Sears, HD, AZ, etc. for extensions to fit the wrench, as there is a handy formula to calculate increased torque with an extension, but have not been able to find those devices - one end must be 1/2" to fit a 30mm socket and the other with either a 3/8" or 1/2" hole to fit the torque wrench (or adapter for same).
Solution?
Thanks,
Tom M.

[takza]

I don't see how an extension would change the torque applied.

Maybe get it to 100 ft lbs and then tweak it another 1/8th turn?

[brianp]

Yes, an extension will not help on a torque wrench, it will still 'break' at the same torque, you will just have to apply less force with an extension to get there.

I think your best bet will be either to go to a shop, or borrow/rent a larger torque wrench.

I don't have have a torque wrench, so usually just tighten to what feels good. Nothing's fallen off yet, but I wonder how necessary the torque requirements are.

[keith]

The type of extension that increases the torque is one that increases the effective length of the torque wrench. For example, if your 3/8 torque wrench is 12" from the drive end to the "clicker" or scale if beam type and you take a wrench and cut a 3/8"square hole about 5" from the head and attach it to the torque wrench, it would increase the effective length of the torque wrench to about 17". That would double the torque applied from the reading, in other words, you would set the torque wrench to about 68.5 ft/lbs.

There are also geared extensions but you won't find them at Sears or any common hardware stores. They are available from industrial supply houses like MCS, McMaster-Carr and Granger. These are on the net, just google them or add a dot com to the name.

You may find that the extensions cost more than a low priced 1/2" torque wrench at AutoZone or similar place.

[Petros]

I use a heavy breaker bar marked on the handle where my weight will achieve the desired torque. I set it up so I can step on it in the right place and carefully balance my full weight on the handle.

A more accurate and controlled way to do this would be to put a long extension "cheater" pipe on the handle and and add a smaller known weight. For example, a 4 foot extender would only require 34.25 lbs to get 137 ft lbs. For the rare few times I need that much torque I have always done this with good results. besides, it is a lot cheaper than buying a really big torque wrench that will be rarely used.

[splatterdog]

I know us tercel guys can be pretty frugal. But there are pretty cheap 1/2 inch drive torque wrenches out there these days. Cheap enough for even the occasional user.

I went years with the best guess by hand or impact method without incident. Then I spent 5 years in a high end shop and had to torque just about every bolt I touched. I was surprised how much I was off + or -. I now have 4 snap-on torque wrenches that have me covered from 5 inch lbs to 250 ft. lbs. This might be a bit too much for most, but I couldn't imagine not having them now.

Even the ones at harbor freight are probably adequate for the infrequent user although I doubt you get a certification statement with them. Still, they are probably alot closer than best guess. If you are reading this then you also have the net to draw upon. From my observations most tech's don't torque anything so most used wrenches are probably still in good shape. Plenty of people with surplus tools that were smart enough to get out of the biz early too. I wasn't. At least I'll have a snap-on casket....

[Petros]

hanging a known weight on a known lever arm length is NOT a "best guess". It is more accurate than ANY torque wrench because it is the definition of torque and how the wrench is actually calibrated.

I agree a "best guess" is not a good practice, especially with the drive nuts at the hub. We actually lost one of these big nuts on our Mazda when the mechanic at a local shop forgot to torque it. It did a lot of damage to the hub and spline shaft, he got to replace the half shaft and the hub bearing for free. I torque nearly every bolt on final assembly as well.

However, the weight and lever method is not guessing. And I am not going to buy a large "cheap" torque wrench that will only get used at most once a year, and is less accurate than the weight and lever method.

[splatterdog]

Didn't mean to offend, petros, but my post was aimed at the masses that go "good enough".

While I cannot argue with the accuracy of your method, it is not at all practical in the automotive world unless all you tighten is hub/lug nuts. Too many odd angles and confined spaces. Also how many of us are going to stay at a calibrated weight?

My opinion is if you are worried about torque, borrow or better yet buy the appropriate wrench. Don't forget about the 1/4 inch one too. Lots of small bolts on our rigs and if you drive/work on anything newer they have gotten even smaller overall, holding down weaker materials that are very susceptible to crushing.

If this shop had actually tightened your hub nut, it's most likely torque would have been determined by impact stall speed. The mechanical gene pool gets worse all the time. They typically don't know, and more importantly don't care.

[keith]

Don't forget about the 1/4 inch one too.

Yeah where do you get one of those. I've been looking for one, they don't carry them at Sears or any Auto Parts stores. I remember when I used to see inexpensive beam types but not any more. There are a lot of bolts that require Less then 120 inch pounds, which is the bottom limit on most 3/8" drive torque wrenches.

[takza]

I have 2 old Taiwan made beam types...had a chance to compare one to a pro click type...it was right on.

[neonsport]

Go to AutoZone and get a 1/2" torque wrench from their loaner tools. Then you've got the larger wrench, and you won't be out any money.

[ARCHINSTL]

Yup - I just discovered that last night - its web site shows no loaner torque wrenches, but the b&m store has it - $90 deposit (same as it sells the wrench). It goes to 250 foot-pounds.
Case solved.
Thanks,
Tom M.

[Snax]

German torques anyone?

GUTEN-TIGHT!

I am dead anal about torques when it comes to motor work, but everything else on the car comes down to calibrated elbows.

[ARCHINSTL]

I am dead anal about torques when it comes to motor work, but everything else on the car comes down to calibrated elbows.

Think again about this when it comes to steering - and axles and suspension, whether front or rear...
Tom M.