928autobahndreamer

The more work I do on the 928, the more I realize the importance of a good torque wrench. The problem I have run in to is that I can not fit my torque wrench in to most of the bolts when working on the 928. So most of the time I have to "go by feel" tightening with a standard spanner or ratchet.

Anyone here have any advice on what works? After looking around, most torque wrenches are pretty big. I don't see how most of these would be helpful in the tight confines of the 928 engine bay. Christmas is coming up and I have asked for a smaller "microtorque" wrench but the gift giver is having a hard time finding what I am looking for. I just assumed that this would be a product that is readily available, but after looking myself, it seems the options are quite limited.

What do you guys use? How did you find a wrench that will fit (for example) on the cam cover bolts.

Jfrahm

IMO a beam wrench is best for the home mechanic who needs accurate torque values once in a while. A click wrench is great if you treat it well and get it calibrated regularly, not realistic for garage work.

-Joel.

jcorenman

Dreamer,

I use rachet "clicker" types, can basically go anywhere that a rachet socket-handle can go. The primary wrench is a 3/8" drive Snap-on that I bought many years ago, cost like $100 at the time (this was in the early 70's) but has been a workhorse, certainly a good investment. It's maybe 12" long, looks like a fat-handled rachet and goes to 70 # as I recall with a mircrometer-style dial.

I also have a big one, 1/2" drive Craftsman for suspension bits and wheel lugs, goes to 250#. And also recently picked up a 1/4" in-lb clicker (another snap-on) from eBay for a song for those pesky 6mm bolts.

I hope this helps, happy hunting!!

M. Requin

I have half a dozen torque wrenches and a torque multiplier in my box, but as a starter you really need two: a 3/8 drive with a range up to about 75 - 90 ft/lb and a 1/2 drive with a range up to say 250 ft/lb. You are right, there are a lot of situations when you can't fit a torque wrench properly (and using a wobble drive or extension changes the torque reading) but by using one consistently you can develop a feel for at least an approximately correct torque value. For economy and ease of use I like Craftsman Digitork wrenches - I think they are a good value and they are accurate and easy to read. There are better, if you can afford Snap-On go for it, but I find what I have completely adequate. And economical, which means you should be able to afford both, which you will need - it's hard to do everything from lug nuts to water pump bolts with only the one or the other. Hope this is useful, and I'm sure others will chime in with their own (and useful) opinions.

V-Fib

From a post I made 6 years ago...

It was the way I was taught through several aircraft courses both Air Force and private schools.

When the 944S came into the family I had to buy an angle wrench. You know, torque the head bolts 90 degrees?

Lopez

About 18 years ago (man, has it really been that long?) I was a mechanic at a racing drivers school. The Snap-on guy would come by once a week in his truck to try and entice us into spending money we didn't have on tools we couldn't afford. At the time, they had in their catalog a kind of remote electronic torque wrench / socket set, where you used any old 3/8 ratchet handle, and these sockets that weren't much bigger than a standard deep socket. They connected via a wire to a small, metal box that had a digital readout of the current torque being applied to the socket. This set was very, very expensive at the time (5k maybe? it's been almost 20 years, I don't remember precisely) and I don't see anything like it in their online catalog now... but I do remember thinking how great that would be for torquing hard to reach bolts.

The only thing a quick web search turned up just now is something similar from Craftsman, but it isn't nearly as low a profile (it looks like a giant 1" x 3" extension that goes between your socket and the handle).

M. Requin

Your advice on use is spot on. Forgot about the angle wrench, it's in the box, too. And dang, should NOT have used the example of water pump bolts and the 3/8 torque wrench - those are going to require a 1/4 inch wrench with a readout in inch-pounds (or metric equiv) if you want to be safe.

Fogey1

<MORE>, please. It's a subject I have often wondered about as I've used extensions when necessary.

Any scientific testing you're aware of?

Any change would result from a "torsion bar" effect in the extension, right? And any effect should be quantifiable, consistent and expressible as a percentage (small?) of the torque shown/set on a wrench. Given the same torque, a higher percentage effect in the longer, thinner extensions and less in the shorter, thicker ones.

Further, I have always considered the most important use for a torque wrench is to achieve consistent clamping force over a number of fasteners holding an assembly with a large mating surface. That is, for example, accurate and consistent torque is more important for a head or water pump or oil pan than for the mounting bolts holding the alternator or A/C compressor or brake calipers. Mission critical vs. "that'll hold it without breaking anything."

Lastly, I've always believed that, since any "torsion bar" effect would be both minimal and consistent, one can get in the range _and_ consistency even with an extension. Am I wrong?

BTW, one of the reasons I like beam wrenches, in addition to their reliabilty, is the excellent visuals one gets during and about the process.

M. Requin

Don't know about scientific explanations (there probably are some) but the biggest problem with using an extension, easily overcome with practice, is keeping the shaft of the fastener in line with the extension so that readings are accurate. If they are out of line the working length of the wrench is changed. I don't think torsion effects would be important, although I suppose they could be with large torque values and small extension diameters - hadn't thought of that before.

As for the importance of torquing single vs multiple fasteners, I think they are different problems: the former is to be sure things don't fall off and threads aren't stripped, the latter to insure (mostly) the integrity of mating surfaces.

And btw, I agree with you about beam torque wrenches - very useful, often underrated, and you can readily see the effects of improper alignment wrench-extension-fastener.

WallyP

Unless you pull sideways on the wrench, there will be no measurable effect from using an extension.

(There are "torque sticks" for use with a rattle gun, but these are a quick, cheap way to try to limit torque when installing wheels at a tire shop. They work by "winding up" when the impact hits, and releasing whle the impact gun is rotating to the next hit.)

Clicker torque wrenches are convenient, especially when you couldn't read a beam-type wrench. They do need to be calibrated often.

A beam-type torque wrench is accurate if properly used. If the wrench isn't damaged, and the pointer is zeroed and properly floating, and the handle is floating on the pivot, the reading WILL BE accurate.

You can calibrate your clickers with your beam wrench. Make an adapter that allows you to connect the wrenches, or use a socket for a 1/2" (or 3/8") square fastener to connect the two wrenches. Set the clicker on the torque that you want, then watch the beam pointer and make sure that it is at the proper reading when the clicker snaps over.

BTW - when the clicker snaps over on the fastener, STOP!

Remember that the torque values on the wrench are not accurate if you are using a crow-foot socket, or anything else that moves the applied torque off the centerline of the wrench.

M. Requin

If you think your beam wrench is accurate.

Like an extension, misused. I think we basically agree, Wally.

Hilton

Its pretty easy to correct for torque variation of crowsfoot however - just a simple ratio formula that takes account of the extra length added to the leverage by the crows-foot, plus some care and attention on the relative position of the crows-foot versus the torque wrench for the final value (i.e. straight off the end for the final torque).

The visual aspect during the process of a beam wrench is something I hadn't thought of.. would make it much easier to spot a bolt or threads that are giving way rather than tensioning up; especially good for those hideous 87-onwards cam cover shoulder bolts.

WallyP

The bending beam torque wrench is "inherently accurate". That is, unless the wrench is physically damaged by bending the beam, and the wrench is used properly, it WILL BE accurate.

P.A. Sturtevant, manufacturer of beam torque wrenches since the 1930's, says that the accuracy of a beam-type torque wrench is +/- 2% of Indicated Value from 20% to 100% of wrench capacity in both directions.

Plenty close enough.

Difficult to use, especially in tight conditions, but great to have. And - they're cheap!

Agreed on correcting for a crowfoot. We had to make corrections for crow-foot sockets, wrench extensions (makes the wrench longer or shorter to get around obstacles) and special tools when I was in the airplane making business. You can actually use the crow-foot or extension at any angle, if you apply the right formula.

jon928se

Beam wrench is likely to remain as accurate as the day it was purchased so long as the beam remains straight. One would have to permanently bend the beam, probably significantly, to materially change the properties of the steel, and that would be obvious.

You should either re-zero the pointer by bending it, or compensate for it's at rest reading.


the most likely cause of error using an extension is by holding both ends of the torque wrench to keep the extension aligned. It is possible to then apply the whole torque indicated on the wrench, not to the subject bolt, but partially between your hands with a corresponding sideways load on the nut. Always hold the extension to keep it aligned.

It is unlikely that you could get the torque through an extension very wrong if you use only one hand as it is more likely that the socket will get angled off the nut, wwarning you that "That wasn't right - try again and hope you haven't rounded the flats on the nut"

928autobahndreamer

Great info here, thanks guys.