Torque level requirements on L series

[easygo]

Just a word of caution on torque. I recently bought and installed wheel spacers on my B7800 and the torque specified was 145-165 ft/lbs. I snugged up all the nuts on the studs and then went at it with the torque wrench at 155ft/lbs. All the parts were included in the kit. The first one that I was about to tighten stripped the thread from the nut. Much arrgghh.... and choice words followed. Not only that but it messed up some of the thread on the hub. So I went down to 130lbs on the rest of the bolts and that is where they are now.
Following day a trip to the supplier for a thread tap and new bolts another 2 hours to take wheel off clean out thread and reinstall wheel.

 

[DiezNutz]

Anything that requires proper torque is listed in the owner's manual that came with the tractor.
...
I'd recommend two things, first is to read the manual, the second is to buy a torque wrench. You need to consider that a torque stick is only effective if:

A) it's good quality, most cheap ones aren't.

B) your impact wrench must have enough power to exceed the torque stick rating, if it can't the fastener won't be properly tightened. In other words, a gun that generates 120 ft lbs can't tighten a nut to 160 ft lbs no matter what torque stick you use or how long it hammers away at it.

Most impact guns are over-rated, mine says it's good for 240 ft lbs. I seriously doubt that, it has a tough time with anything approaching 200. Then you have to factor in air pressure, supply line diameter (a huge factor), battery state if cordless, gun condition, etc.

Mine won't even break lug nuts at 90 ft lbs with a 1/4 inch air line, the gun simply can't get enough volume to work properly.

Not hard to tell, but I believe impact guns are great for disassembly. A torque wrench is the best tool for tightening any critical fastener.

Sean

Good post Sean, I completely agree on all points... things people overlook. :thumbsup:
I use the sticks on lug nuts, etc. just to get 'em on quick without overtorquing, and then finalize with my TW. With experience I've discovered that I can get quite a bit of variation in the torque that the stick applies, depending on how I finesse my application technique.
How would I know this, if I had never put a TW on them afterward.

Btw, mine are Snap-On sticks. Even these will never be accurate, only close. Good enough for lug nuts, if used correctly.

 

[johnrex62]

Good post Sean, I completely agree on all points... things people overlook. :thumbsup:
I use the sticks on lug nuts, etc. just to get 'em on quick without overtorquing, and then finalize with my TW. With experience I've discovered that I can get quite a bit of variation in the torque that the stick applies, depending on how I finesse my application technique.
How would I know this, if I had never put a TW on them afterward.

Btw, mine are Snap-On sticks. Even these will never be accurate, only close. Good enough for lug nuts, if used correctly.

Thanks guys. DiezNutz, you use yours in the manner I was hoping to use them myself. A quick way to snug up without over torquing anything. I do not plan on doing any rebuilding or engine work with a battery powered wrench and a torque stick. I thought it would be safer to snug a lugnut or loose frame bolt with a stick than without one.

I have read the owner's manual a few times and each time I find something I missed before, but there are still a lot of nuts and bolts on the tractor that I have not noticed in the manual. There does not seem to be a parts list or a service manual out yet for the L3700SU. I have gotten a download of a L3400 parts list since they should be very, very similar for all the major components....but no torque specs in that document.

Not being a motorhead, I was unaware of the online torque charts, so thanks for that info. After reviewing them a bit I am still not sure how closely I will be able to interpret them as I have difficulty figuring out what thread I am looking at. I can tell the diff between a wood screw, sheet metal screw and machine screw....but I have major trouble with the pitch and thread size on coarse and fine threads. I hope that won't make enough difference on the bolts I have to work on on this tractor.

Back to the questions you have raised with your answers. How do I tell the quality of a stick set, and how do I ensure I have a good (enough) torque wrench? I am sure there is a $ level I can spend to that will give me a good feeling that I have quality, but is that real? Since I do not plan to do engine overhauls or delicate work, just maintenance and general repair; how good do I really need? I hate to be the guy that spends a thousand dollars on tools to do fifty cent repairs every few months when a hundred dollar set would do just as well.

 

[Chilly807]

I'm not any kind of authority on torque sticks (I don't use them professionally), but torque wrenches are pretty straight forward. The beam type is about the simplest and cheapest, with a pointer that deflects as you tighten or loosen a fastener. I have a Craftsman model that I got years ago. It's acceptable for accuracy on automotive use.

I also have an older Craftsman click-type wrench that has seen a lot of amateur use. I check it about once every year at work (we have a torque wrench tester), and it's surprisingly accurate for a relatively cheap tool, within a couple of foot pounds.

The type of wrench that has a twist handle to set the torque (click type) is the most common these days. They're convenient because you don't have to see a dial or needle to tell you when you've reached the target torque, like upside down or in close quarters. They DO have to be set back to their lowest setting for storage, otherwise they lose accuracy over time.

As usual with tools, the best quality brings the highest price, generally speaking. Most of the stuff we use at work is either Snap-On, Proto, or OEM supplied torque wrenches which scares the he** out of me price-wise.

You'll be fine with a brand-name tool, usually under $100. I'd recommend Craftsman (Sears) based on my experience with them, although most of their stuff is Chinese these days. Any respectable hardware store will have a selection that suits most uses.

It's nice to be able to test them once in a while, although few have access to the test gear I have. You can do a rough check with a heavy duty spring scale. If a wrench is two feet long to the center of the handle, if you have it set for 100 ft lbs it should reach the torque setting with 50 pounds of force applied to the handle.

As for impact wrenches, I'd recommend a decent brand name, like Ingersoll-Rand or Blue-Point, CP is OK but marginal. Campbell-Hausfeld isn't that good anymore. Use at least a 3/8 inch diameter air line, 1/2 inch is better.

My opinions on brand names are just that, I'm sure others have different opinions.

Sean

 

[DiezNutz]

I agree that the best bang for the buck for a torque wrench is the Craftsman Microtorque series, that would also be my recommendation. Occasionally they even go on sale. Although even the cheapie Chinese torque wrenches come with an accuracy % too, you really have know way of knowing if it is within spec without a calibrated test, or if it will stay within spec.
One thing to watch out for with the Craftsman wrenches however, is to be careful unwinding the handle to release the tension (as you're supposed to do), and do not twist it beyond the stop. These have a tendency to unscrew the tension nuts inside the handle, which renders it useless.

I have a different opinion on impact wrenches, however. For the casual user like the OP sounds to be, a cheapie impact should do fine, for no more use/wear than it's going to get. You don't need an impact gun to be accurate, you just need it to beat on a fastener, and even the Chinese crap does that well (even if the max torque may be a bit overstated).

Here's why I say this: I have a couple of those "name-brand" impacts and a Harbor Freight 1/2" one that for some reason or other I picked up a dozen or more years ago. A funny thing happened... because I don't care about the HF gun, it's the one that's gotten almost all of the use & abuse over the years. It's been kicked from one end of the garage to the other, dropped, yanked through piles of dirt & grease, oiled once in a blue moon, you name it. And it still keeps banging away like always. I know their QC isn't the greatest, and I must've gotten "a good 'un".

The IR 1/2" on the other hand, cost probably 4X as much, sits in the tool chest with hardly a scratch on it looking practically new (because it might as well be), and at this point is little more than a trophy piece.

This is why I'd suggest putting the money into the torque wrench, which needs to be reliable and accurate. I don't trust HF for accurate tools, but I have gotten some decent, cheap hammers there over the years.

 

[Transit]

Anything that requires proper torque is listed in the owner's manual that came with the tractor.

Even the translation from Japanese to English is manageable, although I've raised an eyebrow from time to time.

Rear wheels are 160 ft lbs on a 3400, 3700 is probably the same.

I'd recommend two things, first is to read the manual, the second is to buy a torque wrench. You need to consider that a torque stick is only effective if:

A) it's good quality, most cheap ones aren't.

B) your impact wrench must have enough power to exceed the torque stick rating, if it can't the fastener won't be properly tightened. In other words, a gun that generates 120 ft lbs can't tighten a nut to 160 ft lbs no matter what torque stick you use or how long it hammers away at it.

Most impact guns are over-rated, mine says it's good for 240 ft lbs. I seriously doubt that, it has a tough time with anything approaching 200. Then you have to factor in air pressure, supply line diameter (a huge factor), battery state if cordless, gun condition, etc.

Mine won't even break lug nuts at 90 ft lbs with a 1/4 inch air line, the gun simply can't get enough volume to work properly.

Not hard to tell, but I believe impact guns are great for disassembly. A torque wrench is the best tool for tightening any critical fastener.

Sean

Chilly, I agree with much of what you say. As for air impact wrenches, i found that a $59 HF electric wrench is as good as any other brand. If you read and look closely, the HF $59 wrench is the same identical as the $150 wrenches only the paint job is different because they are BOTH made in the same factory in china. Why pay more for the same crap? Red pant dose not cost that much.

 

[Chilly807]

One thing to watch out for with the Craftsman wrenches however, is to be careful unwinding the handle to release the tension (as you're supposed to do), and do not twist it beyond the stop. These have a tendency to unscrew the tension nuts inside the handle, which renders it useless.

Mine did just that early on (I've had it for probably 15 years now) I took it apart afterwards, recalibrated it and used Loctite on the tension nuts. No more problems.

Sean

 

[DiezNutz]

Mine did just that early on (I've had it for probably 15 years now) I took it apart afterwards, recalibrated it and used Loctite on the tension nuts. No more problems.
Sean

Same thing happened to a buddy (which is how I learned not to wreck mine), and from things I've read online, it still happens. Sears told him it wasn't repairable, which we thought was B.S.
Probably just more profitable for them to sell new torque wrenches than it is to train a few goons at the repair center to fix and recalibrate it properly.

You're lucky to have access to good calibration equipment, Sean.