Differencial yoke nut torque?

lostagain · February 27, 2009, 12:25:59 PM

I don't see a crush washer. There is a big spacer between the bearings. I just called The Gear Center in Calgary, and their service manager told me they use a 1" impact wrench and hammer away. Does it damage the gears? No he says. Maybe they like to sell gear sets...
I didn't mark the position of the yoke when I took it off the shaft spline. I hope it doesn't create an imbalance issue, assuming that's what you were refering to, Junkman.

JC

luvrbus · February 27, 2009, 02:50:02 PM

JC, you have no crush washer only the spacer between the bearing to keep from binding the bearings good luck

Utahclaimjumper · February 27, 2009, 03:00:57 PM

Hold the nut firmly in the direction of turning to minimize "slapping" of the gears.>>>Dan

gus · February 27, 2009, 04:05:51 PM

This is a very important spec, now is the time for you to consult the maint manual. There is no substitute for the correct info - this is no time for guessing.

This thing takes an incredible amount of torque, even my little slant six Plymouth took 250 lb-ft.

You can do this with even a small torque wrench if you have a long enough lever. Note what other posters have said about using pipe extensions.

Essentially what you do is use your torque wrench at the end of a long pipe or beam, the longer the better. Then you compute the amount of torque you need to read on the wrench, it will be way below the actual torque at the nut. The longer the extension the less the pull at the end.

Works like a charm if you have enough space for the long extension and even a wimp like me can tighten it!

junkman42 · February 27, 2009, 05:10:39 PM

Gus, correct Me if I am wrong! wouldn't the extension have to be between the drive end of the torque wrench and the socket thus multiplying the torque applied? There is a chart supplied with some high end wrenches for this purpose. john

Utahclaimjumper · February 27, 2009, 07:54:02 PM

I think that was what Gus was saying, but stop and think of how much did it take to remove?? and its probably been on there a long time.>>>Dan

NJT 5573 · February 27, 2009, 08:05:59 PM

You guys can't put an extension on a torque wrench. Its improper use of the tool and won't do it any good at all. I never have used my 600 lb 3/4 Torque Wrench to loosen bolts, it only gets to tighten bolts. It is a specialty precision tool and thats its only job.

If you use a cheater pipe you will have to find a 1 inch socket set (breaker bar) because a 3/4 will bend before you get close. There is no practical way to hand torque this nut. The practical way says IR on it and looks like a tire gun.

Don't beat it up to much with the tire gun, I have seen them snap off just behind the nut.

lostagain · February 27, 2009, 08:29:05 PM

Great discussion guys! Ah, the art of bus maintenance... The gear set assembly is back in the pumpkin, nice and snug. I don't really want to take it back down to hand torque the yoke nut. It was major effort to get it up and lined up to slide back in. At that time, I thought I would leave the yoke and nut till after, because it adds a good 4 inches to the end of the shaft, and the space is limited between the axle and the bulkhead. There is not much space under the bus for extention pipes. And as has been pointed out, it would take a 1" drive breaker bar to do it. So, I will use the 1" tire gun, and hold the shaft firmly in the direction of turning to minimize the slap on the gears, and take my chances.

Thanks for all the suggestions and ideas. This board is so great!

I'll keep you posted about my engine overhaul.

JC

gus · February 28, 2009, 01:59:27 PM

I said use the wrench at the end of the extension and I should have said at the pulling end, again, sometimes I'm not too clear! Yes, it cannot be used at the nut end unless it is a high capacity torque wrench. I meant that an extension can be used with a small wrench for high torque jobs.

However, it is not a good idea to ever use a pipe extension on the handle of a torque wrench even if it is a high capacity one. This is a good way to destroy the wrench calibration. An extension is always better.

There is absolutely no reason not to use a torque wrench at the end of an extension. The torque wrench doesn't know the difference because the torque on it is the same regardless. This can be done with any torque wrench regardless of price.

I don't think anyone said anything about removing nuts with a torque wrench. I think most people know better than that. The amount of torque required to remove a nut is not the same as the torque used to install it. Removing normally takes much more torque than installation, especially if it is rusted or jammed for any other reason. Never use removal torque as a guide for installation.

I don't think I would ever use an air wrench to torque a nut unless the air wrench has a very good torque limiting control. Some have controls but I find that most are not very accurate. I would take my chances with a long pipe even without a torque wrench over an air wrench. A real powerful air wrench can do tremendous damage in the blink of an eye.

JohnEd · February 28, 2009, 02:40:43 PM

You guys seem to be missing something VERY important....and I think I have proof. There seems to be a lot of concern about marking the gears with the impact wrench causing a lot of slap between the meshed teeth. The gear teeth are NEVER supposed to have the torque of the tightening effort applied to them in the tightening process. The yoke needs to be held/restrained/captured and the nut torqued against that restraint. The "tool" looks like a piece of 1/2 inch plate with the dimension of the yoke cut out. The plate slips over the yoke and the plate is then chained against rotation or is in contact with the floor. All the torque applied to the nut is transferred to the restraining bar and the teeth never feel a thing. I think that under normal ops the ring gear is bathed in oil and that oil film prevents metal to metal contact but at a start or in a stall situation the ring would be dry at the point of pinion contact so I guess there is room for intermittent contact but that would never be a hammer blow.

Admittedly, this is "car stuff" experience but I think it should apply. I have never twisted a bus nut in anger so I don't know from experience there or from the Da Book. Am I all wet? Again?

John

gus · February 28, 2009, 09:08:18 PM

I also use the same method as John but have only done it on auto yoke nuts. I assume the same applies to heavy vehicles for the same reason, you really don't want to chip those gear teeth after all that hard work.

JohnEd · March 01, 2009, 02:41:50 AM

Now about that pipe and torque wrench: If you attach that T wrench to the nut and put a "cheater" bar on the torque wrench....the reading on the torque wrench is what the nut is torqued to. Now, if you put a "breaker bar" on the nut and put a 10 foot pipe over the B bar, and attach the T wrench to the far end of the bar the torque read on the T wrench will be one tenth of the actual torque. In neither case was the T wrench subjected to "over torque" abuse. Correct me if I'm wrong. Please!

John

lostagain · March 01, 2009, 07:28:49 AM

How would you attach a torque wrench to the end of a breaker bar or pipe?

JC

buswarrior · March 01, 2009, 09:53:33 AM

weld on an old socket, etc.. to get a mounting point for the torque wrench.

Nothing sinister in it, twisting force is twisting force, no matter by air gun or using a pipe to increase the leverage by hand.

How do you know what torque the air gun is putting out, on this pull?

What sized airline, what restrictive fittings, what size tank is allowing what pressure drop, when was it last calibrated? Manufacturers ratings don't mean squat, a recent calibration on the end of that air supply would be more comforting.

A 1 inch gun needs a big hose and big fittings, a maximum length of run, all the way from the tank to the gun, with a big tank and a healthy compressor to achieve the advertised results. Otherwise, you'll get much the same or worse than a smaller gun on the same small hose.

For the inspired, someone step in with the hose recommendations?

Big boy toys, need big boy tools.

happy coaching!
buswarrior

NJT 5573 · March 01, 2009, 10:25:39 AM

The hose varries. My IR 281-S6 (Japan) works just as well with a 3/8 hose as a 1/2 hose. It is very well engineered and uses less than half the air it takes to turn a China gun or CP, so it depends on the quality of the tool.

Trucks in local service that do alot of backing up have a habit of rolling the pinion nut off. After the first time of pulling the compensator, to get at it, I spot weld the pinion nut so I don't have to keep doing it over.

Gears out of the vehicle get a 2/4 stuck in the ring and pinion to tighten the nut or they start spinning pretty fast and they are real heavy and want to move around on the floor. Good for a laugh but kind of dangerous!

Gears back in the rig don't leave much choice but to put the axels in and just get it done. Spot welding the nut will make sure it stays where you want it forever and if you do that you don't have to be as critical with the torque because it ain't commin loose again. The down side is it ain't commin loose again either.