torque wrench

rer_239

rer_239

Senior Member
the books tell me to adjust the (differential) pinion preload to 20 inch lbs of drag. i don't have a wrench that registers inch lbs. both of mine are foot lbs. is there a way to convert it?
thanks
rer_239
 
You need to use a Inch Pound Torque Wrench as a Foot Pound Torque Wrench will not be accurate if it's a Typical 0 to 150 foot pounds.
 
Much easier to check with a short wrench and some weights wired on the end. 1" long would be 20lbs. 5" long would be 4lbs, 10" would be 2lbs (a couple of large sockets). Just start the wrench in the horizontal position.

or take a long wrench and place the weight so far from the center.
 
It is easy enough to set the pre-load on the carrier and the pinion bearings by feel. Rotate each by hand; they should turn freely with some amount of stiffness. You don't want it to spin free and you don't want to have to apply tremendous hand force to turn it. It should be somewhere in the middle. Use your common sense while turning it. Does it feel close to spinning free, then tighten some more. If it is really difficult to turn looses it a bit.

You don't have to get it dead on 20 inch pounds. Anything above 14 and below 22 will be perfectly acceptable.

I would not attempt to set it with a math conversion for a foot pound torque wrench. If you are going to set it with a torque wrench you need an inch pound dial indicator torque wrench that reads out the value once it is turning.

In past years most people who tried to overhaul the rear axle assembly did not know about setting pre-loads. The suppliers didn't help any by providing two .010 banjo gaskets for an overhaul. People would button up the rear with the two gaskets with no thought to pre-load. In most cases they had it way too tight. Henry's 40 horses would break it loose by spinning the bearings on the mounts. That is why most that I take apart I find the bearings spun.

The fact that you know and understand about pre-load is most of the battle. Set it by feel.

Tom Endy
 
Harbor Freight had an inch # torque wrench a few months ago, may be still available.
May need an adapter from the wrench drive to fit.
 
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What Tom says. It is difficult to convey "touch" gained by experience through the written word. Like he said, the shaft should turn without too much resistance but not spin freely. I hold the shaft between thumb and forefinger for a better feel. Be aware that if the weight of the shaft is on the bearing when you test it, you will not get a good feel. I use a short dummy shaft to avoid this and one the preload is adjusted properly, the pinion bearing "pack" is put into the housing, dummy shaft removed and the proper shaft installed. (Well, that's how I do it.) With no shaft in the bearing pack and a finger poked into the tapered hole, you should still be able the turn the bearing but feel some drag.
Hope this conveys at least in part, the "feel".
 
An engineer friend tested several inch pound torque wrenches for the RadLab. None were very accurate. I have seen the setting of pinion drag demonstrated where the banjo had all the set up in it and was spun by hand with a health pull. If it made a full revolution around the driveshaft before stopping they called it good. I did mine to spin about 1 1/2 turns as I felt the one turn might be too tight. rather a bit loose than spin a bearing. So far that is working well for me.
 
Synchro909 said:
What Tom says. It is difficult to convey "touch" gained by experience through the written word. Like he said, the shaft should turn without too much resistance but not spin freely. I hold the shaft between thumb and forefinger for a better feel. Be aware that if the weight of the shaft is on the bearing when you test it, you will not get a good feel. I use a short dummy shaft to avoid this and one the preload is adjusted properly, the pinion bearing "pack" is put into the housing, dummy shaft removed and the proper shaft installed. (Well, that's how I do it.) With no shaft in the bearing pack and a finger poked into the tapered hole, you should still be able the turn the bearing but feel some drag.
Hope this conveys at least in part, the "feel".
Click to expand...

I like your way! Put a finger in the hole and feel! Practice makes for perfect :-)
 
I believe Tom also likes the 20-25 inch lbs. to rotate the carrier with bearings installed and trumpets installed. An extra spider gear holder drilled for a 3/8 bolt is then spun thru the trumpet axle hole and beam style torque wrench used. Use selected side gaskets to get this preload and pinion ring gear pattern and backlash. Shims can also be made and placed behind differential side carrier races.
 
Yep, its not a good practice to try and tighten something to 1.6 #/ft.
Pre-load on differential bearings [or most] can be set by 'hand' as mentioned.
 
I use an inch pound wrench on any torque value under 50 ftlbs,way more accurate.The value you're looking for is just enough for the bearing rollers to make contact in the races and turn,no actual preload in the text book sense.Tapered roller bearings should err to the loose side during set up by feel.
 
buy one as they are cheap . if you cant find one , ill send you mine ........... steve

harbor freight !!!!!!!
 
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