Can someone explain rolling torque, when setting the drive pinion preload??


when they say rolling torque what do they mean. Please explain.

Thanks,
Al

 

In this case it means that you have two tapered timken style bearings with the bearing cones facing each other. The torque in this case is that "effort" that is required to turn the pinion shaft as the pinion shaft has slightly less than zero end play. IE the bearings are being held together under a slight preload.

If the bearings do not have this preload (and the amount of preload is measured by the rolling torque) the shaft will walk sideways and throw the pinion gear out of alignment.

David

 

Thanks Dave,

[QUOTE=If the bearings do not have this preload (and the amount of preload is measured by the rolling torque) the shaft will walk sideways and throw the pinion gear out of alignment.

David[/QUOTE]

When you say, throw the pinion gear out of alignment; will this cause the rear to lock up? and also how do I / or go about measuring the "rolling torque"

Please explain if you would, step by step procedure in measuring rolling torque in order to obtain the proper setting of the pinion.

This what I've done.
I had to replace the pinion seal. I removed the flange nut without counting the turns while removing the nut. Then I was told that the pinion nut needed at least 350 - 400 ft LB torque. So I used a 18" monkey / pipe wrench on the flange, and a 24" 1/2 drive breaker bar w/ a 4 ft pipe on the ratchet and snugged the pinion nut pretty tight. I then installed it to the 3rd member reinstalled the drive shaft, and took for a test run. I first went back and forth in my yard everthing seemed to fine, no noise. I then took it on the road / around the block, when I reached about 25mph + the rear locked up. I then had to shift to nautral and rock it back and forth to unlock the rear. Once it unlocked I drove it another 100 ft and it locked up again, and again I had to rock it to unlock it.

So! trying to make a long story short, I got some other info on setting the pinion preload, this is what they said;

The torgue is rolling torque, not torque on the nut. And if you notice it is measured in inch pounds, so with the inner diff carrier,removed just the pinion installed make sure you use a beam style inch pound torque not a clicker style. ( I'm not sure I understand this part in bright red) >Roll the pinion around and watch the beam make sure put a little grease on the bearings this

keeps it from jumping, and tighten the pinion nut with a good impact small burps when the sleeve starts to crush it could go fast! and do so till the beam reads 20 to 25 inch pounds of rolling torque and you should be good to go! ( < does he mean put the torque wrench on the nut and roll the pinion gear by hand until the beam on the torque wrench reads 20 - 25 inch pounds) Just remember inch pound beam style not foot pound!! they may be tough to find but when you have one setting pinion preload will be correct every time! This info was obtained on ebay??

Thanks for your time,
Al

 

http://www.autozone.com/servlet/UiBr...3d800a8cf0.jsp

You want to measure the "rolling resistance" of the pinion without the axles in place. the best way to do this is with the carrier in a vice. That way you can check the resistance and bump the pinion nut up tighter with an impact wrench. You can do it under the truck, but you have to have clearance to turn the torque wrench a full circle on the pinion nut.

Put the beam type torque wrench on the pinion nut and watch the pointer as you turn the pinion through a couple of slow revolutions with the wrench. If you see more than 20 in-lbs indicated, you've probably gone too far and will have to start over with a new crush sleeve.

That said, I don't think "too tight" would cause the lock-up problem you describe. It would cause premature failure of the pinion bearing. Lockup could be caused by "too loose" or maybe even a problem in how the brakes went back together.

 

Sport45 said it pretty well . I agree, I don't think that it would cause a rear end lock up.

You need to get a factory service manual before you go any further.

At least that way you wil have something with pictures and words to follow along on -

You don't want to be doing this job again in a few thousand miles, nor do you want ot have a failure along with the potential for a accident / collision if the axle locks up.

David

 

Thanks Guys,

I'm going to check the brakes!

Also I was a bit confused at end of re-install. Listen, before I done anything with the removale of the pinion and carrier housing, I was able to turn the passenger side rear axle, and while turning the axle I could see the flange turning also. Here's what confused me on the re-install after putting it all back together except for the drive shaft.When I was turning the rear axle the flange was not turning, but if I turned the flange, the axle would turn what could that be.

Looks like I'm about to become a rear-end machanic, I'm sure the brakes went back together the same way they came off. But! one never knows?

I have another question; the tag on the rear has 2 rows of numbers can you ID the rear for me. the tag reads- S316D < TOP # BOTTON # > 3 00 9 6E28

It's from a 1986 f150 2wd.

never mind the Id, I got it. top number S316D is Plant code the bottom is 3.00 axle ratio 9 is ring gear dia. 6 stands for yr, E stands for month and 28 stands for day.



Al

 

What you are describing could be an indicator of excessive preload on the pinion bearing. Before, everything was turning free and when you turned the axle the other axle either remained stationary or turned the same direction and the ring gear spun the pinion. Now, it sounds like the pinion isn't turning as freely and the differential is turning the other axle in the opposite direction instead. This is normal action for an open differential. I'd pull the carrier and go back with a new seal and crush sleeve. Maybe see if something in there is something keeping the yoke from going all the way down like you mentioned. Is there a gap in the splines to index things? Put it back together on the bench using an inch-lb torque wrench to check the preload as you incrementaly tighten the yoke nut.

Don't take the carrier apart unless you absolutely have to. Setting gear mesh isn't for the faint of heart.

Good luck and keep us posted. We're here to help.

 

Sunday I'll take the carrier off and check the pre-load, I do think I tightend the pinion too much. I may just take it all apart and start from scratch. Like replace the crush sleeve and maybe the bearrings. I'll see once I have the carrier out. I'll keep all, posted. I need to ask this ? . Can I go from 3.00 ratio gear and pinion to 3.25 ratio with out having to replace the axles or rear axle housing???

Thanks,
Al

 

Yes, that's the beauty of the Ford 9". You can just pop out the 3.00 ratio "chunk" and install whatever ratio you want. No setting up gears or anything. If you're changing ratios anyway, just go to a wrecking yard and pick up a 9" to your liking. You may have to buy the whole axle, but all you need to install is the carrier. If it's out of a truck everything else should fit. (The only thing that might be different IIRC is the spline count on the axles, 28 for cars and 31 for trucks.)

When you're done, put your 3.00 carrier and tag (keep the tag from the donor) on the junkyard axle and take it back to them. Write "Bad Pinion" or something like that on the axle tube with a paint pen so the next guy can be properly warned.

 

Thanks Sport,

Someone is selling a pinion w/ ring gear and a diff with 28 splines already disassembled. the pinion and flange/yolk is fully assembled and has 12 teeth. Not sure what my truck has, either 12 or 13. if it's 12 then I'll purchase the complete pinion that's already together and just mount to the carrier housing. that may work, Yes?

Al