Driveshaft Installation

[spivey6690]

Okay so my rear driveshaft came off my 88 ranger 7.5". Pulled a new one off of a 94 ranger that will fit. Then I screwed up by pulling off the rear differential pinion nut without marking a reference. My questions are:

1. How do I know how tight to turn that replacement pinion nut?
2. How do I align the new shaft properly so that it is balanced?

 

[AgPete139]

You could have just put in the slip yoke part of the driveshaft first, and then wiggled the other side (with the flange) onto the pinion flange on the axle.

Did you take off the flange or just the pinion nut? Did the flange somehow rotate?


1.) Preload typically used is 8-14 inch-lb. Pinion torque 160 Ft/lb.

Note: If pinion bearing preload exceeds specification before this torque is obtained, install a new spacer.


2.) Well, without marking, there is no definite way to check it. You can try to compare the shape/rust/color, but that's about it. In my opinion, it will not be substantially off balanced. If there's vibration, rotate it 90 degrees. But, I don't think you'll have a huge problem with the alignment.

 

[cp2295]

Yeah I've installed my driveshaft not where it was marked before and there was zero difference.

 

[spivey6690]

It is a flange that slides onto the rear differential. The yoke bolts onto that flange. The shaft I have from the '94 requires the larger bolt pattern on the flange, so I have a replacement on the way.

I am pretty new to all of this but eager to learn. I took the whole flange off, pinion nut first. I don't understand the "pre-load" aspect of all this. What are you tightening to set the pre-load? The 160 ft-lbs on the pinion nut seems pretty straight forward. And the spacer--not sure I understand that, either.

 

[adsm08]

Anymore drive shaft indexing is only needed if you have an issue. Since the shaft is a balanced assembly it's not really a problem. That really is a carry-over from older times, even if the manufacturers still tell you to do it. I have disregarded that on many many vehicles, none of which have ever had a problem.

 

[spivey6690]

Okay, I see how the preload is set. Will I have to pull my axle out to do that?

 

[spivey6690]

Anymore drive shaft indexing is only needed if you have an issue. Since the shaft is a balanced assembly it's not really a problem. That really is a carry-over from older times, even if the manufacturers still tell you to do it. I have disregarded that on many many vehicles, none of which have ever had a problem.

Thanks! That makes life simpler.

 

[spivey6690]

Bump!

 

[adsm08]

"Preload" on a bearing is setting a certain amount of pressure on it so that it rides tightly in it's race, rather than flopping and damaging itself.

Preload is set on the pinion bearings of most Ford differentials is set through use a crush sleeve behind the flange. As the nut is tightened past a certain amount of pressure the sleeve beings to deform and crush down. This lets you make the nut really tight without locking up the bearing.

What I usually do when changing out the pinion seal, which is basically what you are doing, is to leave the crush sleeve alone, check the break away torque (the minimum amount of force needed to get the diff rolling), and then tighten the nut down until I am as close as I can get to that original break away reading.

The reason you can get away with it when just taking the flange off, but not when re-building, is because the pinion bearings get stuck when they are torqued down. They get stuck because they are pressed onto the pinion gear.

 

[tmcalavy]

Driveline only please.

 

[adsm08]

Sorry, you are wrong. His question was primarily about drive shafts, which doesn't fit neatly and clearly into any of the other topics.

 

[spivey6690]

"Preload" on a bearing is setting a certain amount of pressure on it so that it rides tightly in it's race, rather than flopping and damaging itself.

Preload is set on the pinion bearings of most Ford differentials is set through use a crush sleeve behind the flange. As the nut is tightened past a certain amount of pressure the sleeve beings to deform and crush down. This lets you make the nut really tight without locking up the bearing.

What I usually do when changing out the pinion seal, which is basically what you are doing, is to leave the crush sleeve alone, check the break away torque (the minimum amount of force needed to get the diff rolling), and then tighten the nut down until I am as close as I can get to that original break away reading.

The reason you can get away with it when just taking the flange off, but not when re-building, is because the pinion bearings get stuck when they are torqued down. They get stuck because they are pressed onto the pinion gear.

Okay, I think I understand. When checking the breakaway torque, do I need to take my tires and drums off, or is it okay to just elevate the rear end?

 

[AgPete139]

Okay, I think I understand. When checking the breakaway torque, do I need to take my tires and drums off, or is it okay to just elevate the rear end?

Neither. You can leave everything touching the ground (unless, of course, you can't fit under your truck).

If you lift the rear or allow the tires and everything to spin freely, then when you go to check the breakaway readings, the entire axle assembly will rotate instead. Of course, you can apply the parking brake to lock the assembly in place. But, again, if you do this, it's just extra work than is necessary.

With the d-shaft off, the tires on the ground, wheels chocked / parking brake on, get your torque wrench + socket and take off the pinion nut. Remember the reading / number right as the nut starts to spin.

 

[spivey6690]

Neither. You can leave everything touching the ground (unless, of course, you can't fit under your truck).

If you lift the rear or allow the tires and everything to spin freely, then when you go to check the breakaway readings, the entire axle assembly will rotate instead. Of course, you can apply the parking brake to lock the assembly in place. But, again, if you do this, it's just extra work than is necessary.

With the d-shaft off, the tires on the ground, wheels chocked / parking brake on, get your torque wrench + socket and take off the pinion nut. Remember the reading / number right as the nut starts to spin.

The problem is that I already removed the nut without checking. Any suggestions?

 

[AgPete139]

Put it all back together. Apply the torque we suggested above.

Shouldn't be too bad. It needs to be tight enough to not back off, but tight enough for a load on the pinion gear.

At this point, I'd apply the 160 ft-lb and call it a day while the wheels are on the ground and chocked. The truck will want to move when you tighten the pinion nut.

Good luck.


Oh, NOTE: Do not crank the crap out of it. Be methodical and smooth on applying the pressure. Do not over tighten it. This will cause your gears to grind later down the road if you're not careful.