Differential imput bearing pre-load

[tgrandahl]

So i have made negative progress today... After going out this morning and buying a $16 13/32" cobalt drill bit i found it wasnt going to drill out the imput flange to my lsd. So after pulling the diff back out to fenagle it up with a drill press im just going to swap the flanges.

I know the importance of correctly pre-loading the imput bearing on the differential has been discussed before, but i cant find any specifics of how to actually do it.

Do i simply notch the nut and input shaft on the LSD similar to removing a steering wheel? It seems that im just missing a torque somewhere here thought.

Can any axle grease be used to fill the flange before connecting the drive shaft back up?

[Ross]

The trick to drilling hard material is sharp tools, low speed and lots of pressure and lubrication. The material should come out in a continuous cutting.
Buy a bit sharpener, it pays for itself fast.

[tgrandahl]

A bit sharpener does sound like a great investment, however i am a little confused as to what type of trouble i am having.

When i swapped my transmission i needed to drill out the output flange on that to 3/8" i believe, i purchased a carbide bit used a corded drill and cutting oil and did it while still on the car. My goal was to do the same this morning and i have been utterly disappointed. the cobalt DeWALT bit i picked up from lowes took off like a champ and about half way through the first hole stopped. I dropped the diff and rigged it up on a drill press to no avail.

So at that point i had two plans, (A) buy a 30mm socket and swap the flanges. (B) buy 8mm bolts and make 1mm bushings so it will fit the drive shaft. i chose A.

Now that i have the original flange off the LSD i clamped it up in the drill press again just for fun and put on one of my beater titanium nitride coated DeWALT bits and it ate through the hole like a champ! it barley even used any oil, i am very tempted to test lowes return policy. Ill admit the nitride bit was only a 3/8" and i dont have a 7/16" nitride bit, yet even bored out to 3/8" the cobalt bit still wont do jack, it just burns off all the oil i give it and then screams.



Anyways i am more concerned with the pre-loading of the bearings now as i have the flange off either way. Although i was a little aggravated to find the stamped metal collar that surrounds the nut and that my 30mm craftsman socket had to be hammered into it.



Anyways, any ideas on the bearing pre-loading. I marked the nut and shaft and counted 7 full revolutions while coming off, but isn't there just a torque in the Bentley?

[gale]

I have swapped input flanges on 2 diff's so far and no problems. What worked well with mine was to torque it to approx. 137 ft-lb with permanent Loctite. 25k miles on one since, with no abnormal noises, and 15k miles on the other, no problems.

The scribe mark method may not necessarily work when swapping flanges, since even the slightest difference in flanges will not line up the same.

What you could do is scribe the old one, loosen the nut & clean & lightly oil the threads, and use a lever type torque wrench to measure the torque required to line the marks up, and then use that torque on the swapped flange. Should be close enough.

[tgrandahl]

I have swapped input flanges on 2 diff's so far and no problems. What worked well with mine was to torque it to approx. 137 ft-lb with permanent Loctite. 25k miles on one since, with no abnormal noises, and 15k miles on the other, no problems.

The scribe mark method may not necessarily work when swapping flanges, since even the slightest difference in flanges will not line up the same.

What you could do is scribe the old one, loosen the nut & clean & lightly oil the threads, and use a lever type torque wrench to measure the torque required to line the marks up, and then use that torque on the swapped flange. Should be close enough.

Good to know you have had success with your swaps, i used a mark on the nut and i had to get my wrench up to 140ft/lbs to get it to line up again. Ill get the diff back in tomorrow, i can prob do it in 10 minutes by now and hopefully things will go better. Although i am still not sure what to use for grease. The stuff that was in there from the factory does not look like the axle grease i have laying around.

[gale]

. . i am still not sure what to use for grease. The stuff that was in there from the factory does not look like the axle grease i have laying around.

Use any full synthetic that meets the GL-5 spec. 80W90, 75W90, or 90W140 for severe/high temp conditions. Amsoil, Redline, Mobil 1, etc.

[tgrandahl]

Use any full synthetic that meets the GL-5 spec. 80W90, 75W90, or 90W140 for severe/high temp conditions. Amsoil, Redline, Mobil 1, etc.

Sorry i should have indicated grease for packing the input flange with for the cv joint on the drive shaft. I filled the diff with 75W90 Mobil 1, i read that this is fine for older limited slips and even open diffs.

[632 Regal]

you MUST have preload on the bearing or it will fail. New crush sleeve or not. I went the no crush sleeve way because I didnt have the luxury of waiting for it to arrive. I used loctite and tightened it until there was good drag while turning the input. Have to take into account the preload on the ring gear but still do-able. Gales comment of checking inch pounds prior to disassembly is great but I believe it was too late for that.

Good luck with it!

[attack eagle]

the grease is molybdenum disulfide grease

[Martin in Bellevue]

The crush sleeves are still available. The local dealer had one in stock last year when I installed the 3.23lsd. With a new sleeve, and the willingness to pull the pumpkin, you can install the input flange with the correct preload and have a better chance of not crushing that front bearing.