bkahler Posted January 1, 2020 Report Share Posted January 1, 2020 Well it may be a new year but it's not necessarily starting out as a good year ? Back when I started the rebuild I took the pumpkin to a local shop to have them go through it and replace bearings. One thing to keep in mind is a lot of things that happened back in that time frame were taking place while I had just brief periods of time at home so I would rush around taking care of things and then leaving town again. When I picked up the pumpkin from the shop all I did with it was slap it into the diff housing and left town again. Thinking back I vaguely remember that it turned a little stiff but assumed it wasn't an issue, besides, I didn't have time to think of the alternative. Then came the move from Nebraska that ultimately ended up here in Kentucky. Fast forward to today and for what reason I don't know but I had been thinking that I needed to adjust the axle spacing with shims behind the backing plates to fix the problem. I should have known that wasn't the problem. Unfortunately memories don't return until I really start digging back into things! So, after pulling the axles this morning I found that the pumpkin is as hard or harder to turn than I remembered. Basically it's really difficult to turn the output yoke by hand. I've now pulled the pumpkin and need tutoring on what to do next I'd like to tear into it myself but it sure would be nice if someone could point me to an appropriate video or two and or some good advice. Thanks! Brad Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted January 1, 2020 Report Share Posted January 1, 2020 First thing I would do is check the backlash of the gears. O don’t have the spec handy, but there should be a small amount of movement of each gear before it contacts, and moves, the other gear. When doing this, you should be able to determine if the pinion bearings are stiff, or if it’s the diff carrier bearings (making the ring gear hard to turn). Or maybe there’s zero backlash causing the tightness. After these initial checks you should be able to determine where the problem lies. Either way it may require a disassembly/ reassembly to correct the setup. 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 1, 2020 Author Report Share Posted January 1, 2020 31 minutes ago, Merle Coggins said: First thing I would do is check the backlash of the gears. O don’t have the spec handy, but there should be a small amount of movement of each gear before it contacts, and moves, the other gear. When doing this, you should be able to determine if the pinion bearings are stiff, or if it’s the diff carrier bearings (making the ring gear hard to turn). Or maybe there’s zero backlash causing the tightness. After these initial checks you should be able to determine where the problem lies. Either way it may require a disassembly/ reassembly to correct the setup. I can check the backlash but will first have to figure out how to do that! I've never worked on a diff before. However, looking closer there is a powdery dusty type substance on some of the castings and parts. My guess is it's the result of condensation buildup over the last 20 years. Aso there doesn't appear to be a lot of lubricant inside at all which concerns me. I'm thinking the best option is likely going to be to tear it down and just put it back together again, by the book. At least that way I will know what shape it's in. With that in mind I guess I'll dig through the service manual to see if it can educate me. Does this diff use a crush collar on the pinion or is the pinion nut torqued to a set value? Thanks, Brad Quote Link to comment Share on other sites More sharing options...
PT81Jan Posted January 1, 2020 Report Share Posted January 1, 2020 It is not very complicated to do the adjustment, I have done it also for the first time two years ago. Just a bit patience needed and first to understand how the parts work together. There are different reasons why the gears are hard to turn. Do you have a manual which shows your type of diff ? Sorry mine is a little different. Maybe that helps a bit ? -> https://p15-d24.com/topic/40534-differential-disassembly/?tab=comments#comment-430298 -> #3 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 1, 2020 Author Report Share Posted January 1, 2020 I do have the factory service manual and it assumes you've been trained. Unfortunately I haven't! I wondering if it's not something as simple as the opinion nut being to tight. I'll spend some time tomorrow evening to see if I can see where the tightness is. Quote Link to comment Share on other sites More sharing options...
JBNeal Posted January 2, 2020 Report Share Posted January 2, 2020 I believe pinion nut tightness is defined as pre-load, which is spec'd out in the manual along with backlash...these carriers do not have a crush collar but do have carrier bearing adjusters. I did my first differential rebuild on the '48, basically took it all apart, cleaned and inspected everything to find only needed a new pinion seal, then put it all back together following the shop manual...only special tools I needed were an in-lb beam torque wrench and a dial indicator, plus a firm work surface to set everything, used a big pipe wrench to hold the pinion yoke in place while adjusting the pinion nut. Getting the teeth contact pattern right with the adjusters while maintaining backlash was the most tedious part of the process, I used ground up old yellow crayons to show the gear meshing but there are other ways to do that thanks to other guys' experiences on the internets...the only thing I oiled was the pinion shaft so I wouldn't damage the pinion seal, everything else was dry more or less to get accurate measurements. I'd suggest leaving it all together, run compressed air through the bearings and turn the pinion for a few minutes, blowing out the bearings occasionally, and see if the dry bearings loosen up a bit...then check preload, backlash and the gear contact pattern, adjust as required 1 Quote Link to comment Share on other sites More sharing options...
kencombs Posted January 2, 2020 Report Share Posted January 2, 2020 I think I can see traces of rust in spots. That would be my first task, remove every trace of that. There are a lot of ways to do that, but for this I'd use Evapo-rust. It is safe to use as it doesn't attack steel as some methods do. You can probably do it with a gallon. Pour in a bucket large enough to sit the unit, gears down. Soak and the turn the diff gear side up and pour the stuff into it. That way you can get all of the gears and bearings treated. Now flush well with water and blow dry. Spray with wd40. this is one of the few uses where wd40 excels. Now you should have all the possible hidden rust cleared out, a light lube that won't interfere with measurements and can assess the cause of the tightness. It is normal for them to have some resistance. first is the measured preload on the pinion setup. then add the carrier bearings drag and the friction from the gear contact. IMO it may be likely that once cleaned and lightly lubed, your fears may be unfounded. Hope So!! 1 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 2, 2020 Author Report Share Posted January 2, 2020 10 hours ago, JBNeal said: I believe pinion nut tightness is defined as pre-load, which is spec'd out in the manual along with backlash...these carriers do not have a crush collar but do have carrier bearing adjusters. I did my first differential rebuild on the '48, basically took it all apart, cleaned and inspected everything to find only needed a new pinion seal, then put it all back together following the shop manual...only special tools I needed were an in-lb beam torque wrench and a dial indicator, plus a firm work surface to set everything, used a big pipe wrench to hold the pinion yoke in place while adjusting the pinion nut. Getting the teeth contact pattern right with the adjusters while maintaining backlash was the most tedious part of the process, I used ground up old yellow crayons to show the gear meshing but there are other ways to do that thanks to other guys' experiences on the internets...the only thing I oiled was the pinion shaft so I wouldn't damage the pinion seal, everything else was dry more or less to get accurate measurements. That's good news about the crush washer, or lack thereof. I feel more comfortable working on it knowing that doesn't exist. I've got all of the tools you describe, except for the crayon Testing pre-load dry would explain why the unit is dry now. 10 hours ago, JBNeal said: I'd suggest leaving it all together, run compressed air through the bearings and turn the pinion for a few minutes, blowing out the bearings occasionally, and see if the dry bearings loosen up a bit...then check preload, backlash and the gear contact pattern, adjust as required The only thing that worries me about using compressed air at this point is all of the powered dust/rust whatever it is that is coating various area. Thinking back to when I picked it up from the shop I don't remember it being as hard to turn as it is now. 20 years of sitting wasn't kind to it. Currently it's a two handed effort to turn the pinion. Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 2, 2020 Author Report Share Posted January 2, 2020 10 hours ago, kencombs said: I think I can see traces of rust in spots. That would be my first task, remove every trace of that. There are a lot of ways to do that, but for this I'd use Evapo-rust. It is safe to use as it doesn't attack steel as some methods do. You can probably do it with a gallon. Pour in a bucket large enough to sit the unit, gears down. Soak and the turn the diff gear side up and pour the stuff into it. That way you can get all of the gears and bearings treated. Removing the dust/rust/ect has been my first thought as well. How long should it be soaked before flipping over? 10 hours ago, kencombs said: Now flush well with water and blow dry. Spray with wd40. this is one of the few uses where wd40 excels. Now you should have all the possible hidden rust cleared out, a light lube that won't interfere with measurements and can assess the cause of the tightness. What is odd is back when I installed the pumpkin in the diff housing I don't remember it being this hard to turn. The point at which it seemed hard to turn was after I re-installed the axles and the backing plates. At that point I figured I needed to possibly add backing plate shims. So when I pulled the axles yesterday and found the pinion still difficult to turn I was somewhat surprised. I know what 20 years has done to me so I can only imagine how the truck must feel ? 10 hours ago, kencombs said: It is normal for them to have some resistance. first is the measured preload on the pinion setup. then add the carrier bearings drag and the friction from the gear contact. IMO it may be likely that once cleaned and lightly lubed, your fears may be unfounded. Hope So!! I'm not holding my breath but I am hopeful Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 2, 2020 Author Report Share Posted January 2, 2020 Last night I was browsing through an old Chilton's that I have and found a pretty decent one page write-up for working on the differential. 1 Quote Link to comment Share on other sites More sharing options...
kencombs Posted January 2, 2020 Report Share Posted January 2, 2020 The only really difficult part of working differentials, at least IMO, is setting the pinion depth. Since that should have been already done, you should have no problem. 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 2, 2020 Author Report Share Posted January 2, 2020 10 minutes ago, kencombs said: The only really difficult part of working differentials, at least IMO, is setting the pinion depth. Since that should have been already done, you should have no problem. Needless to say I really hope you're right! Time permitting I'm going to look a little closer at things and move forward from there. Thanks! Brad Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted January 2, 2020 Report Share Posted January 2, 2020 Hopefully none of the bearings have micro rust pitting. 1 Quote Link to comment Share on other sites More sharing options...
Tooljunkie Posted January 3, 2020 Report Share Posted January 3, 2020 9 hours ago, Dodgeb4ya said: Hopefully none of the bearings have micro rust pitting. Not saying thats a huge problem,but close inspection is necessary. i would pull the ring gear and see whats hanging up. If its pinion, try lubricating it. 15 to 20 inch pounds rolling torque is the norm on most conventional diffs. The principle is the same across all the differentials of similar design. As far as tolerances go, i try to keep them as close To spec as possible. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted January 3, 2020 Report Share Posted January 3, 2020 (edited) The barrel differential side cap can be tough to unscrew with out the proper tooling. I have seen especially on the 1 tons that cap coming loose...the lock pin coming loose probably from previous improper replacement. Those side caps have to be properly tightened , drilled and re pinned to prevent coming loose. I doubt bkahler will have to get inside the diff case. Edited January 3, 2020 by Dodgeb4ya Get to show more tools! 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 3, 2020 Author Report Share Posted January 3, 2020 You're getting into areas that I currently know nothing about. I'm really hoping to keep this diff, it's original and it's a 3:73. First I'm going to try what Ken suggested which is soaking it in Evapo-rust and then washing it off. Until I've got the junk out of their I'm leery of just blowing air through it. I'm hoping to pick up some Evapo-rust this morning along with a bucket. It's going to be raining all day but the temps will be in the 50s so running a garden hose won't be to intolerable Thanks! Brad Quote Link to comment Share on other sites More sharing options...
Radarsonwheels Posted January 3, 2020 Report Share Posted January 3, 2020 Looks a lot like an 8.75 from the muscle car era Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 4, 2020 Author Report Share Posted January 4, 2020 1 hour ago, Radarsonwheels said: Looks a lot like an 8.75 from the muscle car era I believe that is correct. It's currently soaking in Evapo-rust. I'll give it a day or so and then take a look at the progress..... Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 4, 2020 Author Report Share Posted January 4, 2020 The only container I could find big enough to hold the pumpkin required two plus gallons to even get close to the top of the housing. While it was soaking I decided to take advantage of the fluid and added a bunch small parts to the bath. Amazon is delivering a 3rd gallon tomorrow at which time I'll remove the small parts and lay the pumpkin on its side. Quote Link to comment Share on other sites More sharing options...
JBNeal Posted January 5, 2020 Report Share Posted January 5, 2020 The last differential that I rebuilt was the Dana 80 in The Blue Bomber...preload went OK, but backlash was a bear since the Dana 80 uses shims, requiring the carrier to be removed completely to re-shim, re-install, re-torque caps, re-measure backlash...I kept getting .002" under to .002" over specs by changing shim combinations...after the 4th re-shim, it was .001" under, I stewed on that while taking a break to work on something else and reasoned that setting the backlash just a little on the tight side would be OK since all the bearings were new and in time they would wear enough that backlash would eventually get back within specs...so if ya find yourself getting just a whisker on the tight side with backlash, that just means you'll need to drive the truck more to wear it in 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 6, 2020 Author Report Share Posted January 6, 2020 18 hours ago, JBNeal said: The last differential that I rebuilt was the Dana 80 in The Blue Bomber...preload went OK, but backlash was a bear since the Dana 80 uses shims, requiring the carrier to be removed completely to re-shim, re-install, re-torque caps, re-measure backlash...I kept getting .002" under to .002" over specs by changing shim combinations...after the 4th re-shim, it was .001" under, I stewed on that while taking a break to work on something else and reasoned that setting the backlash just a little on the tight side would be OK since all the bearings were new and in time they would wear enough that backlash would eventually get back within specs...so if ya find yourself getting just a whisker on the tight side with backlash, that just means you'll need to drive the truck more to wear it in I'm not sure where things stand just yet. I still have the pumpkin soaking in Evapo-rust. I've removed all the little parts and the pumpkin is now laying on it's side. I ran my gloved fingers inside the splined openings where the axles slide and it got covered in a gooey greasy substance. What I'm wondering is if the grease they used when setting it up 20 years ago solidified making it stiff to turn. I found the receipt for the rebuild and it lists all new bearings so it was completely disassembled and put back together again. I'm fairly confident the shop that did the work did it right. They had always done good work int the past. They are friends of the family and had always been honest and above board with their work. If I have to add shims to the pinion is there a source available for them? Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 6, 2020 Author Report Share Posted January 6, 2020 (edited) Answered my own question. So worst case is I can buy and installation kit. Or.....maybe not. What size of differential is installed in the B3B trucks? I had assumed it was the 8-3/4 with 1-3/8 pinion but now I'm not so sure! What search term(s) would I use while trying to find appropriate shims, etc? Thanks! Brad Edited January 6, 2020 by bkahler Quote Link to comment Share on other sites More sharing options...
JBNeal Posted January 6, 2020 Report Share Posted January 6, 2020 If that's the original carrier, I reckon it is not the 8-3/4 that you are pricing parts because the original does not use shims to adjust backlash. From your pics, your carrier appears to have the bearing adjusters that screw in and out of the casing for bearing adjustments...these are donut-shaped with 14 smaller holes on the flange parallel to the brake backing plates...this gives an infinite amount of adjustment instead of the limited shim adjustments on modern carriers. The setup instructions in the factory shop manual appear more accurate than the Chilton manual you have pictured as the fsm goes into detail about setting the adjusters for backlash and locking them in place, etc. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted January 6, 2020 Report Share Posted January 6, 2020 I would clean up your rear end carrier completely. Look for any pit rusting...if any is found on any bearings...disassembly and replacement will be necessary. Gears if you find a small pit here or there..wouldn't worry too much. Bearings.. any rust marks... the bearings are done. If no issues of rust...oil the gears and bearings make sure it turns over semi firmly and smoothly....install it and set axle end play. The front seal and pinion seal surface might need to be looked at too. 1 Quote Link to comment Share on other sites More sharing options...
bkahler Posted January 6, 2020 Author Report Share Posted January 6, 2020 1 hour ago, JBNeal said: If that's the original carrier, I reckon it is not the 8-3/4 that you are pricing parts because the original does not use shims to adjust backlash. From your pics, your carrier appears to have the bearing adjusters that screw in and out of the casing for bearing adjustments...these are donut-shaped with 14 smaller holes on the flange parallel to the brake backing plates...this gives an infinite amount of adjustment instead of the limited shim adjustments on modern carriers. The setup instructions in the factory shop manual appear more accurate than the Chilton manual you have pictured as the fsm goes into detail about setting the adjusters for backlash and locking them in place, etc. Just goes to show you I've got a lot to learn about this diff and diffs in general. Is it possible to remove the ring gear assembly in such a way that all I would have to do is bolt it back in place? Same for the pinion nut, can I remove it and then replace it without affecting anything? 28 minutes ago, Dodgeb4ya said: I would clean up your rear end carrier completely. Look for any pit rusting...if any is found on any bearings...disassembly and replacement will be necessary. Gears if you find a small pit here or there..wouldn't worry too much. Bearings.. any rust marks... the bearings are done. Depending on weather this week I might try and hose it down one night after work. Otherwise that will have to wait until Friday. I'm going to continue to rotate it around in the Evapo-rust bath to get as much coverage as I can. 28 minutes ago, Dodgeb4ya said: If no issues of rust...oil the gears and bearings make sure it turns over semi firmly and smoothly....install it and set axle end play. The front seal and pinion seal surface might need to be looked at too. The pinion seal was new and a speedi-sleeve was also installed during the rebuild. Since the rebuild 20 years ago the diff was never placed into service. I haven't tried to rotate the pinion since I set it in the bath but might try to do so tonight to see if anything has changed. Thanks, Brad Quote Link to comment Share on other sites More sharing options...
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