- Thread starter
- #61
Ok...I thought I was supposed to set the pinion preload to that magic 6-11in-lb number.
Ring gear backlash question
- Thread starter RWBeringer4x4
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- Thread starter
- #63
so...given that I set the preload with the diff assembled, I should have been shooting for 20? I'm starting to think I should probably just run this and see what happens...The ring gear backlash is good, there is certainly way more preload on the pinion than there used to be (and no play)...What's the worst that could happen? Seems like if this diff didn't grenade before, it probably won't now...but (clearly) I'm clueless when it comes to this stuff.
There is a separate pinon preload vs total preload on most gear sets . If there isn't enough preload against the carrier bearings the ring gear can deflect away from the pinion and create a bad pattern and in some cases fail . That is on the extreme end just as an example , the Toyota 8" & 9.5" use a steep bearing angle that can take a lot of force compared to some others out there . Again , there are extreme examples and I'm pointing out how I do my own - it's for long term reliability and maximum strength .
Pinion starting preload -
New bearing - 16.5-22.6 in-lb
Used bearing - 7.8-11.3 in-lb
In the Toyota manuals it does state to start from a zero side play point and adjust a further one to two notches tighter to preload the carrier bearings . This is with all 4 of the bearing cap bolts tightened far enough to just compress the lock washers flat - make certain to use some light oil on those adjuster threads as these steps will have a different outcome when the adjusters are oiled so they can be turned easily . I preload mine a bit further , most times around 3 notches or simply by giving the adjusters a good hard tug with my tool - similar to yours but made from wide flat stock with heat-treated pins . From that point you adjust both bearing adjusters in the same direction to set backlash to specification , .0059 - .0079" . Then , measure the preload at the pinion nut for total load force on all 4 bearings - 3.5-5.2 in/lb plus (+) drive pinion preload set earlier . Most people miss this step and this is what causes failures of the carrier bearings and gear set .
At that point the carrier bearing cap bolts are tightened and contact pattern checked by holding drag force against the ring gear while using your favorite marking compound . The rest is basic stuff ....
I have found that you can seriously increase side loading on the carrier bearings before hardly changing the total load force , hence my earlier statement about giving some additional torque to those carrier bearing adjusters . Yes , you can go too far and I have tested that theory on a basically junk 8" Toy gear - it did fail pretty easily with both bearings being basically burned - but that took a 2' breaker bar . Any other gear set I've done in the last 20yrs is still running except one Ford 9" that was run with no oil ....
Sarge
Pinion starting preload -
New bearing - 16.5-22.6 in-lb
Used bearing - 7.8-11.3 in-lb
In the Toyota manuals it does state to start from a zero side play point and adjust a further one to two notches tighter to preload the carrier bearings . This is with all 4 of the bearing cap bolts tightened far enough to just compress the lock washers flat - make certain to use some light oil on those adjuster threads as these steps will have a different outcome when the adjusters are oiled so they can be turned easily . I preload mine a bit further , most times around 3 notches or simply by giving the adjusters a good hard tug with my tool - similar to yours but made from wide flat stock with heat-treated pins . From that point you adjust both bearing adjusters in the same direction to set backlash to specification , .0059 - .0079" . Then , measure the preload at the pinion nut for total load force on all 4 bearings - 3.5-5.2 in/lb plus (+) drive pinion preload set earlier . Most people miss this step and this is what causes failures of the carrier bearings and gear set .
At that point the carrier bearing cap bolts are tightened and contact pattern checked by holding drag force against the ring gear while using your favorite marking compound . The rest is basic stuff ....
I have found that you can seriously increase side loading on the carrier bearings before hardly changing the total load force , hence my earlier statement about giving some additional torque to those carrier bearing adjusters . Yes , you can go too far and I have tested that theory on a basically junk 8" Toy gear - it did fail pretty easily with both bearings being basically burned - but that took a 2' breaker bar . Any other gear set I've done in the last 20yrs is still running except one Ford 9" that was run with no oil ....
Sarge
- Thread starter
- #65
Ok, let's back this up a few steps here - when I pulled this differential, it was running basically zero preload at the pinion...The plan was not to go through an entire rebuild/reset of the diff, as it was way beyond the scope of what I thought was necessary (and, quite honestly, capable of). All I set out to do was snug everything up a bit (since it was out). The ring gear was *a little* loose at 0.012. Using the adjusters, I dialed it in to 0.007. This only involved tightening on adjuster 3 notches. The other adjuster is tightened about one notch beyond "finger tight." Since I never intended to completely disassemble this gear-set (was running fine when pulled) is there a good chance I've actually made things worse?
Based on what I've done so far - shaving down the washers and re-shimming the pinion (WHILE INSTALLED). What I was really measuring was the TOTAL pinion preload, correct? Tightening the backlash at the adjusters may have increased this a little further, theoretically, but I'm guessing that my Total preload is still probably "low" based on the factory manual, right?
That said, have I done more harm than good at this point? I've been messing with this thing for the better part of a month, and probably should have left well enough alone...
Based on what I've done so far - shaving down the washers and re-shimming the pinion (WHILE INSTALLED). What I was really measuring was the TOTAL pinion preload, correct? Tightening the backlash at the adjusters may have increased this a little further, theoretically, but I'm guessing that my Total preload is still probably "low" based on the factory manual, right?
That said, have I done more harm than good at this point? I've been messing with this thing for the better part of a month, and probably should have left well enough alone...
- Thread starter
- #66
Bump for opinions. @Weber Sarge and @Pin_Head - I'm leaning toward just running it and seeing what happens. In my head, SOME preload (~9-10in. lbs.) and NO play in the pinion, plus a ring gear dialed in from 0.012 to 0.007 should not be that massive a change that something detonates on me. The ring gear was dialed in by adjusting one of the carrier adjusters 3 notches tighter...Which, according to Sarge, should not be an issue... LOGIC dictates that things will probably be OK, or slightly better than the "OK" things were when I started. Now, LOGIC and ENGINEERING do not necessarily go hand-in-hand. What do you guys, as veterans of this type of stuff, think?
At this point, with summer coming to a close and with no good "shop" to work out of, I'm more concerned with further messing with things outside of my control. Clearly, I've bitten off more than I can chew with this particular project...
At this point, with summer coming to a close and with no good "shop" to work out of, I'm more concerned with further messing with things outside of my control. Clearly, I've bitten off more than I can chew with this particular project...
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- #68
Then I'll slap a pinion seal in and run it (and keep my fingers crossed).
Moving forward to the rear differential, I KNOW I have a small amount of play in the rear pinion. I've pulled the cover, and the gears seem OK. As opposed to going through all of this again and potentially doing more harm than good, would it make sense just to re-shim the pinion, tighten it back up, and run it?
Moving forward to the rear differential, I KNOW I have a small amount of play in the rear pinion. I've pulled the cover, and the gears seem OK. As opposed to going through all of this again and potentially doing more harm than good, would it make sense just to re-shim the pinion, tighten it back up, and run it?
- Thread starter
- #70
So, the previous discussion brings up another point - if I re-shim the rear's pinion (while still assembled) to eliminate the play, should I be targeting the 6in-lb "pinion only" preload, or the 20in-lb "final preload"
pb4ugo
SILVER Star
Usually the pinion is set 1st. I'd see if there any resistance in the assembly 1st. If there's none or very little & the pinion is loose & you know the bearings are good. Then you could set the pinion preload w/the assembly still together. I'd try to hit the lower resistance number because you are using the old bearings. If the bearings are questionable then you should pull the carrier to get to the pinion.
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- #72
@pb4ugo - Back at the beginning of the thread, you'll find that when I initially pulled the differential, there was no play in the pinion, but also ZERO preload (or not enough to register on an inch pound torque wrench). Everything else in this thread is a downward spiral from there. I re-shimmed the pinion first (without disconnecting the carrier/ring gear) to get the 6-11in.lb. target for used bearings. Then adjusted the ring gear backlash at the adjusters by rotating one adjuster 3 clicks, which brought the backlash from 0.012 to 0.007. I'm a little worried that this messed up the contact pattern, but I'm going to run it and see.
Installed the seal today. With the seal installed and the ring gear adjustment I'm at about 13lbs total pinion preload, still no play.
pb4ugo
SILVER Star
My apologies, I re-read my previous post & was confused too. When I replace 3rds I inspect them, looking for broken gears & the like. & making sure the pinion & assembly spins smootlhy. Making sure the pinion has no play in it, up, down, in & out, & the pinion seal was not leaking. Alot of times a leaking seal is an indication of bad bearings behind it. I rarely check preload because I figure the dif was setup correctly many miles ago. I may check backlash & if it seems like it has alot & I may adjust it a little tighter. What I was trying to explain in your case is you checked the "preoad" and had none, so it would figure any adjustment to pinion would be an increase to the overall preload, which was none. I would only adjust to the minimal spec, knowing it is in an assembly. A little adjustment to the backllash might increase it slightly. If you check the contact pattern on used thirds, i'd bet it is not the same as it was when the gears were originally set up, many miles ago. The gears do wear into each other. Now here's another thing to keep in mind, the front 3rd member gears have been driven on the "coast" side of the ring gear & the rears vice versa. .
I'd just run it. Just like what Pin said "If it ain't broke........
I'd just run it. Just like what Pin said "If it ain't broke........
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- Thread starter
- #74
Ok guys, I yanked the rear differential today, and there was DEFINITELY a small amount of "side-to-side" play in the pinion. The mechanic who worked on my truck previously mentioned this, as well. SO, I'm at it again...
The play was not significant enough to even start the pinion seal leaking, and the diff ran quietly when I was driving it around previously, so I'm hoping no significant bearing damage has occurred yet. I'll follow the aforementioned discussion, sanding down the washer and playing with shims until I get a preload in the 6-11 in. lb. range.
That said - a couple of questions. The shims I pulled had DEFINITELY spun - you can see the wear mark in the thin shim, below:
The thick shim was similar - more minor, but still apparent, wear on both faces.
Obviously, I won't re-use the thin shim. With the preload set correctly, should the thick shim be safe to use, even with a wear groove (not super deep, may actually sand out).
Does this wear suggest a bigger problem?
The play was not significant enough to even start the pinion seal leaking, and the diff ran quietly when I was driving it around previously, so I'm hoping no significant bearing damage has occurred yet. I'll follow the aforementioned discussion, sanding down the washer and playing with shims until I get a preload in the 6-11 in. lb. range.
That said - a couple of questions. The shims I pulled had DEFINITELY spun - you can see the wear mark in the thin shim, below:
The thick shim was similar - more minor, but still apparent, wear on both faces.
Obviously, I won't re-use the thin shim. With the preload set correctly, should the thick shim be safe to use, even with a wear groove (not super deep, may actually sand out).
Does this wear suggest a bigger problem?
- Thread starter
- #76
Great news - I'll do what I did previously and set the pinion preload (with everything assembled) and make sure all the slop is out of the system. Assuming I can get rid of it by adjusting the shims, I'll most likely just run it from there (with the locker installed). Learned my lesson on the last one - if it ain't broke, don't fix it...
- Thread starter
- #78
Sorry, that's what I meant by "what I did previously."
I'll sand down the washer and get the preload set at the pinion, and remove the play. I just meant I wouldn't mess with the ring gear backlash this time unless it is grossly out of spec.
Of course, whether this is "right" is subjective, as I'll probably do this with the diff assembled, so really I'm getting some preload "help" from the carrier gears/bearings as well. Preload for the assembled system should be 20 in. lbs. or so, per our previous conversation, but as this is not a complete rebuild, I'd rather err on the side of "tight, but not too tight..."
I'm okay with what pin head said. Going way back to the early seventies doing a tool and die apprenticeship the guideline was just as pin head said, however, you perform the task not straight back and forth or sideways but rather in a figure eight pattern. This action tends to mediate pressure differences your hand applies to the part helping to keep from removing more material from one edge than the other. Measuring frequently is the key.
Its geat everyone is trying to be exact on preload and backlash. It does help it run cooler and last longer..
What i have been amazed is how far wasted/out of adjustment sone rearends can be and show no problems..
Ohh btw they have to be really far out to whine.. the little changes you guys are making wont change the patern enough to whine... imho...
What i have been amazed is how far wasted/out of adjustment sone rearends can be and show no problems..
Ohh btw they have to be really far out to whine.. the little changes you guys are making wont change the patern enough to whine... imho...
