Just replaced a pinion seal do to a massive oil hemorrage and whirring noise while coasting. Did not inspect pinion bearing (stupid me - newbee) just replaced seal, and cranked pinion nut on with an impact. Did not pre-load, torque etc - again (stupid newbee). Just took new seal out due to above symptoms after 25 miles. Question??? Did the botched seal job cause the bearing to go, or did the bearing go bad and cause both seals to go??? Either way looking at a rebuild (will pay closer attention this time - wish I had seen this forum prior.) Have non-posi 3.31 with 454 TH350, thinking of going to 3.73 instead of 3.31 - Thoughts as well?

Bearing got bad first. It took out the seal from its wobbling.

Just another opinion .... You may have over tightened the the bearing(s) pre-load. A few years ago, while replacing a pinion seal, I found a scored surface on the yoke, .. and replaced it an identical OEM yoke. Since, I had marked the nut previously, ... I figured with an identical yoke... and duplicating the nut position, .. I would be fine with the pre-load setting. Wrong, ... Pre-set was too much and it damaged both pinion bearings. I had the same whirring you describe. Removed rear end from vehicle, and on saw horses ... disassembled to replace bearings. Using an inch lbs. torque wrench, breaker bar w/cheater, and a home-made tool/bar to hold yoke, ... I was able to attain the correct pre-load with the new bearings ....and the whirring did disappear.

70 El-Camino (350)
383 stroker soon, 700r4, 12B Eaton posi w/3.42's

excellent reply brimac.ive seen this many times .a quick pinion seal change should include marking the nut and flange before removing the nut.after the seal is installed and the inner and rear lips are filled with vaseline to avoid having the tension spring pop out or the seal rip upon assembly tighten the nut so it aligns with the original mark on the flange where it was before dis assembly and then tighten it an additional 1/16 of an inch beyond the original mark to restore the original preload.why tighter than the original setting ?because the nut stretches.its proven.in reality the right way to do it is to install a new crush sleeve and reset the rotating torque with an inch lbs torque wrench.

In your last 2 posts you keep wanting to know what was the the cause of your situation.It very well could have been a bearing gone bad as suggested but if I had to guess,I would say that when you attacked this problem the 1st time the pinion nut came off very easily as it was probably already loose.From doing rears for over 20 years I would have to say that the pinion nut coming loose is the number 1 cause of rearend failure.As the nut becomes loose the pinion gear developes more radial play than the seal can compensate for and will leak profusely.The clunking noise between forward and reverse was the pinion gear moving for and aft in the housing.Upon removal of the rear cover if you see scaring or wear marks on the OD of the differential,then the pinion nut was very loose.In this situation upon deccelaration the pinion gear is forced back towards the differential and actually touching and in severe cases gouging the differential.If your pinion bearings are real bad then you'll want to pay attention to how easily the races come out of the housing indicating they may have spun in the housing(not good).Also never replace just a pinion to create 4:10's even though GM( and most others) 3:73's and 4:10's both have 41 teeth on the ring gear.gear sets must remain matched.Sounds to me like this housing probably needs to be washed out to be rid of metal contamination.When ever replacing a pinion seal using the preload method on the bearings is imperitive if you want them to live,whether installing a new crush collar or not.I have seen no one mention that if not new,than you had better use loctite(red) or the nut will loosen.A crush collar that has been ran with a loose nut will afford no preload as the edges are worn from rattling around in there and has become dimensionally shorter.Additionaly in this situation the ring gear teeth become worn at the heel.If you remove the axles before messing with a pinion the preload becomes easy to feel as the only resistence left is that of the diff. brgs.,and used diff. brngs. don't afford much or any resistence.
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Wait there's more.When you believe that you have acheived proper pinion bearing preload,then you must spin the pinion some because the rollers in the bearings will now and only now align themselves to the bearing cones,thus preload minimizes or disappears.Then you will have to tighten the nut a very little more and do same(sometimes a few times) until preload remains constant.This all needs to be done before the locktite sets up on you,so make sure everything you need is right there at you fingertips.

Phaque is right on!!! My Differential is showing scarring marks - apparently from the pinion gear. My cross pin was very difficult to remove, the differential came out very easy when I removed the caps. My pinion gear is still in, was going to pull that today. Makes me wonder how much damage is/has been done here. I was planning on replacing the gears going to 3.73 or so, have 3.31 now. Wondering about those EATON bolt in Posi units??? is my chunk ok from the scarring or not???

phague heres some additional info.we do use pinion depth gages here to set up rears and final drive service has been a major part of my business for years.when taking our original pinion depth measurements we use a test bearing with .002"removed from the id so we dont have to press on and off to change shims until our proper depth is obtained against the master housing dimension.we also dont use the cruch sleeve until final assembly.also gm recommends up to 25 inch pounds rotating torque with new bearings and races.we dont agree and use 18 as the maximum for an 8.5 rear.the 25 usually always causes whirring sounds due to overtorque.sure the bearings loosen as they seat but not much dimensional changes occur on the bearing or race during run in except for the surface conditioning between the rollers and the race they run on.i never interchange ring and pinions from one set to another,always use a new crush collar or several on each job if i overtorque on initial setting,check for rotated bearing races by examining the rear of the race and the surface it thrust on.
,clean all debris from housing as well as check rotating torque on cars or trucks that i remove axles on for other service to the diff that doesnt require pinion removal.THIS IS so important because you can experience proper drag and feel on a good known working unit.i hope this info gives you techs out there some fresh ideas and additional assistance when performing future final drive service and repairs.c kokkonis @ ckperformance

Christoforos Kokkonis;I'm sorry you thought that post was aimed at you,it was not.My post just happened to follow yours.This is drathaar 907's 3rd post on this same issue and I was trying to address his and others questions/input from those posts as I have been following them.What I am about to say is not aimed at you either.I agree with all you said and use all the ideas mentioned except I rarely( not never) use a pinion depth guage,because all they do is get you close quick(sometimes dead on if your lucky).This is one reason why so many factory rears fail because a pattern check is never done and must be done to acheive dead on results.I have found a depth guage to be a waste of my time ,usually(ecspecially if there is a original pinion depth shim to start with,plus after you have use a few gear sets by a particular manufacturer they become very predictable),as I have a darned good Idea what shim to go with after reading the pattern from the 1st try.I also use modified brngs. and no crush collar and a yoke that fits only snug(sometimes a sleeve machined from a piece of pipe),so that I can be in and out very quickly.Usally my 2nd or 3rd educated guess is the last.And no I'm not accusing you of not doing a pattern check as I'm sure you do.Just offering a different approach for others to see.Based on your suggested ideas I'm sure you are a quality operation.Modified bearings are the only way to fly when working on a non-GM Dana 60 or70.Don't you just love how some genious decided to put the diff shims between the brng and the diff.case?

i have had difficulty reading patterns using the traditional methods because of smearing of the compound and no positive load on the axle shafts .we use machinist blue dye to aid in a pattern that is readable and understandable by us.also most dont realize that the pattern you see is in reverse because the gear is 180 away from contact when you see it .therefore if the pattern shows that the contact is closer to the rear end cover the immediate thought of the person performing the job is that the pinion must be moved back ie reduce the shim thickness.this is incorrect.by adding shims it will move toward the center because the pattern is opposite when it reaches the area wher you view it from.im sure you understand,many others dont and hopefully this will inspire additional thought into this relatively simple operation.in my research i have found most "scribed info" on the pinion to be correct.do you use the machinist blue dye or marking compound?how do you load the axles /diff hosing to get a good pattern?my method is a 10 bolt on the wheels and tires with 2 nuts each side and no brake drums.just enough to create a drag between the mating surfaces to get a nice pattern.

I have just removed the chunk, it came out very easy. The case is full of metal fillings from - I am guessing the chunk. It appears to have been spinning inside the case, there are marks all around it. Is this thing ruined?? What is the best way to clean the case/axle housing - realizing that the car is on jack stands in my garage. Hose with water, keep at it with shop towels, help!

To clean the axle tubes I use,as simple as it sounds,a cheap,3" round, nylon bristled brush that you can find in a supermarket.I cut off the handle end to where the shaft becomes round.I then epoxy it in the end of a length of appropriate size conduit.You can use PVC pipe but is too flexible to allow you to be able to work the brush in problem areas.When epoxying the brush in the conduit be sure to form a smooth transition at the pipe end so that the sharp edges are gone.This becomes one of many of my home made special tools and lasts a very long time.Pay close attention to the big grooves just outboard of each diff. brng.,as metal accumulates(settles in the bottom of the groove) there big time.You need to loosen these metal deposits for proper cleaning.A 2" wire wheel snapped straight off the end of a pair of vise grips works well here(if using a drill be carefull not to gouge or nick the brng.saddles)If using your fingers in this area be extemely careful,as the edge is very sharp and you will slice your fingers.Also on Most early GM car rears there is a vent on top of the rt. side of the housing which intersects this big groove I'm talking about.Pull the vent out and gives you another avenue to blow compressed air,as in the final proceedure you will need to blow every nook and cranny with compressed air several times to be thorough.Most of the rest of the center housing you can get at with normal parts washing brushes,except the oil feed and return passages which can be accessed with long round brushes of appropriate sizes.Once all debris is loosened I use a common pump up garden sprayer filled with kerosene.I modify the wand end of the spayer to be longer so I can get down the tubes well.Additionaly I have a modified blow gun to be long so I can get down the tubes as well.(now you can buy a cheap,very long blow gun at most parts places and swap meets).You may have to alternate the washing/blowing proceedure a few times with a heavily contaminated housing to acheive a clean housing.Upon disassembly of the rear pay attention to how easily the pinion races and axle bearings come out.If any come out with out a good amount of resistence then the new part will need to be locktited in place.Sometimes a bearing bore is so loose from a brng. spinning, that the housing is junk.If the diff. bearings have spun in the housing,the caps will have to be tightened up via surface plate,combined with some talent and test fitting .If you send me some good pics of your internal parts,I would be more than glad to look at them and give you my opinion. hidden@midtel.net (be sure to put something in subject line so I'm not afraid to open it)Dennis Hidden Valley Performance Ctr.

I use clean white lithium grease to do pattern checks.This works well on new gear sets that have a dark phosphate coating as the contrast in color is helpful.I also use it on OE gear sets,but because of the lack of color contrast,is difficult to see unless you are very use to it(you have to get your lite source at just the right angle,then you can see it).I prefer white grease over marking compound because marking compound does look smeary or non-definitive.When you are close on the pattern(when the main contact area is in a nice position),if you want to get really anal about it(not queer anal)you can tell by the tiny trails left in the grease at the heel of the tooth.These trails will sweep down towards the root or up the other way slightly indicating whether the pinion needs to be deeper or not.Pinion depth is optimum when these trails are parallel with the tooth.This won't work as well with a used gear set,unless they are in super cond.,thus I still use the grease but don't necessarily rely on the trails I've mentioned,but more on the relationship between the drive and coast sides.I've seen some gear sets,(new included), that when set up with a pinion depth guage or without,and the drive side of the pattern looks good,but the coast side is almost off the tooth,Thus sometimes a compromise is necessary.Some gear sets set up easy and are predictable and some are very troublesome.I do mostly Muscle car and race car rears.All the old GM gears have no dimensions on them,so using a depth guage is not an option.I have seen batchs of new gears that are so terrible it wouldn't matter if you used a depth guage or not,then you have to rely on experience and sometimes compromise.Any gear set that is worn and has dimensions on them,then all you can do is use the pinion depth gauge and call it good.Have to go,will detail my method of diff. resistence while doing pattern check later

DO NOT TRY THIS AT HOME FOLKS,as your hand can become hamburger very easily,but someone asked so here goes.To apply preload to a differential while doing a pattern check,I 1st cut off the female end of a 3/8th's X 3" extension.I then chuck it up in a 1/2" reversible drill and use the appropriate adaptor to fit the proper socket for the pinion nut.I mark with yellow parts marker in two spots on the outer circumference of the ring gear about 10 teeth or so apart and also on the diff. right next to these two spots(reason to be explained later).These 10 teeth get coated with white lithium grease,coast and drive sides.I use an acid brush and coat the teeth in a manner parallel with the length of the tooth.The grease can't be sparse or too heavy either.I have the drill adjusted so it spins at a desired speed(fast enough to not labor the drill with the next step incuded).This step can be the dangerous one if you are not careful.I apply the heel off my hand very firmly against the OD of the ring gear(you cannot apply too much pressure as we are nothing compared to engine power but be consistent)While rotating the pinion with the drill 5 or 6 times first in one direction,then the other,as the pattern should be checked for drive and coast.The reason for the yellow paint on ring gear is so you can anticipate the rotation so the ring is never stopped with the greased section at the pinion or you'll need to repeat for a good reading.A fixture could easily be made to apply pressure to the rotating assembly.This method is superior to even most ring gear manufacturers instructions.Some people simply rotate the pinion by hand,this method is very irratic and to me unacceptable.The reason for the matching paint marks on the diff. are this:usually when I'm doing a rear it is to be a posi and I don't install the internals in the posi case untill I'm done with the set up(not to be confused with final assembly)If the ring gear run out was good then you will want to put the ring gear on in the same clock position,as the ring gear run out can change.If you are having a run out problem,sometimes it can be minimized by trying different clock positions.
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I tried a pinion depth tool a few times and I found it to be about .003 off each time. I got rid of it. Reading the pattern is the only accurate way of setting the pinion depth. The gear marking compound works very well if you mix a few drops of gear oil with it. I can usually hit the pinion depth within .001 or .002 on the second try. If you set the pinion bearing preload between 19 and 22 inch pounds you can install an axle and turn the ring gear against the pinion to get accurate markings. The pinion bearing preload provides enough resistance to mark the gear well. The more well known rear end companies that I have talked to recommend turning the ring gear against the pinion instead of turning the pinion against the ring gear. It just works better.

The pinion depth gage is accurate.reading pattern in grease and marking compound is like torquing cylinder heads with a breaker bar.its not accurate.so stop the excuses and accept the fact that proffessional tools are the proper way to set a ring and pinion.call the companies you buy your gears from and ask them if your methods are correct.any proffessional outfit uses gages and views the pattern as a secondary check to see what it should look like when its right.if your eyes could tell .002 " off on a ring and pinion youd be from another planet.this is not a good example of proffessionalism to be used by others attempting to do waork at home.there is nothing wrong with attempting a ring and pinion or final drive repair at home,BUT WITHOUT THE USE OF A PINION DEPTH GAGE,INCH POUNDS TORQUE WRENCH,AND A BACKLASH GAGE YOUL PUT UP WITH THE ILL EFFECTS OFAN IMPROPER INSTALLATION UNTIL YOUR RING AND PINION BREAKS OR BEARINGS SQUEAL AND THE 150 FOR THE PINION DEPTH GAGE WOULD HAVE COST LESS THAN A SECOND OR THIRD REPAIR.DONT PUT AIR IN YOUR TIRE EVERY DAY,PULL OUT THE SCREW AND PUT A PLUG OR PATCH ON IT AND BE DONE WITH IT.dont bother with the rebuttals because this is simply the truth.do we not understand what measuring pinion head thickness is about?

Cris kok,I new this was coming and now you've asked for it.Admit it ,you just don't have the talent or intelligence to read the pattern.I'm so glad you've admitted to all that you lack that talent.I guess I am from another planet,because I can tell a .002" difference in pinion depth by reading the pattern.Half of the rearends that I have done were done 1st by someone like you who is clueless and thinks a pinion depth guage is GOD.Any pinion depth guage on the market tells you in their instructions that when you are done to do a pattern check.Don't bother with rebuttals?,it seems you are the one who does not understand pinion to ring gear relationship.So someone brings you a new set of GM gears for a 12 bolt and says,set it up for me.Now tell me what your pinion depth guage is going to do for you?Now you have to call someone like me because there are no dimensions on the parts and you are clueless.

if you were able to tell .002" it would only be verified by the use of a pinion depth gage.there is no other way to measure it.general motors unmarked ring and pinion set still use the factory master housing dimension and the pinion head thickness to calculate pinion depth as measured .the design of the gm ring and pinions which because of there sometimes up to 70 rockwell should not even be considered for any performance applications.too brittle.if you are a back yarder piecing together rear ends for performance use with 30 year old ring and pinions you are certainly not providing a valued service to your customers.i have not seen any 72 and up differential have and incorrect master housing dimension of more than .002".still in our tolerances.we have a 2.00 puck that sits on the outer circumference of the bearing race and take measurements to check this against the housing dimension before taking pinion depth measurements.no major companies sell ring and pinions without the pinion depth scribed on the pinion.the gears are pre lapped at the factory and as such should be set up as per lap in depth.if your into reading patterns and dont use the gage you have no solid evidence to go by only what you think or assume to be correct.this is wrong and substandard unless you find it ok .i dont.and the gages dont lie,our eyes do.pattern readings that are used for future installations should only be viewed and stored in your mind as valuable able they were generated by the use of a pinion depth gage and verifying master housing dimension is correct which it 99.99%of the time is dead on.now with used factory gears ,and the knowledge that they are not for performance usage or for swapping unless you understand there substandard performance pattern reading is more important because the gear design is made to favor the high part of the ring gear .but once again you are doing a diservice to your customer with used gears by installing a part more likely to fail and guaranteed to make noise.and your public attempt at humiliation doesnt hold any ground.if you travel to my website you will find that i am not someone who is clueless.you have never been approached by someone who i crafted a final drive for either.if your trying to throw me a rope to hang myself with in public tie your tongue with it.i have my own line of transmission brakes,planetary gears,shafts,hubs,converters and the finest automatic transmissions on the planet.certainly not an amuteur.

I have been setting up ring & pinion gears for 24 years. I have talked to MANY of the big manufacturers and big time gear installers and they don't use a pinion depth gauge. They all rely on the contact pattern to set the pinion depth. I CAN tell the difference when the pinion is moved .001 inch by looking at the contact pattern. I make pinion depth adjustments of .002 all the time just by reading the pattern. The pinion depth tool will get you close, but not exact.

If you prefer to use the pinion depth gauge then that is your choice. If you have had good results doing it that way then that is great, but don't tell me that I am wrong because I read the pattern.

This website was started for and dedicated to Chevelles.Someone who has a high dollar Chevelle typically wants GM gears whether they be NOS or good used GM(and then even dated to their car).These gears were made by four different vendors and were made in batches for GM.Many times the ring and pinions aren't even dated the same month,because they were made to "quote" exacting standards.Even if someone has access to the fairly vast pertinent info for all these gears by all the vendors,so that they can use a pinion depth guage,READ YOUR INSTRUCTIONS THAT CAME WITH YOUR PINION DEPTH GUAGE,BECAUSE THEY TELL YOU TO DO A PATTERN CHECK.If a pattern check is so meaningless,then why is this in the instructions.I have done rears for 20-25 years and have not had my 1st failure yet and I would think that if my method is inferior in any way,then there would have been failures by now.I think you are out here answering questions hoping to generate business and could give a crap less about original Chevelles or Camaros.I will ask this question of you:Some one who is restoring a LS-6 Chevelle(you do know what that is don't you ) approaches you.They have purchased a set of NOS. 4:10 GM gears(which you have already said are junk),and they want you to set up the rear for them.You might as well stick you pinion depth guage up your A$$ and because you can't read a pattern,I pity that customer

Wow this is fun reading!!!! Everyone that I have ever seen set up a rear checked the pattern.

eddie my point is this :a correct pattern can only be generated by using the depth gage .and phague when im in cobleskill ill make sure i come by for you to attempt to put that pinion gage in my ass.my relatives are in cairo and catskill,ill be sure and come by and say hello hillbilly.pull out every final drive section of any manual and see what is used for pinion depth.and when you dont have an inscription on the head measure the pinion thickness ,compare it to your mhdimension and there is your depth.then read your pattern.without the gage your just producig poor results and if that is what your happy with dont expect repeat business.substandard results dont exist in my world WHEN i have control over them.SEE YA SOON.