12 Bolt Rear End Noise Diagnosis and Repair

greetings viewers eric the car guy thanks for tuning in today you'll be happy you did because look behind me that's a 1972 chevrolet nova with ls power and it's come to me today because apparently it has a noise coming from the rear differential and i guess due to my recent experiences i'm now an expert it also has some small leaks back there now in preparation for this my friend john who owns this car has brought me a new set of gears 411 gears for the 12 bolt rear end which is what's back there he's also brought me some gaskets some oil a new differential cover and a pinion bearing set which i will need to change over the gear set if that's necessary anyway starts with a test drive to verify the customer complaint let's go for a ride i don't know how he can hear much who i can say that it's more of a rumbly grinding kind of thing i mean it's hard to hear over this exhaust and the steering is questionable with these pizza gutters but it's more like messed up than a noise it's like rumbly grinding and it's on coast it's not an acceleration so much oh there's the how there it is and yes i am wearing a seat belt all this car has his flat belt i now have the nova up on the lift i'm going to first do a nice visual inspection and just sort of feel things around the differential to see if i can find anything that sticks out then i'm going to run it while it's up on the left with the wheels off the ground and see if i can hear that noise here in the shop with it just sitting on the left [Laughter] all right i've got the car part way up it just it might be just these wheels and tires but i just didn't have a whole lot of confidence while i was driving it when you get a car with this kind of power output you want it to be solid same thing here in the back it almost looks like these tires have kissed the inside of this fender well a little bit that's normal i should have put it in neutral well nothing really out of the ordinary there no doubt about it it is leaking and it looks like attempts have been made to seal up those leaks in fact it's there's evidence here on the fuel tank he also mentioned that one of these uh supports up here uh the bolt on or the support on the inside was broken that's the reason why i have a new one of these covers last time he brought it in there was some play here up front not feeling any let's run it up in the air and see if we can hear anything abnormal hard to hear anything with this exhaust i'm gonna get my stethoscope get a listen i think it's time to take it apart i'm going to start by draining the fluid why does that look like got water in it doesn't look like there's a cap on the breather maybe that's why i've looked it up and this is the breather so i'm gonna have to remove what's there and find a new breather if you block off the breather then the pressure can't escape from inside the housing so you will have leaks and guess what we got lots of leaks on this differential so that may solve one of the problems now let's get this differential cover off which i believe has the same quarter inch fasteners this is aftermarket stuff so whatever you have on your vehicle i'm not exactly sure what they are stock but anyway taking the cover off next there's a difference between the gm 12 bolt car axle and the truck axle so i do believe they're not interchangeable so if you have a 12 bolt in a car it needs to be a car and i think you can almost see the difference because the car has this weird shape back here and then the truck has another a different shape to the diff cover i think that's one of the ways you can differentiate the two so both have 12 bolts but they're different shapes and they do not interchange now normally what i would do is i would leave like a bolt or two up in the top of the cover but i can clearly see that this one's glued on and it's not going anywhere here's a closer look okay i just saw it did you see it it's right there what might give it away is the shims the caps are on backwards but you can kind of see how it's flat on this one side the flat should face inside this whole thing should be spun around the other way and here's that broken piece he was talking about it's supposed to have a support on it like this one but this one seems to be broken that's not good i just need to keep it out of the way because this fell off i'm just going to set it to the side so that it doesn't fall and anything falls out but i already went through and looked on the inside and made sure all the needles bearing needle bearings were still in there maybe a little bit of an axle seal leak looks like something got stuck behind the drum on this side should look like that let's get these axles out once you got that center pin out just push the axles in and you can have access to the c-clip that's what we're after i don't need to pull the axle out all the way just out of the differential [Music] it can just rest there i really have never had this much trouble let's try a bigger magnet well it's supposed to be a bigger magnet finally know what was holding you in but you were in there let's get these backwards bearing caps off [Music] and i'm doing this because i'm going to pry out on a differential and i don't want it tumbling out of here so i'll just thread these in by a couple threads and that's why i loosely threaded the bolts on i'm sure to try to get the shims and everything and take it over the bench i wanted to get a closer look at that breather to see if it was clogged or whatever so i'm just going into the top of the hole that's here and i can see that it's not completely blocked off i don't like blowing into it like that but i do plan to clean the inside of this out that does need to be replaced or else there could be contamination from water and other sources road debris this pinion just feels chunky and unhappy so it's probably good we're swapping out these bearings and everything i believe this nut is an inch and a 16. sorry i forgot i didn't have him on oh well that's a lot looser than mine was opinion will come out now and it's crushed sleeve and there's a chunk of something in here wow all right we're learning all kinds of stuff here's an inspection for you so you can see what we got a whole lot of goop there let's get those pinion bearings and races out this is an old input shaft that i've used for stuff like this for a long time i know you're not supposed to beat on hard metal not supposed to beat on hard metal [Music] we are putting new ones in i'm going to knock the races out now you can see the little indentations on either side the same is true from this one coming from the other way [Music] got some distance on that one doesn't look great in there on this side anyway but i try to go in sometimes you'll get like a little bruise or something up here in the middle because it's soft i try to feel with my finger and if i feel any raised areas i'll either go in and and sand it down or sometimes i'll just hit it with like a punch or something and flatten it out but i'm not too happy about all these little things up in here hopefully the race sits in there properly because we do have a leak here you can see some of that bruising a little better over here just want to make sure that this is flat so the race sits in there flush before i get into the gears i'm going to do what i can to make the housing ready which means cleaning this gasket surface just running a tap through these holes to try to get rid of some of the rtv and stuff that's left over inside there i'm going to be using this plastic end here it's cast iron so it really doesn't matter but i just like to use this one for gasket material this is a 5 16 by 18 tap i prefer to use a thread chaser but i don't have one i'm not trying to make threads here i'm merely trying to get the goo out and you can probably see there was a little bit of goo so if you've ever questioned my use of gaskets instead of rtv for diff covers you're looking at it right here just to give you an idea of the stuff that's coming out for good measure i'm also going to do these bolt holes down in here because these in particular on this side didn't feel great 7 16 by 14. i'm gonna clean the housing get all this junk out of here i certainly don't love it because i do see some nicks on this bearing cage and this one too and a piece of there's rtv in there not sure how well you can see it we'll see how good the zoom is but see that right there that is our tv right there there it is you can really see it there some of the damage that i was talking about to this bearing cage up here in this area there was some of that on the other one as well i don't find a chunk of rtv in this one though races you know look normally worn i guess i don't love it though okay here's the pinion bearing and there's our old friend rtv embedded into it here is the outer bearing feels a little chunky a little sandy this guy doesn't seem happy especially being like literally filled our tv there's a lot of it down in there so changing out these pinion bearings is certainly going to help things i'm cert i'm sure to my relatively untrained eye don't look horrible but i don't know our tv guys it's uh not necessarily your friend it does have its applications but i'm not so sure this is one of them this day is flying by and time is getting short so i'm gonna just move along with getting this stuff together getting it up in the car and we'll check it for noise as far as details on assembling differentials i'll post videos in the description i've covered chevy 10 volts ford 8.8 so i will link those down in the description if you want details on this stuff but i'll cover the highlights of what i'm doing here now i noticed that this was not just a pinion bearing set which these are the pinion bearings up here but also carrier bearings so we're good i'm going to take the opportunity to swap these carrier bearings out since i wasn't really confident in what i saw there this seal that came with this kit apparently isn't correct i need to use this seal i believe i mentioned that before we have a new crush sleeve here so we should be all good to go and a new uh nut for the pinion so i believe we have everything we need to move forward and get this thing rebuilt and back up in the car uh i'll probably start with putting these races back in and then start working on the differential parts i'm going to take the old pinion bearing off so that i can get the shim that's underneath it if i'm lucky this bearing will be salvageable and i can use it as a setup bearing if it's the same type as the one going in which i think the ones going in are a timkin set i found that the majority of the bearings out there for differentials for ford and chevy europe tim kin or coyo these are tim ken that was awesome that's what i was after right there i've already cleaned the new pinion off with brake clean and compressed air here's the shin that i removed from uh the old pinion i'm just gonna measure its thickness now it looks like this one comes in at .035 inches just put it on here now i checked my stash of setup bearings and i don't have one but this came off so well the old tim can bearing because you can't put a timken bearing in a coil race which right now there's timken races inside the differential so they have to be tim comparings that you do your setup with so you can't mix and match them this is a timken bearing the new bearing is also a timken bearing exact same thing so i'm going to take some time hollow out the inside of this so that it slides on and off of this shaft easily so that i can use this as my new setup bearing first i'm going to pick out this rtv though and i want that getting into any setup that i might have in the future come on you don't belong here there that's gone and now now i have a tin can the setup bearing for this so this this bearing will slide on and off in case i need to change the pinion shim it'll make it a lot easier and the next time i have one of these bearings in a differential i won't have to go through this but took about a half an hour to get here this is weird so i checked this kit and this is the other pinion bearing the one that goes on this way and as you can see it only goes part way down and it's a coil bearing unlike like i said this this bearing is a timken then they made this bearing a coil doesn't matter so long as the race and the bearing match up you know anyway so i went looking through my bag of bearings setup bearings because i also made a setup bearing for this side and i have a coil bearing that i used on my 10 bolt gm which happens to be the same coil part number i checked them so this one will slide on here and slide off easily unlike this one which is my brand new one which i'm going to set aside until final assembly new pinion setup bearing old crush sleeve no need for a seal or anything i do however need the hub oh looks like there's going to be a little more resistance getting this hub on this set as opposed to what it was before now i need to rethink this put my pinion holding flange on it i'm going to be using this later anyway so i'm just going to leave it fastened up i want a little bit of resistance but not a lot but i can already feel that this bearing is not happy all right let's check the pinioned up all right viewers for you it's only been a couple of seconds but for me it's been a day because i had some challenges well come to expect it here on eric the car guy don't we here on the bench is what i've been dealing with on the bench here i have three pinion gears this is the one i took out of the car this one as the one i was attempting to put in and this is the one that just showed up this morning now yesterday when i went to install the new gear i was checking the measurements i had a massive amount of clearance to take up it was sitting way too low inside the pin inside the axle housing and i'm just scratching my head in fact it would have taken almost this entire stack of shims to make it work i mean that that was definitely a head scratcher i checked my measurements everything uh checked on social media and then i laid it here on the bench and put the straight edge across and i could see that there was a massive amount of difference between these two things now i realize there are going to be differences in gear sizes because there are difference of gears now i think this one here on the left is a 373 what i'm putting in is a 411 but even so that giant gap there is significant anyway as you can see on the new gear all the way over here on the right that gear is pretty much the same as the one i took out and i'm going to install that one now with this shim and check my pinion depth and see if everything's okay but yeah real head scratcher here but know that there are two different gear sets or two different housings and two different setups for 12 volt gm rear ends i think that's what we're dealing with here so unfortunately he brought me the wrong gear well we'll find out in a minute let's get this one in and see how it measures out as far as pinion depth probably saw me struggling a bit trying to get this on and these are snug when they go on for the first time so what i'm going to do is i'm going to hit it with my heat gun and just heat this up a little bit before i try to install it and maybe give it a couple of taps with the rubber mallet to get the nut started so i can get this down on there [Applause] [Music] let's check that pinion depth it's like it comes out to 0.509 3.375 minus 0.509 equals uh so my opinion depth is two eight eight two eight six six two point eight six six i forgot to check the pinion head to find out what the measurement's supposed to be i'm gonna do that now looks like this pinion head says 2.8694 given that i'm at 2.866 i think that's close enough with that finally dealt with i'm going to change the ring gear these are not left-hand threads now i'll install the new carrier bearings and install the new ring gear i start by cutting a groove in the bearing and then i'll come in and hit it with a chisel this is hardened metal it should snap and break out gonna watch it when you do this because these parts when they break they can come flying off and they're very sharp i've gotten cut by them pretty badly before there we go [Music] hmm i spent some time to clean everything up to get it ready for the press all of these bolts i just cleaned them a little messed up on the ends that you can see like this so i'm gonna have to run a die over each one of these these are 3 8 by 24. well that took a while to do but it's done and they all threaded it out nicely i'm going to take a little break and come back and we'll install the ring gear and keep moving forward now let's get these two together what i'm gonna do is i'm gonna pull it up and hopefully get like one one or two of these started i'm going to use them as a guide note that i added a little bit of loctite to each of the ring gear bolts before final installation i've done this exact thing in the past with good results what's going to win me in a fight between wood and metal pretty sure it's going to be metal yep that looks really good now let's go torque them down notice the familiar theme here with the wood blocks it's the only thing actually making contact with the diff here i'm going to run these down hand tight and then torque them to 45 foot pounds no one's not happy i'll have to track down one of these bolts but for now i can get it up in there and check the gear tooth pattern and everything else and install this later passenger sides going in with all of its shims on the driver's side gets its race not the shims yet i'm just using the shims this thing came in the door with if that's even possible it took a little bit of time to get these shims correct i started with the shims that the differential came in with originally and found those to be a bit too tight so i started removing shims until i felt like i had what was an acceptable amount of preload you do want some preload on these carrier bearings but not so much that you really have to hammer in the shim pack once i felt i had an acceptable preload i started swapping shims from side to side to get the backlash i wanted nope needs less than that but i like this preload so i'm just going to start moving shims from this side to this side little bits at a time but that's like 15 thousandths that's too much and we're back now this is the tooth contact pattern that i have now i don't know if i could show you the coast side there a little bit okay anyway it looks a little far in but that's okay because that is backlash so to get this to move more towards the center it's backlash but my backlash right now is 0.009 which is banging spec i don't want to increase it anymore i'm actually very happy with this tooth pattern also so i'm going to disassemble this hopefully for the last time uh press the pinion bearing on and put it all together i'm going to recheck the pattern one last time before i button it up but we're on the other side of getting this differential together back on the road and checking to see if we still have that noise fyi in order to get my opinion depth adjusted where i wanted it i kind of wanted a 39 000 shim but everything is in 10 000 so there's no oddball sizes so i took the thicker one and you might be able to see this and i just lightly kissed it with uh my angled die grinder and a roloc disc and i came up with something a little bit smaller so that i could get it was 36 when it was in there originally i thought it was a little shallow on the pinion so now i was able to get that 39 that i was looking for so this was 40 000 when i started with it and now it's 39 000 where i wanted it so i took a bigger piece and made it a little bit smaller to get it in where i wanted it to be there a new pinion bearing freshly pressed on and shimmed this process has been a little messy so i'm just gonna go in and clean the inside of the housing one final time and these uh rags that i'm using are specifically made so that they don't leave lint or at least they don't leave as much lint as some of the other rags that i've used i'm putting a little bit of gear oil on the pinion bearing before i install it not totally necessary i'm going to fill the differential housing up with fluid but every little bit helps don't want to forget my new crush sleeve the outer pinion bearing is such a snug fit on the pinion it doesn't well it slides onto the old one nicely but not so much the new one so what i'm going to do before i go to install this is i'm going to put on a pair of gloves and i'm going to heat this up with my heat gun prior to installation so that when i install it hopefully it slides down a little bit easier so that i can get the pinion seal [Applause] installed oh that went on there too good this is the old crush sleeve it hit something you okay before you took a dive i was able to get this down on there most of the way i use the old sleeve in my rubber mallet to knock it back into place now i'll be able to install the pinion seal and the outer yoke for this setup i'm using this pinion seal because he has a different type of yoke on here so i'm not using the seal that came with the kit i am going to take a little bit of grease though on the inside of the seal and just sort of ring the inside of it so it's not installed completely dry i use the heat gun and i use my flir camera to make sure that i had this thing nice and toasty before installing it because i don't want to have to beat it in with the pinion seal in place [Music] excellent i heated that up to about 200 degrees fyi and now i've got plenty of threads sticking out so i can draw it up the rest of the way still a little bit of play i'll be installing a new washer and a new nut well not the new washer if not i'll have to reuse the old one i have gotten away from the method of going by the torque reading on this nut what i do instead is i um tighten it down until i feel some resistance and then i measure the rotational force which i'm looking for like 25 ish inch pounds of rotational force this isn't quite there yet i want to try and creep up on it because once once you start tightening you don't want to loosen on that crush sleeve you want to keep the tension on it almost feels like i went too far no not as bad as i thought in fact it's about 24 inch pounds it's a pinion flange holder i'll link them down in the description um i got this one but i kind of like my one from bleep and jeep better which is the one i'll link so it'll be slightly different than this now i can install my carrier assembly yes i did get a new ring gear bolt i installed it with a little bit of loctite and torqued it to spec before final assembly putting that bearing cap in lessens the chance of this assembly falling out on me all this stuff's linked in the description i'm going to 60 foot pounds on these cap bolts i check my backlash again it's actually a little better that went from nine down to just under five hopefully the tooth pattern didn't change too much with the because the setup bearing was the old bearing and i know the old bearing was bad maybe the new bearings being in there even though they were the same brand maybe that's accounting for that difference i find a fresh spot for a new tooth pattern now the pattern moved in towards the toe a little bit more and that's to be expected whenever you decrease backlash that's what will happen so if you got it too far in you increase backlash and that moves out i'm going to count on that wearing in i kind of wish it was a little farther down but i think it's good enough for government work as they say i'm happy with the backlash on this i'd rather have it tight and loose in this situation i think we're ready to put these axles back in and put this new cover on and then go out and check for our noise i had trouble getting this one out this is a brass drift punch i like to put the bolt in as a guide as to where it's going to end up you know what i'm just going to run this out a little bit put a drop of loctite on it i cleaned it before i put the loctite on it we are painfully close to getting this thing back together and getting it out on a test drive here's the new moser uh rear cover well it has these bearing supports what i'm going to do is i'm just going to take a little bit of ultra black rtv and i'm gonna put around the base of this and i'm gonna run it back through that way i've just got a little bit of uh rtb on the threads that way it'll draw it up in and i'll back these about as far out as i can get them so that there is no way for them to come in contact with the caps during installation i think that's backed in there far enough all right these are both ready to go i'm installed on the diff just an fyi here this uh cover comes with 13 bolts not 12 and the 13th is a little bit longer here and that is for the brake line retainer in the back you can put a spacer underneath it and that extra length is there to take up the for the spacer i cleaned the mating surface before i'm going up on there i'm using a gasket not our tv not a big fan of the rtv for this but that's a personal preference and i think we covered that at the beginning of video i like a gasket easier clean up after at least in my mind and this i believe is what they're talking about with this brake line so i've got well a put two of them in there a couple of spacers to bring this out past the cover and then extra long bolt i want to take one of his old spacers for this side make this work this one also got a longer bolt from the old cover these are going to get torqued to 25 foot-pounds i'm just snugging them up on there i'll run these down until i feel they make contact with the bearing caps right there and they're like five foot pounds maximum you don't want to load the bearing cap you just want to basically touch it hold it that's it don't push on it because you'll distort it so i think actually yeah like right there is good my torque wrench only goes down to uh 10 foot pounds this one's kind of snug yeah as soon as it touches just just barely move it the lock nuts get torqued down to 10 foot pounds now let's fill it up here's something i'd like to mention here is the factory fill plug and you can see its location it's just below the axle tube you come over here and you look at where the fill is you can see that it's considerably higher than the axle tube so i like to actually come in and take out the factory fill plug and fill through the other hole it seems to feel easier but this way i avoid overfilling the differential if you like my trick extension hose for the uh diff fluid fill now this royal purple has limited slip additives in it already but if you have a limited slip and you may be using different fluid make sure you put your limited slip fluid in it if it requires it and by the way if i was installing limited slip fluid into this differential i would have uh put some fluid in out of one of the bottles about half a bottle poured the limited slip in the bottle and then used the bottle to put the limited slip in and that's it that was a lot of work i think it's time to take a picture well more importantly time to put the wheels back on and take it out for a drive see if that noise is gone oh yeah i suppose i'll have to reattach this drive shaft too i don't know if it'll go down the road if i don't no i have not forgotten about my rogue bearing cap [Music] a couple of things real quick on this i've already told the owner about that uh breather in the differential extremely important that that gets addressed and he's going to get a new one and he's going to install it himself also with a new set of gears like this it's recommend you take it easy on them for the first 500 miles before you start getting on them that way they get a chance to wear and season up a little bit before uh you actually start flogging them let's say so for the first 500 miles if you put a new gear set in take it easy on it a little bit otherwise just have fun enjoy it hopefully it worked out for you like it did for me let's see if we got a noise now i don't hear anything it feels great i think this uh car likes 411s [Music] doesn't make a noise nothing it is silent nailed it it's a happy car yeah who likes these 411s all right success get this 72 nova back out on the road i like it i like it a lot [Music] oh yeah definitely smile factor smile factor of 11. ls power 72 nova 411 gears i like it like it a lot all right well viewers [Music] that's going to wrap up today's episode we're going to walk away with a win on this one if you want specifics on rear end rebuilds i'll link the description i'll link those videos down in the description that i've done in the past maybe we'll see this back in the in the shop again hey if you uh have automotive questions not covered in this video i ask that you head to air at thecargo.com that'll be linked in the description along with other stuff tools stuff that i've mentioned throughout the video i want to thank you for watching today i hope you enjoyed it be safe have fun stay dirty i'll see you next time try this at home kids try it be a gearhead

Channel: EricTheCarGuy

Views: 107,189

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Id: 5g7LD1VscuU

Length: 42min 15sec (2535 seconds)

Published: Fri Sep 11 2020