Any ring and pinion guru's out there?

[ZEKE68]

This is what I got for a pattern when I checked my contact today before taking the rear end apart. Does it look like not enough pinion shim, and not enough back lash? Contact is on the toe on the drive side and tapers down going to the heel. The coast side looks a lot better, but is still toward the toe. This is my old gear set which I plan to reuse.

[Jrainman]

I would say you will need to shim , you want to see things more in the center , they are web sites that have actual pictures that would give you a better understanding of what your end results should be ,its harder to undertstand if I explane it (a picture is worth a thousand words goes better in this case). But since this is a referance check because you have not rebuilt it yet , I think after the rebuild and more often then not the original oem shim setup should get you where you need to be . but find some online picture of a good setup so you are clear where you need to be .

[ZEKE68]

Yea, I have three or four books that show contact patterns. Just thought that someone who does a lot of rear ends may comment. I have done a few rear end rebuilds in my time, but they are few and far between, 55 chevy, a 91 Jimmy, and now this truck 12 bolt.

[LH Lead-Foot]

Your pinion is too high, so you will have to remove at least one shim around 0.09 - 0.10. This will place the tooth contact pattern closer to the middle on the drive side.
Once you get your pinion height up in the middle with correct preload, the next trick is to set backlash. With the side caps off, slide a feeler gauge of 0.02" one on each side of the shim pack. Check backlash. Adjust shims as needed to move carrier closer or further away. Specs tell you backlash should be 0.06"-0.08". I prefer to go tighter at 0.05 backlash as the carrier will push away from the pinion under load. Once you get the backlash set with 0.02" feeler blades, one on each side, then install a 0.04" shim in pack of both sides. This will set proper preload on side bearings since you don't have a differential spreader that gently opens the case to install side bearing shims.

[ZEKE68]

Thank you very much. Still trying to get the pinion nut off.

[volksworld]

i think leadfoots numbers are off by a decimal point...a .10 shim would be almost 1/8 inch....backlash is usually in thousandths , like .006, not .06 which again is almost 1/16

[LH Lead-Foot]

I will get the correct shim numbers from the garage soon. Going by memory is tricky sometimes, but I have done close to one hundred diff's over the years with my own last year. Chronic pain has it's disadvantages.

Pinion Nut; Use a chain wrench to wrap around the yoke or companion flange as it's called. Not all chain wrenches are long enough so measure if you have to buy one. Place a length of pipe around 6 foot on the handle of the chain wrench for leverage. 2" Conduit pipe from the home improvement store is cheap and will work fine. It will help you get the pinion nut off, but better yet, help you control the amount of force used to tighten it and obtain correct pre-load or rotational force on the pinion bearings. You will want to use a 1/2" ratchet or breaker bar and perhaps a cheater on it as well.

TIP: Use a nylon wire tie on the link of the chain wrench once you have it set. It has to come off frequently during pre-load to check where you're at.

If you are working while in the vehicle, use the lower control arm to lay to cheater bar/tube across as this will free up your concentration on the pinion. Use duct tape to hold the cheater in place temporarily as it will fall if you slip off the companion flange. Don't wear flip-flops.

Crush sleeves are cheap, but if too tight, they cannot be re-used. It will seem like you are wrenching until your arm falls off, but stop. As it gets tighter for the last time, check the pinion frequently as you tighten. It will be sloppy loose forever and when you don't expect it, it is too tight. Best advice is to wiggle the pinion around until you reach a point where it does not move sideways or in & out. This is when you go slow, perhaps 1/8 turn at a time, then recheck rotational force.

Rotational force is measured with a beam type torque wrench in inch pounds that specs vary depending on if you are using new or old bearings. Lube the seal and garden spring on the back only. I always used Loctite 518 red jelly on the outer edge of the seals seat before driving it home. Seal manufactures claim their coating on the seal is all that's needed, but I don't trust it and don't want to repeat the process due a leak.

Many may not know this, but the companion flange or Yoke should have sealant also. I use GM's liquid teflon thread sealant on the end of the pinion splines as well as the first 1/4" of the Yokes splines. It can leak pass it and come out behind the nut, especially if the breather tube on top gets plugged or as truck use a hose, gets pinch. This causes pressure inside a sealed diff housing from cold to hot.
Also, use bearing grease and pack the pinion bearings as well. They don't get lube unless the ring gear moves fast enough to throw gear lube (GL5) into the top cavity of the differential housing that captures the lube between the pinion bearings. It's just good insurance before you get out the door. This also true for the outer axle bearings. They are dry until you turn a corner and lube travels due to centrifugal force and a small amount is captured in the axle housings machined tube end.

Generally, A good starting place with shim packs is to use the OEM shims to start with. Do your pattern and adjust from there. Using new shim kits, measure the OEM shim packs with a micrometer then look for (+) or (-) mark in the new pinion. Add or subtract by thousands of an inch. I have had dozen of perfect patterns just by using the original shims, but then I was installing the manufactures dealership parts.

[Bigdav160]

What is your backlash measurement? I won't take a pattern unless the backlash is in specification.

[ZEKE68]

Back lash was in spec on the tight side at .006". Supposed to be .006" to .010". This truck seems to be unmolested from the factory. The carrier shims only had the ground cast shim on both sides. .240" on the left, and .235" on the right. The truck had 25k on the odometer when I got it which doesn't mean much, but it also still had the riveted in upper ball joints. There hasn't been any problems with the rear end, and the pinion feels good when spinning it but I am afraid to not change out the pinion bearings now. I have redone everything else in the truck, and I am going to have a big block spinning the drive shaft. I would hate to not change the pinion bearings and then spin a race and ruin the case.

[ZEKE68]

Got the pinion nut off, and got everything apart. I got the new pinion bearing races installed into the case, so now I have to get the gear end pinion bearing off and make up my checker bearing before I start back together.

[Ironangel]

Take your pattern check after you have set your new races and bearings, and after you've got the backlash set. The initial pattern you showed was not bad for a truck 12-bolt with 125K on the clock. If it were me? I'd go right back with the same factory pinion shim under the new bearing and button that baby up. .006" backlash is dead nuts on a 50 year old 12T. On final assembly, tighten that pinion nut until you feel zero end play in the pinion, then take your pinion preload measurements after 1/8th turn increments. I'm not a guru, I just rebuild rear ends to supplement my pension and "Nasty Sally's Boutique" https://www.facebook.com/media/set/?...1&l=54c2c06b2e

[Hoosier Rick]

Did this diff have any gear noise prior to this repair? If no, then I would put all the original shims back in their proper places.
How did you take this pattern check? you should have some load on the gears to get a proper pattern.

[kwmech]

Do not mess with the pattern on a used gear.....they will make noise. Just keep the shims in original orientation and replace the bearings as they sit. If those were new gears, I'd take out about .010 from the pinion, set the back lash at .008 ish, then recheck the pattern

[ZEKE68]

I think that sounds like good advise. I am going to put it back the way it came apart with the new bearings. Hopefully with the new bearings it will be near where it was before, because it didn't make any noise or have any other problems. It will just have new bearings and more pinion preload than before.

[ZEKE68]

Parts

[ElKotze]

Do not use bearing grease to pack the pinion or carrier bearings, it will mess up your torque readings when setting the pre-load. It will also prevent proper lubrication later. Always use clean gear oil to pre-lube.

[ZEKE68]

Got the pinion in today just to the point of pulling the drive shaft end bearing up to the crush sleeve. Then I pulled the yoke back off. I used new gear oil to lube the bearings before install. Got to wait for my BFW to get here to finish putting it together and crushing the sleeve. While I was waiting on the BFW, I decided to install the brackets for the No Limit upper sway bar and found that one of my u bolts has stripped threads. Now another rush order to keep things going. Over a year now on this truck redo. I would really like to drive it again some day.

[Boog]

It's the annoying little things like that that can drive you nuts. But you have to know it will all be worth it one day when you can twist the key and drive.

[LH Lead-Foot]

Originally Posted by ElKotze

Do not use bearing grease to pack the pinion or carrier bearings, it will mess up your torque readings when setting the pre-load. It will also prevent proper lubrication later. Always use clean gear oil to pre-lube.

I have never had a problem with bearing grease as it melts quickly when gear lube hits it AFTER you get out in the road. It has never changed pinion pre-load readings regardless of which you use. Considering the pre-load is set first without a carrier installed, it eliminates the mess of cleaning gear lube running down your shirt. I was taught this in 1974 by a seasoned speed shop tech and later by factory instructor in 1979. Hitachi, Dana and Spicer manuals include the use of grease in the installation of pinion & carrier bearings and especially the outer axle bearings. GL5 is compatible with wheel bearing grease and provides protection to loaded bearing surfaces until the vehicle reaches road speeds during test drive. Everyone has their own opinions, but after working under warranty in dealerships for over a decade or more, never had a come back. I use high temp red RTV on the diff cover without a gasket. While OEM carrier bearing shims are one piece cast, aftermarket shims are not. This is where using the feeler gauge of 0.02" on both sides once backlash is correct, you now have to pre-load the carrier bearings. Adding a 0.04" shim (Or thicker cast shim) is in the factory service manuals. This is done using a differential housing spreader or driver with single cast shims. I use a spreader.
To get a correct pattern, I first check lateral runout in 4 places, the with a bar on the carrier, rotate the pinion at least three time forward to achieve a tooth pattern that is usable for diagnostics and should be done first before disassembly. Coast pattern will fall into place, yet should be checked as well.

[ZEKE68]

I was afraid of using the grease because I was concerned of it affecting the limited slip clutches, which is why I used the oil. What do you use to seal the splines and washer, so the oil can't leak through that area?

[ElKotze]

Originally Posted by LH Lead-Foot

I have never had a problem with bearing grease as it melts quickly when gear lube hits it AFTER you get out in the road. It has never changed pinion pre-load readings regardless of which you use. Considering the pre-load is set first without a carrier installed, it eliminates the mess of cleaning gear lube running down your shirt. I was taught this in 1974 by a seasoned speed shop tech and later by factory instructor in 1979. Hitachi, Dana and Spicer manuals include the use of grease in the installation of pinion & carrier bearings and especially the outer axle bearings. GL5 is compatible with wheel bearing grease and provides protection to loaded bearing surfaces until the vehicle reaches road speeds during test drive. Everyone has their own opinions, but after working under warranty in dealerships for over a decade or more, never had a come back. I use high temp red RTV on the diff cover without a gasket. While OEM carrier bearing shims are one piece cast, aftermarket shims are not. This is where using the feeler gauge of 0.02" on both sides once backlash is correct, you now have to pre-load the carrier bearings. Adding a 0.04" shim (Or thicker cast shim) is in the factory service manuals. This is done using a differential housing spreader or driver with single cast shims. I use a spreader.
To get a correct pattern, I first check lateral runout in 4 places, the with a bar on the carrier, rotate the pinion at least three time forward to achieve a tooth pattern that is usable for diagnostics and should be done first before disassembly. Coast pattern will fall into place, yet should be checked as well.

Yeah, I was waiting for that! But You're right, everybody has their own way of doing things. But I didn't comment just for ****s and giggles about not using grease. Just a little about my back ground: I was working as an engineer for British Petrol (BP) in the new product development, all about the lube. Later I was on the team as an engineer and test driver at GM that developed the Corvette C6, some Cadillacs, the works, all high HP stuff. After that I was a test driver for V.A.G., the company that owns VW, AUDI, Porsche and Lamborghini, they mainly use SKF bearings in high HP applications. I still have my pass that I'm licensed to drive on all the high speed testing curcuits in Europe and North America, btw. So I have been around the block a couple of times and bearing grease on Pinion bearings is a big no-no, also on wheel bearings on full-floating axles.Why? Because grease creates a blockage that prevents gear oil from getting to the bearing, lubrication won't be sufficient and the bearing will burn up, plus it will mess up your clutch type limited slip, if present.Also, a pinion bearing spins multiple times faster than a wheel bearing and can create a lot of heat in a short amount of time. Splash-lubrication ensures heat transfer away from the bearing, grease will keep it right there.Oh, and the grease will not "melt quickly", modern grease types are heat and pressure resistant to prevent them from doing just that. Same with the bearings in semi-floating and full-floating axles, they are designed to take a lot of pressure, but can create heat, thus need to be cooled by the gear oil.

[ElKotze]

Originally Posted by ZEKE68

I was afraid of using the grease because I was concerned of it affecting the limited slip clutches, which is why I used the oil. What do you use to seal the splines and washer, so the oil can't leak through that area?

Copper paste

[LH Lead-Foot]

To seal the flange to the pinion, the service manual indicates GM #12346004. It is a liquid teflon sealant. They don't list copper paste.
While formulas of wheel bearing grease are different so as to not copy someones patent, it is still used without failure to bearings or friction materials used on GM corporate limited slips plates or Auburn cone type. I have no opinion, just hands on experience rebuilding rear axles that most pay less than 4hrs. book time to complete. 4.8hrs if limited slip with exciter ring for three channel ABS.

Question, If you have full floating axles, how does the bearings get lubricant? They are on the outside of the axle where gear lube does not flow. The only gear lube that comes out is when you un-bolt the axles. They will burn up with a few days of usage is you don't pack them.

It is just an issue of protection for the bearings before the centrifugal splash flow of GL5 start to sling into the nose of the differential housing to begin to lube the pinion bearings. No one uses 3 lbs. of grease on these bearings, just a coating for initial bearing alignment, seating and reducing rotation force. While gear lube maybe common, it's just fine. Use what you want, I don't care. I have never had any problem after decades. Mine works fine.

Perhaps you can explain the factory ring & pinion "Zero" backlash used on the 1972 Subaru GL Wagon and the Lancia Beta. Or the best way to remove the cylinder head off the 9" block studs on the Fiat X1/9th?

[ElKotze]

Man, those X1/9's are sharp, I always wanted one! But I think the FIAT's all rusted to the ground before you had to do any engine work......LOL.

[Ironangel]

Neveruse wheel bearing grease on pinion bearings, carrier bearings, or full floating axle bearings...All the manuals warn against it's use in those areas. Wheel bearing grease is formulated with a microscopic fibrous binding material that does not break down and mix with gear lube. The GM 12T uses the ring gear to sling oil/lube into the large opening at the front top of the housing. Both bearings are exposed inside that opening receiving cool lube that exits through the small lower drain hole below. The smallest amount of grease can and will dramatically change your preload readings as 12 inch pounds is only 1 foot pound. A lose preload is as deadly to a differential as to much preload will cause excessive wear, heat, and premature failure. Your housing looks good and I'm glad to hear your waiting for a wrench big enough to tighten that nut in small increments. What are you holding the pinion yoke with? Allstar makes a reasonably priced tool that allows you to easily take your inch pound preload readings without having to remove the tool from the yoke. Thats a trick my $200 Kent-Moore wrench wont do. Heres a link for the tool, https://www.jegs.com/i/Allstar-Perfo...SABEgJuP_D_BwE And heres the bad news I see in your pic. If thats a clicker inch pound torque wrench in the pic, you really should be using a dial read type or the beam type. The clickers wont give accurate reads of rotating resistance in motion. The beam type are ok especially if they have a memory pin to mark the resistance. I suppose a digital read will work although I've neve used one, just in case thats a digital unit in that little black bag...Good luck, lookin good!