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Discussion Starter #1
I feel as though I've read every thread in this forum on how to build/set up these diffs but I'm left with some very basic questions about the tools needed:
-What bearing drivers are people using to install the bearing races? I've tried the el-cheapo set from Garbage Freight but they didn't come anywhere close to fitting the races. Yukon makes specific drivers for two of the three bearing races but at $125 a pop, it seems a bit pricey for something I'm might only ever do a couple of times.
-What is the best blind bearing race puller to use on the side adjuster races? I've tried welding on the races and tried a heating plate and the races didn't even budge.

Random Questions:
-Does anyone know what the pinion depth was for factory gears? Not that i intend to buy a tool to check it but i would be curious if its published anywhere. I noticed some very faded numbers, written in some kind paint pen, on the face of the pinion and wondered if that could indicate what the depth was set at.
-When setting up used gears, if i don't have the backlash measurements from before they were removed, what backlash should i aim for? I know the pattern will be key, especially on the coast side, to ensuring the gears don't get too loud but i also understand that some noise is likely since getting a 100% match from where it was is unlikely.
-Difference in backlash between manual and auto cars? I've seen some random comments on it but nothing official.

Thanks!
 

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Hell pecker yeah
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The race beaters I have are made of aluminum and haven't damaged any of the races I've installed so far. I don't have the perfect sized ones for this diff, but haven't had any issues.

As far as installed used gears and not having any of the measurements, it's going to be crap shoot. If you've built diffs before you should have a good handle on what your marking compound is showing you and a feel for it. If you build it and it's a little noisy I would think that you could tweak it a little to see if you could get it back to its original mesh before you wear it in incorrectly.

I have never taken into account what trans the car has it - only built the diff to proper specs. I can't recall seeing different specs for auto versus manual.
 

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My other car has wings
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I put a post out here a while back on the side adjuster race removal.
 

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Many gears have the specs for pinion depth and backlash either stamped or written on them. Those numbers you saw on the pinion was probably the depth measurement. The backlash measurement should be stamped on the side of the ring gear.

If you purchase a new set, you should be given those specs.
 

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Discussion Starter #5
I put a post out here a while back on the side adjuster race removal.
I actually followed your thread and tried it out. It didn't work for me but I think it more a function of the puller jaws I tried to use. I eventually got the races out using a tiny 2 jaw puller and some patience. The races actually slid out pretty easily. The new races pressed in really easily too.


Many gears have the specs for pinion depth and backlash either stamped or written on them. Those numbers you saw on the pinion was probably the depth measurement. The backlash measurement should be stamped on the side of the ring gear.

If you purchase a new set, you should be given those specs.
The gears i'm reusing are stock gears. There are two sets of numbers stamped on the pinion and on the ring gear. The first number is the same but the second one is different.
498906
498907
498908
 

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the .003 on the ring gear should be the backlash, even though it seems a bit on the tight side.

i can't even read the markings on the face of the pinion, but on the motive gears i messed with, the numbers on the face were the pinion depth that i measured to be the best achaivable pattern on the gears. not sure what the "13" means. the pinion depth will be on the order of inches, accuracy down to the thousanth, iirc.
 

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Discussion Starter #7
the .003 on the ring gear should be the backlash, even though it seems a bit on the tight side.

i can't even read the markings on the face of the pinion, but on the motive gears i messed with, the numbers on the face were the pinion depth that i measured to be the best achaivable pattern on the gears. not sure what the "13" means. the pinion depth will be on the order of inches, accuracy down to the thousanth, iirc.
Yeah, the 003 seems pretty tight for backlash. I've been told these cars like somewhere between 005-007. I was think the 013 might be the shim size. Of course ,I went to check it but the battery in my calipers was dead so ill get a new one tomorrow and see if it matches.
 

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you have me wondering if the stamped numbers have anything to do with the gear setup. im trying to find some hard documentation on the range for the OEM gears. Seems that dana/spicers usually are .006-.010 or .004-.010, but those are US versions.

EDIT

i have found some info on the borg warner M78, which is a supposedly similar, albiet a live-axle version. backlash range is .006" - .010". Interestingly enough, it's the same "aussie" rear end that came in many 3rd gen f-bodies. There is also an M75 beam and M76 IRS unit that uses a little smaller set. Looking for info on these, but didn't find much.

also, i think the "0580" specifies the gear set type, the "80" being for an M80, naturally. Which, i think, also means it is an 8" ring gear. So, larger ring/pinion gear set than the M78, and M76/75 as well. Assuming the gears were cut similarly, the backlash specifications should be similar, though. makes me wonder what the three digits after the gear set number are, now.

I would set it up with .006 or .005 minimum and see what the pattern looks like.
 

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one last bit of info, then i'll go to bed.


if you can figure out the diametral pitch of the set, which involves dividing the number of teeth by the pitch circle diameter (if i understand correctly, the point where the teeth contact would be on this circle, with the center of the gear as the center of the circle), then you can get a proper range. i did a real gross estimate, and ended up with something in the 6 - 8 range for the diametral pitch, so a recommended backlash range of somewhere .004 - .010, depending on the accuracy of the gear cut. that's assuming i did it correctly, of course. the range does seem to fit right in with the other data i've looked up.
 

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Discussion Starter #10
Some more interesting info as I dig into this. There are, apparently, two types of cut gears: Face Milled and Face Hobbed. The explanation can be found at the following site: https://www.canadawideparts.com/downloads/dana_tooth_pattern.pdf

Which type of gears you have determines the type of pattern you want to see. I've determined that our stock gears are Face Hobbed, meaning the depth of the tooth is the same from the heel to the toe. After determining this I took a look at the ring and pinion I was going to reuse and saw that, at some point in its life, the gear pattern changed on the coast side and is showing root toe contact (see pictures). The drive side "appears" to be okay. According to the pattern chart, the way to correct this root toe issue is to install a thinner pinion shim but im more interested in what would have cause the pattern change to begin with and lastly, if I should reuse these gears or just bite the bullet and get some new ones.
498940

498941
 

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The pinion nut likely backed off a touch or crush collar crushed more (abuse). If it had an aftermarket driveshaft in it they might have changed the yoke. causing the nut to back off later. O r didnt tighten it up correctly. I shoot for .006-.008 backlash. Bearing could have went bad too causing the secondary pattern.
 
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