MGD72Monte

The only thing that changed is the carrier bearings & races as well as the pinion races at this time. I will be installing the new pinion bearings once I get this pattern right. I might just give up on it and assume the pattern was like that before because my backlash is within 0.001" of where it was before tear down.

Well, looking at the shim options I got based on my installation kit, there are limited options. I changed the 0.029" shim with a 0.040" and the pattern now shows the pinion is too close and my backlash closed up to 0.006" (less desirable). I probably would need a 0.032" or 0.035" shim but no such luck in the kit. I wish there was a 0.002" or 0.004" shim that I could simply add. It's odd, the kit has very little selection and I looked at ordering a specific shim kit but the contents are: (1) 0.020" thick shim (2) 0.021" thick shims (1) 0.026" thick shim (2) 0.027" thick shims (1) 0.029" thick shim (2) 0.041" thick shims (1) 0.042" thick shim So I would be no better off. How are you expected to make micro adjustments with that!? I called a few local shops and the're useless, you'd think I was working on the space shuttle.

Thanks for the feedback Tommy, this will be my first as well. I should have mentioned, the carrier is also unchanged so I'm still scratching my head.

This is the pattern check with the trial set up using the shims that were on the gear when I took it apart. Backlash is good at 0.010" average based on 8 measurements throughout the gear. Based on the pattern and my limited interpreation skill it looks like I will need to add some shims behind the pinion bearing, based on my book anyway. The existing shim is 0.029" any ideas on how much to add if I should add? Coast side Drive side I'm a little puzzled as to why the pattern is not perfect with the existing shims given that it is the OEM gears and the same set of bearings (for this trial fit).

I'm putting the gears back in the diff (this is my old set 8.2" OEM with new bearings). To check all the specs, I installed the pinion without the crush sleeve and using my old pinion head bearing holowed out for easy removal, same shim. I torqued the pinion nut down to get about 20-25in.lbs rotational torque. I find that the rolling is rather choppy, it takes about 140in.lbs breakaway to get it turning then it goes down to 20-25 if you keep it spinning. It's not silky smooth turning like it was when I took it appart it seems. Is that normal? Is it maybe because I have old bearings on new races? I dropped the carrier in, I think it went in way too easy, I've read you have to force it in. The carrier shims (same ones reinstalled - only one per side and fairly thick) can be spun by hand in the case, so I'm thinking the carrier preload is not enough I'll be looking to add some shims that came with my diff kit. Too bad they don't mark the size of the shims, I'm hoping they are stacked in order with two of each size? I checked the backlash quickly in several locations, I'm getting between 9.5 - 11.5 thousands. Before disassembly I was getting about 11 but only measured it in one location. Input welcome. Thanks

Great info, thanks for the quick and detailed responses guys, more questions to come. Mike, I am hoping as you said that since it is the same gear set, the same shims will work.

Any recommendations for Gear Oil brand and specs for a stock 2.73 used gear set. The owner's manual says GL5 - SAE 80. Also, what is the backlash I should be looking for? This is an 8.2" open, used gears with new bearings. The specs I found say 0.006" - 0.0010". It had just under 0.0011" before disassembly. Am I better on the low end of the range or doesn't matter? Thanks

Nice grill, good luck with the job hunt.

That's is in great condition and your garage is impressive. Welcome to the site, your pics are appreciated. Salt damage is bad in many parts of Canada as well. Mine was much, much worst than yours when it was only 16 years old!

I replaced the ones on my 72 a while back and don't recall this feature. Does anyone know if this applies to 72? I don't think it does as the diagram in my factory assembly manual looks different than the one shown.

Nice dash, unusual sound, never heard that before. Did you just change the valvetrain or something else. As per others on the valves, I also have never heard of that type of adjustment but each cam seems to have its own. My Comp Cam called for 0.030"+/-.010 preload achieved by tightening the nut while spinning the pushrod with finger tips until a slight resistance in the pushrod (0 lash) then turning the nut 1/2 turn more. Hope you find the issue. Ditto on what others have said about the need to get the revs up to break in the cam properly. Good luck

Great work, wish the pics were a bit larger though .

Ordered it today - about $45 incl shipping fm Amazon! I had found that one before but was not sure a beam typ would work, thanks for the input.

Thanks Mike, appreciate the words of wisdom. It gives me hope that this could actually turn out, I'm still looking for an affordable dial type torque wrench that will read that low.

Thanks Scott, clarifies what you meant, I'm just having trouble figuring why there are so many different torque specs out there. The reference I found for the GM 8.2" 10 bolt from Yukon Gear and Axle lists 12-15in.lbs for new bearings and 6-7in.lbs for used bearings even for the 12 bolt it only gets to 14-19in.lbs. My Haynes lists 15-30 for new and 5-10 for used, but it is confusing as to whether they are referring to B and O type axles which mine is not, no specs for anything else????? The Jegs Diff kit I got came with no specs at all. I went to a local tranny shop and the guy says he checks it by feel so maybe it doesn't really matter?! The 20-25 you use is in the middle. When I rebuilt my engine I found a great book dealing specifically with the SB Chevy with all the torques, I know there is a book specifically for the TH350 transmission, what is missing is a GM differential book or some listing of official specs in some GM manual. Did the factories burn all their data? I definetly don't trust any of the shops around my area to steer me right. I'll probably go with your recommendation because it is in the middle, but I'm almost ready to resign myself to the fact that this thing will blow up on me no matter what. I guess that's the only way I'll learn I should have gone to a mechanics school... argh. Originally Posted By: MCBeast Well, after going over this entire thread, I've come to the conclusion that I should probably find a shop to do mine. The mag articles point out a few things, but I don't recall them ever getting into this much detail about what's needed! I thought I may be able to do it myself with the right instructional material, and now I'm just worried I'll miss something and end up grenading it. Unless, of course, somebody feels like a road trip to pick up a case of beer or two at some point... I have a pretty good book but it does not have application specific specs. I would not have thought finding simple torque specs to be so confusing. For now and until I get further along, the only help I will be able to give you is finishing that case of beer!

Scott, I'm not sure I understand what you are saying about the bearing rolling torque you use. Sorry if I sound dumb but I've read the first sentence a couple of times and can't tell. Are you saying that the bearings were 20-25 in.lbs type bearings but you torqued them to 10-15?

As I understand it, you need 200 to 400 ft.lbs to crush the sleeve and get to the comparatively small preload amount.

Scott, I'll check the local rental places, but I'm not holding out much hope as I have already checked out the main tool rental place up here. 20-25 in.lbs is a spec I've heard quoted a lot but the only actual ref I found (supplied by Mike (geartech)) linky says 12-15 in.lbs for GM 8.2" ring gear with new bearings. Is there another spec source I should be looking at? Thanks

Originally Posted By: Mike 57 Jegs has the correct crush washer, link as some one stated it is for the OE gear the one you have is for a aftermarket gear. You guys are right, as usual. Thanks for steering me right. Whoever I was talking to the first time I called Jegs was not knowledgeable on the different sleeves when he told me the OE one was discontinued while they still carry it . I had a similar experience when I called today, the guy admited he didn't know and asked me to call back when the differential expert got back. I did and finally was told that it was not the right one for my application. I guess they figure if you order the kit, you are using an aftermarket gear set. For those who might be curious, here is a pick of an aftermarket Pinion and there is a ridge machined into the shaft. Presumably the short crush sleeves rest on that ridge, so it does not have to go all the way down to the head bearing. Definetly educational, wish it would be specified in the kit though or even in the catalogue so you know you have to order a different sleeve separately at the time. I must be the only clueless guy ordering this kit . If only I could cash in on all my ignorance . Anyway, thanks again, now on to my next problem. I'm still trying to figure out how I'm going to check for bearing preload (12 - 15 in.lbs) without having to buy a $250 dial type in.lbs torque wrench . Ideas welcome.

Thanks Mike, I think I am going to call Jegs again and ask for more explanation on how this part is meant to fit and what happens if you need to take it off. It would seem odd that their kit, designed for this specific differential would not have the right crush sleeve. Originally Posted By: Wiham I think this may be the part you're looking for. Crush Sleeve Sam, that would be the one, nice to know they still make it, very good to know if I don't get a good answer on how the new one is supposed to work.

Thought some of you might find this interesting and if I have it wrong, one of the experts pls correct me. When I got my Jegs Differential Installation Kit for my 8.2" 10 bolt I found it odd that the crush sleeve was quite different than the one I removed. The new one is on the left with the original on the right. I know the diff was opened at some point in the past, does any one know if the one on the right is OEM? I called Jegs and they told me the one on the left is a new design and the original is no longer available. Here is what the original one looks like installed. You can see the base of the sleeve is in contact with the inner race of the pinion head bearing and the top is in contact with the tail bearing. Below is the new one positioned on the pinion (not fully installed). As far as I can tell, it uses the taper on the pinion shaft to wedge itself when the pinion nut is torqued down, then deforms at the centre. The wall thickess is about half as thick as the original one so hopefully it will be easier to crush than the old one must have been. My concern would be if I have to take this off, possibly if I overtorque it, how easy would it be to remove and replace this type of crush sleeve. Curious to see if anyone has experience with this type of sleeve. Do you have to cut it off to remove?

Looking forward to seeing the progress.

DJ, Don't know if this will help but the ones I got were from OPG and am happy with them so far. I received one which was a clear return from someone else which had not been packaged properly and got scuffed. I returned it for exchange and they were good about it (no charge and not arguments). Not sure who their supplier is but in general the evolutions in steels over 40 years should make these last beyond my life.

I'm slowly accumulating all the tools to reassemble the differential, but there is a step that I'm not sure I will be able to do. Here are two questions: 1. What are the pinion bearing preload torque to rotate specs for a GM 8.2" open diff with new (Timken) bearings. The generic overhaul book I have states 20 - 25 in.lbs are typical values but a set up spec kit installation sheet someone gave me from Yukon Gear & Axle says 12 - 15 in.lbs for GM 8.2". Those seem to be big differences. Any other or master sources for these specs? 2. Book says too measure the torque I need a dial type torque wrench which reads really low values. I've priced them out at $250 . All I have is a click type that goes as low as 25in.lbs or an old beam type (that one starts at zero but the incredibly small amount of deflection to read such low values would be almost impossible to read.) Any tips on how to measure such low values? Thanks for your time