MGD72Monte Posted June 6, 2012 Share Posted June 6, 2012 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). Quote Link to comment Share on other sites More sharing options...
badddoin Posted June 6, 2012 Share Posted June 6, 2012 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 thinking if you changed the carrier the centerline may not be the same on the new carrier. I put .035 under my pinion bearing on my 12 bolt with new carrier (Eaton Posi) and new Richmind gears. I'm definatly no expert on gear set up, though. Countiing mine I've done one. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 6, 2012 Author Share Posted June 6, 2012 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. Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted June 7, 2012 Share Posted June 7, 2012 Def got to bring that pinion towards the back around .030 or so. Quote Link to comment Share on other sites More sharing options...
badddoin Posted June 7, 2012 Share Posted June 7, 2012 Originally Posted By: MGD72Monte 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 thinking if you changed the carrier the centerline may not be the same on the new carrier. The more I thought about this the less sense it made. Even with a new carrier, it seems that the centerline would have to be in the same place. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 7, 2012 Author Share Posted June 7, 2012 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. Quote Link to comment Share on other sites More sharing options...
Ian Posted June 7, 2012 Share Posted June 7, 2012 Believe it or not back in tech school when we did the rear in my 72 Monte we took a coke can and cut a piece out of the side to make a shim the right size Quote Link to comment Share on other sites More sharing options...
Heckeng Posted June 7, 2012 Share Posted June 7, 2012 So what changed? Is it the same set of gears that were in it before, with the same bearings? Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 7, 2012 Author Share Posted June 7, 2012 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. Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted June 7, 2012 Share Posted June 7, 2012 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. Installing new pinion bearings will put you right back to square one. What you are most likely dealing with is just production tolerances. Quote Link to comment Share on other sites More sharing options...
Heckeng Posted June 7, 2012 Share Posted June 7, 2012 Originally Posted By: 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. Installing new pinion bearings will put you right back to square one. What you are most likely dealing with is just production tolerances. ^^^^what he said Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 9, 2012 Author Share Posted June 9, 2012 Installing new pinion bearings will put you right back to square one. What you are most likely dealing with is just production tolerances. So basically then using a hollowed out used (but in good condition) pinion head bearing is only to get you within the ballpark for shims, it seems I'll have to take a guess based on that, press on the new bearing and likely still end up having to press it on/off a few times until I get the exact shim combination to work with that specific bearing set. Lot's of opportunities for damage by pressing a bearing on and off but I guess it is what it is. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 11, 2012 Author Share Posted June 11, 2012 Well after some back and forth, I decided to forget about the fitment bearing using my old pinion bearings so I decided to press on the new bearings with the original 0.029" shim and go from there. The first thing I found was dramatically different was when I applied some preload to the pinion bearings, the chopiness I experienced before with the old bearings was completely gone, rotation is smooth and breakaway torque is virtually the same as the rotational torque. The difference is absolutely amazing. The next thing is when I checked the backlash, it closed up from about 0.010" to 0.007". Measured in 8 different locations within 0.0015" and finally when I ran the pattern it was finally relatively clear as per below. Coast side Drive side It may not be 100% perfect but it's the best I've seen from previous iterations and it is using the original shim. I'm not going to chase 0.001" so I'm calling this good. Lesson learned: Don't waste your time with a fitment bearing. Quote Link to comment Share on other sites More sharing options...
geartech Posted June 15, 2012 Share Posted June 15, 2012 I haven't been keeping up with your thread, but that looks nice now. I've never had any luck with 'fitment' bearings, except for a pair of Dana 60 carrier bearings I've made like that. They have very thin shims under the carrier bearings so they work well to set it up and then press them on once. For pinion bearings, I've never had any luck though, like you said. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 15, 2012 Author Share Posted June 15, 2012 I haven't been keeping up with your thread, but that looks nice now. I've never had any luck with 'fitment' bearings, except for a pair of Dana 60 carrier bearings I've made like that. They have very thin shims under the carrier bearings so they work well to set it up and then press them on once. For pinion bearings, I've never had any luck though, like you said. Thanks for your input! I just got the beam style torque wrench I bought checked for accuraccy and it looks good, so next step will be the final pinion installation with the crush sleeve. After that I'm looking to get some chims to add some preload to the carrier. When I took it appart it seemed to be in snug but have no preload. It has made it easy to remove and replace through my multiple trials but I read you need to preload these bearings as part of the final installation. Right now although there is no side to side movement, I can rotate the existing (thick) shims by hand, so my thought was that this is not good enough. My book says to add 0.010" of total preload which would mean adding a 0.005" shim on each side. The closest I have is 0.009" shims so I called a machining centre and for $20 they can machine them down to 0.005" so I'm looking to do that tomorrow. Any input on that logic would be appreciated as well. Thanks again for your time Quote Link to comment Share on other sites More sharing options...
geartech Posted June 16, 2012 Share Posted June 16, 2012 what type of carrier shims do you have? the solid cast ones? or the aftermarket type, that are two thicker shims sandwiching thin (varying thicknesses) shims? If you have solid cast ones and you try to put a thin .005" in with it in there, it will just probably destroy the thin one... Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 17, 2012 Author Share Posted June 17, 2012 The shims I have are the big cast ones with bevel edges (0.240" on one side an 0.260" on the other). That's an interesting point, I was wondering how a paper thin shim would fare being squeezed in there. My book mentions nothing about this issue. Because I only changed bearings, you would think that I should not have to add more shims, once again, this is odd, wonder if I could assume that what does not feel like preload actually is? Not, 100% sure where to go from here. Quote Link to comment Share on other sites More sharing options...
geartech Posted June 18, 2012 Share Posted June 18, 2012 You have a couple options, you can find other cast shims that are a different size (.005 thicker), or go with what they usually call a super shim. You used to be able to go to the GM dealer and order what size cast shim you wanted, but they do not have those anymore. A super shim kit is another option, I can take a picture to show what I mean, its hard to explain. It's 2 thicker shims that fit together, with a selection of thin ones in between, that way they dont get destroyed when you put them in. So use whichever thin shims you need in the 'pack' to get it to the thickness you need. I have a super shim kit I can send you if its what you want, also I may have the cast shims, I'd have to look later. So you would be shooting for .245 and .265, is that right? As far as whether you need more preload, if you can turn those shims by hand, then you don't have any preload, you can probably lift the carrier right out? (without prying) Sounds like you're on the right track with .005 per side additional shim to give you some preload. Quote Link to comment Share on other sites More sharing options...
geartech Posted June 18, 2012 Share Posted June 18, 2012 super shim packs (2 zip tied together): Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 18, 2012 Author Share Posted June 18, 2012 You have a couple options, you can find other cast shims that are a different size (.005 thicker), or go with what they usually call a super shim. You used to be able to go to the GM dealer and order what size cast shim you wanted, but they do not have those anymore. A super shim kit is another option, I can take a picture to show what I mean, its hard to explain. It's 2 thicker shims that fit together, with a selection of thin ones in between, that way they dont get destroyed when you put them in. So use whichever thin shims you need in the 'pack' to get it to the thickness you need. I have a super shim kit I can send you if its what you want, also I may have the cast shims, I'd have to look later. So you would be shooting for .245 and .265, is that right? As far as whether you need more preload, if you can turn those shims by hand, then you don't have any preload, you can probably lift the carrier right out? (without prying) Sounds like you're on the right track with .005 per side additional shim to give you some preload. That's right for the shim sizes and yes I can turn the shims by hand when they are in (before I put the caps on) and I can just lift the carrier out by hand (It is a little sticky but definetly no prying). Thanks for the pics of the super shim, I can see the part that holds it together, had never seen that before. Quote Link to comment Share on other sites More sharing options...
geartech Posted June 19, 2012 Share Posted June 19, 2012 What are the inner and outer diameter of the shims you have? mostly the outer diameter. I'm having a brain fade as to which ones they are. I don't really keep track of which ones are for which rear, as I usually have one in my hand to compare to. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 19, 2012 Author Share Posted June 19, 2012 For the shims, the inner diameter is approx 1.88". Outer diameter is about 2.84" for the left side shim and 2.86" for the right size shim (not sure why there is a difference, maybe just machining tolerances, I assume they should be the same.) The shims have a beveled edge (which my book says are installed towards the housing). Quote Link to comment Share on other sites More sharing options...
geartech Posted June 20, 2012 Share Posted June 20, 2012 I don't have the cast shims in that size and the thicknesses you need, I can help with a set of super shims if you want to go that way. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted June 20, 2012 Author Share Posted June 20, 2012 Do you think if I bring the shims to a machine shop they would be able to make a custom sized one of the same design but thicker? Quote Link to comment Share on other sites More sharing options...
geartech Posted June 20, 2012 Share Posted June 20, 2012 A machine shop should be able to do that. Quote Link to comment Share on other sites More sharing options...
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