MikeMeyerhoff Posted May 18, 2015 Report Share Posted May 18, 2015 By some miracle a pick and pull near me (2.5hrs away ) had not one but TWO conquests so I went today and pulled some stuff including both rear ends (an 89 and an 86). I've never had to do anything with my cars rear end and I have some questions. 1st question. About a week ago I found a set of 4.22s from a 89 Ram50 front end. I thought that was the correct size for the 86/87 starquest LSD rear... Is it? I haven't taken it apart enough to get an actual measurement, but just looking at it the Ram50 ring appears smaller. 2nd question. The 86 torque tube splines (and those on the diff) have a "slanted" top surface. Thats basically toast right? It looks different than the 89 and has a definant clunk when switching direction turning it. 3rd question. The splines on the 89 look good and sharp. Could I swap those to the 86 diff? Or are there differences? The torque tubes interchange, but I don't know if there is some other issue with the male differential parts themselves. My goal with all this is to have a 4.22 lsd in place of my 86 flattys one tire fire. I don't plan on doing the diff work myself... not enough time to learn something new unfortunately. I just need to have the right parts to take the shop. mm Link to comment Share on other sites More sharing options...
ucw458 Posted May 18, 2015 Report Share Posted May 18, 2015 I hope you grabbed the 6 bolt axle parts from the 89. 88-89 take 6 bolt axles that are thicker than 83-87 4 bolt units. Link to comment Share on other sites More sharing options...
StarquestRescue Posted May 18, 2015 Report Share Posted May 18, 2015 (edited) 1st question. About a week ago I found a set of 4.22s from a 89 Ram50 front end. I thought that was the correct size for the 86/87 starquest LSD rear... Is it? I haven't taken it apart enough to get an actual measurement, but just looking at it the Ram50 ring appears smaller. 2nd question. The 86 torque tube splines (and those on the diff) have a "slanted" top surface. Thats basically toast right? It looks different than the 89 and has a defiant clunk when switching direction turning it. 3rd question. The splines on the 89 look good and sharp. Could I swap those to the 86 diff? Or are there differences? The torque tubes interchange, but I don't know if there is some other issue with the male differential parts themselves. My goal with all this is to have a 4.22 lsd in place of my 86 flattys one tire fire. I don't plan on doing the diff work myself... not enough time to learn something new unfortunately. I just need to have the right parts to take the shop. mm1 It may fit the smaller diff that came stock in the non intercooled cars. The intercooled cars need the r & p from the rear rear of a 4 cly truck. 2 & 3 The slant indicates wear. If both rears are from intercooled cars, the t tube and coupler will interchange. A non intercooled flatty would have had the small diff stock. Guys have swapped in the 86-87 intercooled rears with intercooled t tube to get limited slip. The non intercooled axles are longer, but have been used with the 86-87 lsd rears with no apparent problems. Edited May 18, 2015 by StarquestRescue 1 Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted May 18, 2015 Author Report Share Posted May 18, 2015 Ok. I was thinking the 86/87 intercooled diff was still the "small" diff and 88/89 was a "larger" one. So I'll need to get the rear ring/pinion from the Ram50 I took the front one from. I can use the good torque tube and splines from the 89 on the 86 intercooled diff to tighen it back up. Thanks.mm Link to comment Share on other sites More sharing options...
ucw458 Posted May 18, 2015 Report Share Posted May 18, 2015 I would use the 89 diff as it is and go get the 6 bolt axles and hubs. The 6 bolt axles are stronger than the 4 bolt units. If you're upgrading gears then why not upgrade the axles too. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted May 18, 2015 Author Report Share Posted May 18, 2015 Its an 86 flatty, so I'd have to 5 lug swap or maybe just the flanges to make the 6 bolt work. Probably not worth it for the power level in this car. I really thought all these years the 88/89 diff was "larger" and "stronger" than the 86/87 but it looks like the only difference is the axle splines. What about the 85- lsd units, are they the same ring/pinion size as the 86+ ? Link to comment Share on other sites More sharing options...
scott87star Posted May 19, 2015 Report Share Posted May 19, 2015 What about the 85- lsd units, are they the same ring/pinion size as the 86+ ? Yes they are, I just went through this. I grabbed an LSD rear from a buddy in Houston before I moved and just got around to putting in the 3:90's and popping it into my 87 flatty. Of course the four bolt axle shafts just spun around by hand, I got a set of six bolt thinking that one of the CV joints would be similar between 4's and 6's but trust me, there is absolutely no commonality. I have an 85.5 waiting for resto so I pulled the LSD out of that and swapped the spider gears from the 85.5 LSD into the later LSD. Yes, the only difference in the spider gear IS the inner diameter. The ring and pinions are identical between the 87 non-LSD, later model six bolt LSD and 85.5 LSD. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted May 25, 2015 Author Report Share Posted May 25, 2015 More info from the 84, 85, and 89 parts manuals. Ring and Pinion set:84 LSD and non-LSD MB18 5451 85 LSD and non-LSD MB24 197985.5 MB28 3430 89 MB18 5351 The 85.5 has a different male spline for the pinion than the the non-intercooled 84/85 parts. Torque tube shaft:84 and 85 LSD and Non-LSD MB16 058285.5 and 89 MB29 0748 I wish I had an 86 or 87 parts book to fill in the gaps. Anybody tear into an 83,84,85 four lug LSD? Link to comment Share on other sites More sharing options...
StarquestRescue Posted May 25, 2015 Report Share Posted May 25, 2015 For the USA market. Think of it as non intercooled vs intercooled. Non got the small riing and pinion, paired with the longer t tube and different coupler. 85.5 would be the large r & p paired with the shorter t tube and intercooled coupler. For 88-89 the Diff halves and spiders were bigger to accept and support the larger axles. So if Scott put 87 side gears in 88-89 diff haves, so he could run the 87 axles , then those axles are not properly supported on the smooth part between the splines and the where the seals runs. This is how i recall things. I do have the microfiche and some of the parts handy to double check if i get time. 1 Link to comment Share on other sites More sharing options...
Malykaii Posted May 27, 2015 Report Share Posted May 27, 2015 May I?Everything I know on the topic comes from what guys on 4x4wire do to get these diffs installed in Montero front diffs. So the 86 and back cars use 7.5 gears with small axles. 88/89 cars use 8.0 gears with the bigger axles. 87 models use 8.0 gears but take the smaller axle in the diff. Correct? Link to comment Share on other sites More sharing options...
StarquestRescue Posted May 28, 2015 Report Share Posted May 28, 2015 For the USA market. Think of it as non intercooled vs intercooled. Non intercooled got the small riing and pinion, paired with the longer t tube and different coupler. The intercooled cars, including the 85.5, would be the large r & p paired with the shorter t tube and intercooled coupler. Intercooled cars went into production in Dec 1984. Non intercooled car were built up to May 1987 Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted May 28, 2015 Author Report Share Posted May 28, 2015 I measured the torque tube on my 86 flatty and its the same as my 84 flatty. IC vs non-IC does seem to be correct no matter what the year. Intercooled got the larger 8" ring and pinion with a shorter torque tube. Thanks SQR. Link to comment Share on other sites More sharing options...
Tim_C. Posted June 18, 2015 Report Share Posted June 18, 2015 The 4:22 may look smaller to the eye due to less teeth. You should check it when you get it all apart. Link to comment Share on other sites More sharing options...
Metric-man Posted June 19, 2015 Report Share Posted June 19, 2015 The 7.5 rear diff. was used on the 3S AWD same part number. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 9, 2015 Author Report Share Posted July 9, 2015 Ok, 86/87 four bolt lsd diff is back from the shop rebuilt as a 4.22. Does this seem normal? play Link to comment Share on other sites More sharing options...
StarquestRescue Posted July 9, 2015 Report Share Posted July 9, 2015 That is not the correct way to measure the back lash. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 9, 2015 Author Report Share Posted July 9, 2015 Lol, I know, but is within the realm of acceptable? Seems like like a lot more than the stock diffs I've done the same to. Shop sealed it up, so to inspect it I'll have to open it again. I was really hoping to be able to trust the work I paid for and not have to put any time into it. I also notice that if I turn it several rotations in one direction it will feel like it is binding. Its dry, so that might be the lsd somehow? Link to comment Share on other sites More sharing options...
StarquestRescue Posted July 10, 2015 Report Share Posted July 10, 2015 The lsd will not be a factor out of the car. The play looks about normal, Maybe the big side of normal. Will they stand behind there work? you can always pull the cover off, you should be able to see the pattern paint markings. The binding could be some stray dirt or metal chip. I started to pull apart one the 2jz guys destroyed last weekend. Some major carnage. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 10, 2015 Author Report Share Posted July 10, 2015 Ok, I feel a little better now thanks. I think the shop is decent, hopefully its all me being paranoid. I'll pull the cover this weekend and attempt to measure the backlash. It'd be great if the pattern paint was still there. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 13, 2015 Author Report Share Posted July 13, 2015 Decided to ask the shop about it before I opened it. The guy who built it had notice the little bit of resistance but didn't think it was anything to worry about. Popped it open today and the patten paint was still there and as far as I can tell it looks decent. http://www.starquestclub.com/forum/uploads/gallery/album_1144/gallery_2764_1144_14296.jpg Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 14, 2015 Author Report Share Posted July 14, 2015 (edited) Measured ring runout at 0.0065. Carrier runout is 0,003. That probably explains why it feels tighter during part of the rotation, correct? Edited July 14, 2015 by MikeMeyerhoff Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 14, 2015 Author Report Share Posted July 14, 2015 Bit difficult to hold the input shaft well enough to get accuracy with the backlash reading. Seems like I'm getting values in the .011 to .015 range. Also noticed that the original pinion bearing is still on the old pinion. Shouldn't they have removed that to get to the shim? Link to comment Share on other sites More sharing options...
kev Posted July 14, 2015 Report Share Posted July 14, 2015 All of the numbers are high. See if you can hold that pinion better with a strap wrench or something and try your backlash again. I don't blame you for questioning their work. It appears too be too much slop My guess is that they used the pinion shim from the new pinion. That shim is my biggest gripe about these differentials. You don't know if it is the correct one until the entire unit is assembled, backlash checked, and pattern checked. You can experiment a little with the ring gear shims but if it still doesn't get into spec you have to start over by fully tearing down and trying a new inner pinion shim. So frustrating. Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted July 15, 2015 Author Report Share Posted July 15, 2015 Thanks for the tip on the strap wrench. A whole $5 at harbor frieght and it worked like a charm. Measuring out at .016-.017 backlash. Back it'll go, not looking forward to this conversation. Link to comment Share on other sites More sharing options...
kev Posted July 15, 2015 Report Share Posted July 15, 2015 Wonder if they even checked the backlash and if they did I wonder if they even looked up the Mitsubishi specification. May just have relied on the pattern and a 'standard' amount of backlash across the board Link to comment Share on other sites More sharing options...
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