Jon M Posted March 13 Share Posted March 13 Good morning, folks. It's getting warmer so I'm picking up where I left off a few months ago with Dolly, the 1984 f150 4X4 in-line 6. One of the many things I have on my to-do list is to learn how to check the integrity of the factory limited slip on my rear differential. YouTube, tells me to just keep one wheel one the ground and put a torque wrench on an axle nut and incrementally go up in torque value. Well, we don't have axle nuts on these trucks so I figure a lug nut will have to do. But aside from that, I'm looking for the original torque specs would be on the factory limited slip so I can see how effective it's going to be and if I need to (eventually) replace it. Unfortunately, this rear-diff is not native to Dolly but the truck came to me with it so I have no idea what generation it is. Based on the smaller, ill-fitting front sway bar that came on the truck (it's off now), I'm wondering if it's from a Ranger - but I suspect most of the limited slips will be spec'd at the same or similar value across many generations. All that to say, I want to find out how much abuse this thing has sustained - is there a listing in this website's documents with the limited slip torque values I should be trying to match during the test? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13 Share Posted March 13 Jon - We didn't have the section from the factory shop manual on the site for the Traction-Lok diff. So I added it on the page at Documentation/Driveline and then the Rear Axles & Differentials tab, the Instructions tab, the Ford 8.8" tab, and finally the Ford Traction-Lok tab. It says: Minimum rotating torques required during bench check after assembly or in vehicle with one wheel on the ground for original clutch pack. 41 Ft-Lb/30 N-m You aren't really going to be able to test that directly by placing a torque wrench on a lug nut because that's assuming you are on the axle itself. However, you can test it if you measure the distance from the center of the axle to the center of the lug and do some math. And you'll have to make sure the torque wrench is directly in line with the two centers for that to work. Also, note that on Page 8 there's a table that shows what the tag on the axle should read depending on what gear ratio you have. That might tell you if you have the original axle or not. But there's another number on the tag that we can cross reference as well if you want. Link to comment Share on other sites More sharing options...
Jon M Posted March 13 Author Share Posted March 13 Jon - We didn't have the section from the factory shop manual on the site for the Traction-Lok diff. So I added it on the page at Documentation/Driveline and then the Rear Axles & Differentials tab, the Instructions tab, the Ford 8.8" tab, and finally the Ford Traction-Lok tab. It says: Minimum rotating torques required during bench check after assembly or in vehicle with one wheel on the ground for original clutch pack. 41 Ft-Lb/30 N-m You aren't really going to be able to test that directly by placing a torque wrench on a lug nut because that's assuming you are on the axle itself. However, you can test it if you measure the distance from the center of the axle to the center of the lug and do some math. And you'll have to make sure the torque wrench is directly in line with the two centers for that to work. Also, note that on Page 8 there's a table that shows what the tag on the axle should read depending on what gear ratio you have. That might tell you if you have the original axle or not. But there's another number on the tag that we can cross reference as well if you want. Thanks Gary! I guess it's back to math class for me. And thanks for adding the traction-loc section. I look forward to digging into it. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 13 Share Posted March 13 Thanks Gary! I guess it's back to math class for me. And thanks for adding the traction-loc section. I look forward to digging into it. Good luck! And if you want to brainstorm the math then give us some measurements and we'll see what we can do. Link to comment Share on other sites More sharing options...
Nothing Special Posted March 13 Share Posted March 13 Good luck! And if you want to brainstorm the math then give us some measurements and we'll see what we can do. If you can get the torque wrench perpendicular to a line from the center of the axle to the lug you are using you don't need to do any math. The lever arm will still be the same as if you were on center. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 14 Share Posted March 14 If you can get the torque wrench perpendicular to a line from the center of the axle to the lug you are using you don't need to do any math. The lever arm will still be the same as if you were on center. Yes, absolutely. Since the lug nut should be torqued roughly twice what the drag should be the nut should not rotate. Perfect! Link to comment Share on other sites More sharing options...
mat in tn Posted March 14 Share Posted March 14 If you can get the torque wrench perpendicular to a line from the center of the axle to the lug you are using you don't need to do any math. The lever arm will still be the same as if you were on center. Yes, absolutely. Since the lug nut should be torqued roughly twice what the drag should be the nut should not rotate. Perfect! just a thought. "if" one had an axle/hub puller then the center attaching point could hold a nut/ bolt combo which gets torqued first at say 60ft lb. then that could be used as an aligned torque testing point. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 14 Share Posted March 14 just a thought. "if" one had an axle/hub puller then the center attaching point could hold a nut/ bolt combo which gets torqued first at say 60ft lb. then that could be used as an aligned torque testing point. Yes, that should work nicely. Link to comment Share on other sites More sharing options...
Jon M Posted March 16 Author Share Posted March 16 just a thought. "if" one had an axle/hub puller then the center attaching point could hold a nut/ bolt combo which gets torqued first at say 60ft lb. then that could be used as an aligned torque testing point. Hey there Matt in TN, I dug around my shop and found exactly that! So it looks like I won't have to go back to school after all. But all of that is on hold as I address switching out the track lock clutch pack. I didn't even know that was a thing until I dug into the service manual chapter that Gary uploaded. It turns out that is a significantly cheaper alternative than replacing the entire LS assembly. Unfortunately I don't know the age of this rear differential because the tag isn't on it. I do have the front Dana44 tag but that won't help with the rear diff. The reason I need the age, I think, is to buy the right Track Loc clutch pack. Can anyone weigh in on how I might proceed getting the right part? Link to comment Share on other sites More sharing options...
mat in tn Posted March 16 Share Posted March 16 Hey there Matt in TN, I dug around my shop and found exactly that! So it looks like I won't have to go back to school after all. But all of that is on hold as I address switching out the track lock clutch pack. I didn't even know that was a thing until I dug into the service manual chapter that Gary uploaded. It turns out that is a significantly cheaper alternative than replacing the entire LS assembly. Unfortunately I don't know the age of this rear differential because the tag isn't on it. I do have the front Dana44 tag but that won't help with the rear diff. The reason I need the age, I think, is to buy the right Track Loc clutch pack. Can anyone weigh in on how I might proceed getting the right part? there are two different models used in these. the first generation comes from the fact that the earlier f100s had a small bolt pattern and therefore had a smaller centering hub for the front disc. this had to be carried to the rear axles centering hub also for the wheels to be interchangeable. all this to say that the centering hub will be about 2-7/8" where the next generation is about 3-1/4". I'm not measuring exactly but the scale is the point. the earlier axles that had the smaller centering hub also have a different size locking tab inside the carrier for the c clip requiring a different size center pin. this is the most relevant difference here. the center pin difference will be 3/4-7/8 approx. I can measure them for you if needed. these are NOT interchangeable withe the axles. axle/carrier combos must be kept together with proper parts. so, if you have the smaller centering hub then you have the smaller pin version of the trac loc. Link to comment Share on other sites More sharing options...
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