1963 Chevrolet Biscayne Positraction Differential Overhaul - Part 2 - Partial Reassembly
Weber State University (WSU) - Automotive Technology Department - Transmission Lab. We take on a fun and unusual project, the overhaul and restoration of the rear differential of a 1963 Chevrolet Biscayne. This 8.2" type 3 differential was used by General Motors from 1955-1964. The differential design utilizes threaded adjustable side bearing spacers to control side bearing preload and backlash.
Reassembly always takes longer than disassembly.
This video is part two of a four-part series on the overhaul and restoration process. Part one includes the disassembly and inspection of differential assembly. Part two includes the positraction differential case setup and overhaul. Part three includes differential case problems found. Part four will include the complete reassembly and proper setup of the differential case in the housing including pinion depth shim selection, pinion bearing preload adjustment, side bearing preload, backlash adjustment, and contact pattern reading and adjustment.
www.weber.edu/automotive
This video was created and edited by John D. Kelly at WSU. For a full biography, see www.weber.edu/automotive/J_Kel...
Visit my other youtube channel / vibratesoftware to see the amazing NVH app for vibration diagnosis!
Donate to the Department of Automotive Technology at Weber State University here: advancement.weber.edu/Automotive
I want to applaud WSU for these excellent how to automotive videos.
Thank you!
Good video series, really highlights all the areas that details can fall through the cracks if you aren't paying attention.
Thank you!
Great Video I just tonight finished rebuilding a posi from a 62 Impala ,could not have done it with out your help..always the little tricks...one note glad I read down to the comments ..on final assembly make sure both of the axle splines are lined up on either side..if you have the axles out of the car loosen the left hand bolts on the posi still keeping the unit together and carefully wiggle the axles till they bottom out, you MUST do this on either side before you do final torque {you can measure down the axle slot and mark with a pen or piece of tape on a stick or ruler ..do the same on the axle and compare..you should be at the same depth}..different depth on right to left side..don't forget or you will be tearing down and reinstalling ..AXLES will NOT go in there are two splines inside the POSI ....like I said thanx again for the video, I wish I had a teacher as good as you when I was a kid your student's don't know how lucky they are ...one note I spent a few years on the rear end lines at GM in the late 80's doing all jobs, machining assembly ,if you could see the way they were thrown together you would be shocked machines we soo old {some were old Cleveland machines dating back to the 40's and 50's refitted a hundred times} tolerance was dirty word ..we used to use the word close enough all the time....and they still ran..very few rejects or returns...this video is a few years old I hope you are still doing well and hopefully teaching...cheers from an OLD hotrodder
Thank you, I ran into the same issue after the video
Thanks for sharing your knowledge Prof. Kelly.....Your students are lucky they have you leading them in their automotive careers...Wish I would have had teachers like you when I went to automotive school almost 50 years ago..
An incredible technician
Some good information here. Thank you for posting your video.
complicated concepts, but you make them much simpler...
+pei bossman Thank you!
Great video! Many thanks.
SiliconSet Thank you!
great video keep it up!!!
Larry Abd Thank you!
Back in the day I tore apart a posi from a vette I think the ratio was 5:13 under the ring gear there was a brass washer shim on one bolt between the ring gear and the case. . I'm pretty sure that's the way it came from the factory. Must have been there to address a runout situation. Very interesting video.
Wow, I have never heard of that before. Thanks for the feedback!
@@WeberAuto it was from the factory ..some after market gear come with it too, only way the gears can get close enough to mesh
"you can't make can't make those marks without positraction, which was not available on the '64 Buick Skylark"
killen joke Great movie! Thanks for watching.
+594bolt Not even close. Marisa Tomei in My cousin Vinny.
🍻😀👏
Dear Weber Auto, vas ist los?... The L-9 Hex Head Bolt is part of the L-9 Fastening System that is designed for high stress and severe service environments. The L-9 system is 20% stronger than the grade-8 bolt and it’s special features control torque tension characteristics to develop high clamp loads when using properly controlled tightening methods. The L-9 system is made from AISI steel. Good Luck, and God Bless, nice shop... Bye 4 now... Work Safe...
+GODBLESSAMERICAONE That is great information! Thanks for the feedback!
You're Welcome...
Hiya, many thanks for making such a great series of videos. I have learned lots from them! :) I have one question and one recommendation: 1 Question - Did you consider machining the inner gearcase in a lathe to remove the runout from the ring gear mating surface? As it wasn't that much? (Maybe you did it but just didn't show it?) 2 (Recommendation) - You camera has a minimum focusing distance. I.e. the closest you can zoom in onto an object, and still maintain it in focus. On most cameras its around a foot or so. If you want to go any closer and still maintain focus, you'll have to switch to a macro mode (if the camera offers that). That's the reason why it wasn't focusing when you zoomed in to show those two punch marks, or the Letter 'L' on the bolts for example. That's it. Once again, thank you for such a great set of videos!
+mictho100 Thank you for the feedback. Good suggestions!
I read that there are many combinations to put "discs & plates", so I may get different reaction of the blocking differential. ¿What happen if I don't use any disc or plates? Does the differential work, obviously without the benefits of blocking, but it would work? By the way, thanks for teaching me through your video!!!!
thanks for the video. I think your very good. What about the run-out for the ring gear? It was not with-in spec. Why didn't it get corrected on a lathe ? or did I miss that. I would have turned the ring gear over on the hot and already had two line-up bolts installed. No way to miss-match bolt holes.
Hi, Thank you!. I did correct the ring gear runout problem in the next video. See this link for the complete set of videos. kzhead.info/channel/PLIn3FrDiB1lz2TQpZGPUhi3U1FfHC6EAl.html Best wishes!
Hi and thank you for the video. juat a question. if only one side of the clutch pack is pressed , is the differntial still able to function as a posi? or we always need both sides to be pressed? thank you
The spider gear cross pin shafts ride up their ramps in the case halves -- thus pressing on the clutch packs...
thanks m8
Where do I get those bolts and the size pls?
One Question- I noticed when you compared the two ring gears., you mentioned the difference in height but you didn't include or mention the spacer you had removed with the 456 earlier. Would that change the backlash on the pinion gear?
Yes, the spacer was used to allow that ring gear to work with a differential case is was not meant to. The backlash without the spacer would be huge; maybe so large that the ring and pinion would not even contact each other. Good observation!
John: Excellent program! Question: due to the cup disks in the clutch stack, does this mean the side gears and spider gears have zero backlash for this differential? Most of the differentials always have a lot of backlash for these side gears and why?
The dished plates preload the clutch disks for a quick reaction.
The spider gear carrier ends are ramped into the housing. This will presumably cause them to apply axial load onto the clutch assemblies and tend to lock them under load conditions. This seems counter intuitive to me because this largely renders the diff. useless when cornering under load and also to be less effective at locking a wheel that is loosing traction as the load is reduced by the slippage. I can only think that I have missed something here and would be grateful if you would comment on this aspect of the design of this mechanism. Those ramps are there for a reason.
The backlash between the side gears and the "spider" gears sets the sensitivity level of the locking of the clutch packs. More backlash = more differential action before the clutch packs apply. There are selective washers to adjust this and can be customized for the needs of the vehicle.
I like that digital torque wrench. I'm a cheap bastard and use a clicking wrench from Harbor Freight. :)
Thanks, I understand that. There are times where accuracy is extra critical (like differential work). There are more differences in torque wrenches than just the price.
the clicker style torque wrench used to be the upscale style torque wrench .................................
Do you happen to know what size arbor press you are using in this portion? Also, could that same arbor press be used for the pinion bearings? I've watched all four of these video's, and they are terrific!! Thank you for putting these up.
Hi, yes, it is a 1.5 Ton Dake Arbor Press. I have used it many times for pinion bearings. It has an 18 inch opening height. See www.dakecorp.com/products/arbor-presses/ratchet-lever-arbor-press-1-1-2b
Thank you! As always, wonderful information.
👍👍👍👍👍👍👍👍
im not trying to be an ass here but could i ask why youre in a wheelchair? im quite impressed that you can do all these things regardless of your condition. good videos by the way.
+Brock Fisher No problem, I have a rare version of muscular dystrophy. it is slowly taking away my strength and muscles. I love teaching and keeping up with automotive technology. Some of these topics and procedures are so involved and time consuming that I decided to video them for my students, rather than demonstrating them each class. I had no idea that anyone else would be interested, but many people have been. Thank you for your nice comments! best wishes to you.
+WeberAuto I think it is a great thing your doing to stay involved! These videos on You Tube will reach far beyond your classroom as well. They will be here for years and years to come. Awesome!
+WeberAuto wishing you better health in the future...
Regarding the radial runout measurement. If you don't measure at the very top of the circle keeping the indicator perpendicular to the arc you won't get an accurate measurement. The farther down the side of the circle you go the lower the runout will appear.
I see what you are talking about, I was not at the top of the circle. Thanks for the feedback. You are absolutely right.
You did not loosen the ring gear bolts in a crisscross pattern. Adding to the possible run-out problem of the ring gear fang. Tight in a crisscross pattern and loosen in a crisscross pattern anything that has machined surfaces.
+Diamond Sword COC Good point! That is very true. Thank you for the feedback!
Diamond Sword COC 🙄
You didn't line up the side gears correctly you won't be able to get the axles in. Been there... done that had to pull it back out and disassemble and alien. Otherwise great video. I've been doing these since I was in high school 45 years ago. Wish I would have had this type of instruction back then would have saved a lot of trial and error.
You are correct, I did not line them up properly. Only one axle shaft would slide in. We had to disassemble it again to realign the other side gear to the sleeve. Thanks for the feedback!
jaws 😨even bigger jaws 🐟🐬
DO A VIDEO OF TORSEN DIFF !!!!!!!!!!!!!!!!!!!!!!!
I plan on it, Thank you for your feedback!
I remember this was a topic on my cousin Vinnie ... the movie kzhead.info/sun/ZtKAgbCJfWOYaYE/bejne.html
+terry1919 Yes, I do too. Thanks for watching!
We're gonna turn clockwise to loosen them *immediately overtightens the bolt*
ExEvolution Gaming It is true, I got that one wrong. In my defense, the bolts do have a upper case "L" on the head which typically indicates left handed threads.
Great video though, I was looking up information on limited slip differentials and why they're often used in racing applications when I came across your video. Great information and good to know how to take one apart and overhaul it.
god these are the shittiest difs I have ever seen
Thanks for your feedback!