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1985 Honda BIG RED Rear Differential Rebuild Part 2 of 2 Assembly



With everything clean it's time to assemble the rear differential. I want to talk about replacement parts and quality before getting into the assembly. I learned a long time ago that it doesn't pay to use cheap parts. This is very true when it comes to the bearings and seals for your rear differential. There's many rear differential rebuild kits out there but I haven't found one that includes name brand quality bearings and seals. I like using SKF or NTN bearings. You will probably need to buy the parts individually and it will be more expensive than the kit but it is well worth the effort and expense in my opinion. HERE is a link to a post that provides the rear differential bearing and seal part numbers for your reference.


Ok I will start with the pinion needle bearing installation. In order to hold and support the differential case while pressing in the bearings I made a simple fixture using some angle iron.



Picture of the differential case holding fixture I made using scrap angle iron.



Here's a picture of the old pinion needle bearing. Note that it is not flush with the case. This is a good reference to have before installation. The bearing is fragile and if you try to press it in too far you will ruin the bearing.



I used the pinion to press the pinion needle bearing into the case. Here's the arrangement I used. A socket on the pinion nut was used with the press.



Used the hydraulic press to press in the pinion needle bearing. Be very careful not to use too much pressure as it will damage the bearing. Be patient and check the installation depth of the bearing multiple times if required. Also use a little lube on the bearing to help reduce friction during installation.



Pinion needle bearing installed.




Now I proceeded to install the pinion bearing on the pinion. Remember to install the pinion shim before pressing the bearing on.



Pressing the pinion bearing on. It's doesn't take a lot of pressure to install.



Pinion bearing installed.



Installed coupler and pinion nut. Note the vice grips didn't cause damage - make sure they are tight.



Pressed pinion assembly into the differential case.





Installed pinion locknut using the special socket. Torque to 65 - 80 ft-lbs.




Stake pinion locknut using a punch.



Press in new pinion seal. Pinion installation is now complete. Pinion should spin freely by hand.




Press ring gear bearings into differential cases.




Bearings installed.




Install the ring gear into the differential case. Don't forget to install the shims in the correct position.




Apply sealant to the differential case splitline. I like Loctite 518. Hondabond, Yamabond, or RTV could be used.




Install differential cover. Use blue loctite on the two larger bolts. Torque the two larger bolts to 33-36 ft-lbs and the smaller bolts to 17-20 ft-lbs. Torque in crisscross pattern. The pinion and ring gear assembly should spin freely by hand.





Install differential case seals using a little grease on the seals. Again the pinion and ring gear assembly should spin freely by hand. There may be a little bit of drag caused by the new seals.






Primed and painted the differential. The rear differential is now ready to install. Make sure to add oil after installation.


Here's a link to a reference video that I found helpful.



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