1989 Eliminator Posted August 12, 2014 Share Posted August 12, 2014 Okay I know this is pretty straight forward and an easy job, but for some people mechanical work is either new or hard for then. So, why not make a thread for reference and pictures! !!!!!!!!!!!!!!!THIS IS FOR A 2WD 1989 MJ. I know most 4WD or other models do not have a one piece rotor and bearing assembly.!!!!!!!!!!!!!!!! . :MJ 1: .Okay so first thing to do is jack the truck up. Either one side at a time or both.Take wheels and calipers and brake pads off.This first picture shows the rotor and axle cap. This cap covers the nut and bearings so no crud gets inside. To take it off, use a small screwdriver to pry the outer side lip away. To re-install this cap you would just line it up and lightly hit around the lip in a rotational pattern and it will then seat in place.This second picture shows what is underneath the cap. Pin, nut lock, and nut. You can't really see the bearings yet but there is the smaller front bearing behind the nut.The third picture shows this pin out.The fourth picture shows the "lock nut"The fith picture shows the back side of the rotor. The main bigger bearing sits underneath the wheel seal. To take the seal out, just pry it out because you should buy a new one.Sixth picture shows main bearing and seal out.Clean and re-grease the bearings and just do all of this backwards to install back in! When tightening the bearings with the big nut you originally took off, the spec is 17-25 ft-lbs. But the way you are supposed to tighten a bearing pack is this: Tighten just past finger tight, loosen a little, turn the wheel, tighten again a little more, loosen, turn wheel, then tighten to ~19 ft-lbs. This is the make sure the bearings a seated correctly. Link to comment Share on other sites More sharing options...
88ComancheMitch Posted August 13, 2014 Share Posted August 13, 2014 What year is this on? My 88 had the hub assembly bearings. Great write up. Link to comment Share on other sites More sharing options...
Minuit Posted August 13, 2014 Share Posted August 13, 2014 Keep in mind that only 2WD trucks had rotors with this type of bearing. It's called a captive rotor. 4WD trucks have unit bearings. Link to comment Share on other sites More sharing options...
FrankTheDog Posted August 13, 2014 Share Posted August 13, 2014 2wd's made after January 20th of 1992 also have unit bearings. Link to comment Share on other sites More sharing options...
91Pioneer Posted September 26, 2014 Share Posted September 26, 2014 Is a 1991 MJ 2WD the same as the 89 shown above? I think I need new wheel bearings. Link to comment Share on other sites More sharing options...
Minuit Posted September 26, 2014 Share Posted September 26, 2014 As far as the assembly itself and procedure, yes. Although the parts might be different. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 26, 2014 Share Posted September 26, 2014 Is a 1991 MJ 2WD the same as the 89 shown above? I think I need new wheel bearings. Yes, the same. This is a decent writeup, but neglected any mention of replacing the inner and outer bearing races as should always be done with new bearings. These should be tapped out of the hub with a brass punch and changed or your new bearings will not last long if the races are worn out and scored. I usually buy National wheel bearings since they come with the races as well as the bearings. Available at O'Reilly's and others. Outer:National - Wheel Bearing Part # A2 Inner: National Wheel Bearing Part # A6 Link to comment Share on other sites More sharing options...
91Pioneer Posted September 26, 2014 Share Posted September 26, 2014 Does someone have the correct torque procedure for re-installing or installing new bearings (2WD)? I would kind of like to double-check my torque before replacing the bearings (re-torque, go for a drive and see if it feels any better before buying parts). I haven't got my repair manual yet. After looking over my setup more closely, the brake pads have lots of life left, the ridge on the end of the rotor is not bad at all, and the cotter pin looks almost new, so I'm wondering if the shop that replaced the brakes last did not properly torque the main nut down. There is a bit of a shimmy on braking and a slightly loose feel when driving. The ball joints feel OK to me which I originally thought was the problem, but now I'm thinking it's the bearings. p.s. Is there a download version of the '91 repair manual? I found the CD version on RockAuto/eBay so thinking I'll just buy that since it's a lot cheaper than the printed version. EDIT: Found answer: This is true. The correct method for the 2WDs is to tighten the bearing nut to 17-25 ft. lbs while rotating the wheel to seat the new bearings/races. Then loosen the nut 1/2 turn and retighten to 19 in-lbs of torque. Link to comment Share on other sites More sharing options...
mikekaz1 Posted October 27, 2015 Share Posted October 27, 2015 sooooo that's why I couldn't get my front rotors off of my 2wd when converting over to 4wd! I thought I was just handicapped. Link to comment Share on other sites More sharing options...
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