bone stock 91 Jimmy rotor replacement...what other parts needed?

[88jimmy4x4]

Okay guys, I have read about 30 threads on death wobble and balljoints so I think I can tackle tearing into the front diff for brakes

I have replaced the brake hoses, calipers/pads and I still get wobble when braking. My 2wd truck had this before and it was warped rotors and this feels the same so Im going to replace them and try this.

Question is...other than the disc rotors themselves, what other parts should I buy? (want to try and have everything to do the job). I dont mind spending extra for bearings etc, just kinda need a shopping list lol.

Also, I swear I read on one of the threads or my chiltons that the nuts shouldn't be reused, is this true?

1991 GMC Jimmy 4x4 stock 6 lug axles, JB5 brakes.

 

[pmack74]

I have this on my "to do" list very soon also. I hope someone posts a thorough list so we have the info in one spot.

 

[496truck]

You will need...
grease, high temp wheel bearing
a bearing repacker, or you can do it the messy old fashioned way
some parts cleaner, I find some spray brake cleaner works good to clean the bearings
lots of clean rags, really a lot of them handy, you don't want dirt in the bearings
a clean work surface, I like to use a big ol' piece of cardboard, lay everything out as it comes apart
new inner bearing (hub) seals, one for each side
you'll also need the hub nut socket to remove the spindle nuts

The rotors are mounted to the hubs via the lug studs being pressed in. A lug nut threaded on to the stud and you can tap them out with a hammer. Then you can hammer them back in once you get the new rotor lined up.

Clean, dry, and thoroughly inspect the bearings and races. Replace if they are chipping or the surface is peeling. Most of the time they are good to be repacked and reused.

You are familar with the proper method of installing the spindle nuts? Just checking. If not, ask away.

 

[88jimmy4x4]

You are familar with the proper method of installing the spindle nuts? Just checking. If not, ask away.

I need all the help I can get, tq specs anything as I have never done this before.

I have only been reading threads and how toos

This one seemed pretty good, but leaves out some info

http://www.398hbx.com/home/gm-10-bolt-8-5-front-axle-rebuild/front-hub-rotor-rebuild

 

[496truck]

That's actually a real good article showing the disassembly. Reassembly is just the reverse of that. Once you get to the preload nut and jam nut is where beginners get confused.

Start with the preload nut, the one that touches the bearing and has a small pin sticking out of the side. Install that one with the pin facing out. Reach in and start threading it on by hand, spin it on the rest of the way with the socket by hand. Grab a short ratchet and use this on the socket to hand tighten against the bearing while turning the rotor with the other hand. I snug them up and back them off a few times while spinning the rotor. Nothing more than grabbing the ratchet and giving a quick tug. Then just snug it down using no real leverage, the rotor should have at least one turn if you grab it and spin it with your free hand. A good way to prevent too much leverage is to hold the ratchet near the socket with your pointer finger and thumb around the socket and the other 3 fingers around the ratchet. I've been setting wheel bearing preload so long by "feel" now that it's like second nature. Not sure if there's a torque spec for it. You don't want it too tight, just tight enough so there is no play in the hub/rotor assembly.

Now you install the lock washer, the one with all the holes in it. It also has the tang in the center that slides into the groove in the spindle. Set the washer in place so that the pin in the inner nut aligns with a hole in the washer and the washer sits FLAT against the inner nut. If it does not line up the first time try flipping the washer around, sometimes it will be close and pop in. If not still, take the socket and slightly back off the inner nut to get the pin in proper position. Then try the washer again. Untill that washer is flat do not move forward, keep at it till it is. I like to take a pick tool and feel if the pin is in the hole properly. Basically, you will be able to stick the pick into the other holes except the one with the pin in it.

Now on to the jam nut, reach in and thread that on by hand. Spin it on the rest of the way with the socket/ratchet. Now you have to tighten that down to something like 150 lb ft. The flat washer and the pin will keep the inner nut from tightening down further. Spin the rotor by hand and make sure it spins freely and has no play in it. Once it's all set you can move on to the locking hub or drive slug, whatever you have.

 

[88jimmy4x4]

Thanks for those tips, the nut/washer sounds a bit confusuing, but Im sure once I get into it I will see what your talking about.
Once the jam nut is on should it still have the same approx one turn of the rotor spin?

any tips on replacing the races?

Im considering buying the rotor/hub together, do you know if that will already have the races or anything pre-installed?

What brands should I get for the parts?

http://www.nordiques.com/pieces/imag...torquesskf.pdf

according to that chart my code is GMM

1988-91 R/V Blazer, Jimmy R/V ......... GMM[12] —4WD

Tighten adjusting nut to 50 ft-lbs/68 Nm while
turning hub. Back off and retighten to 50 ft-lbs/68
Nm. Back off to 0. Install ring and torque locknut
to 160 ft-lbs/217 Nm minimum. Tang on ring must
pres through slot on spindle. Hole in pin must
align with locknut, turn adjusting nut to align.
Endplay should be .001-.010".

what I dont understand is the back off to 0?...I think they mean dont back off at all.

I like your way of feeling the preload tightness, 50ft lbs seems like alot.

 

[496truck]

Guess that's another way of saying to back it off and snug it by hand, cause you are basically applying no torque. Which is one thing I left out of the details, I snug them up and back them off a few times while spinning the rotor. Nothing more than grabbing the ratchet and giving a quick tug. Then I do the final snug by hand. I'll edit my previous post...

You are just replacing rotors right? There should be no reason to replace the bearings/races unless something is wrong with them. I wouldn't even spend the money on the chinese aftermarket hub/rotor assembly. The original hubs should be good, just clean the bearings and repack with new grease. If you do have a bad bearing and need to replace it and it's race, you can punch out the old race with a long punch but you may need a bearing/race installer to punch in the new one. I've seen it done before with a long brass punch very carefully.

Jam nut install and torque should not effect the inner nut if the washer was installed properly, so yes the rotor should spin freely by hand.

Don't get my advice on brands, I bought the cheap chinese rotors and they pulsate like crazy. One of these days I'll get over to my friends shop and have them turned.

 

[88jimmy4x4]

Thanks, I do want to replace the bearings/races too since I will have it all apart.

Heres my issue.....when I apply the brakes the driver side will bounce up and down and I get some left to right steer...makes me think the rotors are warped.

Also while driving, I can feel/hear a grind every now and then like every 500 feet or so...just for a second then goes away.

This Jimmy has gotten where Im scared to drive it to work just 5 miles away, dont want to be stranded from a failed bearing

 

[88jimmy4x4]

Thanks for the advice Brian, I did everything as you said exactly, mission accomplished.....did it myself today


BTW.....If you buy the wagner premium brakes from NAPA, they are made in Canada not China like others.

 

[496truck]

Good to know and glad I could help!