1988 RD 690 Mack axle seal

[Casper1988]

I have a axle seal that has started leaking oil and need to replace. I am hoping someone could give a brief description of what it entails , take down and back together and and tricks involved if there is any. Thinking it is pretty straight forward job. One starting question would be , do I jack in the center of the spring holder and then use 6 ton stands under each axle housing and the proceed with disassemble only lifting those rear drive wheels. New to Mack trucks but not to turning wrenches. Thanks.

[j hancock]

You can just jack the axle you are working on.  A wheel dolly is handy so you can remove both tires, spoke and drum at one time.

Remove the axle hardware and drain the axle tube of oil.  Loosen slack adjuster for a little room between drum and shoes. Take axle shaft out.  Remove axle bearing nut.  Remove tires, drum, etc.  Remove seal and inner bearing.

Clean hub cavity and all mating surfaces.  Inspect bearings and clean.

Not a bad idea to take the seal to the parts counter when you get a new one.  You will need to have a seal driver to do the install.

Put bearings and seal in and  reinstall hub and tires then tighten adjusting nut for .003 to .008 end play.  Torque lock nut to 300-400 ft lbs.

 

Keep in mind, since the bearings run in oil, you can either pack the bearings with grease so they are lubricated until the axle oil gets down the axle tube.  Or lube them in oil and install and "drive" the truck slowly in place on jack stands to get the lube circulating.  Or park the truck on a slope so gravity will get the oil down to them.  After a few minutes, put it on level ground to check and add oil as needed.

Readjust the brake slack.

[davehummell]

Make sure you check the ring were the seal rides. get some emory cloth sand paper and make it shiny clean you may have to get a sleave and seal combo. if you go to a good truck parts store ask about  different seal options there are many. I always used libriplate motor assm. grease in the white tube on the bearings it stays put and it is thin enough to be washed out after a while from the oil. pay attention when you get to the axel nuts are they loose? I always try to figure out why a seal goes I am lazy and I don't want to do it again. I used to put a flat steel plate on the floor and spread some oil on it and slid the wheels out on it.

[Casper1988]

 

I bought the seal today and also a 4 1/8 axle nut socket. I will inspect to see why it went and make sure the lip is cleaned up. I will post a few picks. thanks.

[hatcity]

to tighten-turn wheel as you tighten nut. keep turning/tightening until no mre movement of wheel. torque to 200. back off one full turn, then torque to 50. back off one quarter turn. wheel should spin freely.

Outer nut-as much as you can. I use a five foot pipe.

as stated, pour oil over bearings before you put together

clean axle end good, and use a bit of RTV to ensure seal

[theakerstwo]

And dont forget to fill the hub with oil before sliding it back on.

[39 Baby Mack]

You can just jack the axle you are working on.  A wheel dolly is handy so you can remove both tires, spoke and drum at one time.
Remove the axle hardware and drain the axle tube of oil.  Loosen slack adjuster for a little room between drum and shoes. Take axle shaft out.  Remove axle bearing nut.  Remove tires, drum, etc.  Remove seal and inner bearing.
Clean hub cavity and all mating surfaces.  Inspect bearings and clean.
Not a bad idea to take the seal to the parts counter when you get a new one.  You will need to have a seal driver to do the install.
Put bearings and seal in and  reinstall hub and tires then tighten adjusting nut for .003 to .008 end play.  Torque lock nut to 300-400 ft lbs.
 
Keep in mind, since the bearings run in oil, you can either pack the bearings with grease so they are lubricated until the axle oil gets down the axle tube.  Or lube them in oil and install and "drive" the truck slowly in place on jack stands to get the lube circulating.  Or park the truck on a slope so gravity will get the oil down to them.  After a few minutes, put it on level ground to check and add oil as needed.
Readjust the brake slack.

If you don't have a wheel dolly you can always use a piece of tin with oil on it.
Be careful sliding the wheel/tire assembly back on so as not to damage the new seal.

Ron

Sent from my SM-G900V using Tapatalk

[Casper1988]

Gonna have to replace bearings, races and seal and shoes. Races are really pitted. Makes me think it might be a good idea to look at the others. My new Milwalkee 1/2 " 18v impact was handy.

[Casper1988]

Ok, I see it. Looks like a crack in the spoke casting, ( bottom Left ) I will inspect. Notice the oil reflecting the tree from the sun. Weird. I chose to take the tires off and clean the spoke up and check it out. I may get a used brake hub as mine looks to have seen better days. How do you know when to change it out. ( the brake hub ). Global Truck traders is close to me and a good source for good used Mack stuff. Good people up there.

[hatcity]

1. if the race looks that good, lets see the bearing

[Casper1988]

Bearing dosent' look bad but will be replaced of course. I could feel it when I spun the bearing before I popped the seal out. That was the inboard bearing. I will take a pic and post it. The outboard race was just starting to pit so that gets changes too. All my profit from logging goes to the truck this week, thats how it works right!!!!

[hatcity]

yep. some days you make a buck, other days you spend ten

might want to consider draining axle completely.

all those metal shavings will be in the mix and may ruin all your hard work

possibly have more fun and do the other side too!

[theakerstwo]

Hold the brg up to the light and look inside to the inside of the race inside the brg.

[Casper1988]

Finally getting back to the job, all cleaned up and new bearings, brake shoes and spring kit and drum. Pretty much gonna start looking at all the others at this point. Would think that these could be original as the truck has 116k on it. Not much on it for a 1988. Has 44 rears and the spindle is not a bolt on. Hate to spin a bearing and wreck that spindle and have to find a housing. Will be worth it in the end to know what I'm working with. Thanks for the advice all.

[Casper1988]

Finally got it together this weekend. New seal, races, bearings, drum and shoe and spring kit. The log truck stanchions came in handy for the chain fall. I am a 1 man team and it worked slick. No leaks so I would say that ones done. Guess I will start checking the others when time allows. thanks for the input all.