73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Rear Drivelines, Drive Axles and Gearing => Topic started by: Mike Phillips on October 16, 2011, 12:37:49 PM
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How far to back off the bearing retaining nut on rear axle?
Re-assembling a Corporate 14 Bolt rearend. I snugged the spindle nut down till I could see that the brake drum is dragging when I try to rotate it. Question is how far to back that nut off to allow for expansion of the bearings when they heat up?
I have to insert the key so I'm thinking either backing it off one or two slots too insert the key and then install the retaining spring and then the axle shaft.
:)
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There are two things you need to be concerned with when reinstalling floating drums.
The bearing pre-load and the bearing pre-load.
*First nut:
This nut is very important, it sets the bearing preload.
Bearings don't need any end-play (room to heat-up,) that's already engineered in to them. Pre-load is the pressure between the inner and outer bearing. It is controlled by the very first nut going on the axle threads, regardless of any washer or spacers that is between the first nut and **outer bearing. Tighten it down hard with a large set of water pump pliers, or a 1/2 inch breaker-bar. Make sure you over tighten it (pull hard.) Then spin the drum a few times in both directions, listening for any noises. (if your brakes are not backed off, this will be difficult. You've just seated the bearings, so now comes the important part! Tighten the nut until it just touches the washer / spacer then go another 1/8 to 1/4 of a turn past snug. It's probably about 15 to 20 ft. lbs. Something around the pull of a young child. There is a certain feel to it, you'll know. Ok now that you have the pre-load set, let's move on to the next nut.
Second nut: You probably have something that looks like a star washer with tabs, those tabs hold this second nut from working loose. Install that now, then thread on the next nut and tighten the living crap out of this one. Without a large impact gun you can't get this nut too tight. Then bend one or two tabs on to one of the flat areas of the nut you just tightened. (It's more important to get this nut really tight, then it is to get a tab bent on to a flat area) meaning, you don't need to start over if a tab doesn't perfectly align with a flat area on the nut. Now spin the drum hard by hand and let it go, If the drum coast close to a full revolution, it's too loose. It doesn't hurt (before your test drive) to part sideways on a hill to let some of the oil drain back in to hubs and bearings.
Setting pre-load too tight is far worse then setting it too loose.
*first nut is the nut closest the the backing plates.
**outer bearing is the bearing furthest from the backing plates.
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When I replaced my wheel cylinders, I didnt have the spindle nut socket, so I did what my dad and I always do on the jeeps, which is a flat head on one of the hex points and a hammer hitting the flat head handle. I went off of muscle memory, as in, wgile taking it off I remembered how much force on the hammer it took to make the nut turn, and I used that same amount of force to make the nut turn to put it back on. I also noted where the nut hex points were pointing and marked it, so when i put it back on i got it as close to the mark as I could. Put on the rrtaining wash, and then cranked the outer nut down as much as I could against the retaining washer/inner nut. The outer nut keeps the 2 nuts from turning, like a jamb nut, 2 nuts tightened against eachother to keep them from moving. Have you ever installed water pump studs? Did you do it with 2 nuts tightened together on the stud, then turn one of the nuts which turns the stud? Same concept.
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1979C20:
Yes people do make do with what they have. That said, the method you describe usually is responsible for setting the pre-load a little loose. I can't tell you how many pitted bearings I've seen after removing a pre-load nut that had the marks of being set with a chisel or screwdriver. Truck owners that would take the time to sign up for a forum are the kind of individuals that really like their trucks and plan on keeping them. So my advice would be, buy or rent the socket.
FYI bearing pitting is a sign of loose pre-load.
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I have to replace my brake shoes soon, so ill be sure to rent one when I do. I see that your new to the site, you have some pretty good info. You should post an intro about your truvk and what not.
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my chevy shop manual for a 78 model says
bearing adjusting nut torque: 50 ft. Lbs
bearing adjusting nut backoff: (Back off nut and retighten to 35 Ft. Lbs then back off nut 1/4 turn).
End play: .001 to .010
outer locknut torque: 65 ft. Lbs
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Throw that book in the can. From your book, just quoted a torque setting for the pre-load. If you understood the relationship between the inner and outer bearing and the hub. You would know, that setting .001 to .010 of an inch end play, and torquing down the pre-load nut 35 ft. lbs is an oxymoron Think about guy, how can you have the pre-load nut torqued down 35 ft. lbs and .005 of an inch end play. You just squeezed the two bearings together.
Trust me guys, if you want to fix your truck right, do what I say.
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I'm not going to post my bio but, for the easing of minds out there. This is my automotive experience. I graduated from an automotive trade school in 1981 or 82. I spent the next 15 years, as a tune-up, brake & front end mechanic. The last 15 years servicing a rural UPS fleet with about 27 trucks. At UPS about half my truck were early '70 - late '80 with Chev drive trains, the other half were Fords. The first 5 years my 25 + truck fleet accumulated just under 800,000 miles a year. My last 10 years that number dropped a little to about 750,000 miles a year, but by at time I was a one man shop. There is one thing that became obvious very fast at UPS, the trucks do not go somewhere else if I could not figure out the problem. That reality developed in me an outstanding logical methodical approach to troubleshooting and repairing trucks. There is almost nothing I've not seen.
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for all we know you could be a 12 year old girl in pig tails copying and pasting from other sites. and theres no need to basically call me a retard and tell him if he listens to me his truck will be ruined. lose the smart attitude, sonny boy. nobody needs it or wants it. the impressive resume doesnt excuse uncalled for rude behavior.
I say I agree on your methodology, except guessing and going by feel on fleet vehicles. I do go by feel on my stuff some times, and I'm not saying it's not ok, but if you're gonna be all harsh about it....
Also agree, yes a bit too loose is better than too tight on tapered bearings.
the end play measurment is the golden value, why, because they gave that measurment.
the torque of the nut is not the prelaod setting. it's supposed to get you to that end play reading in a one shot, bam, all done setup. to do it CORRECTLY, you have to set it by endplay. anything else is hurrying. I'm not saying thats bad as I never checked their endplay myself, as I can do it by feel good enough to satisfy myself. and after 40k miles my bearings so far still have the crosshatches in the races.
you will have EITHER a preload setting (meaning the force ON the bearing itself, NOT the turning of the nut) OR an end play measurment, which means torque readings of any kind dont matter to the final result.
if the true preload setting is say 10ft.lbs you dont torque the nut to 10ft lbs. you have to do the math to figure out what torque of the nut (taking into account thread pitch) will put what load on the bearing and torque the nut to that value. with end play, nothing matter except the endplay is within tolerances, preferably in the center of the tolerances. if you have to torque the nut to 1in-lbs or 1000 ft-lbs, if the end play is correct, all else is irrelevant.
And on overtightening the outer locknut, there's no need to honk down on it past the 65 ft-lbs when its got the locking tabs.
I said my piece everybody, I'll leave yall to it. :)
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Chevyrado:
I did not call you a retard, that's your inference. Later, I'll take some time to analyze this retort (because physic have not changed sense my last post,) if not just for the reason of the other individuals here confidence. That said, I can assure you, it's not sunny, and if you want to your truck fix right the first time, take to heart my opinion.
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I'm not going to post my bio but, for the easing of minds out there. This is my automotive experience. I graduated from an automotive trade school in 1981 or 82. I spent the next 15 years, as a tune-up, brake & front end mechanic. The last 15 years servicing a rural UPS fleet with about 27 trucks. At UPS about half my truck were early '70 - late '80 with Chev drive trains, the other half were Fords. The first 5 years my 25 + truck fleet accumulated just under 800,000 miles a year. My last 10 years that number dropped a little to about 750,000 miles a year, but by at time I was a one man shop. There is one thing that became obvious very fast at UPS, the trucks do not go somewhere else if I could not figure out the problem. That reality developed in me an outstanding logical methodical approach to troubleshooting and repairing trucks. There is almost nothing I've not seen.
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Hey thanks for chiming in everyone... as a guy that's earned a living from running a forum since 2004 the last thing I want to do is start any problems with a simple thread asking for help from those more knowledgeable than I.
That said, here's a picture of my bearing type and below it my rear drum assembly.
Note there is no inner nut to tighten against the inner bearing. I've rebuilt everything and the drums are installed but I have not tightened down the spindle nuts. From a practical point of view because of the design of the spindle nut tightening design, I can tighten down the nut and then I have to back it off one, two, three, turns till the KEY can be inserted to keep the spindle nut from either tightening or loosening.
(http://www.showcargarage.com/gallery/files/1/rearaxles02.jpg)
(http://www.showcargarage.com/gallery/files/1/rearaxles01.jpg)
:)
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Here's a picture that shows the nut on the spindle and where to key goes to lock the nut from turning.
(http://www.showcargarage.com/gallery/files/1/rearaxles03.jpg)
I hope this picture explains or shows how the Corporate 14 bolt axle system works. I've rebuilt multiple types of brake systems in my life but never anything this large and heavy duty. Basically I can tighten down the nut till all the slack is taken out and then back the nut off a limited number of turns and then slide the key in. My guess is after tightening to a snug fit either back the nut off to the first location the key will fit in or the second location the key will fit in. I'm thinking turning the nut to the third location would be to loose.
:)
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my chevy shop manual for a 78 model says
bearing adjusting nut torque: 50 ft. Lbs
bearing adjusting nut backoff: (Back off nut and retighten to 35 Ft. Lbs then back off nut 1/4 turn).
The above looks sound.
Tight to 50 pounds to snug up, back off and re-tighten to 35 pounds to more or less re-set and then back off a 1/4 turn and align the key slot on the threaded axle housing with the nearest key slot on the nut.
:)
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Ok, Mike, here is what to do, these are the same I worked on at UPS. This is a one nut system. Forget everything I said about two nuts. You will want to treat this nut as the pre-load setting nut i.e. The same as "nut one" from my earlier post. Over tighten it a little, then back off on the nut until the drum would clunk if you pulled hard in and out. Now, tighten it until all the clunck just goes away. Here you are at zero pre-load. Now, your on your own judgment a little. If a slot is close either left or right try it. Just make sure there is no clunk when your finished. Believe me, one slot will the drum will clunk and rotating clockwise one more slot will be it. One last thing, I always replaced those little wedge keeps, just to be safe. Remember this one nut sets the pre-load and keeps your wheel from coming loose.
Some people think those bolts that hold the axle on, also hold the drum on, they would wrong. If this nut come loose, your wheel, drum, and axle are coming off.
Sent from my iPad using Tapatalk
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Oops... There are no wedge keepers, on this system. The axle flange keeps the square keeper from coming out. So it would be almost impossible for the nut to come loose without the axle coming loose. So I always use blue loc-tight on the bolts going through the axle flange on this type axle.
Your instincts were good here, you were on the right path. even with my wrong info, I was giving you help on a different type brake system. Remember on is brake system, your using your ears and pulling on the drum to to set the pre-load.
Sent from my iPad using Tapatalk
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Just so everyone is clear:
This forum is to exchange ideas, and help each other out. Any belittling, or rude behavior will result in your expulsion from this board!
I don't give a who ha what you have done, were you worked, or what youve seen, or how long youve done it!!!
Your opinion is welcome here as long as its stated in a respectfull way. Any disrespect to others will not be tolorated, period!
If there is a problem with what I have stated here feel free to take it up with me.
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Mile:
Sorry about missing this before my last two posts. Bearings should never, never, be installed dry! put some rear end oil on those bearings! This needs to be done before you install the drum or set the pre-load. You don't need to remove that inner seal, just poor some oil into both bearings and rotate them around the races a little. Then make sure the rear end is filled with the correct oil, park sideways on a hill, let those hubs fill with oil. Then recheck the rear end level. Other then that, spanking nice brake job! Even the parking brake strut spring is correct.
One last thing, You sure those drums weren't cut too much? If they aren't, your certainly not going to get another cut :-)
I once had a shop owner tell me "it's not impossible to have just one plug wire crossed" :-)
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Just so everyone is clear:
This forum is to exchange ideas, and help each other out. Any belittling, or rude behavior will result in your expulsion from this board!
I don't give a who ha what you have done, were you worked, or what youve seen, or how long youve done it!!!
Your opinion is welcome here as long as its stated in a respectfull way. Any disrespect to others will not be tolorated, period!
If there is a problem with what I have stated here feel free to take it up with me.
wheres the like button ;)
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Mike:
Sorry about missing this before my last two posts. Bearings should never, never, be installed dry! put some rear end oil on those bearings!
They were not installed dry. They were only dry when I took the picture. :)
Then make sure the rear end is filled with the correct oil, park sideways on a hill,
Yep, that's next after the axles are installed. Actually have to re-assemble the front brakes and axles and then rebuild the master cylinder and power brake booster, bleed the system out and then put truck sideways for each side and top with gear oil.
One last thing, You sure those drums weren't cut too much? If they aren't, your certainly not going to get another cut :-)
I have all my work done at my local NAPA machine shop, I trust the know their job and what's in spec and what's out of spec and they never brought up any issue.
Thanks for all the info...
:)
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Mike posted a picture of the left rear brake job he did. This picture would be a very good reference for anyone that needed help reinstalling the brake components in there correct place.
I once had a shop owner tell me "it's possible to have just one plug wire crossed" :-)
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Yesterday, exception was taken to statements I made to 78 Chevyrado. This was in reference to a post I made on this thread concerning a pre-load matter regarding a floating axle. As it turns out, I was in error. I was advising someone on the correct way to set pre-load, which unfortunately, I had the wrong axle type in mind. Which caused me to infer 78 Chevyrado was giving out incorrect information, on an important matter. And, in my post I used the word “oxymoron,” which I believe caused 78 Chevyrado to think I was calling him a “retard.” Something, I would never say, nor suggest. There is also another possibility here, my words “If you understood…” were taken by him, to be rhetorical. This was meat to a remindful statement, not a rhetorical question.
I became aware of this after Blazin posted directly below a post of mine. At the end of Blazin’s post he invited anyone to take-up problems they may have with anything in his post.
Ok. My comments now aren’t stemming from a problem I have with what you said, your post has merit. But I do have an issue with what you didn’t say. In 78 Chevyrado response to my remarks, he either, rhetorically or ostensibly suggested I could “be a 12 year old girl…” these comments to my knowledge have generated no pubic response, as my comments did.
In 78 Chevyrado’s closing remarks from his post, he said, this matter was behind him. And I believe him. So, 78 Chevyrado: Yesterday I was quick with a wrong assumption, and was a little sarcastic with the “physic” jab. For that, I am sorry!
This matter is now also behind me. Save for Blazin, I won’t be responding to any comments made to this post.
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Just so everyone is clear:
My post was directed at any, and all negitive, or derogitory comments, I don't care who said what, why or for any reason!
The fact that you had the incorrect axle in mind had nothing to do with why I posted a response. That is an honest mistake we can all, and probably have all made more than once in our lives.
One of the reasons this is the best forum on our trucks is because even the hobbiests / weekend warriors, and racers, here are very knowledgeable. We also have a large number of profesional techs in our little family.
We are all adults here, we all know the rules of the forum. We are laid back, easy going, thats how we all like it. Chris devotes alot of his time to this board. Thats is why he has chosen several of us to keep things in check. I didn't single anyone out. If anyone feels I did feel free to state your case. Any further discusion of who said what, etc. will result in this topic being locked.
Now back to the topic.
Mike, that looks text book to me, all of the info given here is spot on. Its up to you to read it, take it all in, and then do what you feel is best. Looks to me like you have it well in hand, but were just looking for a few second opinions for your own piece of mind.
There is always more than one way to get the same results in the end.
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Mike posted a picture of the left rear brake job he did. This picture would be a very good reference for anyone that needed help reinstalling the brake components in there correct place.
Here's what's funny... I took before pictures but there was so much mud they didn't help much, so I used a picture another forum member posted as a guide. Here's the before and after...
GM Corporate 14 Bolt Rearend Passenger Side
Before
(http://www.showcargarage.com/gallery/files/1/Project78PavementPounder032.jpg)
After
(http://www.showcargarage.com/gallery/files/1/Project78PavementPounder049.JPG)
I'm just glad on on the path towards putting it together!
:)
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Now back to the topic.
Mike, that looks text book to me, all of the info given here is spot on. Its up to you to read it, take it all in, and then do what you feel is best. Looks to me like you have it well in hand, but were just looking for a few second opinions for your own piece of mind.
There is always more than one way to get the same results in the end.
Checked and noted.
I won't have time to work on my truck till this Saturday but now I know exactly what to do thanks to everyone's help... so...
Thank you everyone!
That's what I like about this forum, always helpful and family friendly...
(http://www.autogeekonline.net/forum/images/smilies/xyxthumbs.gif)
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wheres the like button ;)
Well it is at the top of the post on the left... LOL
And you can use the publish button of the post and publish it to your facebook page and like it there also...
With that said, there is also a "report to moderator button" that gets emailed to me directly. Please don't hesitate to use it.