Acceptable play in carrier and pinion?

[denialfans]

I recently purchased a 93 super cab 4cyl 5sp with an open 7.5" rear end from a friend whose dad bought it brand new. The truck has 325,000 miles on it. The engine and transmission seem to be in really good shape considering the mileage, but the rear end is horribly loud, especially when coasting in gear. My friend said that it has been like that for a while; I got the truck cheap figuring I could put a new rear end in it and still be under value.

So, I pulled the rear cover off expecting chunks of metal to fall out, but other than oil being black as night, it appeared normal, no burnt smell either. One thing a noticed right away is that there is a good amount of play side to side on the carrier and front to back on the pinion, enough to clunk. I will admit that I personally have never set up a set of gears before, but that does not seem normal.

Is there an acceptable amount of play or should it be shimmed up enough to not slide that much?

Thanks, Richard

 

[MAKG]

The rear end is hosed. The pinion should be ROCK SOLID.

It's not a matter of shimming. It's a matter of preloading and not screwing up reinstallation.

My guess is someone tried to change a pinion seal without knowing what the F they were doing.

The only things you use shims for on a rear end are positioning the pinion and ring gear relative to one another. And they are really picky about that being just right.

Odds are, the gearset is ruined. ANY pitting, grooves, chips, blue colors, etc., condemn it.

 

[rickcdewitt]

if the tooth faces look smooth and shiny you only need bearings,they can deflect a fair amount before killing the gears.
i'll bet the carrier bearings are gone.i was able to save the 7.5 in my fathers mustang by just putting new carrier bearings in.if the pinion gear is loose though you'll need a dial type inch pound wrench and bearing knife among other things to change the bearings.

if its just carrier bearings i'de change them, if its all the bearings i'de swap in a junk yard axle if you are unfamiliar with axle building.

 

[MAKG]

If you are going to do ANY gear setup, you need gear marking compound and an anal attention to detail. Don't get the pattern JUST right, and your rear end will eat itself in a few miles, even if it's good to start with.

Even if you're just changing carrier bearings, you ABSOLUTELY should check and adjust backlash. If the pinion is floppy (as has been described here), you should check and adjust the pinion depth as well. This is not for the sloppy. Throw it together and it will throw itself apart.

 

[denialfans]

Thanks for the quick replies.

The gears actually looked good. (I've never changed a set of gears but have changed fluid in other rear ends before) I'm attempting to make this a daily driver, it should get about twice the mpg as my 99 Tahoe 4x4, and have no problem doing the work my self. I have been reading the posts here and understand the tight tolerances and proper tools are required. I would rather spend the money on the tools and do it myself knowing it's done right than pay anyone else local to do it. The only difference between me and them is experience and knowledge, and I've learned that with the proper knowledge, patience, and time, I can do the same job they can if not better.

I'm looking at ordering a rebuild kit from Randy's R&P; kit YK F7.5 and a set of AK 1563, but I think I'm going to remove the carrier and get a better look at the pinion gear first.

I own a ft lb. torque wrench but not and inch lb., so I need to buy that; part TLSM10 at Randy's ok? I also own a press.

Richard

edit: I should also mention that I am looking for a good dial indicator. Any links?

 

[MAKG]

The cheap Chinese dial indicators are just fine. You don't need to bend over to let Starett deliver theirs anally.

http://www.harborfreight.com .

Randy's bearing and shim kits are just fine. So is their installation guide (though there are clearer ones around).

You're going to need a LONG breaker bar and a way to hold the pinion flange stationary, in order to compress the crush washer. And you'll need a beam-type inch-lb torque wrench. Unfortunately, these cost more than the much more common 1/2 inch clickers. I have a 1/4 inch I use for this purpose, from S&K. Set me back $60 several years ago.

If you're sufficiently anal and you resist the temptation to rush it, it is very possible to get it right the first time. I did this, completely rebuilding a shot 7.5 inch, on my Bronco II. It survived until the next owner gave it a 4.0L conversion (along with an 8.8 inch rear), at least 100,000 miles.

Now is an excellent time to install a limited slip carrier or other traction aid.

And do inspect the axleshafts carefully while you have them out. It's not unusual for axle bearings to eat them up. Axle bearings need to be changed with a slide hammer.

 

[denialfans]

MAKG, I pulled the axle shafts out when I had the cover off and they looked good as well as the bearings, but if I'm going to rebuilt the R&P, then I'm going to change the axle bearings also.

We have a harbor freight locally and I have purchased from them, (3ton floor jack and press), but didn't know about the quality of their hand tools.

Is there an inexpensive "tool" to hold the flange stationary or would it be cheaper to have one fabricated.

 

[rickcdewitt]

you shoulden't need to re shim anything if you just put in new bearings,not a bad idea to check the contact pattern and backlash though.

get a crush sleeve eliminator set. it will be your best friend if you get the pinion bearing preload wrong the first time.they are reusable and you don't need to worry about over tightening the crush sleeve.you just torque it to spec(i can't remember,somewhere between 150 and 200 lb/ft) and check preload,then add or remove shims.definately best for first time set ups

your inexpensive tool to hold the pinion flange is a long bolt run through until it will stop the pinion from spinning

when you go to put the new bearings on put the carrier and pinion in the freezer and set the bearing on an upturned light bulb until it is hot. they will seat much easier this way but you do need to be fast.

 

[MAKG]

The heat trick does work, but I find it considerably more effective to put the bearing in the oven at 400 deg. Don't bother with the freezer; it takes a lot longer and has substantially less effect.

And make sure the bearing is clean (and unoiled) before you bake it or it's going to make some nasty smells.

Or you can just press it on. It's not THAT bad. Not like SM465 transmission bushings, which just break under a ton or so of pressure.

 

[denialfans]

get a crush sleeve eliminator set. it will be your best friend if you get the pinion bearing preload wrong the first time.they are reusable and you don't need to worry about over tightening the crush sleeve.you just torque it to spec(i can't remember,somewhere between 150 and 200 lb/ft) and check preload,then add or remove shims.definately best for first time set ups

Forgive my ignorance, but is the "crush sleeve eliminator" called by another name? I am unable to locate one but like the idea of not having to worry about crushing the crush sleeve.

 

[rickcdewitt]

it should be 20$ or so from the rearend outlets like randys ring and pinion or the others

 

[Sasquatch_Ryda]

They are also called solid pinion spacers. This is the one i've got, 18 bucks.
http://www.justdifferentials.com/index.php?main_page=product_info&cPath=385&products_id=1562

 

[denialfans]

Thanks for the information. I went ahead and ordered the master overhaul kit and the crush sleeve eliminator. I figured I would need them even if I need to replace the ring and pinion. It will probably be next week before I even have time open it up again.

 

[denialfans]

Thanks everyone for your input. Sorry for the late update.

I rebuilt the rear end in early August and have put over 1000 miles on it. I used a Master Overhaul Kit and the crush sleeve eliminator.

Overall the job was not that bad; I got away with using the original (1 piece) shims and had a good gear tooth pattern with the backlash and bearing preload in spec. I must emphasize the use of the inch/lb torque wrench for anyone wanting to work on the pinion. I bought mine off Amazon (needle style) for ~$35. After reading everyone's comments, I decided to tighten the pinion until I thought it was sufficiently tight and then checked it. It was nowhere near close and I'm sure would have caused major problems; I guess I was too used to wheel bearings. And that was with the crush sleeve eliminator.

To hold the pinion flange, I drilled two holes in a long piece of angle iron and bolted it to the flange.

I highly recommend removing the bed. It gives you more room and light. I had to remove/install both pinion bearing races and the ability to stand above the rear end and swing made the entire job easier.

Since I had the tools and my brother has no money, I rebuilt his Explorer's 8.8 for him. The process was same but we used the crush sleeve; I will never do that again. I didn't want to screw it up and torqued it completely by hand (long breaker bar), measuring the rotational torque every 1/16 of a turn. Obviously it can be done, but I will definitely use the crush sleeve eliminator on any future project.

Again, thanks for all of your help.
Richard

 

[metalmacguyver]

Thanks for the update!