Instillation of 410 gears and Eaton Posi-unit in 8.8 rear

First disclaimer- I am not a professional mechanic. I have been an armature (shade-tree) mechanic for many years. I have been told I could/should make money doing this but what would I do for fun?

I didn't take as many pictures as I wanted. This always happens once I get started.

Let me start by going over the terms you have to research and KNOW prior to this instillation:
-Pinion depth (how close the pinion is to the ring gear center line)
-Backlash (how close the ring gear is to the pinion)
-Pinion Bearing preload (how much bearing drag is on the pinion bearings)
-Carrier Bearing preload (how much bearing drag is on the carrier bearings)
-Contact patterns
Take your time and research this on the web. There really is a lot of information available to you on these subjects. Keep reading until you feel you really understand the information. I will include some links here that will help you.
Randy's Ring and pinion

There are also some tools you will need access to so you can complete this job as follows:
-Foot lbs torque wrench
-Inch lbs torque wrench
-Dial indicator (hopefully with a magnetic mount)
-Micrometer to .001
-Bearing puller – the better the puller the easier the job
-Bearing press (I used the bearing puller in reverse for the pinion bearing and seated the carrier bearings by driving them on with the old bearings, probably not the best way)
-Assorted breaker bars and tools
-Pinion (to drive shaft) flange puller (mine came right off but you may need the puller), a pulley puller will do
-Tool to hold the pinion flange. You will need to make a flange holder out of angle iron if you don’t have something else to hold the pinion flange. I got a piece of 3 ft. angle iron from a local
building and supply. It is normally used to hold brick over a window in construction. You will have to mark and drill this to match two of the holes on the pinion flange. Here is a picture of mine.
Companion flange tool

Now it is time to assemble the parts needed for this job.
-Gears (I used 4.10 Ford Racing)
-Carrier if you are also changing the carrier (Eaton LS in my case).
-Complete instillation kit (Randy’s Ring and Pinion has a real nice kit that includes
shims and bearings with gear marking compound).
-Silicone sealer made for rear
-Good gear lube in the correct viscosity
-Ford Anti-friction if you have or are installing an LS unit.
-New cover (if you are changing like I did).
MY STUFF

Now lets get started
First find a place you can jack up the rear of your truck and be safe. Also the truck may need to be there for a couple of days. I used good sturdy jack stands (the kind with a lever) to hold up the back of the truck. First break loose all the wheel nuts just enough that you can remove later with the rear in the air. Jacked up the rear and placed the jack stands between the U-bolts that hold on the rear leaf springs. Make sure everything is safe for working under the truck.

Second disclaimer - I ACCEPT NO RESPONSIBILITY FOR ANY IDIOT WHO KILLS HIMSELF WHILE PERFORMING THIS GEAR CHANGE.

Sorry about that but had to get that off my chest…

It’s now time to remove the drive shaft. I want to stress this is a very important procedure for getting things right later. Put the truck in Neutral so you can spin the wheels. Turn the wheels until you see a yellow dot that is factory painted on the drive shaft near the rear just in front of the universal joint. You want this dot to be in the lowest (6 o’clock) position. Now back to the cab and put in park (or in gear). Using a 12mm box wrench (I got mine part #45991 Professional series from Sears, It is slim line, longer and works very well) Remove the 4 -12 mm – 12 point bolts holding the drive shaft to the pinion flange. Now gently remove the drive shaft from the tail shaft of the transmission (you may leak a little trans fluid but not much). Now look at the transmission tail shaft. There should be a white mark on the shaft and it should be in the 6 o’clock position. If not then make a mark at the 6 o’clock position with white paint. If the mark is in any other position, your drive shaft may not have been indexed correctly. More on this later. Now put the drive shaft somewhere safe.

Place a pan under the rear of the jackpot and remove all the bolts holding on the cover. You may have to break the seal to get the cover off using a screwdriver. Let all the fluid drain. Clean up the inside with brake cleaner or some other fluid cleaner. Remove the wheels and the rear drums. If you have disk brakes, remove the calipers (and anything else that may get in the way of removing the axle, I have no experience with rear disks).

Now its time for disassembly
Heres the cover off
Rotate the carrier until you see a center pin. This pin has a bolt that enters at a 90-degree angle thru an indent in the carrier. Remove the bolt then slide out the pin. You can now push in the axles one at a time and remove the C-clip holding them in place. Pull the axle out enough to clear the carrier, then do the other side. I left mine in place, but you have to be careful not to damage the seal. My axle seals and bearings were less then one year old so I did not replace them. If yours needs to be done, maybe someone here can help with that. I know the seals just need to be pried out and replaced with a new one. The bearings would have to be pressed off and on the axle.

Its time to remove the carrier. You have to remove the bearing caps and then gently pry out the carrier – the bearings and races will come out with the carrier (the carrier shims also).
Very important, keep track of the shims that come out and what side they are on. Immediately put a tie around the shims and mark a label so you cannot get them mixed up later. You may have one single large shim or a combination of shims on each side. Put them in a safe place. If you can’t get the carrier out (it is tight) try putting a shop rag on the teeth of the ring gear and then rotate the pinion. The tight tolerances of the pinion will help push the carrier out. This worked for me. Remember keep track of the shims.
Empty except the pinion
Now under the truck, it is time to remove the pinion. Try to remove the large nut holding the pinion flange to the pinion. If you can’t turn it, you have to bolt the angle iron you made earlier to the flange and then loosen the bolt. Now see if the flange slides off the pinion. If not you will need a flange puller (any good pulley puller will work). Push the pinion out and pay attention on how the seal shim, bearing and crush sleeve goes on the pinion. Clean everything up and take a break.

Preparing the Pinion for installation
Look at the face of the pinion on the gear end. You should see something engraved into the pinion. There are two possibilities. One is a pinion depth measurement, which won’t do much good unless you have a pinion depth tool (very expensive). If you are installing FMS gears, look closely at the new pinion; it may be marked with a +2, +1, 0, -1, -2. If so, that "number" is added or subtracted accordingly depending on what the orriginal one was(e.g +2 would indicate the addition of a .002" thick shim; likewise, the -2 would require .002" less shim) to obtain the proper shim thickness for that gearset. You will not find a .002" shim. You will have to measure the one you have now and then off to the dealer to buy the one you need (if it didn't just happen to come in your kit). THAT IS IF I UNDERSTAND THIS CORRECTLY, ANYONE WHO KNOWS FOR SURE PLEASE, JUMP IN AND CORRECT. Mine was 0 on the pinion I removed and 0 on the one I installed so no changes were made to the shims. This gives you your starting point for shimming the pinion and will most likely be the correct pinion depth. If the new pinion varies from the one removed, you have to adjust the shims accordingly. Press the bearing off the old pinion, adjust the shims and then press them on the new pinion using the new bearings. Now carefully knock the inner race out of the rear housing by driving it out through the pinion hole from the front. Carefully tap the new race on using an appropriately sized driver (I used the old race). Now lube the bearings using gear lube (not grease), insert the pinion from the rear, slide on the outer bearings but do not install the crush sleeve or seal at this time. Install the pinion flange and using your old nut, tighten to about 3-5 inch lbs (that’s inch lbs, not foot lbs, be careful it doesn’t take much without the crush sleeve).

****I have to do this in two posts because of length*******

 

***********Part two******************************
Preparing the carrier for install/reinstall
(If you’re changing carriers, install the anti-lock brake ring from the old carrier to the new one. It looks like a big saw blade with dull teeth.
Very visable here
Its easy to remove and reinstall but don’t bend it)
If you are installing a new carrier, I suggest you use new bearings. If not, you need to decide if the old bearings are good. Clean and inspect the carrier. Lube the bearings and collect the shims to the proper side. There is no way to instruct you on how to get the carrier back in. It will help if you have an additional set of hands but I was able to do it by myself (very difficult). The carrier is heavy and the fit will be tight and you have to hold the shims at the same time. The tight fit is how you get the carrier bearing preload. After you get everything in tight, bolt on the bearing caps tight but do not torque.

Checking the clearances
Now it is time to get you dial indicator out and mount it to a surface that will enable you to measure the backlash. You already know how to do that or you have not started this install. The backlash should be between .008 and .015. My instructions sayed .012 to .016, I ended up with .011 after everything was torqued so I left it alone. If the backlash is too little then you have to move shims to the right side. If too wide, then to the left side. You remove shims from one side and add to the other. If the carrier is not tight then you can simply add to the side needed. Look on Randy’s ring and pinion web site for some good information on how much change with effect the backlash. The articles there also discuss proper preload but essentially you want it as tight as you can get it without destroying the shims when installing.
Randy's Ring and pinion
Now that you have the backlash right it’s time to check the pattern. Use your gear-marking compound and paint 5 or 6 teeth on the ring gear. Make sure you get all the teeth covered on both sides. Now rotate the pinion so that you turn the carrier several times through the marking compound in both directions. Check the pattern and compare it to the pictures of patterns you have collected to help with this install. Again Randy’s is a good resource. If you get your install kit from them, they include a book with pictures of patterns. Hopefully your pattern will be good. If not, you have to remove the carrier, re-shim the pinion, recheck the backlash and check the pattern until you get it correct. This is time consuming but that why the installers get the big bucks. There is no other way to do it.
If you are lucky like I was, then it will be right the first time.
Looked good to me
The only thing I had to do is change one .010 shim on the carrier from the left to the right because my backlash was too tight. Everything else came out correct. I have a friend who is a Ford mechanic and he says on the majority of these installs, after everything it is set at the factory, then just reinstall the shims the same way and most often, you will be fine.

Now it is time to get everything tightened up
The first thing to do is remove the carrier. Remove the pinion flange and put a crush sleeve onto the pinion between the inner bearing and the outer bearing. There is a spacer (a large shim) that goes on after the outer bearing. It came off of the old pinion and forms a seal with the pinion seal. Now install the pinion seal, reinstall the pinion flange and tighten the (new) nut until it is snug. Here comes the fun part. It is now time to torque the pinion. Install the angle iron holder onto the pinion flange and using a breaker bar, tighten the nut.
Companion flange tool This picture shows the home made tool holding the companion flang.
This is a bitch to say the least. It takes between 250 and 400 ft/lbs to crush the sleeve. You have to go very slow checking the pinion frequently by checking to see if it has any side-to-side movement. Once you get the side-to-side movement out, it only takes about 1/8th turn to torque the pinion so take this part very slowly. If you over-torque it, you have to remove the crush sleeve and get a new one. Torque to a preload of (instructions say from 12 to 14 for new bearings) Other instructions I have read have as high as 29 inch/lbs. My mechanic friend said NEVER that high. My friend said 8, I set mine to 12 (it was there the first time I checked it), you should follow your instructions and decide what to use) (note: that is inch lbs, not ft lbs). You will have to remove the tool to check the preload. Just go slowly.
After you have this correct, reinstall the carrier and torque the bearing caps (this will be ft/lbs). Again check the backlash and pattern. It should not have changed but my backlash did tighten up just a bit. It was still fine.

Now it is time to reinstall the axles. This is just the reverse of the way they came out. First in with one of the axles and reinstall the C-clip. Then do the other side. Reinsert the center pin and bolt. Reinstall the rear cover and torque the bolts. Fill with fluid and let the fluid settle for a while, check level.

Reinstall the drive shaft
When you changed the pinion, you also changed the Run-out of the pinion. Its time to get the Dial Indicator out and mount it so you can check the run-out of the pinion flange. You check this in the center where you will see an alignment lip on the flange (just outbound of the pinion nut). Position the dial indicator on this lip and spin the rear (you will have to reinstall one of the wheels and things will be tight) it again helps if you have a friend. Note the run-out of the pinion flange (the high spot when the flange is rotated on its axis). Mark the pinion flange with white paint at the outer edge to indicate the high spot. You want to reinstall the drive shaft so that the white mark on the transmission tail shaft, the yellow mark on the drive shaft and the white mark you just made on the pinion flange are all aligned (if you did the first step, they will all be at 6 o-clock. The white mark on the tail shaft and the pinion flange both mark the high spot of the run-out. The yellow mark on the drive shaft is the light side of the drive shaft (putting the heavy side of the drive shaft away from the high point of the tail shaft and flange). The idea is to cancel out any vibrations using this alignment. Your drive train was “matched” at the factory so this should re-align everything.
Tighten the drive shaft bolts, reinstall all the brake parts and wheels and torque on the wheel nuts. Take it out for a spin and I hope everything works out like mine did. Take it easy on the new gears for a couple of weeks (follow manufactures recommendations). Change the rear fluid after about 1000 miles (consider synthetic).

Third disclaimer – it’s been a couple of months since I did this install (there was snow in my pictures). I hope I have not missed anything but may have. If you find something I missed then shoot me an e-mail. I cannot guarantee this install will work for you. It worked very well for me. Also, all of the specks are on papers out in the gaurage. I will find them in the next day or so and I will post a responce with all torque specks.

I hope this helps, I think this will give you an idea of what to expect. If you have any question, send an E-mail since I can’t do a search in text for my name (had to choose a 3 letter name). Sometimes I don’t get a chance to read all the forums.

Heres a real good article. This guy writes much better then I do.
http://www.corral.net/tech/drivetrain/gears.html[/URL]

No I do not work for Randy's Ring and Pinion but they are great guys and will get you everything you need.
http://www.ring-pinion.com/

Oh yea, heres the old stuff I took out. Only one year old. Sold them on E-bay for $300. Someone got a great deal.
https://www.f150online.com/galleries...9182&anum=2227[/URL]

 

Just added this to my Favorites.

And people wonder why I spend hours reading stuff on the Internet. :)

 

WLF,
Outstanding, you can't see this but I'm giving you a standing ovation and my boss and the engineer in the office next to me are looking at me like I'm retarded. Hell of a job. Props for taking the time write all this down, with visual aids to boot. As slow as I type, it would take me longer to post than to do the actual gear change. There is a little more to it than I thought, but all in all, it looks like a good weekend job. I'm going to keep a couple of copies in my shop for when it's my turn. Hopefully in the next few weeks. Thanks for taking the time to post, this is going to help alot of us that thought we could do this, but were just not quite positive about it.
Rick

 

OK guys I think I have made all the corrections I need to so if you already printed it, discard and reprint.
Hope you enjoyed.

 

Will do, thanks again.

 

So, how much quicker is it with the 4.10 gears?

 

offroadmaniac,
Problem is I went from 4.30 gears to 4.10. I will tell you there is a large difference from my 3.55 gears. If you have even higher gears (3.05's for example) then the difference is great. The 4.30's were really fast but they had the rpms a little high at highway speeds with my tires. They were also a little noisy.

 

Just got back from a conference in Atlanta. Drove 75-85 all the way. Did the trip in 11 hours including stops. The tach stayed between 2250 and 2500. I'll let you know how the milage is when I do the calculations tomorrow (I need to sleep now) but I think it was 17-18mpg even with the 4.10s. The motor really liked those gears at highway speeds too. Will get back to you tomorrow.

 

It turned out to be 17MPG for the trip. Considering most of the trip was at 80MPH I don't think that is too bad. Many are concerned on how the gears will effect the mileage. I am pretty sure if I kept it to 65-70 MPH I would increase the mileage to close to 20 which is what it was before the gear change. I am also going to install underdrive pulleys and electric fans since they probably effect highway mileage as much as the speed.

 

Now I want 4:10's! Thanks for giving me the itch!

 

Just thought I would give you guys a heads up.
I recently changed the fluid in the rear. About a week later, I noticed the adjuster hole in the right rear was wet. I took off the drum to find fluid was leaking from the right rear axel seal. Thought I had a bad seal but when I replace it the seal looked really clean. They are only a year old.
I refilled the rear then took it off the jacks. That's when I realized that with the truck on the jacks and the front on the garage floor, it put a forward tilt on the jackpot and I was over filling the rear. With the truck off the jacks and flat on the floor, I pulled the fill plug and a good amount drained out.
If you service your own rear, make sure when you refill, you have the truck level. That will save you a seal replacement, not to mention cleaning up the whole brake assembly...

 

One of my faults is that I tell on myself. :o
If I think something is good I will tell you about it.
If I screw up I will tell you about it.
I did this post in May of 2003 and one step I left out of the post and out of my job is to be sure to use Locktite on all the bolts when final assembling the rear; especially on the ring bolts.
This summer I developed a drivetrain vibration following a catastrophic failure of my transmission. It took a while to finally figure out the vibration was on the rear side, not the transmission side.
This is the result of not using Locktite



and this is what happens when one of these bolts cycles through the ring and pinion



Theres 9 more of these still attached to the pinion.
The pinion tooth was not off when I found and fixed the bolts but must have been cracked and it failed soon after.
Needless to say I am doing this job again. It has been near three years so I brought up my own post to refresh my memory.
Got all the parts in today. Wish me luck...

 

Got everything apart today and reassembled to the carrier. Backlast is .030 so I have to change some shims around. I'm calling it a night. The instructions I gave before worked just as well this time.
BTW The Eaton LS is very easy to rebuild.

 

Everything is back together. First run smooth and quiet. I highly recommend Ford Racing gears. Mine had -8 on the pinion and I subtracted .008 from the nominal .030 for stock and it was perfect the first time. Had to make one shim change on the carrier to get a backlash of .014 and a perfect pattern.
It was unfortunate it had to be done but the first set lasted 3 years and the second time was easier.
Started at 11 am yesterday. Quit at about 10pm last evening and in less then two hours today had it finished. It would have been faster but I was lying on my back on the floor of my garage.