How to Rebuild a Ford 9 inch.

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How to Rebuild a Ford 9 inch.

This is the Second iteration of my blog entries on Rebuilding my Ford 9". Originally this was a rambling collection of thoughts and multiple posts. I've tried to cobble everything back together since the original entries were lost. The Goal is to walk you through my story and how i went about solving the problems i had, and to reassemble my blog into a more coherent post, and to help you take a 3rd member apart and put it together again.

How this all started: in 2007 i went through an extensive rebuild of my car in an effort to make it road worthy.

I had my share of engine problems but the drive train of my car was in decent shape. I was encouraged by friends since I was already pulling the engine out that it was a good idea to freshen up my transmission and 3rd member.

So i sent my uni-body to one place for metal work, my engine to another, and my transmission and 3rd member to a local shop to be rebuilt. I was quoted about 1100$ for the work on my transmission and 3rd member. I was told this was a good price by others and i should go for it. The transmission place called and told me my transmission needed work. My 3rd member was apparently in good shape and just needed a new pinion seal, because it was leaking. I was satisfied that my car was in good hands. The work was completed by the transmission place within one week and both units returned to me.

I was not happy with the spray paint job the transmission place did to "freshen up" my cast aluminum C6. and since they barely touched my 3rd member it looked like hell. Since my car was going to be mechanically restored i wanted the "freshened up" parts to look nice. I took it upon my self to clean the parts up and repaint them so they looked their best.

So without taking anything apart and not knowing how anything worked i simply cleaned everything up and returned them to an external factory finish.

When completed the transmission and 3rd member went on a shelf for almost a year as the engine builder and metal fabricator were not able to complete there jobs in a short amount of time.

As 2008 draw to a close I finally re-assembled the car and was able to drive it before the first snow.

Lots and Lots of problems sums up 2008 and 2009 as i worked out the kinks and tried to break in my stallion.

One discovery was the transmission place i used had basically scammed me, this required me to learn about transmissions and make repairs myself.

As the year dragged on one nagging issue i had since the 2008 rebuild was the sound of running water coming from somewhere.

I could never track the sound down. But it would only happen at cruise speed, or if i lightly touched the gas pedal.

I thought it was a problem with my fuel delivery system because of the sound of running water the problem made.

A process of trial and error over 2 years led me to believe the sound might be coming from the drive line.

The same drive line that before being worked on by the disreputable transmission shop was ok.

Over on VMF I posted a thread about Differential Fluid. at the time i was ruling out all the things that could make a running water sound in a car. One was low differential fluid. I wanted to make sure i had filled the 3rd member with the correct fluid and fill level.

Over the course of the thread, i disclosed the noise my car was making and a very helpful member said it sounded like my car had a problem with 'float'. This is where you have a drive line noise under light load or cruise. the gears are floating between fully engaging and just rolling along in a neutral state. This would be a light load situation, your floating along the road. After googling the "float" issue I had a better understanding of what was going on.

I also found a way to test for float based on what i read.

I took the car for a test drive and really listened for the noise with the windows rolled up and the interior as quite as possible. Sure enough i found the noise was actually present under all load conditions and would simply get louder the faster i went. It also took 3-5 minutes from the car being cold, until the noise would become present. Some more googling on the internet led me to believe my 3rd member was suspect. I made the decision to rebuild my 3rd member myself and learn all i could about them.

So it began.


My first step was constructing a large workbench.

With plans from the internet and 1 day getting lumber i was able to construct a bench large enough and strong enough to work on a rear axle.

I did research and found a wonderful video by Bad shoe Productions.

I highly recommend checking out the bad shoe site and ordering his videos they are amazing.

With information from Bad shoe and the internet i was able to assemble a tools list.

I would also need a shop press.

I now had all the basics covered. a place to work on my 3rd member, the tools, and the knowledge. Now i would gain the experience.


The time had come. Drop the rear end, and examine it, and fix it.

Armed with information it only took me a minute to know this rear end was completely shot and miss-assembled by the worst transmission place on earth.

First I checked the pinion shaft by turning the yoke. The entire thing was loose. The bearing pre-load was completely wrong and it was very easy to turn the gear set.

There is suppose to be a pre-load on all the bearings in the 3rd member.

Because the Bearing and bearing carrier are separate pieces they must be forced together to prevent slippage and any movement up and down and side to side.

I was able to wiggle my yoke up and down and in and out, so i knew my bearings were shot. I would find out how bad later in the inspection.

Then i noted that my original gear set was keyed. Just timed gear set for the crank and camshaft of an engine some gear sets are machined and Lapped so that

only certain teeth may contact another tooth and the pattern between the pinion and ring gear do not overlap.

In the picture above you can just make out the Yellow paint that show how to assemble a timed set. These marks should be lined up. with the single painted pinion gear tooth, resting between the 2 painted teeth of the ring gear.

as you can see my set was about 2-3 teeth off.

This was the cause of my 'water flowing' noise that started me down this path of rebuilding my axle mechanically not cosmetically.

The Gear set was miss timed it was making a whine noise that i was mistaking as water flowing in a pipe. This was actually a good thing because it told me my rear end was in big trouble.

Additional inspection of the gear fluid revealed lots and lots of metal particles because the bearings were chewing themselves to death.

The reason that in 2007 i had no gear noise and in 2008 i had noise was because when the transmission place replaced the leaking pinion seal.

They removed the pinion and bearing nose from the rest of the 3rd member. To replace the seal you must take apart the pinion and bearings and yoke.

now you are also suppose to replace the crush sleeve that sets the pinion pre-load and then set the yoke retaining nut to the correct torque spec.

These YOYOs did not replace the crush sleeve, reused my old one, and put the pinion and bearing nose back together incorrectly set the bearing pre-load

leaving the bearings too loose, and when they put the pinion assembly back into the 3rd member housing totally ignored the timing marks on the gears.

They got me for a one, two punch! miss matched gears, incorrect bearing pre-load. by having the incorrect pre-load the pinion was allowed to move around.

therefore my bearings and my original gear set was destroyed by the incompetence of this transmission place, any by my own ignorance for not knowing any better at the time.

Time for Further inspection.


when it rains, it pours

Deeper inspection of my 3rd member on the workbench led to more surprises. I checked bearing play and it seemed stable enough to look at the ring gear run-out.

I also took the time to inspect the ring gear carefully.

Somebody hammered the heck out of the back side of the ring gear. The gear set turned out to be 2.75:1 not 2.90:1 or 3.00:1 as I was told.

This damage to the back side of the ring gear made checking run-out difficult. It showed that somebody had been in insides the guts and did a lot more damage.

The best set i got for run-out was .008 spec is .003-.004 or less. not good.

I thought maybe things would work out because of the bearing damage and the damage to the original ring gear, so i went ahead and attempted to use my original posi traction unit.

I felt the bearings and gear set was beyond trashed which was a shame because it turned out the gear set was in fact original to the car.

At some point in the past, somebody found a junk yard 28 Spline Posi traction unit, removed the cars original open differential,

reused the carrier bearings and gear set, and put everything back together. I came along when the Rear Seal killed itself and the trans place did the rest of the damage.

In short this rear end was Very over due for a complete tear down.

At this point I tried to measure the backlash i was having problems with the dial indicator mount and the best reading i got was over .022 Spec is .015

Again this tells me the rear could not be saved and needed to be completely torn down.

next i put marking grease on the gear set and looked at the mesh, From that i could see:

1) cross bearing situation.

2) Incorrect pinion spacer.

3) The Contact pattern of the ring and pinion gear was Oval, not round.

This told me the gear set really was toast.

This was my Chance to change my rear end gear ratio.


I fall to pieces.....

after discovering that the bearings were in bad shape i decided to just take the whole thing apart for a closer look at the case itself.

Here is a clearer shot of the timing marks on the original gear set.

Note here: the Carrier bearing Caps, these are specially machined left and right, DO NOT mix up parts, you may want to mark them left and right before you take them off the case housing.

be very careful once again they are Keyed left and right, the caps and the adjusters keep them separated when you remove them to prevent big problems later.

The original posi traction unit. The Case showed deep tool marks and further damage.

At best i hoped to save this unit from the scrap heap.

this is how bad the bearings were.

New parts start to arrive.

pulling more apart.

Inspection of the bare 3rd member case, all cleaned up, you want to check for any cracks in the case, i was lucky my case housing looked to be in good shape.

the bearing surfaces were not mared and it looked good.

With the case in good shape I installed the new pilot bearing for the pinion shaft.

I put new bearing carriers into the pinion nose and got everything ready for final assembly.

I also counted the splines on the original pinion shaft (28) to be able to replace it with the correct aftermarket motive gear set.

It was time to take a part the original posi traction and see how bad things are inside it.


Clean up and inspection of the posi traction.

I began by taking the original posi traction completely apart.

What i found was more damage. At the time my inspection of the Case led me to believe the unit could be saved. Aimed with misguided goals i proceeded.

I installed New main carrier bearings. on the posi traction case.

I then cleaned everything up and did a deeper inspection:

I found the main Differential shaft was badly worn, along with my trust washers and side gear shims.

The new shaft

The Thrust and side gears were in good shape and i would reuse them.

inspection of the Posi Traction clutch pack showed it was completely worn out, and the incorrect shimming was used on it.

This was interesting because 1 year prior i had experienced an odd handling issue that was caused by my posi traction being too loose.

here was the explanation for that issue. Again showing how worn out my rear end really was.

A new clutch pack was ordered and installed, with correct shimming.

clutch side is done.

All the Shafts and washers were replaced and the gear set was rebuilt.

the axle is placed in the vice to help line up all the gears and plates and acts as a

mount for the gear side install keeping everything in line is very important for final assembly,

the pressure plate and spring is extremely strong if your alignment is out just a

little bit you will never get the axle back in so now is the time to get the alignment 100%

all that is left is pushing the top into the bottom using bolts through the ring gear hole you compress the posi halves together, then tighten the flat head screws when the sides are compressed together.

At this point my confidence was high and i was waiting for my new gear set to arrive.

A fresh rebuilt posi traction sitting in the clean case with new bearings.

At this point with time on my hands I cleaned up my Axles, discovered one wheel bearing was no good and replaced both wheel bearings and retainers.

i also cleaned up my axle and got all the bad fluid out of it making it nice and clean for a fresh install.


Progress and regress.

You need the pinion and ring gear before you can start finally assembly,setting case spread, check ring gear run out,

and setting all the bearing pre-loads and set the mesh of the gears.

I went with a Motive 3.00:1 Gear set.

I was not really impressed with Motive Gears. they are not machined like original. the biggest issue was the pinion shaft is not tapered like the original ford set.

This caused some installation issues of the pinion bearings in the pinion nose carrier. It made serving the Bearings in the future more of a pain in the butt.

this gear set is not a timed set like original, so you can see there are no paint marks on the pinion or ring.

this means you do not have to worry which teeth are contacting others on the gear set.

The instructions that came with the set didn't have any new information. I was a little surprised that they want the backlash

between .007" and .009" instead of .012" to .015" like on the original ford set.

Always use the backlash the manufacturer recommends.

Torquing the ring gear to the posi; I would of never guessed that would of just drained the life out of me the way it did.

just a lot of problems getting the vise to hold everything while trying to torque to 77 ft/lb, I had to clean the thread on

the ring gear with a tap, i put red locktite on all the ring gear bolts and kept going around and

around the gear checking the torque spec over and over i even used a second torque wrench to confirm the correct Foot pounds.

i was really nervous that the vice would damage the side of the posi, thankfully all was as good as it was before.

Always use Red thread lock on the ring gear bolts, and torque them to Spec. 77Ft/pounds in my case.

remember to install the outer bearing in the carrier first, then press in the new pinion seal into the nose case. if you have an oil slinger you must install it now before the pinion seal.

Assembly of pinion unit in shop press. the inner bearing is pressed onto the pinion shaft first until its seated.

then the new crush sleeve is placed on the shaft in front of the inner bearing. slide the pinion shaft through the nose through the outer bearing, and oil slinger if you have one, then through the pinion seal.

(if you have an original ford pinion, everything will slid together smoothly and you will be ready to install the yoke, in my case...)

now in my case because of the aftermarket pinion, i needed to assemble everything with the yoke and then press the entire unit together as one piece. BE CAREFUL DO NOT RAM THE PRESS HOME!!!

you just want everything together so you can start to fit the new pinion nut on the side with the yoke.

Here is where people Screw up big time when rebuilding a 3rd member. Setting the pre-load on the pinion.

What you do is install the nut on the end with the yoke and tighten it down. Now your ready to set pre-load. you will need a 6 foot breaker bar, and a Inch dial indicator.

you take the entire pinion assembly and insert the yoke into a large vice, tighten down the Pinion nut using the breaker bar, and wiggle the pinion nose around,

tighten the nut until you feel all the play come out of the pinion nose this is the bearings starting to tighten up and the crush sleeve starting to crush down.

at this point you need to WATCH OUT, you will need to alternate taking the yoke out of the vice and placing the pinion nose in the vice so you can turn the pinion with the dial indicator on the Pinion nut.

your looking to have the correct amount of resistance to turning the pinion around. There is suppose to be tension here provided by the crush sleeve.

Now I had a hell of a time with a 6 foot breaker bar getting the pre-load in spec and not over shooting it with the crush sleeve.

It fell just with in spec on the loose side at 20 in/lb spec is 16-29, i dared not attempt to make it just a hair tighter.

a 1/32 of a turn more on the breaker bar would of over shot the pre-load by a lot. if that happened i would of had to start

all over with new parts. Go slow alternate back and forth tighten the nut 1/8 of a turn and then check it with the dial indicator.

if for any reason you over shoot the bearing pre-load spec, you will have to take everything apart. Replace the crush sleeve with a new one, and start all over again.

Checking pre-load with Inch Dial indicator.

Now when I felt proper pre-load and how tight the pre-load was suppose to be compared to how somebody set it on my original gear set I was shocked.

No wonder I had a pickle of time trying to see what the original backlash was it would have been impossible.

The way it was originally it was so loose it could of spun forever.

Pre-load is super important and the biggest thing people mess up.

The pinion portion of the 3rd member is now 100% complete.

Because my rear end had so much wrong with it I decided to put everything together and start to double check measurements.

With the pinion temporarily installed and torqued to spec (minus the o-ring seal) I started the process of test assembly.

I knew i was going to have to mess with the pinion shim because somebody had installed the incorrect one to start.

I left off the O-ring seal to make it easy to pull the pinion assembly on and off the case housing.

setting case spread to .010"

Setting up measurement of backlash.

Here i started to notice a major problem, my backlash was varying greatly, from .05 all the way passed .10" this was not good.

at this point i suspected a major problem.

and i checked the run-out of the posi on the new ring gear face.

what i found was shocking. The run-out was over .08" spec is .03" max

my posi traction housing was bent, and rendered junk.

Out it had to come after all that work.


well that was a waste of time.

The new Ford racing Posi arrives, i install new bearings on the posi.

then re-install the new ring gear with new hardware and mock it up in the case housing, and setup pre-load of the bearings again.

YES!!! its in spec under .02" in fact.!!!

I notice a piece of paper in the new ford racing posi box.

Due to a manufacture screw up, I may have to shave material off my right side carrier housing.

Sure enough after i checked the run-out and i shifted the carrier adjusters over to fit the pinion gear i see the posi is hitting right where the paper said it would.

Now I have to grind a ton of casing off my rear end case to get this after market posi to fit.

And I noticed it's very close to the pinion pilot bearing housing as well

I grind and fit, over and over, making sure not to contaminate everything with metal shavings.

Finally i make the clearance i need.

I ended up grinding both the pilot bearing and the carrier area.

I can see the mistake ford racing made; First they didn't turn down the cap area like on the original ford part and they messed up the taper on the case by the

pilot bearing. On the original ford posi the taper has an area that is turned down as well. They left full thickness on the aftermarket posi.

What a headache direct drop in my foot, metal shavings all over.


Round 2, fight!

So the old posi traction was damaged beyond hope.

What was wrong with it? basically it was bent. The trueness/run-out of the plane that the gear sat on was no longer level. The max allowable was .003 and

some manuals allow .004. This unit was .008" out of level. So it was scraped after all the work i did.

My hope was that the problem was with the original gear set and not the posi, i was wrong.

I took the opportunity to upgrade: the old posi was a thin walled 2 gear 28 spline traction lock with the weakest known clutch pack housing and it was over 35 years old.

the new posi is a 28 spline, 4 gear, nodular iron chuck of metal and its new, and almost ready to install.

With the grinding of the case Carefully done according to the ford racing instructions sheet i was finally happy with the fit and clearance.

I setup the case spread on the carrier bearings and put the entire hog head together.

Case spread is another area people mess up. the way its done: looking at the picture:

The left side of the case has the ring gear. with the pinion installed, start to tighten the left side carrier bearing cap, MAKE SURE the right hand side cap is loose as you tighten the left side.

remember the carriers are keyed left and right with left and right threads for the carrier caps. tight then left cap just until you feel all the play between the pinion gear and the ring gear go away.

STOP! do not try and tight it, just let the gear mesh kiss, now tight the right side cap, stop when you feel pressure, and install your dial indicator as show in the above photo.

now tighten the right side bearing carrier cap down until you get the correct case spread to ford spec of .010" this will force the posi traction back over to the

Left side of the carrier and get you almost dead perfect for setting the backlash for the gear mesh.

I Starting with a .20 spacer. for the pinion.

I started checking the backlash

it was a little low so i increased the backlash, into the .007-.009 range. This is low for a OEM ford gear set,

but the motive gear set required this lash as the gears were lapped for this range.

next i looked at the gear mesh. i painted the special grease on the gear faces, and got to it.

I wasn't happy, so i tried a .018 spacer and reset the lash

Still not happy I went to a .024 spacer and now I found my mesh going out in the other direction the same amount when i used a .020 spacer.

I needed a .022" shim

I got lucky i ordered an extra set of bearings and found a .010 spacer in the set to go along with a .012 spacer i got in the first kit,

I put them together and was very happy with what i saw i had the drive and coast side of the gears meshing almost 100% centered.

with the the correct spacer installed now i was concerned with backlash.

The Question is what are you trying to do here?

There are 4 main areas to a tooth, the coast side the drive side and the heal and toe.

the coast and drive side are the faces of the teeth, the heal and toe are the bottom of the tooth and the top of the tooth.

the idea is you want the Coast and drive side gear mesh to be centered between the heal and toe of the tooth but also on the drive and coast side.

if you find the marks of your mesh are in the middle of the tooth but what you look at the drive and coast side of the gear one side looks a little higher or

lower then the other. that means you need to adjust the pinion shim.

you want everything in the centers of the teeth on both sides.

the backlash is how much play there is between the ring and pinion gears you want that with in spec as you adjust the pinion depth.

it takes some messing around but think of it as a very sensitive X,Y and Z graph

the pinion shim shim moves your X and Y and Z is the backlash.

a .005" change in the shim makes a huge different in gear mesh on the coast and drive side of the gears.


Done. Almost.

Basically I finished the pumpkin.

I went with the .022 pinion spacer.

I set the case spread at .010

My pinion pre-load at 20 inch pounds

My back lash is between .007 and .009 around the gear.

And my run-out is .002 on the ring gear.

I torqued my pinion to case bolts at 40 ft pounds with red lock tight.

My carrier housing is torques to 77 ft pounds with red lock tight.

My bearing adjusters at 20 ft pounds with red lock tight.

My mesh pattern was centered a little high on the tooth. But I went by the manufacturer's recommended lash.

I measured the thing 9 ways to Sunday and feel I got the settings as best as I could by the book numbers.

At this point the pumpkin is complete. I rebuilt the entire thing from the ground up.

I replaced the wheel bearings so I'm going to replace the axle seals also. This makes sense, i already replaced the wheel bearings so the seals should be replaced as well.

Cleaned up my workbench.

Check your axle vent tube at this point make sure its not clogged, good time to replace the hose also.

Phew: Word of advice if you install a rear end make sure you have 2 people, i did it alone and it was not fun.

Drive shaft back in: i added some grease to the rear zerk fitting.

I'm letting the gasket setup for 24 hours then I'll add the fluid to the rear.


Test drive 1/ Heat cycle #1

I'm back from my first test drive. So far so good. I took it really easy on the back roads for 15 minutes.

The original whine sound I had before I started all this is completely gone. I cruised at different speeds on and off power, set the trans in low and revved up slowly,

no burnouts or anything just slow acceleration and listening for noise, cruised up to 40mph climbed a few steep hills and brought it home to cool down for 24 hours.

I didn't hear any weird noises from the rear end, and didn't even hear any clunking from the new posi when making a turn.

my off idle hum is gone. I really didn't feel anything different with the acceleration with the 3.00:1 compared to the 2.75:1 but i have not opened her up yet.

once the car has cooled I'll check under it to see if anything is leaking that shouldn't be.

after that it will be heat cycling the rear on longer and longer drives and after about 500 miles starting to open the throttle.

so far i'm happy lets see what more drives tell, least my whine is gone, lets hope forever.


Heat cycle #3

well its been raining here for a while and its cold but today i finally had a chance to take the old girl for a spin.

so far so good, I have 50 miles on the new rear now. I've flogged it a little, nothing too exciting. Its so quite inside the car now,

well until you get on the throttle.


Wanted to add some more info.

Before installing the 3rd member clean off the marking grease from the ring and pinion gear, you can use electrical cleaner or parts wash, but try to get as much of the white grease off as possible. The white marking grease can contaminate the diff fluid.

When installing the bearings and setting up the back lash and case spread use a little motor oil on all moving surfaces. You want to make sure everything is free moving and has some lubrication so no bearing chase is dry when you first drive it. Think of it like moly grease on a cam for first start up. So put a little oil on the bearings surfaces. Do not load things up or it will contaminate the diff fluid, just use enough to wet the bearings surface.


Aftermath Discussion.

I started the project in AUG 2010 and finished in the middle of October 2010.

Q: thanks for all the info and great pics. My rear-end is making some noise as well, going to dig into it this winter. If you don't mind me asking, what did it cost to fix all that?

A: well it will depend on what damage your pumpkin has if you take out all my mistakes and tool costs. To go from a bare case like i did to a complete rear end.

Fluid 40$ plus 17$ for friction modifier.

Complete install kit for a traction lock, bearings, and hardware. 92$

Wheel bearings 34$

New u-bolts 6$ with nuts.

Pilot bearing retainer 3$

New 28 spline traction lock 400$

New copper washers 3$

New axle seals 25$

Motive gear set 190$

So for raw materials 810$ to completely rebuild an axle ground up and replace everything except the case.

Dealing with a traction lock will be more expensive then an Open rear, the traction lock has the added cost of the clutch pack and having to check the shimming.

there is added cost if you have a 4 side gear unit verse a 2 gear, the 2 gear has one main shaft while the 4 gear has 3 shafts.

assuming it just needs to be freshened up, your looking at 220$ in parts for a traction lock and about 150$ if you have an open rear. This is just for parts.

If your having a shop do the work i would expect a quote in the 540-600$ range. Its mostly labor might be dealing with possible mechanical damage or rust so that will require a lot of labor on the final bill.

i did it myself which cost me more since i didn't have the tools needed to start the project.

Q:How did you hold the diff in place when you torqued the crush sleeve? I'm almost willing to try a rear end rebuild myself, except I can't picture myself getting that much torque on something without the weight of the car to hold it still.

To torque the crush sleeve I had the pinion support separated from the case.

The yoke, pinion, bearings, pinion support, bearing seal,crush sleeve I assembled as a unit on my shop press.

Then I took the unit over to my bench, inserted the yoke into a large vice and began to torque it down. First you get the play out of the pinion support, then carefully to have to alternate between pulling the unit out of the vice and clamping down the pinion support using a inch pound dial wrench checking for pre-load, you have to go back and forth about 1/8 of a turn at a time until you get a reading in spec.

If you over shoot spec on the pre-load you must take it all apart install a new crush sleeve and start over. You could also convert to a solid pinion spacer instead of a crush sleeve, you may need to do this with really low ratios and you may need to convert to a dayton a pinion support with larger bearings.

Once you have setup the pre-load if you know the spacer is correct you could install it back in the pumpkin.

There are methods for repairing a bearing or a new seal without pulling out the pinion support but its really not reliable. And it's easy to accidentally over shoot pre-load that way.

Also if you have a timed gear set it will be impossible to confirm the marks are lined up unless the entire chunk is off the axle.

Truth is it's actually harder to install the ring gear bolts and torque everything to 77ft pounds, I tried a bunch of ways to hold the chunk without damaging the case, in the end I ended up jamming it in my vice, and marring the outer case slightly I tried holding it with the axle shaft and it was impossible to torque all 10 bolts that way. Do not use an impact wrench to install, you can use it to remove the bolts only.

I did have to build the workbench in the photos because the forces involved in torquing required it. I had a 2 foot long breaker bar with a 5 foot pipe on the end to get the force needed to start to crush the sleeve.

I've learned a lot about rear ends. What is interesting when searching the web about rebuilding a rear is all the misinformation or skipped steps. one problem is how do you compile the info properly? I've learned from at least 5 different sources including a video by bad shoe production. I would encourage anybody to check out Bad Shoes videos and website there is a lot of information covered in bad shoes 4 hour tapes on rebuilding different things.

here is a sample on the ford 9"

any of Kenneth's videos should be added to your library, very informative and educational.

I've decided to try and take an existing tutorial on rebuilding a ford 9" that is incorrect and fill in same gaps and point to reference material when i can.

a lot of people complain about whine in lower ratios under 3.8. in my research I've found that lower ratios are harder and more sensitive to setting up the gear mesh. It is possible to get a defective gear set. as the ratios get lower the angles of the gear mesh change greatly from the taller gears what can happen is the stock pinion bearing carrier can be weak and not handle supporting a very low ratio. so you have to see if the instructions recommend the use of a daytona type carrier or even a modified pilot bearing, and using a solid bearing pre-load spacer. some times you can't count on the crush sleeve and you must go solid. any slight vibration on the low gear sets esp once you get into crazy ratios like 5.83:1, 6.50:1 will not only cause whine but can melt actually melt the gear face. setup is critical.

the biggest mistake I saw was not understanding pre-load on any bearings. some people just think if its tight its good. some people think the rear end is suppose to be free and have no friction at all.

when ever you read that you must place friction on a ring gear to check the gear mesh with the marking grease, that person has completely misunderstood pre-loading the case and the pinion bearings in spec, when a rear end is setup correctly the pinion will take some effort to turn, combine that with the ring gear carrier pre-load and it will surprise you how much effort is required to turn a pinion gear. that resistance is suppose to be there it helps you set the mesh and back lash of the ring and pinion gear.

i found that methods people used during dis-assembly and reassembly were often wrong and would cause more damage to the rear end, you really do need proper tools when working with these critically machined parts. As evidence take my original posi, it was damaged beyond repair due to incompetence in the past.

Measurement is very critical, if your off by .02 of an inch you will see it, i was surprised just how critical you need to be.

take my pinion spacer, from the factory a .24 spacer was used, this would of most likely been ok had i used a ford gear set.

you start with what you have. since i used an aftermarket gear set it turned out that .24 caused the mesh to occur at the toe on the coast side and at the heal on the drive side.

swapping for a .20 spacer caused the opposite: mesh occurred on the heal of the coast side and toe on the drive side.

this was a difference of .02 of an inch and made for a radical change. i ended up with a .22 spacer which was almost perfect, most likely i needed a .215 spacer which doesn't exist.

with the .22 the mesh was almost dead center on both the drive and the coast side of the gear.

back lash further makes things critical, the difference of .002 of an inch is ENORMOUS! in the gear mesh world.

The easiest way i approached it, worry about the pinion spacer first, get the mesh on both sides of the tooth(drive and coast) to be as centered up and down as possible. once that is set worry about the backlash which controls how deep in the tooth the mesh falls.

think of it as centering on the X and Y axis. that will get you in the ball park, then you go to the instructions and see what the manufacture recommends. when ever you make any backlash adjustment you must be 100% even on your turning of the carrier screws to maintain correct case spread or bearing pre-load on the carrier bearings. I found this to be the biggest mistake people make. they loosen up one side to match the backlash then ignore that they have changed the pressure on the case unevenly, they throw it in the car and oops you have whine.

or they ignore the correct procedure for installing pinon bearings and the pre-load on that with the crush sleeve.

well I've rambled on too long Big Grin

Q: how hard was it?

A: Here is the deal, the skill in changing the gears is pretty easy you take your time and check things with dials and micrometers.

The problem is the cost of tools. I wanted to do this myself, and I most likely spent at least 1500$ in tools I did not have. I didn't have a press nor any dial indicators the mount for the table to hold the rear end so I could work on it was 400$ by itself.

If you take your car to a competent transmission shop they should be able to swap the gears in one day and it should cost you about 600$ max. Most of that is in labor, now if the rear is really damaged then the cost can skyrocket due to replacing bearing chases, if they find damage inside the differential then the labor costs will increase again.

Let's look at the cost of just materials involved in my rear end swap.

Taking out all the wasted money I spent on dead ends and starting with parts discovered damaged and needed to be replaced.

Fluid 40$ plus 17$ for friction modifier.

Complete install kit for a traction lock, bearings, and hardware. 92$

Wheel bearings 34$

New u-bolts 6$ with nuts.

Pilot bearing retainer 3$

New 28 spline traction lock 400$

New copper washers 3$

New axle seals 25$

Motive gear set 190$

So for raw materials 810$ to completely rebuild an axle ground up and replace everything except the case.

This does not cover labor.

Where I live the average labor rate for automotive is 80-120$ an hour.

Let's be nice and say it took me 4 hours at 80. That is 320$

For grand total of 1130$. Realistically that number should be much higher because during the checking of the original parts more labor would be involved.

So you spend 200$ on a gear set expect at least 100$ in bearings and new parts to set the pinion pre-load. If they discover no surprises figure 4 hours labor. Let's say you find a guy that quotes 60 an hour I would expect a quote to be reasonable in the 540-600$ range. To have somebody else install the gear set with profit.

A quote in the 300$ range is telling me to watch out.

Because that would mean they will reuse your original bearings if they are good or bad.

They may or may not be smart enough to replace the crush sleeve on a 9"

They will defiantly give you a used gear set from a junkyard.

And will not replace any seals or axle bearings or they will tell you they found one or 2 really bad bearings and charge you another 100$ over quote to replace just the bear minimal.

Most of the cost in that will be labor and you will have a sub par rear end.

As you can see I wanted a totally new rear end and the knowledge to go along with it so I paid steeply for my rear end rebuild but I know everything inside has the best of my abilities and care.

My total costs I'm sure are in the 3000$ range, but I would do this again, I have fresh insight into costs, and if I want I could make some money off my services with friends.

Knowledge is power.

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