FORD 9" ring & pinion swap/ install- An amateurs guide

[dogsbody]

I was a bit nervous about my 1st diff build but the hardest part was finding the right information! Heres what i learned from scouring the net and from my experience of building my centre section:
(Some of this applies to MOPAR and other rear ends too)

(1) You'll need a rebuild kit, a big torque wrench and the mechanical abilty to pull it apart without instructions.

(2) Get the bits that are missing from the rebuild kit. (you won't get ring gear carrier bearings and if you have a Daytona pinion you'll need a pinion shim pack and (maybe) a heavy duty pinion bearing. Oh and the little retainer clip thingy that holds in the pinion nose bearing which you'll destroy getting it out)

(3) Assemble the pinion- this involves the infamous 'crush' sleeve (unless, like mine, you have the heavy duty 'Daytona' housing which comes with the nodular iron case fitted to Boss Mustangs etc. In this case you use a solid sleeve and shims- personally i'd bin the crush sleeve and do this anyway!) I assembled it with one shim (thickest of 5 in the kit) and slowly tightened the yoke retaining nut until the bearings got tight- not enough shim! I stripped it, added a shim and kept trying until i could tighten the nut to 200lb and still turn the pinion with slight resistance (supposed to be 8 or 30lb/inch turning resistance depending what you read...). Then i stripped it one last time, fitted the big front oil seal (remembering the flat washer behind it!), loctited the nut and wound it up to 200 one last time. Now the pinion assembly is ready to bolt into the main housing (known also as- 3rd member, pumpkin, center section, ham, diff case, chunk, rear end... does any other part of a car have so many names?)

(4) Again, it's shim time. Shims go between the pinion housing and main housing, this adjusts the pinion depth in relation to the ring gear. I guessed at the two thickest shims to start (out of about 8 of varying thicknesses).

(5) Make yourself a stand or use lumps of wood to prop up the centre section, it's time to fit the ring gear/ diff assembly. This is really fiddly cos its pretty heavy, it sits in taper bearings which will move all over the place and you have to hold all that together whilst fitting the bearing caps and the ring gear bearing adjusters in whatever order you find easiest. Once you've got it all in place and the adjusters aren't cross threaded (careful!), tighten the cap bolts so you can still turn the adjusters by hand, but only just.

(6) Now adjust the backlash by moving the ring gear side to side ( by turning one side adjuster out, then turning the other in), so it meshes closely with the pinion. (i made a tool to do this out of a short bar with 2 bolts through it) You'll get somewhere near by rocking the ring gear as you adjust it so it clonks against the pinion. A big gap and you're too far out (too much backlash), no clonk and you've none! (Check also that the ring gear isn't hitting the case around the pinion nose bearing- its a bit close here!).

(7) Once you think you're somewhere near, it's out with the marking grease. To start i just painted 3 or 4 adjacent ring gear teeth, both sides. Press a rag against the ring gear to create some drag and turn the pinion by hand so the marked teeth make contact a few times. Once you can see the wear pattern you're on the way. This is where you need one of the little charts you'll find somewhere on the net (good one here- www.drivetrain.com/ringpinioninstal.html)

(8) The pattern is a product of the pinion depth AND the backlash- you have to get both right. You change shims for the pinion depth THEN try to adjust the backlash. If the pattern won't come right, you need to change pinion shims and try again.

(9) Once it's looking right, mark the whole ring gear and do step (7) again. The pattern has to be even all the way around, if it's not, you got a problem! Most common cause is the ring gear distorted or not properly seated on the diff housing.

(10) Take out the pinion assembly one last time and fit the large 'O' ring seal. Before refitting:

(11) Set the ring gear bearing preload- tighten the adjusters evenly until you reach the correct rolling resistance (couldn't find figures for this but- slight rolling resistance and no play) and torque the caps down. Refit pinion assembly, check your wear pattern hasn't gone off and CONGRATULATIONS!!! YOU, LIKE ME, HAVE JUST BUILT YOUR FIRST 3RD MEMBER!!!

(12) BEFORE YOU DRIVE IT PLEASE NOTE this was my 1st go, i'm not a trained mechanic, i ain't run it yet and this is just me sharing the information i've spent weeks trawling the web for and what i've learned whilst building the thing, purely in the hope that it'll make life easier for the next guy. Use your common sense- i did.

(13) Use GL5- spec semi-synthetic lube.

(14) Run it for 5 mins with the wheels off the ground, in high gear at idle. STOP, leave it an hour.

(15) Drive gently for 10 miles. STOP, leave it an hour.

(16) Repeat 14.



(17) Pour yourself a beer and feel EXTREMELY smug

(18) Dump the lube to get rid of any spiders, spring washers, bits of rag, etc that got in during assembly, refill with fresh lube.

(19) Feel free to pass this on, print it, copy it to wherever. I found people very reluctant to hand out info on Ford 9" building (pro-touring excepted) and a lot of what i found didn't make sense or was contradictory. People are even SELLING this info! This is my way of saying STUFF YOU

(20) If you know better and i've made any mistakes here, please add your comments but hey- be nice

[oestek]

Nice summary, dogs. Here's a couple videos to go along with your notes... we shot this at Strange Engineering a couple years ago as they set up a 9" with a Camaro housing. The build is in the last video, the first one is a Strange shop tour.

http://v8tvshow.com/content/view/179/28/

[Steve1968LS2]

Nice.. I tried to do this once and it such a pain in the butt.. then I had gear whine.

Now that I found out that Currie will do it for $125 I take the easy way out. lol

I consider setting up a third member as one of the toughest things to do on a car.. I would rather rebuild an engine.

[dogsbody]

Hey thanks oestec and thanks for the link- it's nice to see it done by a pro!

[dogsbody]

I love a challenge Steve.

Though if mine whines after all this i wil sulk.

A lot.

[dogsbody]

I'm not convinced about step (11) now- i'm struggling!!

[dogsbody]

Well i reckon i've got it now!
It took quite a few hours of messing around to really get a 'feel' for it. Once i'd learned the way each adjustment changed things, it all fell into place and i got much more confident.
A few further tips-
Spend an evening just playing around with it. Don't have any expectations of success, just get familiar with it all.
Set the ring gear carrier bearing preload with the pinion out. Once you have that set- DON'T mess it up! When adjusting always move both collars EQUAL AMOUNTS.
Paint marking grease on ALL teeth from the start (especially important for used gears)- my ring gear has a couple of thou runout. It's within spec (Richmond gears instructions allow .004) but it meant the pattern varied around the ring gear by enough to confuse the hell out of me!
Also bear in mind that each manufacturers gears have their own contact pattern- like fingerprints. If, like me, you don't know the manufacturer, you just have to aim for the pattern to be central and fairly oval.
Once i started looking at the whole ring, i could see my pattern was fine over 3/4, but high for the last bit. I had to settle for the best average.
Don't use too much grease!- if it's squishing out all over the place you'll struggle to see a clear pattern.
I screwed a long bolt into the yoke with a long socket (a bit of metal tube would work fine) over it- this made a perfect handle to spin the pinion easily.
With this method (and a rag pressed against the ring for resistance) i could whizz it round and get a dozen turns of the ring gear both ways in seconds, making a really clear pattern.
BE METHODICAL- don't change thing randomly cos you'll forget what you did.

Mark 5 vertical coloumns on a sheet of paper. List your shims down the side (you'll need to add 2 or more shims for thicker spacings).
Your centre coloumn is for the correct backlash (usually .008) Start with say, the thickest single shim. Set backlash to .008. Check your pattern, draw or write it in your table.
Decrease backlash by one notch, check pattern, add it to your table.
Carry on with this method (it took me a couple of hours) and you'll start to see a pattern of gear patterns emerge- you'll see the gear pattern go off gradually in different directions and this will point you clearly back to the right settings.
It sounds long winded but there really is no shortcut here. I tried all the shortcuts, drove myself mental for a week, then worked out this method.
Good luck!