Mustang Gear Install: Ford Racing 8.8 Ring & Pinion (1986-2009)

Mustang Gear Install: Ford Racing 8.8 Ring & Pinion (1986-2009)

If you’re like a lot of
other people out there, you’ve probably wondered
at some point in time whether or not you’re
capable of installing rear gears in your Mustang. Well, there’s no
clear-cut answer to that. You will need above-average
mechanical capabilities along with some specialized tools. All I can do here
is show you how I go about the
process and the tools that I use to get the job done. You’ll want to have on hand
a bearing and seal driver set– this will help
you squarely and safely install pretty much
any bearing or sealed that you come across–
a two-jaw puller to help remove not
only the pinion flange but a couple of
the bearings as well. You’ll need a beam-type
inch-pound torque wrench to check the
rotational resistance of the pinion bearing
once you’ve tightened down the pinion nut and crushed
the new crush sleeve, a couple of large,
high quality drifts to drive out old bearing races,
a mag base and dial indicator to check your backlash, a
pinion flange holding tool. This will help you keep the
pinion flange from rotating whenever you’re removing the nut
and tightening up the new nut and crushing the sleeve. You can buy a tool
that’s specifically made for this purpose,
or you can make your own. Either way, you’re going to want
to make sure that it can accept a 1/2-inch drive breakover bar. And a couple of things
I hope you don’t need are a pinion depth checking tool
and a caliber, be it digital or dial. If you’re going to be replacing
your axle bearings and seals, you’ll want to swing by
your local parts store and go ahead and
rent you a slide hammer and an axle
bearing attachment. Finally, a hydraulic
press is going to make your life a whole lot
easier, along with a good set of press plates and
a bearing separator. Along with the
specialty tools, you’re going to want to
make sure and have a nice collection of common
hand tools along with the stack of new parts, most namely
a new set of Ford racing gears for your 8.8,
along with an install kit and some axle
bearings and seals, if you want to make sure
that those are replaced, some quality gear oil and
some friction modifier. A couple of things you
may want to think about is a reusable cover gasket
and, if your Mustang has some miles on it, one
of these seal savers. That way you don’t end up
with a leaky pinion seal. From our website,, you can download and print
the Ford racing instructions for this gear install. That gives you step by
step written instructions along with all of
your measurements and torque specs
for the install. Lift and support your Mustang
and remove the rear wheels. If equipped with drum
brakes, remove the drums. If equipped with disc brakes,
take loose the caliper, remove the pads, caliper
brackets, and rotors. Then remove the ABS sensors. Remove the 10 differential
cover bolts, drain the oil, and remove the cover. Remove the carrier cross pin
bolt and then the cross pin. Doing one at a time, push in
an axle and remove the C-clip. Slide the axle out
of the housing. Noting the orientation
of the main bearing caps, mark each cap if
it will help you. Remove the two bolts per
side and set the caps, keeping them in order, be
it right-hand or left-hand. Carefully pull out
the differential and keep the shims located in
the right-hand or left-hand position. Mark your drive shaft
and pinion flange. Remove the drive shaft bolts. Then remove the drive shaft
or tie it up out of the way. Using the flange holder
tool, remove the pinion nut. Use a two-jaw puller to free
the flange from the pinion. Remove the pinion
from the housing. Pry out the old pinion seal
as well as the outer pinion bearing and oil slinger. Using a hammer and
a drift, remove the inner and outer
pinion bearing races. Take an opportunity to
remove any remaining oil from the rear axle housing. Using a hammer and
the race driver, install the new inner and
outer pinion bearing races. This is a great opportunity
to replace your axle bearings and seals. Using a slide hammer and
axle bearing attachment, remove the old
bearings and seals. You can rent these tools
at your local parts store. Using a bearing and seal driver,
install the new axle bearings fully seated in the housing,
followed by the seals. But the seals just need to be
flush with the housing, not fully seated. Clean off the new pinion
bearing races with Brakleen and wipe them down
with fresh gear oil. Take your new outer
pinion bearing, and coat it thoroughly
with fresh gear oil. Then slide it into place,
followed by the oil slinger. And finally, tap the new
pinion seal into place. Using a bearing separator
and the hydraulic press, remove the old inner pinion
bearing from the old pinion and remove the pinion shim. Clean it up, and slide
it on to the new pinion. Again using the hydraulic press,
install the new inner pinion bearing onto the pinion. Thoroughly coat the inner
bearing with fresh gear oil. Slide one of the new crush
sleeves onto the pinion, and slide the pinion
in to the axle housing. Inspect your pinion flange. If a groove is present
on the seal surface, either replace the flange or use
one of the seal saver sleeves to repair your old flange. Slide the flange
onto the pinion, and install the new pinion nut. An impact will only
get you so far. Some good,
old-fashioned muscle is needed to crush the
new crush sleeve. The combination of the flange
holding tool and a couple of 1/2-inch breaker bars
get the job done for me. Check the tension
of the pinion flange often as you’re tightening as
you don’t want to over-tighten. Using a beam-type
inch-pound torque wrench, you’re trying to
achieve 8 to 14 pounds per inch rotational
resistance with used bearings or 16 to 28 pounds per inch
of rotational resistance with brand new bearings. As with a lot of things, you
simply find what works for you and stick with it. I take a cut-off wheel and
remove the cage and rollers from the carrier bearings. Then I use a combination
of a block off plate and a two-jaw puller to remove
the remainder of the carrier bearings. Remove the ten ring gear
bolts, and either tap or press off the
older ring gear. Use the hydraulic press
to install the new carrier bearings. Slide the new ring
gear onto the carrier, and start a couple of
new ring gear bolts to pull it on slightly. Loosely install the
rest of the bolts. And snug them up in
pattern, and torque them in two stages, first to 35 pound
feet and then, final torque, to 97 to 102 pound feet. Thoroughly coat the new carrier
bearings with fresh gear oil. Grab the new races. Clean with Brakleen,
and coat with gear oil. Position them on
the carrier bearings along with the old carrier
shims in the same orientation they came out, and reinstall
the two bearing caps. Tighten and torque the cap
bolts to 90 to 100 pound feet. Using a mag base and
a dial indicator, check your, backlash. You are shooting
for 0.008 to 0.012. Finally, check the tooth
pattern with the supplied marking compound. Use the illustrations of
acceptable patterns in the FRPP instructions to make sure your
gear set installation passes. Finally, slide your
axles back into place. Clean the cover and the housing. And reinstall the cover using
one of our optional reusable cover gaskets. Fill the axle housing with
new oil and friction modifier, and completely finish
resembling the car. At this point, you’ll want
to correct your speedometer by using a new speedo
gear, a speed calibrator adjuster, or programmer tuner,
depending on your year model. Once the car is
back on the ground and the wheels are
torque, take a test drive. And drive responsibly for
a couple of hundred miles, so the gears can
set a wear pattern. And that concludes a successful
rear gear installation that required no adjustments. If you’re replacing
factory-installed gears with Ford racing gears, you
should end up just as lucky. However, there are
exceptions to every rule. That’s where some of these
other specialty tools will come into play, like the
pinion depth checking tool. It comes with its own
set of instructions on how to use it to get the
correct measurement to select the right pinion shim. If your marking compound
shows a pattern that indicates the pinion is
too close to the carrier or too far away, you’ll
want to pull this out, along with your caliper, measure
out, select your new pinion shim, and start by
rechecking your backlash. If your backlash
is out of whack– let’s say it’s too
tight– then that means, when you’re looking at
the back of the rear end, you’re going to want
to move the carrier from the right to the left
to give yourself a little bit larger backlash reading. If it’s too lose, than it
needs to move from the left to the right to tighten it up. You want to take your caliper
and measure your existing carrier shims and then use
the selected shims provided in the install kit to transfer
some of your shim thickness from one side to the other. A quick look at the
Ford racing instructions will show you how much
of a thickness change will impact your
backlash readings. Also, common sense
comes into play as you’ll want to make sure
and clean everything thoroughly throughout the
process and definitely make sure it’s all clean
before you go back together. That way you don’t have to
worry about any problems down the road. I also like to keep around some
old bearing casings and races for installing the new bearings. This will help you make your
installation of a little bit smoother and a
little bit quicker. If you want more in-depth
information about our gear kits and you’re not viewing
this on our website, be sure to click the link below
to gather all that information. Also, check out for more driveline
modifications and installations for your Mustang.


  1. Is there a break in period after new gears? I currently have 3,000 miles on these 3.73 gears and want to see if I have to change the oil after a certain amount of miles.

  2. Great vid…I'm looking to tackle this project soon and feel more confident after watching your informative vid…keep them coming!!!

  3. This may be a dumb question, but how do I know which gear kit to buy? I have a 2012 3.7L V6 in manual transmission.

    Do I get 3.7? or 4.1.0?

    what will fit me the best?

  4. My dear, congratulations on the video! I live in Brazil, I have problem in my Ford Explorer 2004, she gives a jolt, sometimes they constantly put in reverse or "d", the stride is giving this more when I'm moving and shooting off the throttle once , gives the stride, when floor once also gives the stride, like a hit metal, or something working loose, what do you think? May be in the transmission box? Or differential? Underscoring that peaceful machas pass without any stride. I'm grateful for the attention.

  5. Damn… Was considering doing this soon but I think I'll start with the new intake manifold throttle body, heads cam and exhaust first… This is a little complicated for the ammount of experience i have at the moment haha

  6. Outstanding video. Clear visual. Detailed and with a swift pace to hold attention. Good question asked below … what is the range of expected total cost for this modification, by a professional, to install 4:10's with all new bearings, seals, axle bearings/seals, etc.. for a 5.0L Foxbody – to race 1/4 mile drag?

  7. i got my deferential and all the axle replaced and my mechanic fixed it good but the abs light won't go off!? is it normal for a 2005 mustang gt?

  8. Thanks for posting. this is the first video that that i have seen on this topic that has a clear, simple and logical explanation for this procedure. 

  9. I Used this video twice after that I've been doing them on all my buddy's mustangs greatest thing u guys have done that guy needs a raise lol

  10. When doing the bearing races in the axle the new one won't go in because there is a small nick on the one side is there anyway to correct this

  11. @Late Model Restoration whats a good gear to put when i go turbo i have 4.10 rite nownand i know thats no good. 3.08?

  12. Hi, i have a set of used ford racing 3.73 that i want to install.. i have alk the tools needed except for dial indicator..
    they have about 1000 miles on them so pinion is lighty marked by normal use/wear so if i go by those marks lining exactly the same do i still need a dial indicator?

  13. Well you have convinced me NOT to do this. Strut/spring cartridges are one thing – this is too much math. So, what would a reasonable mechanic charge labor wise? I'd provide my own parts since I do not want Japanese in my Moose.

  14. I cant find the instructions on your website , I looked in the Tech , Faq and Download sections and cant seem to find it …… can your provide a link to the instructions for download ?

  15. Isn't it a bad idea to press the bearing onto the carrier using the race? This transfers all the press force through the races and needles. I have seen hub bearings go out because of not supporting the inner race when the hub is pressed in.

  16. Is the gear setup and rear end on this generation mustang the same as the 1999-2004 generation? I'm looking at changing to 3.73's or 4.10's in my 2000 GT.

  17. if I had you as an instructor for college I would have stayed in for another semester as others might concur your narration and information is poignant and has inflection that annotated transitions from point to point keep up the good work ,Sir.

  18. Buy the whole kit guys and not just the 4.10 ring and pinion… I tried to skate by and re-use everything but it didn't work. Now I have to take everything back out and do it all over again. Trust me, spend the extra money for the kit with new seals and bearings.

  19. @latemodelrestoration great video, my GT only has 43,000 kilometeres on the odometer, do i have to replace all bearings? They dont have hard use

  20. I was hoping you would show the install of a modified shim pack. As they can be pretty tricky to get everything to stay in line (shim packs and the diff) as you are installing it in rear end. I remember trying to use grease to try to get the shims to stick together. It didn't work! I ended up flipping my stock shims and it worked out that way. Is there a trick to getting the diff in with the aftermarket shim packs? I think I had like 8 shims on one side and 2 on the other where the stock is easy 1 and 1. Hope that makes sense!

  21. The instructions on your website are completely different than what you have in this video, where did you get the ones in this video because the "correct patterns" are different and I'm not sure which one I should be going by.

  22. I'm looking to get a mustang, and am thinking about doing this job. I know where I can get these tools and I think I can do it, the only problem I can see is time. I work too much :/

  23. I put 373's in my Cobra Ford racing gear kit, at about 6:58–7:08 on you video you got the shims going in does the bevel on shim go toward bearing race or towards axle, I put it towards axle first time and I think it's wrong , does beval on big shims go to the bearing race or axle? please help!

  24. A somewhat simple step my step but damn. I think I will regrettably will need to pay a shop to install these gears.

  25. Does a new shift governor and or shift kit need to be installed after a rear end gear change, or is only the speedometer gear need replaced as the only modification to the transmission?

  26. this isn't even that bad! first time doing gears, and I did it on jack and stands! It's just a commitment

  27. everyone says you need a very expensive inch pound dial torque wrench, but you suggest a beam style inch pound torque wench (which is a lot cheaper). is there any good reason to buy an expensive dial torque wrench or is this cheap beam style just as good for this job ?

  28. Thank God I have family members who have rebuilt more rear ends than I can count cause there's no way I could do this on my own.

  29. This is intense. So there's all this to do and he didn't get to replacing the spider gears or clutches. Nightmare.

  30. it's cheaper to pay someone than to purchase all the tools , fixen to have trac-lok with 3.31 gears installed in my 07 merc gran marq ….were there no pretty girls wearing bikinis you could have filmed doing the install …you would have gotten a lot more views

  31. LMR, if i am just replacing the rear differential pinion flange and seal – can i just remove the driveshaft to replace these parts or do i need to tear the whole differential apart?

  32. Just wanna say, it's really cool of u guy's doing these video's, they help out a lot,please keep'em coming.

  33. 4:07, literally looks like the race driver just nicked the middle section of the outer race lol. I've seen this in other videos too for some reason i believe this but apparently someone told me this is not true.

    6:35 i think thats bad on the tapered bearings because you're loading the bearings pushing them in with the hydraulic press, i believe if you used a driver set with the tapered side facing up and that 2 jaw piece that on the bottom, not to mention take off the outer race and i think it might be better, IMO!

    These are great steps 1-10 instructions, Great work!

  34. I did this once, this time I'm using all new bearings…. We have a hydrolic press at work…. Otherwise I'd use same bearings.

  35. Cool video…let me start calling shops how much they charge cus for damn sure i dont have any of those tools or even plan on taking on a job like that

  36. Man I failed at this once and a shop I used did it last time (howling failure) as well . Can’t figure this dam 8.8 out , think 🤔 I’m upgrading to a 9inch which I know I can set up👍

  37. What gear ratios are recommended? I have a 5 spd. currently with 3.55 rear end. Speedo reads about 5 miles more so if I am doing 65 I am actually doing 60 mph.
    Originally it came with 3.08 rear end but Ford snuck one in off the parts shelf and put in a 3:55 rear end without telling me which is why the speedo is off..

  38. I know this is problem a long shot but anyway you guys could help me? I’ve got an 86 that someone supposedly swapped a 3.08 into.. when I drive down the road, it shakes pretty bad. Wondering if it’s got something to do with the gear not installed correctly?

  39. This is probably the best and easiest video I've seen on doing this. I need to find a hydraulic press at a garage sale or craigslist and I am going for it.

  40. And for all the guys who have original fox bodies if you’re getting this done somewhere else make sure they give you your rear end factory tag that’s on the rear diff cover . Because half the time they throw it out , Because they’re scumbags . Nothing on the fox body is hard to do yourself don’t be scared . Especially with YouTube easy accessibility these days .

  41. so I pulled out the differential without knowing which side the shims go on which side I noticed one is bigger than the other would I notice incorrect backlash and wear pattern and adjust or how do I fix this mistake?

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