How to change gears and add a limited slip to a Ford 9-inch

Swapping in 3.70 gears and a trac-loc into a Ford 9-inch.
6:46 -Pinion crush sleeve trick
12:30 -Ring gear install
14:27 -Trick to torquing the ring gear bolts
18:07 -Measuring ring gear runout
19:15 -Pinion carrier install
20:12 -Carrier bearing preload+backlash setting
22:39 -Gear wear pattern

[@squidusn71]

This is by far one of the most informative and detailed video I've watched.

[@AustinCoulson]

Thanks! I wanted to take away some of the fear of gear swaps for people

[@Texasknowhow]

Very well done and edited. I’ve got two trucks I need to do. This will def help. Clay

[@kadenkaps7764]

Awesome video thank you this helped so much

[@Kevin-kb6uq]

Great video, thank you.

[@blackforestvintagefords7872]

Wow, this is the best video about this topic I have seen so far. I am in front of rebuilding my 9" rear axle of my '73 Mustang 351C 4V w/ 4-speed. It has original 3.50 gears, 28-spline and open diff, will change to a Ford Trac Lok and keep the axles and gears. Your video gives a good overview what and how to do - thank you very much!

[@AustinCoulson]

Thank you so much. My goal was to take away a little of the mystery and fear people have with swapping gears. I think you will love the Trac Lok, its a great LS

[@blackforestvintagefords7872]

@@AustinCoulson Yeah, goal achieved! I think, too, that I will be much more fun than the open one. That car ever called for one ;-)

[@charlespartak2435]

nice video. i'll be swapping out a 2.75 and installing a Richmond 3.23

[@joemartino6976]

Thanks! Need to do the same thing on my new 1978 Ford F150 with a 351 Windsor, 3 peed automatic, 15" wheels and a 2.75 rear end. AOD + 3.70 rear + larger tires seems to be the way to go.

[@giantpune]

Those original gears were 2.75, not 2.73. Axle code 2 with the open diff. I have a couple 73 mustangs with that rear end I'll get around to swapping one day. And however bad you think that is, I just swapped out the factory 2.54 gears in my 82 C-10. :D

[@theeddies]

Nice job. I recently watched DeBoss do this on his Goat rear end, the slight differences were interesting. Based just on the size of that pinion gear, I would have swore it was out of a truck lol. Good stuff!

[@AustinCoulson]

Thanks! The 9 inch pinions are just massive. I ordered new gears for an 8.8 at the same time and it's crazy the difference side by side

[@robbyrob8349]

@@AustinCoulson I have a ford 9" rear on my 1974 Lincoln Mark VI. I want to swap my 2.75 gears for 4.86 gears. Do I have to change the differential?!

[@AustinCoulson]

@@robbyrob8349 that's a pretty dramatic gear change. I know on some carriers you need to do extra work grinding some steel if the ratio is really high, but I haven't gone beyond 4.56 on a 9in so I'm not sure. The process for 4.56 was exactly the same as this video shows

[@andrewdiamond7360]

Great video... Wish you were still in the Nashville area. I have a Ford 9 that needs to go from a 3.00 open to a 3.50 limited slip.

[@AustinCoulson]

They really aren't that hard to do if you just take it one step at a time. email me @ [e-mail] if you try and get stuck

[@petejoseph8257]

FYI, No friction modifier needed with clutch less carriers.

[@garybounds7339]

You are very creative 👌! I've been retired for 10 years now and I have worked around many mechanics. If I have anything to help you from experience, it's the red rag lint issue. Please take my advice without taking offense. Otherwise I would hire you in my days of twisting bolts Gary Bounds 69 years young.

[@AustinCoulson]

Ugh, I hate those red cloths. I prefer microfibers for that exact reason, but I was given a ridiculous amount of these red ones and was burning through them

[@bposkier51]

He has according to his measurement .027 inches (.71mm) of play. He needed to place an indicator on the housing, measure the axial movement and press again little at a time reducing play down and into the tolerance, whatever that is, maybe .008-.015 or something. This will be a problem when setting the gear lash to the ring gear. Good luck

[@wolfebi001]

Very nice video. I'm currently getting new gears in my 9" (4.11). Was going to do 3.89 but he went threw two sets of gears and both had whine. He said that 3.89 tended to do that. He said 4.11 are better cut and should be more quite. I have a Tremec 6 speed Magnum so I am not worried about high revs on the highway. What are your thoughts on 3.89 gears and the whine? I also have a clunk sound when loading and unloading (especially in 1st gear). They are hopfully going to get that straighten out too.

[@AustinCoulson]

I have not heard of a specific ratio having a whine. Generally, the higher numerically you go, the more of a whine you experience, but the whine should be all but gone once the break in in over. These 3.70 had a little whine for the first 500 miles, but it's practically impossible to hear over the flowmasters after the break in. The clunk sound scares me more than the whine, there really shouldn't be a noticeable clunk when loading/unloading. The pinion play should be tested after installation and again after 500 miles and should stay within spec (.010-.015 I think?). Usually when I hear that clunk, it's pretty far out of spec. If it's in spec and It's still there, I will try a different fluid with a slightly higher viscosity.

[@robertclymer6948]

Nice! Did you install those pesky brass washers on the casing studs before torqueing them? I am sure you did, you do it right!

[@AustinCoulson]

Are you talking about the tapered brass split washers?

[@ltdjag7577]

I found this video to be extremely useful and informative. The explanations were clear and to the point. I’m disassembling a 1966 Thunderbird 9” soon. There is noticeable slop in the yoke I found after removing the driveshaft U joint. If I have questions, do you have an email link? Thanks so much. Bill in Oklahoma

[@AustinCoulson]

[e-mail] Excessive play is common on higher mileage rear ends and usually just indicates normal bearing wear, and can be fixed easily when swapping gears

[@DELTRANIO99]

Great vid Can you tell me by deducting 5 thousands on pinion dept ,How many thousands would it add or deduct on backlash ?

[@AustinCoulson]

5 thou pinion depth will pull the pinion away changing the wear pattern, but because the carrier position and preload are so easy to adjust you should be able to loosen the pass side carrier nut, tighten the driver's side minimally (1/16th of a turn or so) and end up with exactly the backlash you need, just with a preferred wear pattern. If you didn't adjust the carrier, I would expect the backlash to increase between .002-.005

[@Mohamedseddek]

♥️👍👍👍👍

[@6516545]

By any chance do you know what type of rebuild kit you used or where did you buy it, thanks

[@AustinCoulson]

I think it was US Gear and I got them from Summit racing

[@markbohannan]

How has this held up? What brand did you use? Do they sell a kit including all seals and bearings

[@AustinCoulson]

Holding up great, Ford Racing gears, Timken bearing kit bought separately

[@cak8895]

What did you pound your new races in with?

[@AustinCoulson]

The old races

[@jeffmalloy8200]

Appreciate the information but why have the camera so far away?

[@robertclymer6948]

Great video. I have a 9 in nodular with a full spool with 4:11 gears. I want it streetable so I need to pull the spool and replace with a Trac-loc . I am scared to death to do this myself. How much would it cost to have this done at a good shop? Thanks.

[@AustinCoulson]

I wouldn't be too scared to do this yourself if you have the tools. Swapping the spool for a Trac loc should be a lot easier than doing gears as the shims probably won't need to be adjusted. Prices can vary a lot by shop and location. If you supplied the Trac loc I'd expect 900-1400 in labor, if you had the shop supply the Trac loc I'd expect 4-500 more. I think 1500-2500$ is pretty common for gears and a posi installed

[@robertclymer6948]

@@AustinCoulson Thanks Austin! Do I need an axle spline count before I order the "Posi" unit?

[@AustinCoulson]

@@robertclymer6948 yes, but you can get that super easy with just a 9/16 socket after you remove your tire and wheel. You have 4 bolts that hold the outer bearing and axle and once those are gone, the axle slides right out. You can count the splines and slide it back in in a matter of minutes. Where are you located? I may be able to direct you to a shop if you aren't going to tackle the full install yourself depending on what city you are in.

[@robertclymer6948]

@@AustinCoulson Thank you so very much for donating your valuable time to me. I appreciate it so much. I live in Westland, Michigan, a burb of Detroit actually next to Dearborn. I wont have a problem pulling one axle, I got that down pat. I have spoken with a couple of shops and I actually have just one I trust who is a 30 year vet at transmissions and axles ect He has an outstanding reputation too. Thanks again for everything. Looking forward to yur next videos.

[@AustinCoulson]

@@robertclymer6948 thanks for the kind words. I am happy to do whatever I can to keep older vehicles on the road. When you pull the axle, that's a great time to check that bearing and if you have a 28 spline and are running a lot of power, you can always buy the 31 spline Trac loc and swap in 31 spline axles at that time. I don't upgrade axles until I get over 400hp to the wheels, though. Sometimes the cheapest way to get axles is to buy ones that have long splines that you can then cut to length. Take care and good luck! Reach out if you have any more questions. You will LOVE the Trac loc compared to a spool on the street. Spools are for wild teenagers IMHO

[@tonyrink9999]

Great video. I am looking for a video like this for the 1961-1969 Chrysler 8-3/4" differential. Let me know if you know of one. Thanks for sharing.

[@AustinCoulson]

Next time I do gears in one, i'll film it

[@nilla003]

Regarding the crush sleeve: Could one just measure the old one then machine a sleeve with the same dimension and forget about crushing at all?

[@AustinCoulson]

The issue is that with new bearings the size may be different otherwise you could just reuse the old crush sleeve with new bearings. That's why the torque wrench is required to determine preload. Some guys do use a machined sleeve in place of the crush sleeve, but they still have to verify preload.

[@nilla003]

@@AustinCoulson Thanks.

[@donthompson4033]

Looked to me that the pinion was in too deep, did it make a whining noise?

[@AustinCoulson]

No, it's been great. This rear end has about 5k miles on it at the moment.

[@RalphSampson...]

I'd love to have that 2.73 gear set. Send it my way.

[@AustinCoulson]

I think they'll fit in a flat rate box. You pay for the shipping, i'll throw in the mail to you. I checked the pinion threads and they are all good. [e-mail]

[@AustinCoulson]

@anonymous he did take those, sorry

[@robertclymer6948]

Are you sure you don't want at least 3:73 gears? Better performance for a cruiser.

[@superduty4556]

@@robertclymer6948 these cars are easily beaten by stock trucks and Honda civics. You might as well keep the rpms down and get decent mileage and look good doing it.

[@robertclymer6948]

@@superduty4556 Oh yes Austin, so true! Even my F-150 2.7 eco twin turbo puts out around 325 HP.

[@petejoseph8257]

RTV on the spines, not oil. You didn’t measure the pinion head to get that reading for pinion depth.

[@jeffmalloy8200]

More light would be good.

[@AustinCoulson]

This was an old video. I have gotten a little better with the lights and sounds

[@davereith54]

Really metric measurements?! 1mm = .03937 inches. It’s a Ford not a Honda. America!!!

[@AustinCoulson]

My apologies