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9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? #776492 08/18/10 11:28 AM 08/18/10 11:28 AM
Joined: Oct 2005 Posts: 340 Houston, Tx T56DAK OP enthusiast
T56DAK OP enthusiast Joined: Oct 2005 Posts: 340 Houston, Tx	This posi swap refers to an '02 Dakota with a 9.25 Diff. I currently have 4.56's with a factory Sure Grip in it and want to upgrade to a Detroit TrueTrac as the clutches are going out. My question is if I were to remove the carrier and put the old ring gear on the new TrueTrac and reinstall everything with the old shims will the gear mesh be the same or will variations in the new carrier create a change in the mesh? I'm a DIY person but have yet to tackle a gear swap. I am leery to take it to a shop as it has custom disc brake conversion brackets on the rear with Viper calipers/rotors and it may not be something the Tech has seen before. Thanks for any advice.

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: T56DAK] #776493 08/18/10 12:09 PM 08/18/10 12:09 PM
Joined: Jan 2003 Posts: 473 Fort Lauderdale, FL Suregrip mopar
Suregrip mopar Joined: Jan 2003 Posts: 473 Fort Lauderdale, FL	I took the factory Sure-Grip out of a 1985 Ram Charger and installed it in my 1977 Warlock. Both trucks had 9.25 rears. I put my original ring gear on the Ram Charger Sure-Grip. I put it all back together and have been running it almost daily since the mid nineties... Some people you just can't reach...

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: Suregrip] #776494 08/18/10 01:00 PM 08/18/10 01:00 PM
Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL Commando1 master
Commando1 master Joined: Mar 2007 Posts: 9,336 South-Central (Sebring), FL	OK. What did I do wrong on my 9 1/4: My 1976 9.25 open 2.71. Bought: 3.55 R&P Out of a 92 Jeep) used for $25 R&P gears looked new. Dropped out carrier, unbolted 2.71 ring gear, installed 3.55 ring gear, reassembled. I took 2.71 pinion out, pulled off gear, left shims in place, installed 3.55 gear. Reinstalled pinion into carrier 100% by the FSM Reinstalled carrier . Everything new . Reputable Master Kit. Set side-to-side thrust by special tool going down the axle housing. By the manual. Again: Took a test drive around block. WHINE @45 Drove directly to a shop that specializes in custom drivetrains. Redid the whole thing I did using my existing parts, in abut 45 min. Bolted it up and said you're good to go. And he was right. I need this for a future "Ask me how I know..."

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: T56DAK] #776495 08/18/10 01:59 PM 08/18/10 01:59 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Thats where I would start, and you will probably be ok with the old shims. Still gotta check the pattern when you have it all together. Fastest 300

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: Commando1] #776496 08/18/10 01:59 PM 08/18/10 01:59 PM
Joined: Oct 2005 Posts: 340 Houston, Tx T56DAK OP enthusiast
T56DAK OP enthusiast Joined: Oct 2005 Posts: 340 Houston, Tx	I am leaning towards a shop redoing the whole thing with a set of 4.10's I got from a friend who had them in his daily driver for 10k miles, but I am not sure how gears like to re-mesh. Definitely not for the faint of heart from the sound of it and magnetic base/dial indicator is required to properly set up the mesh. What is a real pain is having to break it all down and put in new shims before you can see if you are close. Redoing is not a quick procedure. I would really like to do it myself so I can learn but I don't want the truck sitting in the garage for several weeks. Expecting the birth of our son soon. Thanks for the help/info guys.

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: Commando1] #776497 08/18/10 02:05 PM 08/18/10 02:05 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: OK. What did I do wrong on my 9 1/4: My 1976 9.25 open 2.71. Bought: 3.55 R&P Out of a 92 Jeep) used for $25 R&P gears looked new. Dropped out carrier, unbolted 2.71 ring gear, installed 3.55 ring gear, reassembled. I took 2.71 pinion out, pulled off gear, left shims in place, installed 3.55 gear. Reinstalled pinion into carrier 100% by the FSM Reinstalled carrier . Everything new . Reputable Master Kit. Set side-to-side thrust by special tool going down the axle housing. By the manual. Again: Took a test drive around block. WHINE @45 Drove directly to a shop that specializes in custom drivetrains. Redid the whole thing I did using my existing parts, in abut 45 min. Bolted it up and said you're good to go. And he was right. I need this for a future "Ask me how I know..." Well, he obviously changed something you did - ether changed the shims or backlash setting. You need to ask him. Fastest 300

Re: 9 1/4 Diff Ques: Replace Posi, Gear Mesh Changes? [Re: T56DAK] #776498 08/18/10 02:17 PM 08/18/10 02:17 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: I am leaning towards a shop redoing the whole thing with a set of 4.10's I got from a friend who had them in his daily driver for 10k miles, but I am not sure how gears like to re-mesh. Definitely not for the faint of heart from the sound of it and magnetic base/dial indicator is required to properly set up the mesh. What is a real pain is having to break it all down and put in new shims before you can see if you are close. Redoing is not a quick procedure. I would really like to do it myself so I can learn but I don't want the truck sitting in the garage for several weeks. Expecting the birth of our son soon. Thanks for the help/info guys. FYI, I went from a 3.23 to a 3.55 to a 3.90 to the present 4.10 I am running all with the same shims and never had a problem. All switches had good patterns and no noises. Yes, you will need a magnetic base dial indicator to set back lash and the tools that go down the axle tubes ( I made mine )to set side bearing preload and backlash. To make tightening the yoke nut a little easier I also made a holding fixture that bolts up to the u-joint bolt holes. You could use a large pipe wrench for this. You will also need an inch pound beam style torque wrench to check pinion preload. Tightening the pinion nut is the ball buster in the operation. The rest is easy. Fastest 300

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