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Old 01-04-2018, 04:48 AM   #1
87Skier
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Regearing and rebuilding my axles

I've been working on my 72 GMC Jimmy for a while. It now has a 4.8L, 6L90, and NP205. With the overdrive, I really need to do away with my 3.07 gearing.

I also broke a couple studs in the front axle, they are both open carrier, and I'm pretty sure nothing has been done to the suspension in its lifetime, so I need to redo pretty much everything.

It has a 12 bolt in the rear and a Dana 44 up front. I am going with 4.10/4.11 gears, I have a posi for the rear, and I'll need a new carrier up front. I haven't decided if I want to spend a few hundred extra to get limited slip in the front or not, but I'll decide when it comes time to order parts.

This is mostly a street truck. It will not see deep mud or rock crawling. It may see some overlanding use, but for the most part it is like a hunting rig. It has 33's on it now. I won't go any bigger because I won't lift it, but I may go back to a 31" tire.

Please tell me if I've overlooked something:
For the rear:
Replace all bearings and seals
Check pinion preload
Check wear pattern (get shims for this)
Replace leaf bushings
Brakes have already been done, including frame to axle rubber line
Check u-bolts for rust and corrosion
Replace shocks

For the front:
Replace all bearings and seals, including wheel bearings
Replace u-joints
Replace brake discs
New carrier
Check wear pattern (get shims for this)
Bearing pre-load
Replace leaf spring bushings
Check u-bolts
Replace shocks
Check steering stabilizer
Check steering joints
Rubber brake lines have been replaced
Calipers were replaced 2 years ago
Check for hub wear

I plan on using timken bearings where I can. What brand of gears should I go with? Any good guides out there?

My plan was to leave the axles installed and remove the leaf springs if I have trouble with the bushings. If I do this, I will replace the u-bolts.

Thanks for any suggestions!
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1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205
1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears
1996 Chevy Suburban K1500 350/4L60E
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Old 01-04-2018, 09:35 AM   #2
sweetk30
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Re: Regearing and rebuilding my axles

here play with this a bit . http://www.grimmjeeper.com/gears.html

at 70mph rpm = x

31" tires = 2084
33" tires = 1958

if you get a posi and no hard core wheeling look in to detroit true track . no clutches to wear out . lots of guys like them for street / light offroad / and specifically front axle use also .
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Old 01-04-2018, 09:45 AM   #3
sweetk30
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Re: Regearing and rebuilding my axles

Quote:
Originally Posted by 87Skier View Post
I've been working on my 72 GMC Jimmy for a while. It now has a 4.8L, 6L90, and NP205. With the overdrive, I really need to do away with my 3.07 gearing.

I also broke a couple studs in the front axle, they are both open carrier, and I'm pretty sure nothing has been done to the suspension in its lifetime, so I need to redo pretty much everything.

It has a 12 bolt in the rear and a Dana 44 up front. I am going with 4.10/4.11 gears, I have a posi for the rear, and I'll need a new carrier up front. I haven't decided if I want to spend a few hundred extra to get limited slip in the front or not, but I'll decide when it comes time to order parts.

This is mostly a street truck. It will not see deep mud or rock crawling. It may see some overlanding use, but for the most part it is like a hunting rig. It has 33's on it now. I won't go any bigger because I won't lift it, but I may go back to a 31" tire.

Please tell me if I've overlooked something:
For the rear:
Replace all bearings and seals. if doing re-gear just get the master kit . but they tend to not have the axle end bearings .
Check pinion preload . if doing re-gear go soild pinion spacer over crush sleave .
Check wear pattern (get shims for this) comes in re-gear master kit.
Replace leaf bushings

Brakes have already been done, including frame to axle rubber line
Check u-bolts for rust and corrosion . there cheep just go new . and upgrade to 5/8 over 9/16 . stronger and more clamping force .
Replace shocks go good ones . bilstiens seem to be the hot ticket these days for great ride on our old trucks .

For the front:
Replace all bearings and seals, including wheel bearings wheel bearings can be cleaned / checked and re-greased most of the time .
Replace u-joints spicer life series for best quality and bang for the buck .
Replace brake discs
New carrier
Check wear pattern (get shims for this) master install kit again will have parts required
Bearing pre-load
Replace leaf spring bushings
Check u-bolts again if you dont trust them just new . same info as above
Replace shocks same info as above
Check steering stabilizer there cheep just get new stock replacment . your size tires only need 1 anyways .
Check steering joints best handeling and road feel ditch stock shaft and go u-joint shaft . rag joints suck and flex/box joints wear out .
Rubber brake lines have been replaced
Calipers were replaced 2 years ago
Check for hub wear

I plan on using timken bearings where I can. What brand of gears should I go with? Any good guides out there? good call on timken stuff . koyo is also oem installed so dont pass on them . yukon gear / usa gear / nittro gear just to name a few you will be fine with .

My plan was to leave the axles installed and remove the leaf springs if I have trouble with the bushings. If I do this, I will replace the u-bolts.

Thanks for any suggestions!
read my red replys
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Old 01-04-2018, 03:08 PM   #4
Jcfcamaro
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Re: Regearing and rebuilding my axles

Look up a place called Quick Performance in Ames IA.They quoted me 1280.00 for 2 posi units and gears,bearings, install kit ECT for my 72 k10. It's a Yukon gears, posi unit and all name brand stuff. On there web site there showing a truck 12 bolt Eaton posi, Yukon gears, bearings ECT for 620.00
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Old 01-06-2018, 04:36 AM   #5
87Skier
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Re: Regearing and rebuilding my axles

Quote:
Originally Posted by sweetk30 View Post
read my red replys
Good info here. I plan on buying a master kit, but wanted to be sure all this stuff was included.

Good call on the thicker u-bolts, hadn't heard of people using bilstein shocks around here, solid spacer is good too.

I'll look into the u-joint steering shaft too, my rag joint looks bad.
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1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears
1996 Chevy Suburban K1500 350/4L60E
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Old 01-09-2018, 11:34 PM   #6
'63GENIII
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Re: Regearing and rebuilding my axles

Just went through my front 44. Replaced all bearings except for the pinion. Went through Yukon for the carrier bearing set. Good USA Timkens in the kit along with inner axle seals, shims, grease paint and cover gasket. I only replaced the carrier bearings (water got in and pitted them) since the pinion was fine. I used a pry bar as a spreader which worked well.

Outer bearings were a different story. I wanted Timken as well. When I picked them up, the Timkens that I received said "Hecho en Chine" on the box. No thanks. The Koyos that were in it looked great, cleaned up well and went back in.

The spindles got new Torringtons.

U joints are the newer sealed Spicers without a Zerk. They'll be fine for what you're doing.

If you have a press, you're all set. If not, try and find one cheap. The used one I got for 80$ has been used well more than 80$ worth.

+1 on the bigger U Bolts. Almost any OTR truck supply will be able to make them for you in short order if not while you wait. Just bring your old ones with you for a template. I've used Betts Spring 30 minutes from home.

Upper and lower ball joints were pretty bad when I started taking it apart. What I didn't know was that the drivers side knuckle had been damaged at some point living both of the ball joint "bores" wallowed out. Luckily I found a drivers side knuckle from a 10 bolt. Used Moog joints that were USA made. If you do the upper / lower joints, don't forget the little preload chingas that go in. They should be replaced ever time a new set of ball joints go in and have a special spanner for getting them torqued / preloaded right.

Ive used the front axle quite a few times since I finished it and so far it works great. Even better, it's finally done and crossed off this list!

Best of luck.
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'63 k15 long step
Vortec 7.4 - L29 Blackbear tune, Five 0 Motorsports injectors, Chris Straub Cam, NV4500, divorced 205
52" front and 63" rear spring swap
D44 / 14bff - disc axles
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63" & B52 Spring Install http://67-72chevytrucks.com/vboard/s...ng+swap+thread


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Old 01-10-2018, 03:35 AM   #7
RedRoad
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Re: Regearing and rebuilding my axles

I recently did the 44 on my K20 as well and X2 on everything Chris said. The only issue I had with mine was the outer seal/slinger. The 44 on my truck was a first series which used the bronze slinger, the available seal kit comes with a plastic one which was the wrong diameter. One of them was scored badly but luckily I had a core with a single good slinger to donate. I was able to get USA Timken wheel bearings at my local autozone, maybe just old stock.
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