Installing POSI ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72chevyLWB · 05-08-2002, 07:40 PM

I am putting in my posi and it won't fit because the shims are too wide on the outside. Do I just grind down the shim on the opposite side of the ring gear? or grind them both even? It was and is still a 4 series carrier with 3.73 gears.

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72 Chevy C/10
87 Chevy Silverado 4X4
www.geocities.com/chevylwb/chevylwb.html
Aberdeen South Dakota
WANTED: Drop Spindles
F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires

Mike C · 05-08-2002, 08:33 PM

NO GRINDING! The shims are parallel ground and you can't duplicate that. Go to your local driveline shop and buy a shim kit for about $20. Then play around iwht it ot get the right backlash and gear preload.

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70 GMC 3/4 ton Sierra Grande 402/TH400
72 Jimmy 4WD 4spd 4" & 35's
64 Corvette Coupe
68 Camaro 'vert TPI & TH700
69 Z/28 355 12.6's @110
72 Datsun 240Z-ol' reliable

*Fast68Chevy* · 05-08-2002, 08:35 PM

most of the time it is a tight fit when removing or installing a carrier, the case spreads very easily to allow installation evewn though at rest it seems like it wont fit in there. if you set the whole axle on a block or something on the center housing somewhere and press down on the axle tube ends with the diff housing opening facing up it will spread out the saddle area that the carrier slips into and seats into, doesnt take much effort to do so, and cant reccommend grindign shims, you have to add same amount to opposite side of carrier as you removed form the other in order to move the carrier, there are many many different thickness of shims out there, differnt numbers of notches and such on them that stand for thickness

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Randy- Lincoln, IL
randy@ccaonline.com 2177353230
*many GM parts bought, traded, or sold -am parting out: '81 Cutlass Supreme Brougham

current fleet: -71 C-10 350/CH465/3.07- basketcase, #1
-90 Cavalier 2.2L sky blue, a driver
-84 Z28 5.0L/700R4/3.73 daily driver
-84 Firebird/SE 2.8L/T-5/3.73/engine bad, project #2
-82 purple Trans Am, project #3
*Paint is overrated*
© RSS Enterprises 2000

[This message has been edited by Fast68Chevy (edited May 08, 2002).]

72chevyLWB · 05-08-2002, 08:39 PM

The diff is still on the truck though. so how would I go about doing that? Also for grinding, we have a grinder at school that can make it perfectly level and smooth. With a shim kit do you get alot of different shims then? I can get the carrier in, but leave out the shim on the right side. Then when I try to put in the shim, the race will cock to one side and not allow the shim to go in.

------------------
72 Chevy C/10
87 Chevy Silverado 4X4
www.geocities.com/chevylwb/chevylwb.html
Aberdeen South Dakota
WANTED: Drop Spindles
F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires

Mike C · 05-09-2002, 07:41 AM

Just get the shim kit. It comes with plenty. If they have the interlocking kind they are easier to install. With practice you can get the iron races to go back in, but the secret is EVERYTHING has to go in simultaneously which makes you a contortionist to hold the carrier, races and shims all side by side and stick it in. MUCH easier with rear axle out on saw horses! But you'll get it. The shims are the correct way to do it.

05-08-2002, 08:39 PM	#4
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	The diff is still on the truck though. so how would I go about doing that? Also for grinding, we have a grinder at school that can make it perfectly level and smooth. With a shim kit do you get alot of different shims then? I can get the carrier in, but leave out the shim on the right side. Then when I try to put in the shim, the race will cock to one side and not allow the shim to go in. ------------------ 72 Chevy C/10 87 Chevy Silverado 4X4 www.geocities.com/chevylwb/chevylwb.html Aberdeen South Dakota WANTED: Drop Spindles F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road.

05-09-2002, 07:41 AM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Just get the shim kit. It comes with plenty. If they have the interlocking kind they are easier to install. With practice you can get the iron races to go back in, but the secret is EVERYTHING has to go in simultaneously which makes you a contortionist to hold the carrier, races and shims all side by side and stick it in. MUCH easier with rear axle out on saw horses! But you'll get it. The shims are the correct way to do it. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

05-08-2002, 07:40 PM	#1
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	Installing POSI ? I am putting in my posi and it won't fit because the shims are too wide on the outside. Do I just grind down the shim on the opposite side of the ring gear? or grind them both even? It was and is still a 4 series carrier with 3.73 gears. ------------------ 72 Chevy C/10 87 Chevy Silverado 4X4 www.geocities.com/chevylwb/chevylwb.html Aberdeen South Dakota WANTED: Drop Spindles F/S: rebuilt Turbo 400 & Aluminum wheels w/ tires __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road.

05-08-2002, 08:33 PM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	NO GRINDING! The shims are parallel ground and you can't duplicate that. Go to your local driveline shop and buy a shim kit for about $20. Then play around iwht it ot get the right backlash and gear preload. ------------------ 70 GMC 3/4 ton Sierra Grande 402/TH400 72 Jimmy 4WD 4spd 4" & 35's 64 Corvette Coupe 68 Camaro 'vert TPI & TH700 69 Z/28 355 12.6's @110 72 Datsun 240Z-ol' reliable __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

05-08-2002, 08:35 PM	#3
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	most of the time it is a tight fit when removing or installing a carrier, the case spreads very easily to allow installation evewn though at rest it seems like it wont fit in there. if you set the whole axle on a block or something on the center housing somewhere and press down on the axle tube ends with the diff housing opening facing up it will spread out the saddle area that the carrier slips into and seats into, doesnt take much effort to do so, and cant reccommend grindign shims, you have to add same amount to opposite side of carrier as you removed form the other in order to move the carrier, there are many many different thickness of shims out there, differnt numbers of notches and such on them that stand for thickness ------------------ Randy- Lincoln, IL randy@ccaonline.com 2177353230 many GM parts bought, traded, or sold -am parting out: '81 Cutlass Supreme Brougham current fleet: -71 C-10 350/CH465/3.07- basketcase, #1 -90 Cavalier 2.2L sky blue, a driver -84 Z28 5.0L/700R4/3.73 daily driver -84 Firebird/SE 2.8L/T-5/3.73/engine bad, project #2 -82 purple Trans Am, project #3 Paint is overrated* © RSS Enterprises 2000 [This message has been edited by Fast68Chevy (edited May 08, 2002).]



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