Posi is dying, what to do
05-31-2012, 02:05 AM
#1
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Posi is dying, what to do My posi is slowly getting worse over the last couple months and was wondering if it's worth buying a whole new one or to replace the clutches in it. I seldomly take the car to the track anymore so I don't need anything crazy but I can't seem to find a posi rebuild kit. Has anyone come across them or have another fix? Thanks.
05-31-2012, 07:48 AM
#2
Either buy one of these: http://www.summitracing.com/parts/ETN-19599-010
or get one from the junkyard. Perfect time to throw some 3.73's or 4.10's in it while it's out. Or drop $2K+ on a 9" or 12 bolt of course.
or get one from the junkyard. Perfect time to throw some 3.73's or 4.10's in it while it's out. Or drop $2K+ on a 9" or 12 bolt of course.
05-31-2012, 08:56 AM
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This is my current situation. I'm going to just find another stock rear and put it in, while I save for a 12 bolt.
I've found used rears for 1/3 the cost of a new posi.
.02
I've found used rears for 1/3 the cost of a new posi.
.02
05-31-2012, 09:30 AM
#7
I was in this same situation when my car was on the old cam only setup....one wheel peels are not cool lol....although I could leave one really long tire stripe.
I went with the brand new Eaton and decided to upgrade to 4.10's "while I'm down there" and a TA girdle too for insurance. FWIW the Eaton seems lock up quicker than the stock one did and you get the peace of mind you aren't putting some crusty POS posi with 100K+ on it ready to blow out at any moment as mentioned 
(it comes with 1 year warranty too). Looking back, now that my car has a 383 a 9" would have been money better spent, but for a street driven car that does not see slicks it has held up just fine to plenty of abuse from the 383 with a 6spd so far...
I went with the brand new Eaton and decided to upgrade to 4.10's "while I'm down there" and a TA girdle too for insurance. FWIW the Eaton seems lock up quicker than the stock one did and you get the peace of mind you aren't putting some crusty POS posi with 100K+ on it ready to blow out at any moment as mentioned (it comes with 1 year warranty too). Looking back, now that my car has a 383 a 9" would have been money better spent, but for a street driven car that does not see slicks it has held up just fine to plenty of abuse from the 383 with a 6spd so far... Last edited by ahritchie; 05-31-2012 at 09:41 AM.
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05-31-2012, 10:41 AM
#8
OP LT1 cars mostly came with Auburn cone type posi units (5 yellow springs in the center) and they are NOT rebuildable. That's why you can't find any parts for them. If you have a Torsen posi that's also not rebuildable.
Both Eaton (clutch type) and Auburn (cone type) offer replacement units or you can look for a used rearend. My original rears posi was still working good at 115k when I replaced the whole rear with one with 72k on it that I built with 4.10s, point being used ones can still work good with high miles on them.
Speed inc or Jaws gear have a good selection of parts:
http://www.speedinc.com/catagory.cfm.../%20Driveshaft
Here's a link to a thread with a description of the GM service manual method of checking the serviceability of the posi clutches. See post #15 and on:
https://ls1tech.com/forums/gears-axl...ed-advice.html
Both Eaton (clutch type) and Auburn (cone type) offer replacement units or you can look for a used rearend. My original rears posi was still working good at 115k when I replaced the whole rear with one with 72k on it that I built with 4.10s, point being used ones can still work good with high miles on them.
Speed inc or Jaws gear have a good selection of parts:
http://www.speedinc.com/catagory.cfm.../%20Driveshaft
Here's a link to a thread with a description of the GM service manual method of checking the serviceability of the posi clutches. See post #15 and on:
https://ls1tech.com/forums/gears-axl...ed-advice.html
Last edited by guppymech; 05-31-2012 at 10:54 AM.
06-02-2012, 12:12 AM
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Mine isn't entirely dead yet, if I'm going straight and spin them they'll both break loose but if I'm in a turn and try to kick it sideways only the inside tire will spin
06-02-2012, 03:34 AM
#14
Ale76051, How much friction modifier are you using? I use 4oz per 2qts of oil as recommended by Randy's ring and pinion, and am happy with the rears performance. Using more friction modifier will make the posi cones slip more and using less will make the cones grab more.
I've also read where some guys don't use any friction modifier to make their posi grab more, which I'm sure it does but I'm not convinced this is a good idea for a daily driver.
I've also read where some guys don't use any friction modifier to make their posi grab more, which I'm sure it does but I'm not convinced this is a good idea for a daily driver.
06-02-2012, 01:42 PM
#15
Ale76051, How much friction modifier are you using? I use 4oz per 2qts of oil as recommended by Randy's ring and pinion, and am happy with the rears performance. Using more friction modifier will make the posi cones slip more and using less will make the cones grab more.
I've also read where some guys don't use any friction modifier to make their posi grab more, which I'm sure it does but I'm not convinced this is a good idea for a daily driver.
I've also read where some guys don't use any friction modifier to make their posi grab more, which I'm sure it does but I'm not convinced this is a good idea for a daily driver.
