65GS.com - Buick Gran Sport Enthusiasts!
General Discussion => Q & A => Topic started by: Turbonut85 on March 08, 2017, 12:01:36 PM
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My GS came from the factory with the limited slip differential...but it's either been swapped out, or its shot. It's a one tire frier now. I'm looking at this posi unit...but cannot confirm if it's the correct one. I believe my car has the 3.08 gears in it....(ST300 auto car) but I plan to upgrade them to 3.73 gears...which this carrier is for....I just want to confirm the axle spines/bearings/etc are compatible. Any help is appreciated. Thanks. -Keith
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Can anyone verify the one I posted will work?
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Yes it will work. Those auburn posi units work pretty good. I've had one in my black gmc for about 15 years now.
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The 542060 is the Pro series unit, 542013 is the High Performance unit. From the descriptions, the pro unit has 'higher bias torque' .... sounds like it has higher preload on the clutches. Either unit will fit. Chevy units and later 68-70 Buick units are different.
The HP unit is over $100 less, would be fine for a street car. I'd be hesitant to use the pro unit in wet or snowy conditions, it may not slip enough and cause the rear tires to slide out.
An Eaton unit is another option for 3.55+ gears. It uses conventional clutch discs vs the cone type clutch of the Auburn.
Best bet is to contact one of our Buick specialists.... Jim Monzaz has his own site at www.jdrace.com (http://www.jdrace.com)
He can set you up with everything you need at a good price.
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Auburn=JUNK IMHO rebuild the factory unit of buy an Eaton.its not hard to install new clutches
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Auburn=JUNK IMHO rebuild the factory unit of buy an Eaton.its not hard to install new clutches
:thumbsup: :thumbsup:
Says the retired former Eaton Automotive employee! Actually, the Eaton engineers consider the Detroit TrueTrac to be superior to the Posi in both consistency of torque transfer and in durability. All other things being equal, that's what they recommend. YMMV.
:cheers2:
Chuck
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Could you elaborate? Personal experiences? As far as my car goes....some douche replaced the factory posi with a 2.78 peg legger....
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I think all I can add is that the Eaton engineers competitive analysis concluded that the Eaton Posi is superior to the Auburn unit. It is more robust in design and maintains expected torque transfer performance longer. And, as stated above, they rate the TrueTrac even higher due to more consistent torque transfer (% of transfer) and longevity of expected performance. Where the Posi has clutch packs that can and will eventually wear, the TrueTrac has a set of helical gears that don't wear like the friction material in clutches does. More info here:
http://www.eaton.com/RU/Eaton/ProductsServices/Vehicle/Differentials/detroit-truetrac/index.htm (http://www.eaton.com/RU/Eaton/ProductsServices/Vehicle/Differentials/detroit-truetrac/index.htm)
http://www.eaton.com/RU/Eaton/ProductsServices/Vehicle/Differentials/eaton-posi/index.htm (http://www.eaton.com/RU/Eaton/ProductsServices/Vehicle/Differentials/eaton-posi/index.htm)
That's Eaton's professional opinion. I have no meaningful experience with any limited slip differentials.
Chuck
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Auburn=JUNK IMHO rebuild the factory unit of buy an Eaton.its not hard to install new clutches
:thumbsup: :thumbsup:
Says the retired former Eaton Automotive employee! Actually, the Eaton engineers consider the Detroit TrueTrac to be superior to the Posi in both consistency of torque transfer and in durability. All other things being equal, that's what they recommend. YMMV.
:cheers2:
Not really Just an old guy that has drag raced for years. I run stock 10 bolt GM gears with 1.29 60 ft times and have only broken one gear set in 16 years.GM uses Eaton Design the auburn cone style are non rebuild able.In the drag racing world eaton gears is whats used and just go to Yellow bullit forum and do a search.If the rear end needs clutches all i saying is why change the whole unit cant you get clutches for it check with moser and see
Chuck
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No drag racing with this car....that's what my turbo Buicks are for....lol
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No drag racing with this car....that's what my turbo Buicks are for....lol
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Relative to your comment about the missing posi, it was pretty common for them to be left out "by accident" in the 60's. My GS was such a car as was my old mans 65 Chevelle. Both received a $50 credit for it. Another common mysteriously deleted item was the hall effect "boinger" on the radio.
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According to the original purchase agreement from 1965 (which I have) it came with the posi....
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I personally would go with a rebuildable unit.Cone styles are not,if memory serves me right.
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