8.5" question

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84cutspreme

Royal Smart Person
Jun 4, 2009
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What would need to be done to an 8.5" non-posi rear to be converted to posi?
 
A posi differential.....Try the detroit tru=trac...I have heard these are good units for the price..I'm sure others will pipe up. Not that big of an issue, especially if you have the highly sought after 8.5 rear!!
 
What kind of gear oil do you guys use?
 
I use NAPA gear oil with their posi additive... 8)
 
JBreu said:
A posi differential.....Try the detroit tru=trac...I have heard these are good units for the price..I'm sure others will pipe up. Not that big of an issue, especially if you have the highly sought after 8.5 rear!!

Jbreu - I have a trutrac in my truck, its an 8.6 rear so its similar to the 8.5. I don't find it useful at all, its noticeable when going around turns quickly, but not much more than stock. Though I've heard lots of good things about them from everyone else, I think they perform much better in an automatic car than a manual truck. It takes a few seconds to engage off a stop, which is very annoying, and its pretty slow to engage from driving speeds and in the wet. I wouldn't get anything less than an air locker if I had to redo it. Or for cornering + everyday driving an adjustable clutch type lsd
 
custom442 said:
JBreu said:
A posi differential.....Try the detroit tru=trac...I have heard these are good units for the price..I'm sure others will pipe up. Not that big of an issue, especially if you have the highly sought after 8.5 rear!!

Jbreu - I have a trutrac in my truck, its an 8.6 rear so its similar to the 8.5. I don't find it useful at all, its noticeable when going around turns quickly, but not much more than stock. Though I've heard lots of good things about them from everyone else, I think they perform much better in an automatic car than a manual truck. It takes a few seconds to engage off a stop, which is very annoying, and its pretty slow to engage from driving speeds and in the wet. I wouldn't get anything less than an air locker if I had to redo it. Or for cornering + everyday driving an adjustable clutch type lsd
Custom442,
That is very good info that you have on that trutrac.....Thanks for clearing that up for me as well as others.. 8)
 
84cutspreme said:
What kind of gear oil do you guys use?


Me personally.... I'd make sure I ran the GM additive. You can use whatever brand gear oil you prefer but put the GM additive in it.
 
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