Eaton Posi's these look different which is better?

[greeneyegi]

i see a local Eaton posi and gears for sale,and my unit is 120k miles so it got me to lookin into it.the one for sale is in the box new ,the ones i searched here show a spring in the middle.whats the difference in these styles.And is their a big difference in 28-30 spline?the fastest ill run is high 10s,but alot of 11s at the track with DR's.will a 28 spline and axles hold up or should i wait for a 30 spline and new axles?

View attachment 210253

 

[toofastforyou]

The first one is probably a stock GM posi unit and the other one (pictured four times, with the small springs in the middle) looks like an aftermarket replacement (Eaton???) and is very likely, the better between these two.

Claude.

 

[greeneyegi]

i changed the pic with one that shows the whole unit,i got this pic from another thread on this site http://turbobuick.com/forums/thread...n-differential-w-3-73-gears-19k-miles.395792/

it says eaton posi unit,was he wrong ?im still learning alot with these cars.

 

[TurboDave]

The first picture in your post with the "S" curve spring in the center is a stock posi unit.

 

[greeneyegi]

ok,so my goals are 1.4 60' times ,should i save the money for a 30 spline or will a 28 spline hold as well?thats the count on the new unit.it also comes with brand new 3.77 ring and pinion and install kit.all new in boxes.any ideas on the amount to pay?hes asking 750 for all,but i think that can be purchased from summit at that price.

 

[pacecarta]

to be clear they are both eaton , the first is GM factory installed eaton, the second is an aftermarket eaton and is much stronger than the GM unit and because of the spring pack it can be had with 200# or 400# preload springs (the 400# can feel clunky like a spool at times ) or in the moroso unit you can get it with 800# preload spring
that factory eaton with the S preload spring was about 100#
the aftermarket eaton takes larger bore carrier bearings than the factory unit , the larger bearing is often called 'spool' or 'eaton' bearings when you purchase a complete install kit with bearings and shims

the stock gm was 28 spline and the aftermarket can be had 28 or 30 spline but
i would not recommend 28splines , even 28 aftermarket axles , for 1.4 60s so the aftermarket 30 with new axles would be the minimum i would want to see ,
the 30s are tougher but not unbreakable, only step up from there is the 33spline axles but you would need to do a spool and eliminators for those axles because they dont make a posi to fit them with the 8.5 rear

 

[greeneyegi]

to be clear they are both eaton , the first is GM factory installed eaton, the second is an aftermarket eaton and is much stronger than the GM unit and because of the spring pack it can be had with 200# or 400# preload springs (the 400# can feel clunky like a spool at times ) or in the moroso unit you can get it with 800# preload spring
that factory eaton with the S preload spring was about 100#
the aftermarket eaton takes larger bore carrier bearings than the factory unit , the larger bearing is often called 'spool' or 'eaton' bearings when you purchase a complete install kit with bearings and shims

the stock gm was 28 spline and the aftermarket can be had 28 or 30 spline but
i would not recommend 28splines , even 28 aftermarket axles , for 1.4 60s so the aftermarket 30 with new axles would be the minimum i would want to see ,
the 30s are tougher but not unbreakable, only step up from there is the 33spline axles but you would need to do a spool and eliminators for those axles because they dont make a posi to fit them with the 8.5 rear

great info ,thanks.i dont do twice ,what i could have been done once.

 

[greeneyegi]

to be clear they are both eaton , the first is GM factory installed eaton, the second is an aftermarket eaton and is much stronger than the GM unit and because of the spring pack it can be had with 200# or 400# preload springs (the 400# can feel clunky like a spool at times ) or in the moroso unit you can get it with 800# preload spring
that factory eaton with the S preload spring was about 100#
the aftermarket eaton takes larger bore carrier bearings than the factory unit , the larger bearing is often called 'spool' or 'eaton' bearings when you purchase a complete install kit with bearings and shims

the stock gm was 28 spline and the aftermarket can be had 28 or 30 spline but
i would not recommend 28splines , even 28 aftermarket axles , for 1.4 60s so the aftermarket 30 with new axles would be the minimum i would want to see ,
the 30s are tougher but not unbreakable, only step up from there is the 33spline axles but you would need to do a spool and eliminators for those axles because they dont make a posi to fit them with the 8.5 rear

are the factory gears ok to use?unless i see physical wear or cracks,can they interchange on the carriers,and not have to replace?

 

[pacecarta]

t