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Sure grip Questions

pistol_grip_polara

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I don't get on here much anymore, to much going on with work and diesel truck stuff... my car has sadly been neglected :-( hopefully that can change here pretty soon.

Anyways. I currently have a 489 case 3.23 suregrip. My dad is looking for a sure grip for his car, however I have recently found 2. 1 is a 489 case 2.76 ratio and 1 is a 741 case 3.91 ratio.

he is looking for some 3.23's.. Question is.. can we pull one of those sure grip units out and say put them in a 742 case? or pull the 489 case apart and put in a 741 case for example?

i know the pinions are different and can't be swapped per unit, but just looking at the suregrip unit. I've looked on the internet and can't find a definitive answer.

as always, thanks for the help.
 
Sure Grip units (carrier) interchange between the 3 cases you mentioned.....it's the pinion/ring gear that does not.
 
Yeah everyone says the 741 pinion is the weakest....but how many have you seen broken? Most of the ones I've killed involved shaved teeth and not broken pinions and that includes all of the 3 different ones. Other than that, the link is helpful.
 
thanks for the replies... thats what I needed..

ya, I have heard the 741 pinion is the weakest but haven't broke one or came across a broke one yet.. lol
 
Rather than fooling with old stuff that may or not be OK you might want to use a new unit, the Eaton 913A572 truetrack is nice, just put one in my car, it's a gear type with no clutches. 489 case likely will have the later cone clutch sure grip which is not rebuildable. 741/ 742 should have the dana power lock (replaceable clutch plates) which is much more desirable. 489 and 741/742 use different ring gear bearings but they fit in all cases (outside race diameter is same).
 
The 741 is the weakest of the three...
It's the smallest of the 3 but it's for sure not exactly weak.....

Rather than fooling with old stuff that may or not be OK you might want to use a new unit, the Eaton 913A572 truetrack is nice, just put one in my car, it's a gear type with no clutches. 489 case likely will have the later cone clutch sure grip which is not rebuildable. 741/ 742 should have the dana power lock (replaceable clutch plates) which is much more desirable. 489 and 741/742 use different ring gear bearings but they fit in all cases (outside race diameter is same).
The cone unit is still a good one if you can find one that some moron hasn't totally wasted once it quit working right. Once they quit pulling both wheels, quit using it. The cones can be remachined to work good as new again (and they worked well when they were new) that is if the previous moron didn't keep trying to make it work and wasted the spiders and side gears and messed up the cross shaft to the point it spun in the case. Once that happens, it's junk. I've done way too many of these for anyone to tell me different. I've even run into someone that was welding up the carrier halves and remachining them for a new cross shaft but man, I guess they are getting to the point where it's worth doing that much work on them.....?
 
ya, I know the early 741 742 cases used the clutch style and the 489 used the cone style for the most part. I have a cone style in my car and it works fine. I have a tru-trac installed in my diesel and know a few other guys that like em. If I can get the clutch style one from him I will probably grab it and put in my '63 with my 742 case 3.30 gears, and then let my dad run the 489 3.23 gears in my car at the moment.
 
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