'59-60 posi
- Thread starter ejw 71
- Start date
Just turn one tire (or hub if it doesn't have tires-lol) If the other side turns in the same direction, it's posi.
You can also figure out the gear ratio by counting the revolutions of the tire and compare to the revolutions of the driveshaft flange. See how many times the tire turns for every 1 revolution of the shaft.
If it's not posi, you may have to turn twice for every shaft revolution. (limited slip is that way)
Hope that makes sense...
Also, compare the code with the differential code chart on this site.
You can also figure out the gear ratio by counting the revolutions of the tire and compare to the revolutions of the driveshaft flange. See how many times the tire turns for every 1 revolution of the shaft.
If it's not posi, you may have to turn twice for every shaft revolution. (limited slip is that way)
Hope that makes sense...
Also, compare the code with the differential code chart on this site.
Hey, Bob
You can check the ratio that way, but the tire is only going to turn about 1/4 to 1/3 of a turn to one turn of the driveshaft. It is more accurate to turn the tire (for a posi) one turn and count the driveshaft revolutions.
For a non-posi, jack up only one wheel and turn the tire 2 turns and count the drive shaft revolutions. I usually put the valve stem at the bottom and use it as a reference point.
Ron
You can check the ratio that way, but the tire is only going to turn about 1/4 to 1/3 of a turn to one turn of the driveshaft. It is more accurate to turn the tire (for a posi) one turn and count the driveshaft revolutions.
For a non-posi, jack up only one wheel and turn the tire 2 turns and count the drive shaft revolutions. I usually put the valve stem at the bottom and use it as a reference point.
Ron
I should have checked my notes.Thanks Crawler. From where did you get the info? I have another hogshead to decode. Decided to tear this one down. It won't rotate, ring gear has busted teeth. By dividing number of ring gear teeth by number of pinion gear teeth ratio calcuates to over 5:1. You can generally tell if hogshead is a posi by seeing the center localed springs. This unit's posi section is more enclosed and internals not visible. Ed
SS425 HP, Thanks for the reply. It has 4 gears rotating around two gears in an enclosed housing. It doesn't have springs like a posi. I'm not certain that this unit is '59-'60 Chevy. In an open 59-60 unit (for comparsion) 4 spider gears rotate round each other.
Ed
Ed
posi
The old Positraction units have clutch discs in them. About 10, I think. The cross bar has a triangle shape. When pressure is applied, this triangle like shaft twists and applies pressure to the clutch pack, which then locks the axels together. It takes some pressure to do this. On ice or snow, it might not happen, as there is not enough pressure to twist the cross shaft. We used to apply some emergency brake on ice to get enough pressure to make the thing work.
Fred
The old Positraction units have clutch discs in them. About 10, I think. The cross bar has a triangle shape. When pressure is applied, this triangle like shaft twists and applies pressure to the clutch pack, which then locks the axels together. It takes some pressure to do this. On ice or snow, it might not happen, as there is not enough pressure to twist the cross shaft. We used to apply some emergency brake on ice to get enough pressure to make the thing work.
Fred
3725899 = open diff (non posi)
You gave the last digit as a '8'
It's actually a '9' that just looks like an '8'
probably due to a small casting imperfection (this is very common)
Your casting date G208G2 has too many digits. I will assume you mean G208
G208 = July 20 1958. This rear could have come in a very late 58 car, but probably an early 59 car. Your assembly code stamped on the passengers side of the 'hogs head' will tell you. It's usually two letters and three numbers. If your rears are out of the car, a toothbrush and solvent should reveal this code. (If it's rusty, try a bit of steelwool.
crawler
You gave the last digit as a '8'
It's actually a '9' that just looks like an '8'
probably due to a small casting imperfection (this is very common)
Your casting date G208G2 has too many digits. I will assume you mean G208
G208 = July 20 1958. This rear could have come in a very late 58 car, but probably an early 59 car. Your assembly code stamped on the passengers side of the 'hogs head' will tell you. It's usually two letters and three numbers. If your rears are out of the car, a toothbrush and solvent should reveal this code. (If it's rusty, try a bit of steelwool.
crawler
Crawler, Yep, last digit was a 9, not an 8. Checked the other casted code, certain it reads G2062. This could this decode to July 20, 1962, assuming hogshead was replaced. Counting teeth produced a 3.36:1 ratio. The stamped code on the other side reads BB0727. This hogshead was removed from a '59 ElCamino, not from '59-'60 Impala as stated earlier. Thanks again for your assistance. Ed
Yes, I think your right, That number G2062 means July 20 1962. Only rears built in Buffalo NY had two digits for the year (as does yours) ('62' rather than just a '2') This is further confirmed by your stamping code starting with a 'B' - only rears built in Buffalo started with a 'B'. Your assembly date '0727' means July 27, so it's a Buffalo rear that was assembled seven days after it was cast. The last piece of the puzzel is the 'BB' ratio code. I would guess this means 3.36 if your count came to that, but I have no info to confirm this cause you have gone out of my area (1959-1961). Maybe one of the others on this fourm have a listing for the 1962 axel code 'BB'?
crawler
crawler