12 bolt 70's El Camino rear end gear selection. Help!
04-27-2015, 09:53 AM
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12 bolt 70's El Camino rear end gear selection. Help! I have a 1950 3100 pick'em up truck I'm putting back together after a tear down.
The truck currently has a 12 bolt rear out of a 1970 El Camino in it. I will be tossing the peg leg that’s in there and plopping in a posi. I need help picking gear ratios and pointers if there are any odd tips or tricks I should look out for with that particular rear end.
Motor: STOCK LQ4 with a little cam and headers
Transmission: 4L80E stock everything including converter
Tires: 255/70 15 29.06" tall tire
Rear-end: 12 bolt 1970 El Camino rear
Intended use: Cruiser with fair amount of freeway driving expected.
Help me out! I would like to get this done first so I can get the truck back down on the ground so I can level out the motor and start the rest of the buildup.
The truck currently has a 12 bolt rear out of a 1970 El Camino in it. I will be tossing the peg leg that’s in there and plopping in a posi. I need help picking gear ratios and pointers if there are any odd tips or tricks I should look out for with that particular rear end.
Motor: STOCK LQ4 with a little cam and headers
Transmission: 4L80E stock everything including converter
Tires: 255/70 15 29.06" tall tire
Rear-end: 12 bolt 1970 El Camino rear
Intended use: Cruiser with fair amount of freeway driving expected.
Help me out! I would like to get this done first so I can get the truck back down on the ground so I can level out the motor and start the rest of the buildup.
Last edited by roust84; 04-27-2015 at 03:27 PM.
04-28-2015, 01:51 AM
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Thanks for the replay.
This makes me feel more confident with the 3.73 selections. Added to that, the gear calculators says ill be turning around 2200 rpm at 70 MPH, not too bad. It seems like the best of both worlds.
The old 1/2 ton chevy trucks with the straight axle front ends and 6 bangers were close to 3120-3257 LBS depending on what document one looks at.
I have an El Camino front clip int there and apparently a v8 small block is lighter than the stock 6 that the trucks had..... so I think its fair to say I'm around that 3200-3300 Lb range? Maybe a bit more since the front clip does add some heft to the whole thing.
This makes me feel more confident with the 3.73 selections. Added to that, the gear calculators says ill be turning around 2200 rpm at 70 MPH, not too bad. It seems like the best of both worlds.
The old 1/2 ton chevy trucks with the straight axle front ends and 6 bangers were close to 3120-3257 LBS depending on what document one looks at.
I have an El Camino front clip int there and apparently a v8 small block is lighter than the stock 6 that the trucks had..... so I think its fair to say I'm around that 3200-3300 Lb range? Maybe a bit more since the front clip does add some heft to the whole thing.