65 C10 Rear End Question

[Daron Craig]

My truck has the 12 bolt rear end in it. I'm not 100% sure what ratio. I do know that when I spin the driver side wheel one way the passenger side wheel spins the opposite way. I planned on pulling the cover and changing the fluid so I can count the teeth. If it turns out to have at least a 3.5 something gear in it, what would be a good option for making it a posi? Locker? Weld the spider gears? Any info or pictures would be greatly appreciated. Thanks,

[1964FarmFreshC10]

Unless you plan on strictly drag racing the truck don't weld the diff.

The current gear ratio has no bearing on your ability to make it a posi as you would need to replace the diff and could change the gearing to whatever you wanted at that time anyway. Odds are your truck is a 3.73 as that was common.

[Daron Craig]

Originally Posted by 1964FarmFreshC10

Unless you plan on strictly drag racing the truck don't weld the diff.

The current gear ratio has no bearing on your ability to make it a posi as you would need to replace the diff and could change the gearing to whatever you wanted at that time anyway. Odds are your truck is a 3.73 as that was common.

So would you recommend putting a locker?

[scottofksu]

What kind of carrier you run is entirely dependent on your use model. Each choice has its benefits and detriments.

Open Differential: Great for predictable street manors and generally one of the cheapest options. Downsides include driving on slick services being the worst of any option as both tires will experience a torque reduction if one slips.

Small Carrier LSD/Positrack: Great for predictable performance and street driven manors and driving on slick surfaces as torque is provided to the wheel that is not spinning. Spider gears can be a weak link especially if towing.

Locker: Maximum straight line performance. Downsides include being less streatable and especially on tight corners where the outside tire will drag a bit due to not being able to spin faster than the inside wheel. Personally, I would only go this route if you are building a truck that will mostly be used for drag races.

Within these options there are further options based on the bits of machinery they use to produce the performance in keeping with the differential type. For example, LSD/Posi differentials either use clutches and springs (i.e., traditional posi) or helical screws (i.e., Trutrak) to facilitate limited slip. Personally, I am going with the Trutrak due to it not needing additional maintenance (e.g., changing clutches and springs) beyond changing gear oil. I have also never seen one broken, but I am sure some have found a way! LOL

[SkinnyG]

I am a huge fan of the Helical/Torsen/TrueTrac limited slip. It flat out works, doesn't wear out, and has zero maintenance.

If you lift a wheel off the ground it will act like an open diff, but as long as it sees at least some traction on both wheels (so it can TORque SENse), it is awesome.

I have put TrueTracs in my last three vehicles ('61 Apache, '77 Silverado, '86 RWD/V8 Pontiac Firefly (Chevy Sprint)). I love them.

You don't want a spool on the street.

You don't really want a locker; they are good for dirt, drift, and drag, not much else.

[cj847]

It really depends on what you use the truck for and how its equipped.

As mentioned, there are spools, true lockers and limited slips. Personally, I prefer a true Detroit locker. When on a budget I use a lock-right type set up.

I would not use a locker with a standard transmission. With an auto they are fine. You do have to learn how to drive with one. Basically, it is like a spool when you press the gas. When turning you must let off.

The reason I like a locker is because both wheels pull when you are on the gas, even is a tire is in the air, or on ice, or on wet grass. I have seen people "stuck" with their limited slips on a wet lawn slightly off camber.

[SkinnyG]

Originally Posted by cj847

The reason I like a locker is because both wheels pull when you are on the gas, even is a tire is in the air, or on ice, or on wet grass.

That is not unique to Lockers - driving both wheels (limiting the slip) is what all limited slips do.

...Unless they are broken.

[lilpoindexter]

I had a 9" built for my '63 with 3.70 gears and an eaton true trac

[Heater63]

'63 with 3.73 which came peg leg. had mine all rebuilt and added an EatonTrue Trac and love it.
I'm running an overdrive TKO-500 which really works with that rear ratio.