Why are some guys locking the diff's. I know both wheel will turn at the same time.

I know limited slip on 1 to 1 cars is a plus.

What are the pro's and con's.

Just for better traction. Thats all but where you have better traction you lose steering. You can put thicker diff fluid to help gain traction and still keep good steering. I think its mostly bashers that lock the diffs because its pretty much worthless to lock the diffs for racing.

I own a tc4 and recently installed a mamba max 5700 combo, the rest of the car is all stock, and I've broken something in the rear diff as im getting no drive in the rear wheels, I've removed the top cover off the diff and everything seems to be in order. Would locking the diff fix my problem and how would I go about locking the diff? I don't race the car but don't wanna lose any speed from it.

To lock the diff you can fill it with epoxy, not sure how long that would last though.

As for WHY people lock diffs, on some surfaces (snow, slick mud, ice) a locked diff gives you better handling, like straighter take offs and more controlled turning. However, on other surfaces where there is a bit more traction it can cause ALOT of strain on the drive train, as well as cause the truck to take MUCH wider turns.

With a limited slip diff, the tires slip at the beginning and begin to slow down due to the viscous action of the silicone, so this allows you to turn tighter but come out of the corners under power without causing the truck to want to spin 180 degrees.

I don't recommend locking the diffs unless you run on ice or snow. And the moment you hit asphalt, be prepared to break things.

Nandaracing: Remove all the bevel gears in the diff and check the holes where the pin of the bevel gears sit. Sometimes it gets used up causing slop in the diff, and making the gears move around. I strongly recommend investing in a stronger diff when using that much power. Remeber, it's not broken, it's just an excuse to upgrade.

I don't think locking them would help. Somethings broke somewhere. Maybe a drive pin between the center drive shaft and the diff? You would get more help in the electric on road car section.

Isn't the TC4 a ball diff?

You might just have to tighten the screw inside the diff cup.

never lock my diffs, dunno why bud, just dont n at. Seems a waste of energy to bother, does give better traction, but also loads parts of the driveline with heavier forces, LOL, even with UN LOL locked diffs you hardly get stuck, UNLESS your MUD bashing or on ice !