12 bolt locker

[kinada]

What do I need to know to make sure I order the right diff for my 12 bolt? The open diff has to go. Its embarrassing! Lol. Am I right in thinking I can check my gears by jacking up one rear, turning 2 full revolutions and counting the turns of the shaft?

Anybody on here use a Detroit Locker on the street?

 

[marks86]

I have one and its awesome, you only notice if your taking a very sharp turn but has great street manners for a locker

 

[kinada]

Thanks Mark. I've heard they take little getting used too. But once you do they are awesome. I just need to know which one to order? Are all truck 12 bolts, 30 spline?

 

[HotRodPC]

I forget the spline count on a Truck 12 Bolt, but they are all the same. Not like 10 bolts where the early was 28 spline and the later was 30 spline.

Not sure how much hp you're running ,but you could also get by pretty cheap with a Richmond Powertraxx LockRight or Spartan Locker. Those are aka lunchbox lockers. Pretty much just take out your spider gears, and replace them with one of these lunchbox lockers in about an hour or so, and there you go, ready to get sideways and lose the peg legger. Supposed to be for up to 300 hp easily.

 

[kinada]

Thanks for the info HotRod. Currently only about 300hp maybe less. But plans are for a motor in the 500-600hp range. So maybe the Detroit Locker is the better choice?

What oil should I be chucking in with the diff?

 

[marks86]

Thanks for the info HotRod. Currently only about 300hp maybe less. But plans are for a motor in the 500-600hp range. So maybe the Detroit Locker is the better choice?

What oil should I be chucking in with the diff?

I know for a detroit they say not to use synthetic oil for some reason, if I was you I would call to verify

 

[kinada]

Will do. Thanks Mark.

 

[HotRodPC]

I agree with Mark. Go with the manufacture suggests for the unit you install. The oil they called for 10 years ago, maybe different than what they call for now. Chances are it'll be 85W-90 but not sure if it's going to be GL4 or GL5 or maybe even higher. And I never have been a fan of synthetic oil in diffs or auto transmissions. From what I understand, some of the never 6 speed autos require synthetic, but Auto Trans fluid in it's petroleum based state is some bad ass good stuff IMO. And damn sure don't put synthetic trans fluid in a well used auto trans.

 

[highdesertrange]

if you are planning on that much hp I would go with a 14 bolt. you are going to eat that 12 bolt up. highdesertranger

 

[kinada]

Really? How much hp can a 12 bolt handle? 14 bolts are hard to come by in England.....

 

[marks86]

I know someone with a 66 chevelle with like 550hp with a 12bolt posi has not had a prob
someone with more 12bolt experience will chime in for ya

but highdesertranger does have a point if you know your buying a power adder soon along with some big fat tires, maybe your should eaither go with a bigger splined axles along with a locker for that spline count

idk how strong semi flow 14bolts are but I do know is a 14bolt FF weighs like 500LB

 

[kinada]

I guess how much traction you have is a major factor on the longevity of the axle. The truck is not a daily driver and mileage per year is low. Maybe I'll see how the 12 bolt does. If it breaks and a 14 bolt comes up I'll throw that in.

Whilst we're on the subject, how much can the stock TH400 put up with?

 

[highdesertrange]

well, didn't realize you where in England. use it and see what happens. I was just talking from experience when I had a k10, I ate up a few 12bolts I finally put a 14bolt ff. end of exploding diffs. highdesertranger

 

[HotRodPC]

I guess how much traction you have is a major factor on the longevity of the axle. The truck is not a daily driver and mileage per year is low. Maybe I'll see how the 12 bolt does. If it breaks and a 14 bolt comes up I'll throw that in.

Whilst we're on the subject, how much can the stock TH400 put up with?

A stock Th400 will tolerate quite a bit so long as you're not launching off of a NOS bottle, and of course if it's stock you're not launchign off a trans brake. If you add a trans brake, there are some other hard parts and mods you'd want to make. But in stock form, a Th400 tolerate some hell as long as you keep it relatively cool or normal temp.

 

[kinada]

Thanks for the info Hotrod. No plans for a trans brake or NOS here.