Ricky5

Gonna be in the market for a WS6 soon and dont really understand the whole 12 bolt 9in rear end lingo.

I read the 'so you wanna go fast' thread

I will be getting an M6. Basically if i want to mod the car I need to spend $2500 on a new 12 bolt rear.

Why would I not just get the 3.73 gear in it to take some of the stress from the low end torque out of the car?

Can I have a 12 bolt rear end and put the gears in it? Would that really be needed?

My goal is to have a nice streetable ws6. full bolt ons with supporting mods. I would like to make it heads cam ready in case i wanna go that route in the future

Mike TA

iTrader: (6)

It really depends on how you want to use the car. The 10 bolt seems to hold on pretty well in the autos even with decent power. The 6 speeds seem to be hit and miss but if you aren't doing 4-5000 RPM clutch dumps I would let the 10 bolt easy until it gives up the ghost. On my last build I knew I was gonna beat the **** out of it so I went ahead and bought an S60. My full bolt on stalled auto before that I just ran the 10 bolt. Never had an issue.

Ricky5

gives up the ghost= breaks?
S60?
First post sorry

Would I want to put gears in a full bolted car with the 10bolt rear? Why or why not? for an M6

Mike TA

iTrader: (6)

No sweat man. Yeah, give up the ghost means break. Long story short...the Strangle S60 is a rear end based off of the Dana 60. Google search Strange S60 if you want to know more. Again, long story short..manual transmissions are harder on the rear end. Again, if you search on the forum for some old posts you can collect tons of data on it.
Put gears in a 10 bolt? There are really to 2 trains of thought on that. One is that the 10 bolt is junk and you shouldn't spend any money on. Ride it till it breaks then replace. The second is that the 10 bolt isn't complete junk and if you know what your doing you can make it last.
I'll say this...there are plenty of guys on this forum running pretty fast times and putting down decent power on the 10 bolt. It has its merit. While not strong it is extremely efficient and reasonably light. There are also guys who have destroyed them in a stock car. It's truly a roll of the dice. In my experience they aren't made out of glass. I would say use it until/if it breaks and then switch if you want. If you want gears go for it.

Ricky5

ok cool that makes more sense.

My last question would be if I decide to get 3.73 gears (or a different one) and I keep the stock 10 bolt and happen to break it is the first thing that breaks the gears?

Then I just wasted money on the gears

Or is it another roll of the dice thing?

Mike TA

iTrader: (6)

Roll of the dice but usually, yeah, the gears are toast.

JD_AMG

This is grossly over exaggerated. What breaks the stock rear ends are the sudden shock they receive from a hard launch on sticky tires, or from wheel hop. If you don't get wheel hop or launch the car hard with a clutch dump then you will be fine.
First, the "low end torque" isn't the problem. Second, adding 3.73 gear will only make the rear end more prone to breaking, the factory ones are 3.42 for the M6 cars. Getting a steeper gear like a 3.73 or 4.10 increases torque to the wheels.

The 10 bolt and 12 bolt are different rear ends and parts will not swap between each other. The name "10 bolt" and "12 bolt" comes from the rear housing bolts, there are literally 10 bolts and 12 bolts holding the rear cover on. The 12 bolt and 9" rear end (9" refers to the ring gear size, there are no bolts for the rear housing on this rear end, a 12 bolt has a 8.8" ring size, a 10 bolt from the fbody has a 7.5" ring size) are simply physically larger rear ends compared to the 10 bolt and thats what gives them their extra strength. The larger the ring gear size, the stronger the read end, all else equal.
10 bolts are found in smaller GM cars and trucks (like the S10)
12 bolts are found in larger GM trucks like the Silverado
and the 9" is a Ford design rear end found in their mustangs and trucks.

Mike TA

iTrader: (6)

JD,

Correct me if I'm wrong but my understanding is that the shock generally flexes the housing and causes the ring gear to walk up the pinion gear.
I do agree that the weakness of the 10 bolt is over exaggerated. I have broken them but it was on DRs and a hella lot of abuse. As I stated, my stalled auto bolt on car never hurt it. No noise, no whine, no nothing and I was pretty hard on that car. I just kept it properly maintained.

1LE Hugger Orange

Not into drag racing, my 10 bolt has no issues with 3.73 gears and a M6, mine is built for road racing on a track. Sticky tires and doing doing dumps will kill it.