hpjunky98

iTrader: (3)

ok i was thinking of replacing my rear suspension peices and getting a 9 inch or 12 bolt with 4.11s, but now i searched and found that i could loose 10-30 hp!!! will my car be faster or slower if i do this!??!??!!

01FbTaWs6

iTrader: (12)

slower, you will have ALOT more drag, and it weighs a ton. Everyone on here is so worried about the 10 bolt because they are known to granade. But if you have the right setup, you can get away with it, I know 2 people now that are running 10 bolt rear ends in low 9 second carts, both pulling the wheels hard.

hpjunky98

iTrader: (3)

what is the "right set up"

hpjunky98

iTrader: (3)

please...id like to know how i can run 9s with the stock rear....

hpjunky98

iTrader: (3)

anyone else?

01FbTaWs6

iTrader: (12)

i didnt say stock 10 bolt. Those 2 guys i was talking about are running 8.5 10 bolts, but the weak link in the stock 7.5/7.625 rear end is the posi unit, and the killer is wheel hop. Ring gears can pose a problem also, but not near that of the posi unit. Get a good posi, and prevent wheel hop, and some aftermarket axles, such as moser, and you could easily run good e.t's with that. If you are looking for 9 second passes there smart guy, you obvioulsy have alot of cash to spend. And as for the 12 bolt slowing down the car, it does use alot more power, and has alot more drag now doesnt it? Also weighs alot more now doesnt it? Pretty hard concept to catch, I know.....

hpjunky98

iTrader: (3)

ya i got that part...i never said i wanted to run 9s, all i said was i wanted to know how i could have a solid set up that could survive 9 second passes. i wasnt aware that there were alot of things you could do with the stock 10 bolt. quite honestly, if there not going to do it right from the factory, id like to get a new part instead of investing into somthing that most people will agree will eventually break. oh, and i do have alot of cash to spend, i just want to spend it in the right place. i'm not looking for a 9 second car, just something that can be extreemly fun to drive, and something that i dont have to worry about while i'm ripping throgh the gears. i really dont want to spend alot of money on my motor if my drivetrain / suspension cant handle it. and wont the added weight of all of the 10 bolt add-ons and beefed up parts have the same if not slightly less drivetrain loss as a 12 bolt? it seems to me if your going to get better parts, no matter what, its going to add rotational inertia to the rear axle, so why would those people running 9s not just get a better engineered 9 inch? i'm just having a hard time relizing how a rear end can add "drag" to a car. weight, and rotational mass i understand, but drag....i dunno, mabie i'm just a newbie.

hpjunky98

iTrader: (3)

anyway thank you for the help, ill hold of on the new rear for a while. again thanks

2000TransAmWS6

iTrader: (12)

i have read that the Ford 8.8 rearends are more efficient than the 12bolts or 9in. and from what i understand they can handle alittle more power than the 12 bolts can.

personally i'd rather go with a 9in, although you're losing more power to the wheels you're putting that power through the strongest rearend available (and the easiest to work on). i feel as if any power i lose throught the driveline i will more than be able to make up by leaving the line harder and on stickier tires.

01fabtaws6, if i understand you correctly you're basically saying the weak link on the 7.5 10-bolts is the carrier, axles, and gears. maybe we just have different perceptions of the 10bolts, but IMO the weak link on the 7.5 10bolt IS the 7.5 10bolt itself.
apparently you haven't ripped up any gears in your 10bolt, but i can understand where hpjunkie98 is coming from, and the 10 bolt is getting replaced as soon as i can afford it. also i would be willing to put dollars to doughnuts that IF you do know of someone pulling the front wheels on low 9 sec cars that they aren't manual transmission cars.
read more, talk less, small sig pic.

01FbTaWs6

iTrader: (12)

you are correct about not manualk tranny cars, but th400's with like 4200 stall. That is alot of power coming off the line with a 400 shot of juice. They are both 8.5 10 bolts tho, not our 7.5. But as far as an aftermarket rear would go, if I was to get one, it would be a 9 inch, because they are the strongest rear end, and have been proven time and time again, but there are plenty of guys running 10 bolts that are running a pretty decent times, and launching pretty hard, and on the other hand, there are also some that break when they are stock, so take that as it is....

hpjunky98

iTrader: (3)

ok so as i see it, the rear adds drivetrain loss (obviously) so to counter this, what would be the smart thing to do:
a) more power - just ge more boltons until i have the same amount of hp to the wheels as before.
b) focus on the drivetrain - lighten the drivetrain to attack the initial problem of drivetrain loss, ie. lightweight flywheel, driveshaft, rims, etc.
c) both - lightweight flywheel, and some boltons.
i want to do this for as little money as possible, so what do u guys think would be the best route to go?

02WS6Bird

iTrader: (2)

It's not how much power your car makes, it is how efficiently it is put to the ground. Yes if you have identical setups say you put 4.10s in the 10 bolt and 4.10s in the 9 inch, you will probably win with the 10 bolt (assuming nothing breaks, or goes rong) This is probably because of the weight of the rear alone. The difference that is witheld is that you can adjust the 9" to where it is most effective and you can Pound on it with much less worry. This is where the efficiency comes in also witht eh fact it will sustain a steeper gear.

Yeah so instead of having 360-370 rwhp/tq with the 10 bolt w/ 3.42's and about 350(w/ 4.10's) you may put less power down at the wheels, but realisticlly you still are making the same HP and TORQUE. Dyno's are for Tuning Purposes only, NOTM bragging rights

So If I was you, I would make sure I can pound on my setup- AND bring in the bigger and better mods, Heads/Cam, Blower, Turbo, etc. you name it.

CATCH ME

iTrader: (1)

the dyno numbers are not what you need to worry about. granted yea it is cool to say to someone i have 430 hp at the tires but i think it would be way cooler to say that i run 10's in the quater mile. and regardless, you are probablly going to have way more fun with the car when you get the 9"/12-bolt

BBQLS1

Yeah, you will be adding weight with the 9 inch or 12 bolt, but right now they are the way to go. The stock 7.5 is garbage. 8.5 is better, but not easy to work with because you need the torque arm provision on the housing, which 8.5s don't have normally. Same problem with the 8.8. Read the sticky on the 8.8, but I don't know of anyone who has had sucess with welding on the torque arm provision. For the 12 bolt, some of the people on the sight are having problems with whine, which makes it a less feasable option. The 9 inch is good, but you have to get real creative and fabricate a way to use your ABS. Now I hear in 3-6 months DTS will have a Dana 60 that will weigh in between the 9 inch and 12 bolt. I imagine the rotating weight will be greater though. But the Dana will be able to retain ABS, not whine, and be indestructable with the 9.75 inch ring gear. Not breaking parts is more important than losing more HP.