Alright so the plan for my car is to build a 300hp - 350hp motor built for a turbo setup. I have a fully rebuilt 700r4 so I'm not worry about that (yet at least). I'm wondering what I should be aiming for upgrading my rear to. I plan on making 500hp at the wheels once I put the turbo on the motor. I'm planning on 3.43's beause its going to be a daily driver and obviously posi. I've been looking into picking up a 3.43 rear from a 4th gen since its an easy cheap swap. What I need to know is what kind of hp can the 4th gen rears hold up to? How many bolts / inches is the 4th gen rear? And can I buy a used 4th gen rear and rebuild it for strength?

 

4th gen rears are not much stronger than most 3rd gen rears. Pretty much the same thing. The 4th gen rears are from some peoples opinoins, not even good enough for a stock LT1/LS1. Basically research the Ford 9" Rear or the 12 bolt. The 12 bolt's advantage is that it weighs less. The 12 bolt is about 8.875".

9-Inch Vs. 12-Bolt Rearend Compararison - Tech Article - Chevy High Performance Magazine

 

there are next to no differances in the 4th and 3rd gen rears. if you're really wanting to up grade get a 12 bolt or 9" from curries, strange, or moser.

 

I was looking to spend not alot of money... Like 500 tops

 

Omg... I just realised that a rear for 500hp is going to cost me $2000 minimum... I better get a good deal at the Englishtown swap meet next month. If I buy say a 12 bolt does the housing its self have anything to do with the width or is that all in the axles?

 

500HP costs a lot of money, your rear end probably won't be your biggest expenditure by far.
You could always just beef up the 10 bolt. If you don't plan on drag racing it on slicks every weekend, it'll probably be just fine.
You can't just nab any ol' 12 bolt or 9", you need it custom fitted to your car, so it'll have the spring perches and TA setup and whatnot. If you want to shoehorn in a 12 bolt from a different vehicle, axle measurement (length) is, again, the least of your concerns. Once you've fabbed up mounts for all the rear suspension, or swapped to a totally different suspension setup, you'll be close to the cost of a $2000 9"/12bolt rear from moser or the like, and it'll still be a butchered home brew, rather than the spiffy looking powder coated ones moser has. you definately pay for quality eh?

 

Yeah thats the plan I'll probably never run the track with slicks. Its suppose to be a daily driver street car so I want my street tires ran because I want my et I'll run on the street. So say I get a 10bolt out of a thirdgen. I can put in a posi and the gears I desire inorder to "beef it up" right? I know I can weld the axels for strength too. I guess thats what I'm doing then.

 

Any comments on a 9 bolt for a budget build? Guys on fbody said it was stronger than the 10 and is a step between the 10 and a 12.

 

good luck finding a good one an good luck finding parts.

 

Its only a very little bit stronger than a 10-bolt. Its nowhere near as tough as a 12-bolt or a 9".

If you want a good 'budget' rear end, use an 8.5" 10-bolt. They are quite strong.. almost as strong as a factory 12-bolt, and they can be found in almost any RWD GM cars from the '70s, F-bodies included. You'd have to figure out a way to attach the torque arm to it though. An aftermarket 12-bolt will have a torque arm mount, but a factory 12-bolt or 8.5" 10-bolt will not. You'd have to find a way to do it for it to work.

 

if you're not reallllll good at fab, just stick to your 10 bolt.
Based on your lingo, i'm kinda guessing you won't reach your HP goal. It's tricky, and you'll probably fall short, plus you want to cheap out, so, might as well beef up the 10 bolt.
I know i've personally made a handful of posts on how to do it, do a search with my username for a schwack of info.

 

Base on my lingo? What ever thats suppose to mean I'll put money my car reaches at least 450rwhp when I am done... Just because I am a studen and looking for the cheap way out doesnt mean I wont build the 500hp behind a shitty rear anyway.

As far as what I'm building. Its not that hard to build an 8:1 300-350hp motor and fab a turbo to it for an increase. I've done my fair share of research and questioning to know I am capable of doing this. Just because I dont know rears doesnt mean I dont know engines. Sorry for not knowing all the weld this replace that lingo in a rear. I am new to diving into the full knowledge of cars but I've worked my way through everything I am interested in and have slowly learned alot about engines, then about trans, now about rears. I'm actually quite interested in rears so I'd appreciat no further discouragment.

 

hey hey, relax guy, i'm a student too, and building my hotrod as well. I just set my sights lower, and more realistic, a 10:1 350, that'll make ~350HP.

And yea, it actually is pretty hard to fab up your own turbo on a carbed motor, and get it working well, otherwise you'd see every mcdonalds employee with a turbocharged vehicle. The sad fact is, many people scoop up the JY turbos or ebay turbos, with visions of fast cars, than they collect dust in their garage for many years, while someone who might have used it searches furiously...

But don't get me wrong, i'd be more than happy, and impressed, to see you prove me wrong, and get the 500HP car running for... next spring? if that's your goal. That would be cool. I'm just saying crap happens right? And if you have never built a motor before (which is what it sounds like, based on how you talk, just guessing here, meaning no offense), that you're probably biting off a fair bit. I went with an "easy" setup, tried tested and true, carbed V8, nothing fancy or exotic at all. and I still can't get the POS running right.

Anyway, you're taking on quite a big task, 500HP is nothing to sneeze at, it's terrifingly fast, i've never even ridden in anything with more than ~300+ HP... So i'm just saying, if you fail in your goal, and only get 380HP with your turbo setup (like, worst case scenario), you'll still be PLENTY fast, and, most importantly, your 10 bolt will probably live. Turbos build HP, not torque, which is a good thing as far as parts breakage goes.

There, i'm done here, good luck!

 

i wouldnt build a 9 bolt if u only want to spend 500 you arent gonna get much ring pinion and setup kit is like 300 there then for someone to do it your looking at more money the rear that i have is a redone 10 bolt with gears center section and axles + labor it was almost a 1000

 

Alright sorry I flipped but I have built an engine before and thats what brought me into cars. As far as fabbing up my own turbo thats my next section of day in day out reading. I need to learn how to read the charts ect. And the goal isnt spring lol its the spring of 08 so I have plenty of time... I know I've got my expectations set high but this car will see low 11's even high 10's as long as I dont crash it before then. Just gotta keep my head out of the cloud of running a flat 10 v8 street car daily driver. That just isnt gonna happen and thats why I am going turbo because you really only get the power when your mashing it. Realisticly 500hp is the absolute everything went perfect in my budget goal. Its not that rediculous if you really figure that you can easily build a 300hp 8:1 motor with a turbo cam that will run a 13 w/o the turbo. When you put a turbo on a stock 305 tpi you can yield an 50% power increase from the stock 200hp. Applying that concept to a 300hp motor BUILT for turbo and your looking at 500hp only being a 30 or 40% increase in power from NA.
Its amazing what a turbo can do... The only problem is building the engine for it right.

Now tha that rant is done and probably half of it doesnt make sense and or is jumbled... if I go with a 2nd gen 10bolt (the bigge one correct?) will the be any width issues like the 2" of tire overhang on the 4th gen 10bolts?



PS as for blowing through a carb its not that hard a weekend of renting a dye grinder and hacking up your brand new holley carb.

 

I spent $1450 on my 10 bolt. And behind my mild 355 it'll probably break.

Even if you use a stronger posi than I did, and pay less for the install than I did, you'll still be around 1000 to 1500 to get the 10 bolt done right.

So If I had researched before I built the rear, I would have bought the 12 bolt from Currie.

 

If I go with a 2nd gen 10bolt (the bigger one correct?) will the be any width issues like the 2" of tire overhang on the 4th gen 10bolts?

 

I would check out NastyZ28 Home Page... they can tell you more about 2nd gen rear end than most of us could. But yes, a 2nd Gen Camaro or Firebird would have the stronger 8.5" 10-bolt.

You would have to move all the brackets from your 7.5" to the 8.5" to make it work though. Most of them wouldn't be a problem, but the torque arm bracket might give you a headache.

 

Yeah so I think I am just gonna move all the brackets over to an old 12bolt because the 10 doesnt seem like it will be worth it. Now I just need to find a car that came with a 12bolt the same width or close to what my third gens is.