Hi, guys I need the advice from some fellow third gen members. I have a 1982 Z28, and I want to do the famed third gen LS swap, I have all the motor and transmission components all chosen, but I have a question about the rear end. I want to keep the stock rear axle but I'm unsure if it can take the power and stress from the LS. What would I have to do to keep it, I am swapping out the diff to a posi though: would I just have to get stronger axle-shafts, or new housing, or what? I really like the way that the rear-end fits, and there are a lot of nicer wheel options for the 3rd gen rear-end setup as compared to swapping to a 4th gen rear-end. Please any responses would be greatly appreciated.

 

No help here but in same situation with my 91 camaro. In for answers.

 

If you’re planning on launching the car hard with slicks/sticky tires than you might want to consider a 9" or 12 bolt to handle the load. If you’re going to run street tires that won’t hook than a 10 bolt upgrade might be for you. Some of the guys here have pushed a 10 bolt to some amazing times and made quite a few passes at the track so it can be done.

If you swap out your stock differential to a"new" posi unit most of us upgrade the new posi/carrier to 28 spline and buy 28 spline axles to match. They are thicker than the 26 spline axles you have so stronger. Also you will now is a good time to upgrade to a 3.42,3.73 or higher gear ratio. It’s not cheap/inexpensive to replace your stock parts to new. Here’show I built mine https://www.thirdgen.org/forums/tran...de-photos.html
A 90,91,or 92 should already have 28 spline axles but the rest should apply.

 

I really like your setup man, very nice. So if I start pushing out 500+ with the LS would you recommend going to a 12 bolt setup? and does that fit in the stock housing or would I just have to swap to a different housing?

 

Most go with a 9".

Don't let the price scare you. There are other ways to build a 9" that wont cost as much. Still quite a bit more than a 10 bolt build but it won’t break. These are what the big boys are using and what you will need if you start launching/hooking with that kind of power.
= http://www.spohn.net/shop/1982-1992-...-Complete.html

 

If you're running a manual or slicks, just keep an eye out for used aftermarket 12 bolt or 9 inch. Maybe a Dana 44. No reason to posi yours and break it soon after.

 

I agree. If you want to start putting down higher hp, spend the money for a rearend that can take it. No point in building a 500 hp motor and then not being able to use it in fear of breaking your stock rearend. Spend the money now and be done with it.

 

This x2

I know lots of ppl on stock 10 bolts running between 9's and 12's in the 1/4 with automatics and sticky tires with no issues. Try to find a 4th gen zexel torsen diff and 28 spline axles from a later 90-92 fbody. They are stronger and shouldnt break. I beat the hell out of my 4th gen 10 bolt and been many 1.50's to 1.41 60' times on 9-11 sec combos and lived

My 127k mile 99 trans am has been 1.6's at 3600 lbs and low 12's just fine. I wouldnt worry with an auto and no tbrake

Manuals, you have to be careful and not do higher rpm clutch drop/quick slips on sticky tires. They break alot of 10 bolts on stock motors let alone any mods. Now some have lived behind 10-11 second cars but you have to shift softer and launch softer

 

Maybe Orr89Roc can help out here but will a car making 500 hp be streetable.
And don't you have to have a roll cage at the track with that kind of power. Also beefing up the 350 he has can get him around 400hp and still be nice to drive on the street, right ? If its primarily a street car 500 hp IMO is a little over the top especially if the OP has never driven some thing with that kind of power.

 

500 is very streetable in an lsx motor once well tuned. Thats the key.

You can do 500 or more on a sbc and still be streetable. My combos are pretty wild by most standards but the car is street driven and no real issues. Drives fine but its all in your definition of what streetable is. To me there is nothing wrong with a 800-1000 hp turbo car on the street

Roll bar is for 11.49 or quicker et's i believe. If car is light enough you can get there with less than 500 hp but generally most cars will need closer to 500 since they arent optimized for drags

 

Update the internals as suggested above and use one of these covers. It helps to strengthen the housing and wont allow the pinion gear to walk up on the ring gear as much. A stock ls is not gonna put much more to that rear end than a L98 350 TPI.

 

My question would be after modified an engine to make 500 hp or more and being on the street how and when do you get to use WOT. Would you only be able to feather it from a stop light or any where for that matter without the tires breaking loose? And if it’s an automatic would you need a higher stall converter so you will need higher RPMs when pulling away from a light? What I'm trying to say is what is "different"between driving a 500 hp or higher car and a stock LS on the street? What will change with your driving style? Nice to know if its your first time driving a car with that kind of power.

 

Depending how you go about making the power. A stock ls is more than capable of tearing tires apart after 3000 rpm on stock stall. A cammed ls1 will like a looser converter but it isnt necessary. You just may have a softer bottom end feel since ls engines make best torque in the 4000-5000 rpm range. Alot higher than tpi. Bottom end off idle is alittle more sluggish but still plenty to move the car. So a big cam small cube motor may be abit more difficult to drive than a big cube motor because of where the power is. Thats why street motors making big power should be large cubic inches to keep a lower rpm power band and to make that torque

So if you had good heads and a smaller/medium cam that made 500 hp, you could drive it like a stocker, but wot is gonna be alot faster and likely more capable of spinning tire on the right downshift and speed. I like drag radials on the street to help combat this.

If you do a converter with high stall, you will need to get used to it. But they are every bit as driveable, just have alittle more rpm off the line. Especially up hills. Its not terrible tho. Just need to be aware of it. I actually think a converter gives you more control over the cars power because of the slipping effect

My first time driving a stalled car really opened my eyes and would spin tire quite easily because i was so used to giving more gas to move a stock converter car from a stop. But once you get used to it, its a great mod to have

 

See that's exactly the info I was hoping for. Modifying my car with even bolt on's is taboo here with smog. Anything from the cat back is OK but I even have to swop back to my stock air intake assembly every two years when I take it in to have it checked. When the time comes to replace the 5.0 I am going to try to sneak in a 350 that looks identical to what I have now.. Maybe aslightly larger cam if that's even possible.

This is the reason why I went and spent the money to upgrade the differential. With that and a Corvette servo it has given me a car that's RELLY fun to drive. I have found that I have to respect the power/torque my car has. It may only be a 5.0 but its quick off the line and that's plenty for my stop light to stop light DD driving.



Side note = I like it when you say that a modified 10 bolt can take some abuse. Makes me feel even better about my build.

 

So he shouldn't bother changing rear diff, nor engine. Got it.

 

Thank you guys a bunch for all info, I think I might reconsider the LS for now and just focus on strengthening all of the rear end components . My overall goal is to make the car a true performance monster like they used to be, but able to somewhat compete on a modern level. Hopefully sometime soon I can really start my build now I've got the car alive again, I'll have to keep you guys posted. Again thank you all

 

if your going to run the car any more then a few times in the summer. and run over 350hp. it's your pinon gear that lets go.

have done it 3 times before going to a 9" back in 94.

have had all the bolt on goodys. for 7.5 ten bolt they make.. the T/A support cover to the beefy you name it.. sticky tires and a 1.54 60 foot.. say goodby to your ring gear..have a stack of ring and pinons that say so..

dump the 7.5.. it will let you down. when you make power!

 

I wouldnt invest in parts to beef up 10 bolts. I would just use stock posi's from 4th gens and gm 3.42 gears from 4th gens. Thats all. If breaks find another rear drop out, and save for a 12 bolt or 9"

Trust me, a mild ls1 thru an auto wont hurt a 10 bolt for as little racing you will do on sticky tires. For street you wont hook as much so you will not stress that rear

My 4th gen has 127k miles and been on stock rear. I had it for 3 years and been racing alot at 3680 lbs. its fine
I've put 800 hp thru a different stock 10 bolt and never broke it. 9.73 1/4 mile and that car always is on the throttle when i have it out. Not saying everyone will be as lucky but they can take alittle abuse

 

Where did you assume I said All that. He did not say he was putting a MONSTER engine or anything like that. Just an LS swap. A good ,tight ten bolt will hold you for a good while. For a couple hundred bucks you could swap worn out 4th gen rear ends every year or two. They are a dime a dozen if you look and are no stronger than the later third gen 10 bolts.

If you are not going to put slicks on it and are not into side stepping clutches I would think a fresh 10 bolt will hold for quite a while.

Ultimately It is your Money and decision.

YOU CAN BREAK ANYTHING IF YOU ABUSE IT RIGHT..

 

I need someone who Has ls swapped cars before to tell me how much money they spent on their cars and if this project would be possible. I am new to this website sorry If I messed up posting this

 

The cost for a swap is going to depend on what you want to swap and what your mechanical ability and aptitude is.

If you are comfortable doing the work yourself and take the time to source your parts (junk yards, etc) then you could be in for a few thousand.

If you go all new and have a shop do the work then the sky is the limit on how much it would cost.

Check out the search bar at the top right corner of the page. You can type in keywords like "LS Swap" or even just "Swap" and get tons of threads where people have done this work.

Additionally if you look in the upper left corner and click on the "Forums" drop down box you will see that there is an entire sub-forum dedicated to Engine Swaps. If you click on that you'll find all kinds of info.

 

I've seen swaps done for $2k and swaps that are $100k. All depends on what you want, what you are willing to do yourself, and how many tools and resources that you have on hand. There is no way to answer this without knowing a little more detail. I'd spend some time reading up in the swap forums. Start with the locked threads (stickies) at the top of the page and spend some time reading. After that, read them again and again. You will start to see what options you have, what it entails, and other obstacles and considerations that need to be tackled.

 

If you do "Road Kill" style with just bare minimum to get the car driving and sell your old parts, then you can do it for about what you pay for the engine and trans with wire harness and ECM.

Start adding $1K to $3K for each thing you want to upgrade after that.