NEW to BMW, rear diff strength/improvements

[jonaddis84]

Hello, I am extremely new to these cars, dont even own one, but want to soon. You guys might hate me for this, but all I really want is the body, I will be swapping in either a 6-700hp N/A SBC or a 1000+hp Turbocharged LS1 or SBC.

In either case, I dont think the stock rear diff in a say '95 325Ci 5spd (the car Im hoping to get), is up to the task of handling over 600lb/ft of torque.

So what are my options? I dont know much about IRS as all Ive owned is a 4th generation camaro (500hp+slick road=wrecked). Im guessing Im either going to have to spend a buttload of $ to upgrade the IRS or swap in a live axle out of a domestic.

Before you criticize too much about other things. The car will first be recieving a 10+ point rollcage to keep the frame straight. And I know for a fact that this swap can be done, at least with an LS1 and a 6spd, sounds like it all went smooth for the guy too.
http://www.nash8503.com/index.html

Thanks for any info provided, the project is still just thoughts inside my crazy head so I have some time for research.

 

[Kirby]

I doubt even a M3 rear would hold up to that. You can at least start with these two sites. They supply racing quality parts and could tell you if they can supply something, or where to find it:

www.bmwdiffs.com

www.tckline.com

 

[jrt67ss350]

Hey jon - welcome to the board!

First off, as a fellow Camaro guy, let me warn you that you are going to get all kinds of crap from the BMW purists about this. Don't listen to them. If you want to undertake the project, by all means, go for it. That aside, I think it's a cool thing to do, especially if you have the skills/means to fabricate up the needed brackets and modifications and make them look cool. I like originality in projects like this one that you are going to undertake.

Yeah, the original 325 diff almost definitely isn't going to stand up to that kind of torque and hp. You could swap in an M3 diff, but I'm not even sure that would hold up to that kind of power. Then, you'd have to worry about destroying the halfshafts. I think you'd be better off (and probably cheaper in the long run if you can fab the adaptations yourself) to go the Ford rear end route like in the link you provided.

Definitely keep us posted (at least I'm interested) on what you discover.

Definitely stick around and ask any BMW questions you have. You sound like you are already well-versed in SBC knowledge, but if you need any help in that department, I'd be glad to help out where I can - I'm a big Chevy guy.

If you are interested - check out my Camaro. www.furman.edu/~jtrauner

 

[epj3]

The only problem I see, as both said, is the E36 chassis will NOT hold up to that. Honestly you'll twist that chassis the first time you accelerate hard, especially with the unimaginable torque you'll be making. E36's have problems with the body falling apart with the stock 160 - 190 hp, let alone 1000. If there's any bmw you can put that kind of power in, it would honestly be an E34 (5 series) with major reinforcements, an e30 with major reinforcements, or a super dooper reinforced e46. E36 would probably be the last BMW I would put that kind of power into.

BTW if anyone gives you crap about THAT, they should just ignore it. I'm usually against that stuff but a turbo LS1 would just be insane.

 

[frolf]

make sure you swap turns signals up front, that orange stuff wasn't engineered in the e36 and you will most likely shoot turn signal fluid all over the place the first time you jump on the gas. e34's didn't have this problem, neither did e30's or e21's, it alllll started with the e36 because BMW said it had "thunderous" horsepower even though it never broke 200bhp unless you went with the m3. even then 240bhp isn't ANYTHING, i really mean nothing at all, not even fun, just boring ya know. especially when at 190bhp if i dump the clutch just right i can get all the plastic inmy e36 to rattle reall hard, and it makes up for me needing an aftermarket exhaust just to sound cool. one mod that will score you major points and make it feel like your old camaro is if you dilute your brake fluid and go 50/50 water and brake fluid.

now that i have my "purist" bmw rant out of the way that JRT predicted i will give a two cents that won't piss you off.

1. e36's are not the bad cars that people make them out to be, they are the scapegoat for people who don't own them.

2. even if you somehow get 600bhp to the wheels through a CRAZY custom rear end, with the kind of rubber you can fit under an e36 without heavy modificatoin what will it matter.

3. back to my bmw purist rant that JRT predicted would come, sounds like a heavy motor dude, reall take that into account for what you are going to do with the suspesnion, the 10 point cage is more even weight, but that big motor out front is going to change a LOT of things.

 

[epj3]

make sure you swap turns signals up front, that orange stuff wasn't engineered in the e36 and you will most likely shoot turn signal fluid all over the place the first time you jump on the gas. e34's didn't have this problem, neither did e30's or e21's, it alllll started with the e36 because BMW said it had "thunderous" horsepower even though it never broke 200bhp unless you went with the m3. even then 240bhp isn't ANYTHING, i really mean nothing at all, not even fun, just boring ya know. especially when at 190bhp if i dump the clutch just right i can get all the plastic inmy e36 to rattle reall hard, and it makes up for me needing an aftermarket exhaust just to sound cool. one mod that will score you major points and make it feel like your old camaro is if you dilute your brake fluid and go 50/50 water and brake fluid.

now that i have my "purist" bmw rant out of the way that JRT predicted i will give a two cents that won't piss you off.

1. e36's are not the bad cars that people make them out to be, they are the scapegoat for people who don't own them.

2. even if you somehow get 600bhp to the wheels through a CRAZY custom rear end, with the kind of rubber you can fit under an e36 without heavy modificatoin what will it matter.

3. back to my bmw purist rant that JRT predicted would come, sounds like a heavy motor dude, reall take that into account for what you are going to do with the suspesnion, the 10 point cage is more even weight, but that big motor out front is going to change a LOT of things.

Actually the e36 was the first BMW designed with the aid of computers, and are arguably one of bmw's most problematic cars. So don't act stupid. I've said I'd buy one and I'm not lieing, but they are still arguably one of the weaker cars. As justin posted in another thread - a LS1 weighs just about the same as the S14 in the e30 m3.

 

[epj3]

You're right. My judgement when driving and test driving good condition e36's must be skewed becuase I compared them to the cars I owned. I dont give a shit about the water pump. They arent as sturdy. Simple fact, can't change that.

hahah nice deleted post dan

 

[frolf]

come on silly pants, my e36 drives just fine. sure the waterpump has gone, but everything else is money g's. nothing has fallen apart, weird huh? i can't wait til you eventually own an e36 then go back and read all your stupid posts ragging on them.

 

[epj3]

come on silly pants, my e36 drives just fine. sure the waterpump has gone, but everything else is money g's. nothing has fallen apart, weird huh? i can't wait til you eventually own an e36 then go back and read all your stupid posts ragging on them.

Dan, we've gone through this time and time again butt buddy! I rag on them on atrt becuase its what you own. If you owned an e30 i'd find a reason to make fun of it becuase you own it. I'm sure you saw this " I've said I'd buy one and I'm not lieing, but they are still arguably one of the weaker cars" becuase that's true.

 

[frolf]

this is what i read

e30's and e34's are the best because i own them, i know everything because i parted out my e30, bla bla bla bla bla

and you're trying to tell me this isn't what you typed?!?!?

 

[epj3]

this is what i read






and you're trying to tell me this isn't what you typed?!?!?

No but i will say i know more about the mechanics of a car than you (unless you've rebuilt engines and never told me)

 

[frolf]

yeah you do, but i'm also not a dumbshit and you can't keep selling people on how crappy e36's are when they are not. maybe i can be fortunate enough to get in a head on someday, then i can be at your mechanical level.

 

[jrt67ss350]

Well, I've helped destroy a few E36s in my time, and I must say that they aren't as sturdy as the E30s.

I can't comment on how durable the E46 is compared to the E36 or E30 because I haven't abused one of them.

 

[jrt67ss350]

Actually the e36 was the first BMW designed with the aid of computers

Is this true? That's interesting because the 1967 Camaro was the first GM car to be designed with the aid of computers (although very primitive ones).

 

[epj3]

Is this true? That's interesting because the 1967 Camaro was the first GM car to be designed with the aid of computers (although very primitive ones).

This was posted on a forum that both dan and I frequent and you can't refute any of them.

Has anyone ever been in an e36 318ti? Ick. Dan my whole point is that the quality is lower than most bmw's. It is. But the fact I still say I'd buy one means that there are more good things than negative about them (like it says in the article clip). I had more automotive knowledge than you did when I was 15 and helped a friend rebuild a 4g63 motor so being in an accident and having to part your car becuase you otherwise couldn't afford another one (when you dont have parents who wont buy you stuff, its tougher). And hey, when you're going to a commuter college and you need to work to pay for that college, you do what you need to do to get a reliable car.

For all its good qualities, and there are many, the E36 3 Series has proven to be the least durable and least reliable of all the 3 Series body styles. Its overall quality is generally not up to the standard of either the preceding E30 or the succeeding E46...

The E36 also suffers from having been BMW's first CAD-built car. Computer Aided Design tells engineers exactly how strong components have to be, and it tells bean counters the same thing. By contrast, pre E36 BMWs were designed using mathematical calculations and rigorous testing to figure out how strong a component had to be - and then the engineers would apparently double that, which explains why we can modify an E30 3 Series suspension 200% beyond factory specifications and never have the rear suspension carrier tear out of the rear floor. Not so the E36, although rear floor failures are admittedly rare. Electronic problems are common, however: expect anything electronic to break eventually, from the ECU to the climate control.

 

[jrt67ss350]

I've never been in a 318ti, but I've been in a couple E36 318i's that were built in the plant in Spartanburg, SC and they were really crappily built - I told myself I'd never have a BMW after riding in those cars. Famous last words, huh?

 

[epj3]

I've never been in a 318ti, but I've been in a couple E36 318i's that were built in the plant in Spartanburg, SC and they were really crappily built - I told myself I'd never have a BMW after riding in those cars. Famous last words, huh?

Can you believe I was considering a few mid-90's A4's? Thank god I found the e34 before becoming despirate. Talk about money pits.

 

[frolf]

This was posted on a forum that both dan and I frequent and you can't refute any of them.

Has anyone ever been in an e36 318ti? Ick. Dan my whole point is that the quality is lower than most bmw's. It is. But the fact I still say I'd buy one means that there are more good things than negative about them (like it says in the article clip). I had more automotive knowledge than you did when I was 15 and helped a friend rebuild a 4g63 motor so being in an accident and having to part your car becuase you otherwise couldn't afford another one (when you dont have parents who wont buy you stuff, its tougher). And hey, when you're going to a commuter college and you need to work to pay for that college, you do what you need to do to get a reliable car.

you are soooooo smart

i say this argument comes to an end now. not cause your 15 yr old self beats me at 15 in the realm of mechanical knowhow, but because i can see you become more and more childish with each and every post and i'm trying to save a little face for everybody.

 

[Kirby]

For all its good qualities, and there are many, the E36 3 Series has proven to be the least durable and least reliable of all the 3 Series body styles. Its overall quality is generally not up to the standard of either the preceding E30 or the succeeding E46...

The E36 also suffers from having been BMW's first CAD-built car. Computer Aided Design tells engineers exactly how strong components have to be, and it tells bean counters the same thing. By contrast, pre E36 BMWs were designed using mathematical calculations and rigorous testing to figure out how strong a component had to be - and then the engineers would apparently double that, which explains why we can modify an E30 3 Series suspension 200% beyond factory specifications and never have the rear suspension carrier tear out of the rear floor. Not so the E36, although rear floor failures are admittedly rare. Electronic problems are common, however: expect anything electronic to break eventually, from the ECU to the climate control.

There are REALLY only 2 FACTS here (in bold), the rest is conjecture and pure opinion by a magazine writer. I can easily disprove at least one of his opinions. He says the E36 is not as reliable as the E46. Count the number of posts related to electronic problems here or anywhere else and compare E36 to E46 - E46 is worse hands down.

His comment about "design and double" is pure crap.

Just because it is in print in a magazine doesn't mean it's fact...

 

[epj3]

There are REALLY only 2 FACTS here (in bold), the rest is conjecture and pure opinion by a magazine writer. I can easily disprove at least one of his opinions. He says the E36 is not as reliable as the E46. Count the number of posts related to electronic problems here or anywhere else and compare E36 to E46 - E46 is worse hands down.

His comment about "design and double" is pure crap.

Just because it is in print in a magazine doesn't mean it's fact...

Ok - but this forum is mostly e46 owners. If you go to bimmerforums you'll see 5x more posts about electrical problems in e36's than e46's. Besides the reliability thing (becuase if we were concerned about reliability, we'd all be on honda forums instead), you really can't argue about the body strength. There are so many reinforcements for the e36 chassis, both in the rear and the front suspensions. I've only heard of a few E46's having that problem, but not many.

Again I'm not bashing the e36 or saying it's a bad car - but I am saying its build quality simply isn't as good as the cars before and after it.