Rear End Swap

[toothandnail0]

I'm new to the ZHP world and I'm not too mechanically inclined, either.

My father swapped the rear end on his non-ZHP 330 to get from a 2.93(?) final drive to a 3.46 final drive ratio. He's suggesting I do the same on my ZHP as he likes the quicker acceleration and because reducing top speed has few implications at non-Autobahn speeds of daily driving.

My mechanic is quoting me at ~$900. Is this kind of mod worth it? What are the cons (besides price)?

[Hermes]

Is that with labor? Get a M3 rear end (Limited Slip)

[az3579]

That quote definitely doesn't include the cost of something. $900 is far too cheap, even if it's just parts alone.


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[JohnnyGraphic]

If that is the price for a non-limited slip including labor, then I think it's reasonable. Maybe even a bit high. The labor isn't that difficult and you might be able to source a 3.46 from an automatic (I'm assuming you have a 6 speed) that will fit right in.

This was one of the first 'performance' upgrades I did on my car. IMHO, it is one of the MOST worthwhile upgrades that you can enjoy in just about every gear on any street.

Johnny

[az3579]

Oh wait, hold on a second... Are we talking about an M3 rear end swap or a regular???


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[toothandnail0]

$900 includes labor.

I'm pretty sure this is not the M3 (limited slip) rear end. Besides the limited slip diff, what is the difference between the M3 rear end and a non-M3 rear end? Would that have a 3.46:1 ratio as well or even higher? Would a limited slip diff. affect my all-around/everyday performance?

And, yes my car is a 6 sp.

[Taliben]

I dunno man, you could source the parts for way cheaper and just do it yourself.

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[HokieZHP]

How much does a m3 LSD swap cost assuming I did the labor myself?

[az3579]

$900 includes labor.

I'm pretty sure this is not the M3 (limited slip) rear end. Besides the limited slip diff, what is the difference between the M3 rear end and a non-M3 rear end? Would that have a 3.46:1 ratio as well or even higher? Would a limited slip diff. affect my all-around/everyday performance?

And, yes my car is a 6 sp.

The difference is that the M3 diff is a limited slip diff. The standard E46 one is not.


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[Taliben]

Depends on where you got it from, but just for parts, i got quoted anywhere from 1200 to 2000 and that was a buddy's pricing.

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[JohnnyGraphic]

Yes, once you go to an LSD, it gets VERY expensive. It's a very good upgrade, but you have to ask yourself if it is worth the cost just to have an LSD. Others will probably chime in here as far as pros vs. cons of an LSD (mostly cost).

M3-I'm not sure, but I think their rear ends are quite a bit higher (numerically) aren't they? Also, I'm not sure if they will fit a standard 330/ZHP drivetrain.

I have a NON-LSD 3.46 diff (a 10% increase). You have to weigh the difference in cruising speed, fuel costs, parts/labor vs. performance/fun increase. For me, the 3.46 was perfect. I'm not so sure I would have liked a higher diff (numerically). In those odd moments, when taking off from a stop, the ramp-up in 1st gear comes VERY fast. Nice that it accelerates so quickly, but it 'changes' the way you drive. Not bad...Just different.

If you were local, I'd let you drive my car and see how you like it.

Perhaps if you told us what you want to accomplish with it, we could possibly answer YOUR specific questions/concerns etc.

Johnny

[kaboom]

An LSD is great for any performance car but after tracking my ZHP I came to the same conclusion most other e46 non m owners come to. With reasonable driving and good tires, even coming our of a tight second gear corned at wot, the ZHP doesn't have enough body roll or power to lift and spin the inside rear.

Now hooligan driving or drifting obviously requires an LSD. But that doesn't get you fast lap times.

[az3579]

An LSD is great for any performance car but after tracking my ZHP I came to the same conclusion most other e46 non m owners come to. With reasonable driving and good tires, even coming our of a tight second gear corned at wot, the ZHP doesn't have enough body roll or power to lift and spin the inside rear.

Now hooligan driving or drifting obviously requires an LSD. But that doesn't get you fast lap times.

After coming back from today's auto-x (like many auto-x events before it), I once again find myself in the "I seriously beg to differ" category. There were numerous corners where an LSD would have allowed me to properly put down a little more power without unnecessary wheelspin.

I desperately need an LSD.


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[M0nk3y]

After coming back from today's auto-x (like many auto-x events before it), I once again find myself in the "I seriously beg to differ" category. There were numerous corners where an LSD would have allowed me to properly put down a little more power without unnecessary wheelspin.

I desperately need an LSD.


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Takes one off camber turn to loose grip

[Taliben]

After coming back from today's auto-x (like many auto-x events before it), I once again find myself in the "I seriously beg to differ" category. There were numerous corners where an LSD would have allowed me to properly put down a little more power without unnecessary wheelspin.

I desperately need an LSD.


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welded diff? #winning

[Jlastor]

Is the M3 rear end compatible with ZHP sedans? I know that in order to replace the diff we must get the entire rear subframe, but is it trully that "bolt-on" on sedans? I have a nice deal on an entire subframe with the diff for about $500, and the guy is holding it for me until next week.

[M3TA5IN]

E46 M3 rear diff you will need the following.

Rear subframe
Diff housing
M3 sway bar (M3 diff will hit your stock sway bar)
M3 half shafts
M3 drive shaft (are you 5 or 6 speed?)
M3 abs sensors

Basically I would go with Quaife at this point if it was me.

Dont the steptronic ZHP have a 3.64 ratio? That is another option if you don't want to spend a ton.

If you can source the right diff out of a ZHP auto or step and do the labor yourself you could do it for a couple hundred bucks. Don't be scared, diffs aren't hard until you start trying to set ring and pinion gears yourself. Which you don't have to do.

Is a rear diff swap worth the money? IMHO one of the best damn mods you can do!!! Everyone talks HP gains Hp gains but for the money you spend to get more HP an the minimal impact it provides I say rubbish. Swapping the rear end is something you can truly feel and will give you way better acceleration. Will you have fancy dyno numbers to post? No, but who cares. This is one of the next things I want to do to the e90. Like said above, we don't have the ability to drive at high speeds like the autobahn and unless you are hitting some serious speeds on track I don't see any disadvantage.

[johnrando]

Yup. The only thing missing is the LSD. (on the STEP diff)

[Jlastor]

My car is a 6 speed MT zhp. Basically the person selling me the parts has a totaled M3 which I would use to get all the parts. I told him I would buy everything including the brakes, but now I see that the drive shaft changes. Could be a game-changer for me since I basically need to do my mods on weekends and have the car ready by Monday.

[M3TA5IN]

My car is a 6 speed MT zhp. Basically the person selling me the parts has a totaled M3 which I would use to get all the parts. I told him I would buy everything including the brakes, but now I see that the drive shaft changes. Could be a game-changer for me since I basically need to do my mods on weekends and have the car ready by Monday.

You need his driveshaft is all and you're good to go. 5 speed cars can't retain the stock M3 driveshaft.

Brakes would be nice, but if you're trying to budget yours will work but hell if you can get a good deal that makes things way easier. Just drop that whole rear end hub to hub and put it in yours.

[Jlastor]

Yeah, that is the idea, simply get the entire thing out of the m3 and into my car. Ill see if the drive shaft is good. Any idea if I cant source a good original m3 drive shaft?

[prowlerflyer]

That's my plan for the future, swap in an entire M3 rear end. Should be relatively easy over a weekend. It buys you a LSD (really needed w/TS2), slightly upgraded rear brakes and stronger axles.

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[danewilson77]

E46 M3 rear diff you will need the following.

Rear subframe
Diff housing
M3 sway bar (M3 diff will hit your stock sway bar)
M3 half shafts
M3 drive shaft (are you 5 or 6 speed?)
M3 abs sensors

Basically I would go with Quaife at this point if it was me.

Dont the steptronic ZHP have a 3.64 ratio? That is another option if you don't want to spend a ton.

If you can source the right diff out of a ZHP auto or step and do the labor yourself you could do it for a couple hundred bucks. Don't be scared, diffs aren't hard until you start trying to set ring and pinion gears yourself. Which you don't have to do.

Is a rear diff swap worth the money? IMHO one of the best damn mods you can do!!! Everyone talks HP gains Hp gains but for the money you spend to get more HP an the minimal impact it provides I say rubbish. Swapping the rear end is something you can truly feel and will give you way better acceleration. Will you have fancy dyno numbers to post? No, but who cares. This is one of the next things I want to do to the e90. Like said above, we don't have the ability to drive at high speeds like the autobahn and unless you are hitting some serious speeds on track I don't see any disadvantage.

Added to DIY thread.

HTC Thunderbolt+TT

[Hornung418]

So I just found out some super information for those wishing to swap their rear end for the M3 LSD!!


The e46m unit can be re geared with Oem m division ring and pinion to 3.23 and 3.15 ratio. LSD center can be clutch type or gin visco-lok. I just built one up for turbo use (3.15 e46m clutch LSD diff). This would allow non m cars to Pnp a LSD in matching ratio to a 6500 rpm engine with a m3 rear subframe swap.

The e46m rear diff can be configured with genuine BMW parts to have a 4 bolt front flange that will mate with non m 4 bolt driveshaft 4 bolt pattern, this would allow upgrade of e46m of diff without buying a zhp 6 bolt driveshaft

Also the late model 2005/6 325ci/cabrio 6 speed SMG cars have a 4 bolt driveshaft in 6 speed length, they run a ZF 6 speed gearbox with identical length and mounting position in the body to the e46m gearbox.

So we can get the LSD from an M3, although pretty weak compared to aftermarket options, but swap the ring and pinion for a more useable ratio.

See the entire thread HERE (http://forum.e46fanatics.com/showthread.php?p=14255263) on e46fanatics.