# LSD/Final Gear ratio conversion for ZHP



## wheel-man (Sep 28, 2004)

Just wondering if anyone has any experience or recommendations about the best way to proceed with an LSD and changing the final gear ratio (? 3.61) to one similiar to the E46 M3.

I know Rogue Engineering just grafted the E46 M3 rear differential/brakes/suspension to their E46 wagon, but was wondering if anything from Quaife, etc has been done.

Thanks in advance.


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## Raffi (May 18, 2002)

Do a search here, it's been done before. 3.61 would be way too high, imo.


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## MicahO (Apr 19, 2004)

wheel-man said:


> Just wondering if anyone has any experience or recommendations about the best way to proceed with an LSD and changing the final gear ratio (? 3.61) to one similiar to the E46 M3.
> 
> I know Rogue Engineering just grafted the E46 M3 rear differential/brakes/suspension to their E46 wagon, but was wondering if anything from Quaife, etc has been done.
> 
> Thanks in advance.


The slip rear in th ZHP is a 3.07, slight step up (down/whatever) from the 2.93 in the non performance package 330i stick.

Ben did a swap of a whole rear end and got the M differential, but he also swapped the motor and tranny, so he ended up with a rear end ratio that was well-suited to the gear ratios feeding into the diff. His surgery is not for the faint of heart or wallet, but you do end up with a very strong rear, and the M locking diff is a torque biasing rear, like a Quaife unit. Nice to have. Once the M rear and carrier are in there, there are a LOT more options for differentials not available in the normal e46 rear.

Limited slips can be built by a couple of shops. Brett Anderson of Koala Motorsport writes:

~snip~
We do a custom LSD for the E46. It's 80% custom fabricated parts, and the housing is so tight that we have to build it inside the diff case, it can't be "inserted" like earlier diffs.

As a result of the custom parts and the difficulty of assembly (about 9 hours to build), they're not cheap. $2650 is the base cost, if you don't want a ratio change. $3950 is the highest cost. Price is ratio dependent, between those two numbers. If you want to keep the 3.07, it's $2650. 3.91, 4.10 or 4.33 are $3950. There is a middle ground, 3.15, 3.23, 3.38 and 3.46 are $3250 and 3.64, 3.73 are $3750 
~snip~

Dan at Diffsonline.com also builds into the e46 case, using a Kazz LSD unit. The size of the Kazz unit restricts him to a minimum (maximum, whatever) ratio of 3.15:1. Since there is a ratio change required, his cost will be about $2800. Other ratios are available at the same price. His recommendation was actually a 3.46, too big of a change for me, but it would add some serious 'pop.'

Core charges apply to both of the above items.

Turner Motorsport also sells their own e46 racing diffs for around $4500 each, no core available - they just sell you a complete new diff and have no use for your old diff or parts.

Quaife does not yet make a unit that fits in the 188 case on the e46. From my own calculations, a 3.15 would keep you in second gear just past 60mph, and let you finish the Quarter without a shift to fourth gear. Something like a 3.38 or higher would give you a good bit more torque multiplication, but will force an extra shift for both 0-60 and quarter mile runs. The shorter gearing will also have an effect on overall gas mileage, though 6th gear on these cars is pretty steep anyhow.....


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## Andy (Jul 16, 2003)

I'll be installing an LSD this winter.

I'll be getting it from Jim Blanton from Performance Gearing. This guy is highly recommended by some of the best BMW race teams in the country&#8230; Turner Motorsports, TC Kline Racing and BimmerHaus.

You can get one for about $4000.


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## MicahO (Apr 19, 2004)

Andy said:


> I'll be installing an LSD this winter.
> 
> I'll be getting it from Jim Blanton from Performance Gearing. This guy is highly recommended by some of the best BMW race teams in the country&#8230; Turner Motorsports, TC Kline Racing and BimmerHaus.
> 
> You can get one for about $4000.


NICE! I didn't know that Jim Blanton was now doing diffs for the e46. One more option.


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## bluetree211 (Apr 19, 2004)

rumratt said:


> I just find it annoying that the 330 doesn't have an LSD as an option, and there aren't even any reasonable cost aftermarket options available.


 :stupid:
I got lucky and found someone selling their slightly used kaaz 3.46 LSD for < $1500


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