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M3Kris View Drop Down
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Points: 39 		Direct Link To This Post Topic: LSD upgrade, any thoughts
    Posted: 16-May-2006 at 12:41

Hello (e30)M3 race and trackday experts,

I am having my diff done because it started making noise. Now my thinking is while they are at it I can as well have it upgraded from 25% to 40% Lslip. But, what would it get me. I use the car for track days and to get to them and for the occasional drift practice.

Any thoughts on this? Thx, Kris

 
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Points: 1780 		Direct Link To This Post Posted: 16-May-2006 at 14:55
Drop, JON90 a PM, he's got some 40% slip rings in
his.    Mine are still sitting on the shelf........
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Points: 616 		Direct Link To This Post Posted: 16-May-2006 at 15:03
M3Kris

Is your noise an 'offbeat rotational droning' ? I think mine has got a prob!

Does anyone know rough costs for having a standard one rebuilt.?
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Points: 39 		Direct Link To This Post Posted: 16-May-2006 at 16:37

M3CK,

 

I have the wining noise, first when the diff oil was warm, now at all times. In NL and Germany they quote around 300 Euro for rebuilding the standard diff with normal wear. What is the mileage on yours?
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Points: 616 		Direct Link To This Post Posted: 16-May-2006 at 16:40
Just gone 100k (m)
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Points: 39 		Direct Link To This Post Posted: 16-May-2006 at 16:44
Mine has just over 100k m as well....recent oil change did not improve anything so have to go the rebuilding way.
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Points: 616 		Direct Link To This Post Posted: 16-May-2006 at 16:49
Snap!
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Points: 3450 		Direct Link To This Post Posted: 17-May-2006 at 05:24
Kris

Very worthwhile upgrade is changing the diff ratio as well

Assuming you have a standard car you will have a 3.25 diff. Change this to a 3.64 and it will make a world of differnece. Thats what I did with my Cecotto.
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Points: 292 		Direct Link To This Post Posted: 17-May-2006 at 05:59
My diff rebuild (std) cost me around £150.  I'd assume a little bit more (+£50? labour on top of the extra parts) if upgrading to 40% slip rings.
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Points: 616 		Direct Link To This Post Posted: 17-May-2006 at 12:46
Eamo

Is the recommendation to change to a 3.64 (40%?) diff so it's better for track use.....or.....better all round in and more in character with the car.? (If you know what i'm trying to say!)

Thanks for the figures 'jpb'
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Points: 39 		Direct Link To This Post Posted: 17-May-2006 at 13:42

Eamo,

I now have 3.25 which seems to suit the Spa racetrack and Ring. When I drive in Germany it is max if possible and then the standard gearing gives max revs at 250 kph on the clock. For shorter gearing I opt for 205-50 tyres. But what will be the advantage of having the 40% LSD, can I accelerate harder out of corners? 

The diff upgrade would be around 400 euro + some 150 for worn bearings etc.

 
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Points: 233 		Direct Link To This Post Posted: 17-May-2006 at 16:17

Originally posted by Eamo Eamo wrote:

Assuming you have a standard car you will have a 3.25 diff. Change this to a 3.64 and it will make a world of differnece. Thats what I did with my Cecotto.

Originally posted by 215m3 215m3 wrote:

I would not go with a 3.64 diff as the gearing is wrong. Go for either a 3.46 or a 3.73.

?????

Can someone please explain?

John
A properly sorted E30 M3 is still 'King of the Ring'
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Points: 3450 		Direct Link To This Post Posted: 17-May-2006 at 17:26
Upgrading your standard 3.25 diff to a 3.64 diff will vastly improve acceleration up through the gears however it will lower your top end speed by 10/15mph.


depending on what tracks you visit most can determine the best ratio diff to be used i.e. if the track is short, twisty with short straights then a 3.91 is perfect for you. However the down side to this is that your top end speed will reduced to around 120mph.
I found that the acceleration with this diff to be fantastic but road use was not nice as the car was at high revs most of the time.

the 3.64 while not having as much acceleration as the 3.91 was still a huge improvement over the 3.25 and a perfect compromise for regualr track and road use.

If however you have a evo2 or se which have a 3.15 diff, a 3.46 diff from the 320is would be a sensible upgrade.
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Points: 3450 		Direct Link To This Post Posted: 17-May-2006 at 17:29
sorry - also meant to say that hardcore m3 track guys will depending on the track change diffs based on the track they are going to
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Points: 233 		Direct Link To This Post Posted: 19-May-2006 at 04:02

Eamo,

I normally drive my car to the circuits which means on the motorway it normally does 4000 rpm (with standard 3.25). How much will that be with the 3.64 fitted?

John
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Points: 3450 		Direct Link To This Post Posted: 19-May-2006 at 04:27
JOhn

In that scenario I think you'll be hitting arond 4800rpm instaed
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Points: 3450 		Direct Link To This Post Posted: 19-May-2006 at 04:31
Actually John try this online diff calculator

Just enter wheel size, gearbox ratio and diff ratio
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Points: 39 		Direct Link To This Post Posted: 19-May-2006 at 05:05

Got my final quote for a reman diff with 40% LS and Z3M cover, total 580 euro ex. VAT.

John,

Which tracks are you visiting?
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Points: 825 		Direct Link To This Post Posted: 19-May-2006 at 06:04
Eamo where will I get the ratios for the standard gearbox please?
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Points: 3450 		Direct Link To This Post Posted: 19-May-2006 at 06:12
Originally posted by falkster falkster wrote:

Eamo where will I get the ratios for the standard gearbox please?



here ya go boss

click link
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