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  #1  
Old 06-23-2004, 12:10 PM
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teamdfl teamdfl is offline
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E30 limited slip diffs for autox: Quaife vs. factory

I'm looking into rebuilding a diff for my E30 autocross car for some semi-serious autocross use. As far as I know, my options are a factory limited slip unit (with an extra clutch or two) or a Quaife. Anyone care to offer any opinions on my choices? In theory, the Quaife offers better turn-in but at significant added expense. Factory LS units with extra clutches will be much easier on the wallet thanks to the collection of diffs in my garage in various states of crunchiness. If I go for a factory unit, how many extra clutches should I add? Do I even need extra clutches at Street Prepared levels of power assuming the diff is in good shape?

FWIW, I would like to build up a 4.10 diff. If funds are available (which means factory LS unit), I would like to build up a 3.91 for faster SCCA courses too.


Ed
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  #2  
Old 06-23-2004, 04:21 PM
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Bruce Bruce is offline
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Mein Auto: 88 E30 M3.2, 08 451
I have an E30 M3 4.10 LSD for sale.

PM me if interested.
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  #3  
Old 06-24-2004, 09:59 AM
dngo dngo is offline
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I went with a Quaife for a few of reasons:

1. My driving style lends itself to how the Quaife works.
2. I didn't want to deal with higher lockups on the street with a clutch-style diff.
3. The Quaife will not wear out over time like the clutch style LSDs.

You can make a clutch diff work much like a Quaife by changing the ramp angles. This doesn't get around the problem of wear, though. Extra clutches give you additional lockup - from what I've seen, 40% is about as high as you want to go on the street. Otherwise you'll get funky binding noises when making tight turns. I'm not sure how many additional clutches bring you up to 40%, though.

If you do end up getting a Quaife, I'd seriously look into a finned diff cover for it as the Quaifes get hot on the track. Do M Roadster diff covers fit E30 diffs? If so, you may wnat to look into buying a factory Torsen unit from a Z3 from a junkyard - 3.46 gears (can always replace those) and much cheaper than a Quaife.

You can drive my car at this Sunday's event to try out the Quaife if you'd like.

Dave

Quote:
Originally Posted by teamdfl
I'm looking into rebuilding a diff for my E30 autocross car for some semi-serious autocross use. As far as I know, my options are a factory limited slip unit (with an extra clutch or two) or a Quaife. Anyone care to offer any opinions on my choices? In theory, the Quaife offers better turn-in but at significant added expense. Factory LS units with extra clutches will be much easier on the wallet thanks to the collection of diffs in my garage in various states of crunchiness. If I go for a factory unit, how many extra clutches should I add? Do I even need extra clutches at Street Prepared levels of power assuming the diff is in good shape?

FWIW, I would like to build up a 4.10 diff. If funds are available (which means factory LS unit), I would like to build up a 3.91 for faster SCCA courses too.


Ed
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  #4  
Old 06-26-2004, 11:51 AM
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TeamM3 TeamM3 is offline
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Mein Auto: a BMW killer
before yo do anything, what autox class are you intending to run?

If you lift an inside wheel (or it bumps off the ground) with a Quaife/Torsen it ceases to function as a limited slip.


depending on how serious you are:

----------
This tech information comes from Jim Blanton, owner of Blanton Transmissions. Jim is a well known and respected individual in the area of BMW transmissions and differentials. Blanton Transmissions performs rebuilds and upgrades on BMW transmissions and differentials to each individual owners specifications and requirements. Jim Blanton can be reached here:

Blanton Transmissions
1427 West 9th Street
Kansas City, MO 64101
816-221-8584
jblanton@sky.net
http://www.performancegearing.com/aboutus.asp
---------

http://www.kaazusa.com/default.asp

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http://www.koalamotorsport.com/mall/...ribequaife.htm

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  #5  
Old 06-26-2004, 08:04 PM
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teamdfl teamdfl is offline
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Quote:
Originally Posted by TeamZ4
before yo do anything, what autox class are you intending to run?

If you lift an inside wheel (or it bumps off the ground) with a Quaife/Torsen it ceases to function as a limited slip.


depending on how serious you are:
After winning two regional championships in a row several years ago in ESP with a different car, I'm considering getting back into SCCA Solo2 by running DSP with my E30 325i.

I have enough threaded adjusters and 2-1/2" ID springs lying around to kill an elephant. I'll probably redesign my old camber plates to take advantage of the significant amount of room in an E30 strut tower. A good set of used swaybars is already sitting in the corner of the garage. Items that will require captial investment include a good set of shocks and struts, exhaust parts, clutch and lightweight flywheel, and a diff.

I guess if I wanted to be realistic, I would just rebuild a factory LS diff because the Quaife would represent a significant portion of the cash required to get my E30 up to regional or perhaps divisional competitiveness. Parts for a for a factory diff rebuild will run me $300 or less. The Quaife alone is $1000+. Is the difference better spent on shocks/struts? On a 60 second course, what time advantage will a Quaife offer over a well built clutch type limited slip? Assume the courses are flat enough that wheel lift is insignificant.

The loose nut behind the wheel is a whole different story.


Ed
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