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  1. #1
    Teddy
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    Info on LSD differential for e38

    I have alot of questions abuot the dif for the e38. First of all, I have a 95 740il. And at Dinan, for a 96 and on, you can get 3.15 dif for 1,500, while for the 95, its over 4k. Would the 3.15 work in a 95? ALso, i heard abuot vac motorsports, and was wondering how much a dif would cost for a 95 740il from vac motorsports
    response much apprecaited
    Teddy


  2. #2
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    95 already has a 3.15 rear


    Greg
    95' 740i
    Greg's E38 Pages


  3. #3
    papadoc
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    Dinan rear diff for '95 E38


  4. #4
    papadoc
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    Re: Info on LSD differential for e38

    The Dinan differential for the 95 E38 is a 3.73 diff which will give you the best performance upgrade short of supercharging. They do not make this differential for the later years to my knowledge, but it makes the car much quicker and you do not sacrifice much re: freeway cruising. Talk to Jeff at Dinan in Mountain View and he will give you the straight scoop. This was easily the best performance upgrade I did for my E38.

  5. #5
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    I went for a VAC 3.45 (or is it 3.46) (m)

    I looked seriously at the Dinan diff, but could not justify $2k more just for the name... The '95 has a 3.15 - but it is an open diff. There are many advantages to going to LSD. I thought the 3.45 offered the best compromise for my '95. I could have built a 3.73 for the same dollars, but felt that it was too extreme for my needs.

    Bottom line: Dinan 3.73 LSD at $4k, or VAC at $2.2k.... I believe VAC quality to be at or above Dinan. You also have your choice of which gearing to go for. Tony at VAC is very knowledgable and they build diff's for many other shops.

    I hope not to sound overly negative about Dinan products. They build quality products and have a great reputation. However, with a little research, IMHO you can do better in many areas. They are still the only game in town when it comes to engine & tranny software and CAI's (for now), but when it comes to suspension, diffs, brakes, exhaust, and other miscellaneous upgrades, you have options. Do your homework and you can decide for yourself.

    Jack
    1995 Calypso Red 740i
    1972 Verona Red 2002

  6. #6
    Reed Hunt
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    Wow, an 18% gearing change (m)

    that is a pretty big jump...

    I bet your car literally jumped afterwards, though your MPG probably dropped accordingly.

    -Reed

  7. #7
    Reed Hunt
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    Can you also specify diff lockup % with VAC?


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    I haven\'t seen you for a while. Is it installed?

    What do you think???

    Dave Clement
    Chief Technology Officer, Seattle 7's
    1998 750iL w/2001 Facelift
    http://www.seattle7s.com
    http://www.cardomain.com/id/daveclement


  9. #9
    MikeM
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    VAC's is 40% if I remember from our conversation..

    However, I've been under the impression that Dinan doesn't actually have a LSD for the e38. So I've never even considered Dinan. That's what Strictly BMW said for my 2000. Besides, I already have a 3.15 open diff with my 2000 740i Sport. I think I need to chat with Tony, but I'm holding off til the market dips up a bit.

  10. #10
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    text right out of dinan's e38 brochure

    Dinan offers a 3.15 differential for non-sport 740 models, featuring a shorter final drive ratio. The 3.15 final drivfe gearing takes advantage of torque multipliation, lowering the stock 2.81 gearing for a 12% increase in torque delivered to the ground. The improvement in acceleration comes with only a minor increase in engine speeds at cruise and no effectivfe reduction in top speed. Sport models havfe been equipped from the factory with the 3.15 final drive ratio.

    For even faster acceleration, as well as improved handling, a 3.45 Limited Slip Differential is available for both sport and non-sport 7740i/iL models. The 3.45 gearing provides a 23% increase in torque to the rear wheels vs. the stock 2.81 gearing.

    Dinan offers a 3.73 LSD for 1995 740s, lowering the stock 3.15 gearing for faster acceleration, with no effective reduction in top speed. Limited Slip improves the car's hadling as well as providing for faster starts.

    1998 Calypso Red 750iL
    1997 Vermont Green 740iL
    CarDomain Site: http://www.cardomain.com/id/markcaldwell



  11. #11
    RevHigh
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    Go with the VAC unit....

    Call Tony and tell him you are from Roadfly...
    VAC

  12. #12
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    VAC is 40% - but can customize - (m)

    Talk to Tony at VAC and he can tell you more.
    Jack
    1995 Calypso Red 740i
    1972 Verona Red 2002

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    RE: Differentials

    Gentlemen,


    My opinion of the E38 differential as a performance enhancing option is that, it is a worthwhile investment because off the line acceleration improves at the expense of a few mph at the top. How many of us routinely hit 145 ~ 150 mph?

    On the other hand, and I dont want to appear as though I am saying \"Do as I say, not as I do\".....
    but unless you are going to attend Driver\'s Schools or you plan on serious performance driving, I cannot see the benefit of spending 8k + labor for a Limited Slip diff from Dinan or anyone else for that matter.
    Add a couple of grand and put in a manual gear box instead. In Baby\'s case Tony from VAC suggested a Limited Slip diff because of the increased power to the wheels from the SC and the manual tranny set-up. VAC bought me an E39 M5 Limited Slip diff and shimmed the lock to @ 60% because I do racetrack driving. BTW the cost was somewhere @ $3,500.00 or so.


    I took a moment to visit the Dinan web site to view their E38 differential offerings and a copy of their price list/offerings is below.

    Please note Italicized Annotations are mine.

    Excerpt of Dinan webpage follows....


    Page 25 D
    Year Description Part No. Code Price Labor Notes
    DRIVELINE MODIFICATIONS:

    All 96-01 3.15 Differential D773-0744 G $1492 + 40 units (7)
    -Non-Sport Models open diff.
    Limited Slip versions follow


    740i 1/97-6/00 3.45 Limited Slip Differential D770-0741A G $6999 + 53 units (17)
    -Non-Sport Models
    740i 7/00-01 3.45 Limited Slip Differential D770-0741B G $7799 79 units (18)
    -Non-Sport Models
    740i 1/97-6/00 3.45 Limited Slip Differential D770-0741B G $7799 79 units (18)
    -Sport Models
    740i 7/00-01 3.45 Limited Slip Differential D770-0741B G $7799 79 units (18)
    -Sport Models
    740iL 1/97-6/00 3.45 Limited Slip Differential D770-0742A G $6999 53 units (17)
    -Non-Sport Models
    740iL 7/00-01 3.45 Limited Slip Differential D770-0742B G $7799 79 units (18)
    -Non-Sport Models
    740iL 1/97-6/00 3.45 Limited Slip Differential D770-0742B G $7799 79 units (18)
    -Sport Models
    740iL 7/00-01 3.45 Limited Slip Differential D770-0742B G $7799 79 units (18)
    -Sport Models



    While the Dinan organization offers superp performance enhancement products for our cars, I have a tough time comprehending the price levels they command. I suggest that were you to remove the internals of an E38 diff you could have a LS clutch assy and new ring and pinion custom made for the E38 diff\'s dimensions for a hell of of lot less than 7~8k.

    Needless to say I suggest VAC Motorports for those of you that have the courage to do mods other than those from Dinan. Personally I have never heard of a BMW differential failing. That is not to say that they haven\'t or won\'t, but I am unaware of such an occurance. Which, in my mind, begs the following questions...
    What are we buying when we buy a diff from Dinan?
    A BMW diff that Dinan re-worked themselves?
    A BMW diff that someone else re-worked for Dinan?
    A diff made by Dinan?
    Why is it $7,000?

    If you want to change your diff, I won\'t say don\'t go Dinan, but I will say, consider several sources and the product & warranties they provide against the costs involved.
    Ultimately it is your car and your money.


    Sorry for being long winded

    Cheers,


    Simeon,
    "Baby" SC 6-Speed '97 740iL
    "Nanny" '83 733i


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  14. #14
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    Well said (m)

    With one caveat: My 3.45 lsd diff from VAC + install will cost me less than $2500. BTW - thanks for all your great advice in this department, Simeon!


    Jack
    1995 Calypso Red 740i
    1972 Verona Red 2002

  15. #15
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    I didn\'t know Tony\'s pricing. VAC sponsored me.


    Simeon,
    "Baby" SC 6-Speed '97 740iL
    "Nanny" '83 733i


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  16. #16
    Rick740iL/s
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    Re: RE: Differentials

    Simeon - any thoughts on the Quaiffe differential? It is a different engineering approach / design and I have not heard much as to the pros and cons. I am trying to sort through the process of trading my '01 740iL/s on an '03 M5 or increase the "sports" factor on the E38 with some reasonable mods - the 3.15 diff being the best bang for the buck. LSD is not all that crucial for me - but the Quaiffe runs about $1700 or so (I think) and that looks really attractive plus it is a sort of LSD. Thanks

  17. #17
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    RE: Quaife Torsen Units

    Rick,

    I received the following explanation about the Quaife units. Quaife units behave similarly to a LS diff except that there are no clutches in a Quaife. At the same time a Quaife will spin the raised wheel were it to come off the asphalt as happens in a high speed turn. It will continue to deliver power to the full contact wheel as promised but the other wheel will also receive power.

    A Quaife is apparently a good thing if you happen to be driving a engine-over design car such a 911 where rear wheel lift is less likely. Because the OEM BMW LS diffs are so well built, VAC Motorsports saw no need for the additional expense for a Quaife unit to replace the internal LS clutch of the M5 diff that already had LS ability.

    I am not trying to knock Quaifes, rather I was dissuaded from buying one.

    Regards,


    Simeon,
    "Baby" SC 6-Speed '97 740iL
    "Nanny" '83 733i


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