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Thread: Best Diff ratio

  1. #1
    P Plater HJsandman75's Avatar
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    Best Diff ratio

    I'm looking to get my diff overhauled and want to ask what the best diff ratio is for a 308 coupled to a M21 gearbox on standard 14" wheels?
    My ID plate states states GV4 which is 3.36:1
    Currently my ute has a 3.55:1 open wheeler but I have a 3.08:1 LSD at home in the shed. I want something that is nice to drive and not rev its head off at 100kms (like the 3.55).

    Any one have any thoughts on this?

  2. #2
    Night Rider Innuendo's Avatar
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    It's always a compromise. Put a 3.36:1 in and you match what Holden decided was best. Go 3.08:1 and you lose some off the mark speed but drop the RPM at highway speed improving fuel economy. The fact you have the 3.08:1 LSD already and you want to drop the cruising RPM I think the answer is in front of you.

  3. #3
    Night Rider Valencia's Avatar
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    Go the 3.08 lsd they work fine with that combo

  4. #4
    Night Rider Vombil's Avatar
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    ive had a 308 m21 with 3.55 and it is a total bucket of shit combo. i cant see 3.36 being that muych better
    BQZ

  5. #5
    P Plater HJsandman75's Avatar
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    Thanks guys, you have confirmed my thoughts, 3.08 it is.

  6. #6
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    3:08 LSD for sure. Unless you want to swap for my 3:36??

  7. #7
    Night Rider Valencia's Avatar
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    Quote Originally Posted by Vombil View Post
    ive had a 308 m21 with 3.55 and it is a total bucket of shit combo. i cant see 3.36 being that muych better
    Now if you had a 202 with triples that 3.55 would be perfect

  8. #8
    It's a rockin' agr071's Avatar
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    I had a 2.78 in mine, but because of the roof spoiler creating soooooo much drag, i've put the 3.08 back in. Haven't driven far enough yet to decide.
    BO6 = Rarer then a Sandman

  9. #9
    It's a rockin' Big Rob's Avatar
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    Yep.... 3.08 is a good choice unless you are in the middle of the city with traffic lights at every intersection.
    Vans.... This is the 2nd time round the block, 40 years later! talk about turning back the clock!

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