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  1. #1
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,586

    Upgrade to T56 Tremec Magnum LS7

    I know someone who is looking to increase his top gearing for touring by replacing a TKO600 too Tremec T56 Magnum.

    Presently fitted Tremec T56 Magnum in a Dax De-deion chassis with LS7 engine.

    My thoughts are does the tunnel or chassis need to be modified to accommodate the extra size.

    The Magnum come in two versions close and wide ratio box. 6th gear being 0.64 or 0.50.

    TKO600 is 0.82 @70mph 2630rpm

    T56 Magnum to 0.64 @70mph 2060rpm

    I think the 0.50 is just to a higher gear.

    Found this great app for gear ratio calculations https://www.blocklayer.com/rpm-gear.aspx

    The shift and trace is a nice feature.
    Last edited by jon1d; 02-05-21 at 11:59 AM.
    Dax 351 Cleveland T5 2.88 PL

  2. #2
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
    Age
    55
    Posts
    3,816
    Hi,

    I’ve got a T56 (non magnum) behind an LS, it’s got the .50 6th gear. I ran it for years with a 3.31 diff and found that it was ace for cruising on the German autobahns at +100MPH, below that and it’s a bit of stretch. I’ve now got a 3.54 diff and it’s OK for 70-80MPH.

    If I had the choice I’d go 0.64

    Cheers

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  3. #3
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,586
    Thanks Jim,

    Yes 0.5 sounds fine for autobahns. I think your doing 1700rpm at 70mph with 0.5 ratio so no get out for accelerating from trouble.

    Cheers

    Jon
    Dax 351 Cleveland T5 2.88 PL

  4. #4
    Join Date
    Feb 2011
    Location
    Northampton
    Age
    42
    Posts
    4,742
    I have the T56 Magnum in a DeDion chassis - well, I did when it was last in there anyway.. and it fits but it is a very tight fit! The rear mount needed a little trim to have more than a mm clearance to the chassis rails, and the prop shaft is basically just a stub; it's also impossible to get in once the gearbox is in (so has to go in all at the same time with the engine and box) as I found out!

    It's also a gnats away from the backbone chassis brace, but does clear.
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

  5. #5
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,586
    Would you drop the diff in the future to do a clutch change?

  6. #6
    Join Date
    Feb 2011
    Location
    Northampton
    Age
    42
    Posts
    4,742
    I'd take the engine out - that's the only way you're getting the gearbox out There's no way it would come out on its own - you couldn't move it backward far enough to get free of the spigot bearing, and if you try to raise the tail of the gearbox so it would slide back.. the top of the shifter housing would hit the backbone bracing. It's very tight!

    That's assuming, of course, that my engine sits in the same place.. if the engine were further forward it might just sneak out.
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

  7. #7
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,586
    Thanks for the info Aaron. It looks a tight squeeze. It's not going to have to come out often. I think I saw a post on the lock out solenoid can get in the way of the back brace.

  8. #8
    Join Date
    Feb 2011
    Location
    Northampton
    Age
    42
    Posts
    4,742
    Yeah - mine clears (just .. and you can even still get the plug on ) but the gearbox sits quite low in my car as the gearbox mount is sort of U shaped (it hangs below the chassis rails). Any higher and you'd probably need Sammy the Sledge to adjust the chassis brace a tad - or delete the solenoid, if you prefer. Personally I kept the solenoid and wired up the speed sensor based reverse lockout circuit - but that's largely because MDL provide that as part of their kit of parts

    I can take some pics if it helps?
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

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