What Gearbox

  • The MX6 came with KLDE & KLZE but are the gearboxes the same for both?

    Also, while there is no bolt on kit to do so but would one of these gearboxes withstand a KLZE with a supercharger? or is that too much of an open question.

  • Well they generally come with the same gearbox. I think the odd jspec mx6 had a factory option LSD fitted. Quite rare though, seem to be more lantis type rs with them.

    The strength of the boxes are pretty much the same. We're also lucky the mx3 has the stronger mounting locations on the box. They generally are fine around the 300bhp mark. A kinder clutch setup helps avoid exploding them. So far somgood with my klze supercharged

  • sorry for offtopick what is best option for swapped klde to run it with my K8 gearbox or with KLDE gearbox ???

  • KLDE Gearbox.

    From what I've seen posted on here, the KLDE has too much power for the K8 gearbox to handle in someway.

    (Correct me if I'm wrong guys!)

  • If i have read right before,

    MX6 gearbox is the best with the K8 flywheel as it is lighter

  • **The manual gearboxes are essentially the same across the range, just with slightly differing ratios and final drives. And it's not power that's the problem - it's torque.

    Gearboxes are torque multipliers - that's their job. While they step down (or up) engine speed to road speed by the gear ratio * final ratio, they step up (or down) engine torque by the same factor.

    So, say you have a G25M manual transmission. You're in first gear, your engine is doing 2,500rpm. This goes into the gearbox and gets stepped down by the first gear ratio (3.307), gets stepped down by the final gear ratio (4.388) and the output shaft, as a result, turns at 172rpm. With 205/55R15 tyres on, this equates to a road speed of 12.2mph. At the same time your engine is producing 115lbft of torque. This gets stepped up by the gearbox by the first gear ratio and the final gear ratio, and you end up with the output shaft subject to 1,669lbft.

    Now you drop in a ZE engine. The speeds are all the same, but this time you're putting out 170lbft of torque. The output shaft is now trying to channel 2,467lbft of torque at the same road speed - nearly 50% more. This is going to fail.

    The 'box with the 2.5 engines has a lower final ratio of 4.105 (I think). Result? You're doing 13mph at the same engine speed, but you reduce output shaft torque by 10%. Not much, but it makes life less stressed for your gearbox!**

  • I picked up a mx6 box during my ze conversion however it was not the 28 spline mx3 shaft, it was 30 i think? anyhow it didnt fit the mx3 shaft. Hoped it was a LSD mx6 version but it was not. So sold it on.

    So be careful!.

    Im getting hold of two boxes locally ( mx6 and 323 ) to build one decent box and add differential to it. So i can look at the differences between the two when i get into it.

  • Well I've been using 2 different k8 boxes for 20k with my ZE. And now a few thousand with the ZE supercharged setup. So far so good! I did however swap in a taller 5th. It drops the revs about 600rpm for cruising. These boxes aren't tough but they're not the worst, and are fine until you get up to about 300whp+ unless you're ragging them. As I said the before the Act 6puck plus stock De pressure plate makes it easier on the boxes too. Oh and finally get some AWR engine mounts!

  • Marco, You got any technical info on your supercharger, looking to go the same route but with a Centrifugal as i hear that's the best?

  • Yes mate, found some various bits of tech spec. Unfortunately I'm in London on my phone so can't link ATM. It's an Eaton m62 short snout with a clutched pulley from a mercedes slk. I believe it's a 3rd gen eaton, so no internal bypass unfortunately. And yes centrifugals get much more power generally, but that's going to be a tight fit without a transfer shaft! Unless you move the rad forwards or fit a half rad.

  • Oh work will be done :)

    Anything that does not need to be bolted to the Engine will be removed and moved to the boot area.

    Can ya link it whenever you get back from London please bud,


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