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Thread: when a gearbox goes bang

  1. #1
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    when a gearbox goes bang

    What exactly happens when you break your gearbox. Is it only one gear that goes and can you manage to still limp home when it breaks.

    Im getting worried now as im planning a trip to the nurburgring next year and power will be running 320 bhp upto 350bhp easily with a GT2871R. But the last thing i want to happen is my gearbox to break and get stuck in the middle of europe

    So i am wondering when a CA gearbox brokes with this much power how could i be effected driveability wise. Could it get completely fooked and brake down or just brake a gear but i'd still be able to get home eventually.

    thanks.

  2. #2
    Guest M.D.'s Avatar
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    im wondering the same thing acctually because ill be going to the same place and the RB20 box is basically the same,

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    TMNT Kieran_E1's Avatar
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    Quote Originally Posted by lsd View Post
    What exactly happens when you break your gearbox. Is it only one gear that goes and can you manage to still limp home when it breaks.

    Im getting worried now as im planning a trip to the nurburgring next year and power will be running 320 bhp upto 350bhp easily with a GT2871R. But the last thing i want to happen is my gearbox to break and get stuck in the middle of europe

    So i am wondering when a CA gearbox brokes with this much power how could i be effected driveability wise. Could it get completely fooked and brake down or just brake a gear but i'd still be able to get home eventually.

    thanks.

    it really depends on what goes wrong.

    i've stripped a cog and lost just that gear but i've also killed a release bearing and lost all gears so anything can happen

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    Guest R3K1355's Avatar
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    It's probably not a great idea to run that level of power/torque then thrash it round nurburgring, if it don't break the box there it won't last very much longer.

    Let's not forget the youngest of these boxes are 14 years of age now, and you'll be doing well to find one thats had an easy life.
    Last edited by R3k1355; 10-01-2008 at 15:53.

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    Guest Buffy's Avatar
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    there are many ways to break the box (I've done most of them ) stripping the teeth from 3rd gear is common (drive home but sounds like big ends have gone lol). snapping the tailshaft (call the AA). If you've got an s14 box fitted, shearing the keys for the second motion shaft (call the AA again). breaking selector forks (drive home with 2 gears missing). I could go on lol

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    Guest Ol'_200sx_thing's Avatar
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    prob best to get european break down conver

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    isn't there a good few S13's running 1.2 bar. would this much boost put much stress on an CA box?

    There is even some SR's running 1.4 bar. Would this be an overkill on a CA box or are they pretty much the same?

    Any less boost pressure would be a waste of 2871r i think. What about all the people that bought one of these turbo's from the apex offer, what will they do or what can bo done to extend the life of a gearbox with one of these turbo's?

  8. #8
    Guest Ol'_200sx_thing's Avatar
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    Its not boost that kills box's, its torque and harsh driving eg a trip to the ring

    Unless you have breakdown cover, or a spare box and tools with you i would advise against it. Or you could be facing some very expensive overheads if it does

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    Sorry, maybe i have it all wrong, i was thinking alone the lines of:
    more boost = more bhp = more torque = more stress on the box or am i wrong?

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    Banned 2 Black Lines's Avatar
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    Quote Originally Posted by Kieran_E1 View Post
    it really depends on what goes wrong.

    i've stripped a cog and lost just that gear but i've also killed a release bearing and lost all gears so anything can happen
    You can also break the bell housing... or was that Kev?

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    TMNT Kieran_E1's Avatar
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    in the most basic sense you are correct.

    i ran 325 bhp and 1.2 bar through a 2871r and a trackday or two. biggest issue i found was gears would crunch if i tried to shift too quickly, slower smoother shifts and smoother throttle inputs will help but i stripped the teeth off my first box at 270bhp so there is no rule of thumb unfortunately

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    TMNT Kieran_E1's Avatar
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    Quote Originally Posted by 2 Black Lines View Post
    You can also break the bell housing... or was that Kev?
    that was me and it was me being stupid trying to do a 3rd gear burnout!!!

    that's bad m'kay!!!

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    I split the casing of my GTR gearbox clean in two, on the way to JAE in 2006

    Obviously I didnt make it to JAE in 2006

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    Remember that the box on the CA and SR are basicly the same. Its just that 3rd on the CA box seems to be weeker. Possibly of the ratio meaning the teath are thiner.

    Me and SM were going to take a spare box on our Spa / ring trip in 2006.. but I needed the spare box before we went

    Ive not broken one properly yet... Ive just keep destroying the syncros!

    Time I got a box with no syncros

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    Member alanjuggler's Avatar
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    did you not manage to salvage those syncros out of the knackered box i gave you?

    but yes, i snapped the woodruff key thingy - i managed to limp a couple of hundred yards in the only gear with any drive (4th) but it's not exactly practical
    white '94 s13 200sx scrapped - mapped to 1.45bar. OS giken box, garrett GT2876R, 950cc injectors, ORC twin plate, nistune. 349bhp/325lbft @ 1.3bar CA18DET
    white '96 s13 180sx - type g with more kouki bits - RB25DET, GTR steel twin turbo conversion, RB26 crank & rods. 2.6L VVT twin turbo, SR20 OSG box, OSG STR twin plate clutch, Z32 ECU w/ nistune.

    current status: 180 a bit broken but to be repaired.

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    Still got them... but we have only built one box... and SM broke that in a few days... after doing a max speed run with it!

    Was our first try so Im quite chuffed it did that well seeing as we didnt do any shimming

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    Banned 2 Black Lines's Avatar
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    Quote Originally Posted by Kieran_E1 View Post
    that was me and it was me being stupid trying to do a 3rd gear burnout!!!

    that's bad m'kay!!!
    Weren't you going Backwards at the time tho?

  18. #18
    Guest M.D.'s Avatar
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    to be honnest unless your launching or drifting, clutch kicking etc) then the really harsh breakages like broken shafts, smashed bell housings and the things that normally mean you have to AA home are less likely than things like syncros, stripped teeth, and warn bearings (whiney box but still drives) whic are more likely when on the track or even on the road with that much power.

    ive both killed the syncros and killed the bearings on mine before, both allowed you to drive fine, just didnt sound good,

    i still personally wouldnt go without any sort of cover and or a spare gearbox, remember you can take just the box and remove the bell housing so it takes up less space in the boot lol

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    Quote Originally Posted by lsd View Post
    Sorry, maybe i have it all wrong, i was thinking alone the lines of:
    more boost = more bhp = more torque = more stress on the box or am i wrong?
    Quote Originally Posted by Kieran_E1 View Post
    in the most basic sense you are correct.
    Well what way is there to explain torque to help me understand it better so ive more of an idea of whats going on.

    If torque kills boxes whats the easiest way to reduce it when i go to the ring other then turning down the boost though it has being pointed out to me earlier in this thread boost doesn't kill boxes but i don't have any other ideas how to reduce torque for that period of time.

  20. #20
    Guest R3K1355's Avatar
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    In physics, a torque is a vector that measures the tendency of a force to rotate an object about some axis. The magnitude of a torque is defined as force times its lever arm . Just as a force is a push or a pull, a torque can be thought of as a twist.

    So very basicly torque is a measure of the twisting force applied, more torque more twist. Too much torque and SNAP!!

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