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Discussion Starter #1
Search around but I couldn't find any info.

All of us are talking about 500, 600, 700 bhp.

However, I can't find any info on what power the gearbox can take before it shatter. :(

I have seen somewhere that anything after 550bhp, your gearbox is going to be in trouble. Is that ture? If so, what are the first thing to go.

Clutch is no included in this section because it is a wear and tear item if you ask me, but what will go due to massive power?
 

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Depends on shock loading not torque level - plus wear in the bearings/teeth and condition of oil.

Seems to be 3rd and 4th gear gear that strip judging by the jap books I have.
Also the centre plate can crack.

I am building for 700hp and am using OS Giken gearset and probably a GREX centre plate. I will not be abusing the box too harshly though.
 

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SteveN said:
As well as how hard its used, loading up the transmission rather than dropping clutch on an unloaded transmission makes a huge difference.

Something I try and remember to do when I'm going to give it some stick away from the lights:D
 

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Nocturnal said:
So.... 600bhp @ 6500 RPM with launch control probably won't be healthy for the box then? :p :p :p
Depends if you load up the transmission, like said.

Rocket Ronnie won the first TOTB using a standard box (or was it the 2nd, i forget).

I know someone who launches at 7300rpm with about 750bhp and with 75bhp of Nitrous, on proper drag slicks, runs 10.1's, all on a standard box, and though it breaks, its not all that often.
 

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Discussion Starter #8
Okay, I think I need to get the defination of "loading up the transmission", as I think my understanding of it are burry.

(Or it is because it is almost 2:00am on Friday night after finish working 8 hours) :rolleyes:

I would think droping 750bhp at 7000rpm with a triple plate clutch as "loading it up" and will cause failure...

But then I aren't sure.
 

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skyline69_uk said:
I would say that's loading it up alright :smokin: .
No, its the complete opposite, just dropping the clutch from completley disengaged is what makes the huge shockloads that destroy boxes.

I remember (peter prob does too as he was there) a 200mph challenge day at Brunters that Redline did a whiler back.
Simon was there in the Norris Evo7 and he was launching at 7k+ as youd expect, but he was having trouble keeing ther car still, even using the handbrake, as he loads up the transmission so much before launching it.

Put your fist flat againt a wall and push it against the wall as hard as you can with all your strength.
Now put your fist about a foot away and do the same thing, fist towards the wall with all your strength.

One you back from casualty I think youl understand the effects of loading up the transmission to stop the shock loading...
 

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SteveN said:
No, its the complete opposite, just dropping the clutch from completley disengaged is what makes the huge shockloads that destroy boxes.

I remember (peter prob does too as he was there) a 200mph challenge day at Brunters that Redline did a whiler back.
Simon was there in the Norris Evo7 and he was launching at 7k+ as youd expect, but he was having trouble keeing ther car still, even using the handbrake, as he loads up the transmission so much before launching it.

Put your fist flat againt a wall and push it against the wall as hard as you can with all your strength.
Now put your fist about a foot away and do the same thing, fist towards the wall with all your strength.

One you back from casualty I think youl understand the effects of loading up the transmission to stop the shock loading...
Good explanation...You should work for a magaz....Doh
 

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Discussion Starter #12
SteveN said:
Put your fist flat againt a wall and push it against the wall as hard as you can with all your strength.
Now put your fist about a foot away and do the same thing, fist towards the wall with all your strength.
Just got back from the wall, my hand is in alot of pain right now. I think I understand. :D :D :D
 

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Like Nocturnal would someone explain what 'loading up the clutch ' actually involves/means?Thought i knew but not so sure after reading above.:)
 

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Discussion Starter #14
Okay, the pain in my hand just stop now, so I can type again.

Yea, what is loading up the clutch. Back in the days of Auto Stick (Automaic that we stick it down into lower gear), we use to load up the torque converter.

Basically that mean we step on the throttle half way, with the other foot fully on the brake. As soon as the light turn, we just launch the car GT4 style...

However, that style of loading up the gearbox with a twin plate clutch will be a bit hard. :D

Come on Steve, show us the light!!! :p
 

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On the handbrake , feel the bite .

Release handbrake & clutch / apply more throttle ,
almost all at the same time ish.......:)

Dont try for the first time on the start line at Santa Pod :eek: ;)

Might save your input shaft , but IMO not so good for your clutch .
 

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Bit like what jay said, but slightly less extreme, his method is more for creating tons of load to bring in the boost quicker, bit like loading up an auto by using a transbrake or whatever.

Basically the main thing is make sure the cogs in your box are actually TOUCHING each other before you launch it, hence my fist against wall explanation...

GTRs and most 4wds with plenty of traction usually benefit from a dumped clutch rather than feeding in the throttle, and loading up the tranny means you still dumping the clutch, but just without the shockloads.

Hold it at whatever rpm wou want to launch it at with the clutch fuly depressed, bouncing off rev limiter if you want, then bring the clutch up so you JUST feel a slight bit of bite, smaller the better really.
That should be enough.
Depending on your clutch and depending on how good your control is it might not be a prob and you can get it biting so slightly the car dont even more forward even off the brakes, but the handbrake is often a good plan as the car will usually wanna creap forwards.

Some clutches, or if you REALLY loading it up like Jay said, takes a bit more effort, sometimes handbrake ok, sometimes need a line lock as car is really trying to move forwards.
 

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There's the beauty of the carbon clutch which likes a bit of friction into it. The heat builds up, the rubbing does no damage to the plates, and with the heat comes the bite for a good controllable launch, saving your linkages, I figure.
 

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Fantastic info guys as this has always been a concern of mine as well. Having a carbon clutch I was wondering how to get some heat into it as well pre launch...

Guess some practice is in order.....
 
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