question about Zs tranny...
 

I have a 40th anniversary Z and tonight I ran into a evo 10 and I don't do this often but we were in 1st gear and we both punched it to redline (7500) and I went into 2nd gear hard and obviously chirped my tires...I won the race but the question is, if I chirp second gear every now and then, will this destroy my car/tranny? I don't race all the time but is it ok every now and then?

IBTL.

Running it hard is inevitably going to wear it faster.

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Your transmission will not suffer as long as you're not grinding between shifts.

Please Observe Forum Rules Thank You.

It actually saves the driveline when the tires break loose.

The only reason the tyres break loose is because the torque down the driveline has peaked high enough to overcome the grip of the tyre.

Picture it this way.

A gearbox is a torque multiplication device. 1st gear ratio is 3.7949:1, 2nd gear is 2.3248:1.

The size of the teeth in the gearbox is approx 14mm wide and about 5mm tall. On average, there are two teeth engaged on any gear at any point in time. The engine makes 363Nm at 5200rpm. Therefore when you pop the clutch in 2nd gear, the two teeth transmitting the full torque load (363Nm) have to do this with a surface area of 2x14x5 sqmm or an area of 1.5 sq cm .......... now Mr Nissan has engaged some reputable engineers and selected the finest steel money can buy (if you beleive this, then welcome to the land of the tooth fairy).

And you ask whether it will shorten the life of the transmission. Can I suggest that the answer might well be "yes" ......

The shock load is akin to hitting these two teeth with a 36Kg hammer swinging thru an arc of 1 metre - the pressure would be 36kg per 1.5sq cm .... I am hoping that Mr Nissan's metalurgists know their business.

I suspect that if you continue the mechanical abuse of your motor vehcile in this manner, you need to make a dentist's appointment (for the teeth on the gears in the gearbox of course, not for you!!).

Sorry - I forgot ... the load is roughly doubled because of the multiplciation effect of the 2nd gear ratio ..... although only the tyre will see that load.

Oh ... by the way, if you trawl back thru recent posts in this forum, two cool dudes who sort of did what you did with the Evo dude finshed up in front of a judge and 12 of their fellow citizen's trying to explain culpable driving as an "accident". Save the racing for the track please - it is much safer that way.

RB

This guy right here^ He's awesome. And OP if you would like since I'm now a reverand when you kill your tranny, I'd be more then happy to give it last rights if you're interested.

So what if your at the track, you don't chirp 2nd gear or powershift? Since it destroys your tranny...

You are right, at the track I don't flog the car. It is called being smooth .......... and providing some mechanical sympathy (by not banging thru the gears).

My race car transmission costs $22K, and contains gears cut from the same material used in NASCAR and LeMans sports cars boxes. Its has large diameter shafts and massive selector forks and gears that are 26mm wide. This gearbox I am happy to abuse because it is engineered to take it.

Mr Nissan's finest, I treat with some sympathy so it will reward me with long life. No attempts to power shift and no hard standing starts, simply because the gerabox will need a trip to the dentist sooner rather than later.

/\ What they said.


:iagree: I think OP got his answer already. I'm going to close the chread since it's street racing related.