Knocking from engine, 2nd gear unusable :'o( please help!
 

I was doing a right at a set of lights and pulled away in first gear.

I accelerated fast, but not on full boost, engaged second gear and once engaged, hit full boost.

My knocklink hit 2 oranges, and then back to 1 green LED, then 2 oranges, then back to 1 green LED, then 2 oranges, then back to 1 green LED again in quick succession before I closed the throttle and dipped the clutch.

Once all power was cut and i was just rolling i heard a knock.

I pulled over and popped the bonnet and the engine was running really smooth with no knocking noise to be heard. I raised the rev's but still no knocking noise.

I got back in the car and listened carefully and approx every 2 seconds i could hear a faint knocking noise. But when i dipped the clutch, the noise went.

I chose to drive a little bit up the road and see what i could hear and in 1st i think I could just make the knock out, in 2nd a really loud knock could be heard, and in 3rd, 4th and 5th the noise was gone.

It can only be heard when second gear is being driven, or when on tick over with the clutch pedal up.

My defi’s recorded no unusual readings, and the car drives perfectly in 1st, 3rd, 4th and 5th, i was trying to see if i could feel any vibration coming through the gear stick but its hard to distinguish from the usual vibrations. My sync hubs have gone in 4th and 5th and have been for some time.



Has my gearbox or my flywheel gone!? Would the knocklink have picked that up?

Does anyone know what the problem is?

sounds like you may have nocked a tooth off the gearbox, or soemthing a miss with the gearbox/flywheel/clutch reagion

I'm thinking that i may have shredded the teeth in second?

It seems to engage ok and i can drive with the gear but makes a horrible clunking and knocking noise, but i didn't try applying any power through it.

If i did, and i had shredded the teeth, i imagine it would slip?

bump

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Call David at APi for advice mate.

Ns04

common problem 2nd gear, ive stripped 3 boxs now all the same problem 2nd stripped. the thing is that 2nd gear is half the width of 1st which means less tooth contact for the amount of torque being transmitted once you chip one tooth its a dominos effect.

Not quite correct there mate.

P1 first gear is 16.5 mm tooth width with 38 teeth and 2nd gear is 14mm tooth width with 32 teeth.

The teeth are 6mm wide at the point where they bottom out, on both gears.

The helix angle of the teeth changes to be able get the number of teeth into the fixed diameter of the gears.

It is nothing to do with gear teeth width or size it is purely a metal fatigue / age problem that snaps 2nd or 3rd gear teeth off. You are correct however that the 'domino effect' usually takes most teeth off once one has failed

David APi

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