Transmission Failure

[Sekred]

Recently I experienced a transmission failure at 31,000kms. The transmission literally went "bang" as I was driving to work. I exited a roundabout in 2nd gear, put my foot back on throttle and there was a large bang follow by a consistent rattling sound. The rattle was directly relate to road speed and not changing with the gear selected.
Stripped the transmission to find quite a lot of damage some of it secondary because of the initial failure which appears to be the final drive output that bolts to the differential, think crown wheel if you like.

Final drive gear. I cannot be sure of the exact type of fracture here and the cause.



4th gear, countershaft. Brittle fracture caused by impact damage from the chunk spat out from the final drive gear.



There is also damage to 2nd gear, countershaft. One tooth is deformed on its edge. I cannot be sure of when this happened and if it is related to main failure.



There is also surface damage to the countershaft drive pinion gear meaning it is now US. Damage to the reverse pinion gear which is also US.

 

[TyphoonFiST]

What type of fluid were you running? If so how much was in the Trans? Mine failed @24k. New unit came with 2L of fluid in it....it was drained and Ravenol put in as soon as it got home after the New trans was put in.

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[LITTLEVADER]

Damn Man, sorry to hear!! If I may ask how fast were you going?

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[Sekred]

I was running 2 litres of synthetic Redline oil. The bearings are perfect so nothing wrong with the oil I was using. Recently I remove my BT kit and went back to stock. With the BT kit I was pushing about 300/300 through the front wheels. In 2nd gear the tyres would break traction at 5000 rpm, spin hard enough to smoke and this was with a LSD. This use to happen a lot and think this maybe the reason for the damage on 2nd gear. I was pushing a lot more HP than the transmission was ever design for so I guess I just have to suck it up :-(

 

[TyphoonFiST]

I was running 2 litres of synthetic Redline oil. The bearings are perfect so nothing wrong with the oil I was using. Recently I remove my BT kit and went back to stock. With the BT kit I was pushing about 300/300 through the front wheels. In 2nd gear the tyres would break traction at 5000 rpm, spin hard enough to smoke and this was with a LSD. This use to happen a lot and think this maybe the reason for the damage on 2nd gear. I was pushing a lot more HP than the transmission was ever design for so I guess I just have to suck it up :-(

With that type of power being pushed its all just a matter of time. I too am also BT but have decided to save my driveline and limited boost until 3rd gear...but i know even with that ....its just a matter of when...where and how it gives up the ghost.

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[M-Sport fan]

I always wondered how our tiny ring gears (and pinions for that matter) could ever handle all of that power (no matter where it 'comes on'!) some are pushing through them, on very sticky tires no less.

I cannot imagine these parts lasting very long in the 400+ to the wheels apps, with a lot of hard launches, or repeated WOT in 2nd and 3rd gears.

 

[PunkST]

Might have been a flaw in the material that just let go.

 

[Sekred]

Might have been a flaw in the material that just let go.

Yes it could a flaw in the material which are called Inclusions. It looks like the fracture started in the middle of the tooth and went out wards. The last part of the fracture on the edge of the tooth is "Brittle" to look at like 4th gear.
I am very interested to know exactly what happened here, everything breaks for a reason.

 

[Se7eN]

wheel hop maybe?

 

[M-Sport fan]

wheel hop maybe?

Yes, the oscillations/shock force from wheel hop has been known to break ring (and pinion) gears, as we know from the (very weak) 7.5" ring gear,10 bolt rear axle LS1 F body world.

 

[Se7eN]

Yes, the oscillations/shock force from wheel hop has been known to break ring (and pinion) gears, as we know from the (very weak) 7.5" ring gear,10 bolt rear axle LS1 F body world.

broke 2 of the big pinion gears once. car still ran though lol

also my Fiesta's trans also got a weird noise after a lot of wheel hop the diff was pretty shewed up.

 

[gtx3076]

Wheel hop is terrible. After experiencing it at the drag strip I got my ms3 fully mounted. I was so worried I broke something.

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