Broken Gearbox - some pictures
Discussion
, it's your own fault for being such a hooligan !! 
chillidog said:
An interesting crack has appeared:-
Hmm, mashed isn't it:-
More mash:-
As we suspected it's 5th gear that's disintegrated.
The replacement stronger box is being fitted this afternoon.
--
Richard
Hmm, mashed isn't it:-
More mash:-
As we suspected it's 5th gear that's disintegrated.
The replacement stronger box is being fitted this afternoon.
--
Richard
Where did you get the strengthened box from? was it a standard one you have had beefed up or did you just give a spec and buy a new box?
Is it too rude to ask what the box cost: new / beefed up?
F.C.
mr.man said:
Did the whole gear box lock up when it broke and lock the back wheels?
No, I got a bang noise and loads of rev and no power. Swapped to 4th and it worked for a bit, shifted up again, loads of revs, then more bangs, then 4th got very difficult to select. Plans didn't know what I was talking about when I came into the pits (nothing new there)!
--
Richard
Here's a copy of what I posted on the US forums about it:-
As far as I understand, the new gearbox has the nylon bearings replaced with steel ones and is shot peened which hardens the suface of the gears.
Why did it break? Well you never really know but I guess it's had 2 years of track days use and had around 430 lb ft going through it when it finally broke.
The current tune has a nice flat wide torque spread and was deliberately limited to prevent clutch slip (which we had on the rollers) and to reduce the liklihood of the gearbox breaking. We also took the ooportunity to upgrade the clutch to a stronger (Helix) unit when replacing this gearbox This should be actually running tonight and tested tomorrow. Oh it's also fitted with an oil cooler.
We actually have a film of the gearbox dying on me in 5th gear and it didn't show any particular abuse by the driver at that point in time. I suspect the failure wasn't down to poor gear-changing skills but then I would say that wouldn't I .
Possibly the nylon bearings developed some play in it or the crack developed and the shaft moved apart putting more load on the ends of the teeth. Or a tooth broke and jammed in the works and that cracked the casing. We'll never really know and it's certainly inexperienced conjecture on my part as to what actually caused the failure.
Regards
--
Richard
As far as I understand, the new gearbox has the nylon bearings replaced with steel ones and is shot peened which hardens the suface of the gears.
Why did it break? Well you never really know but I guess it's had 2 years of track days use and had around 430 lb ft going through it when it finally broke.
The current tune has a nice flat wide torque spread and was deliberately limited to prevent clutch slip (which we had on the rollers) and to reduce the liklihood of the gearbox breaking. We also took the ooportunity to upgrade the clutch to a stronger (Helix) unit when replacing this gearbox This should be actually running tonight and tested tomorrow. Oh it's also fitted with an oil cooler.
We actually have a film of the gearbox dying on me in 5th gear and it didn't show any particular abuse by the driver at that point in time. I suspect the failure wasn't down to poor gear-changing skills but then I would say that wouldn't I .
Possibly the nylon bearings developed some play in it or the crack developed and the shaft moved apart putting more load on the ends of the teeth. Or a tooth broke and jammed in the works and that cracked the casing. We'll never really know and it's certainly inexperienced conjecture on my part as to what actually caused the failure.
Regards
--
Richard
Conventional wisdom is that the nylon bearings allow the shafts to move slightly and the bearing housings (the bit of the casing that's cracked) flex enough under the sort of loads Richard's engine produces allowing teeth on the cogs to jump. Once ones jumped they all shred like confetti. 5th was the gear that Lee kept on breaking so Richards in illustrious company.
Regards
Paul C
Regards
Paul C
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