Can a Rocket III take down the establishment, and rule this island

[Kevin frazier]

Man im glad you didnt loose this motor. Crisis averted! Way to be patient, using experience and not acting a fool. Yeah gonna need a better gear for sure.

 

[TURBO200R4]

wow
I think that you need to harden that key so it don't get beat up and try to roll and break the gear.

 

[Gerald]

wow
I think that you need to harden that key so it don't get beat up and try to roll and break the gear.

Are your spring pressures so high, faulty gear, valve timing slip and valves hitting pistons, what have you concluded caused this. Could harmonics thru balance shaft cause this? Did you have a reason to go into engine or were you plain ol lucky.

 

[Kevin frazier]

Maybe time for nevilles tensioner also?

 

[Gerald]

wow
I think that you need to harden that key so it don't get beat up and try to roll and break the gear.

Where it separated is the weakest part of the gear, as long as key fits tight in keyways don't believe you could roll it out, although you could shear the key. We are just speculating.

 

[TURBO200R4]

Where it separated is the weakest part of the gear, as long as key fits tight in keyways don't believe you could roll it out, although you could shear the key. We are just speculating.

My (theory) is that it rocked back and forth until it messed up the keyway then the pressure of the keyway broke the gear at its weakest point. That is why I said heat treated keyway and I would also put two good spot welds on each side of that gear to keep it stable. You can always use a diegrinder to cut it off
I did a spline on a 200 trans like this that was shearing when I hit the nitrous

 

[Gerald]

My (theory) is that it rocked back and forth until it messed up the keyway then the pressure of the keyway broke the gear at its weakest point. That is why I said heat treated keyway and I would also put two good spot welds on each side of that gear to keep it stable. You can always use a diegrinder to cut it off
I did a spline on a 200 trans like this that was shearing when I hit the nitrous

Adding power will always show the weak link. Keep improving to find next weak link. I'm sure adding nitrous will show up several weak spots, but what a rush.

 

[Gerald]

Adding power will always show the weak link. Keep improving to find next weak link. I'm sure adding nitrous will show up several weak spots, but what a rush.

What were you running, sand racer, mud buggy, sounds like something fun and exciting.

 

[R-III-R Turbo]

Are your spring pressures so high, faulty gear, valve timing slip and valves hitting pistons, what have you concluded caused this. Could harmonics thru balance shaft cause this? Did you have a reason to go into engine or were you plain ol lucky.

Maybe time for nevilles tensioner also?

My (theory) is that it rocked back and forth until it messed up the keyway then the pressure of the keyway broke the gear at its weakest point. That is why I said heat treated keyway and I would also put two good spot welds on each side of that gear to keep it stable. You can always use a diegrinder to cut it off
I did a spline on a 200 trans like this that was shearing when I hit the nitrous

I have 3500 miles done since the build, the gearbox was feeling a bit awkward and I became paranoid about something breaking, the titanium valve retainers need replacing and I was getting paranoid about how the pistons were doing with all the power and my tuning.
So decided it was high time to tear the engine apart and inspect most stuff, while doing the work above including transmission upgrade (before something broke).
Unlucky that it broke but lucky it was caught before serious damage.

It seems the crank pulley spigot might have held it together, after it fractured.
It might just be plain ol' bad luck and was a weak unit, seeing as nobody has had the issue before that I know of.
But I'm not really happy with just replacing it and hoping for the best.

I do have some very vague recollection of the key being a tight fit, but that was in the crank side rather than the sprocket side iirc.
Have to check my detailed files to see if the sprocket itself was tight going onto the crank nose.
If it was tight, maybe thermal related expansion might have been a factor.
E.g. crank swoll more under heat than the sprocket, and cracked it.

The key appears a bit damaged too (surface damage) so this might be a clue.

FYI Kev I use Nev's tensioner.
Before I buy a replacement timing gear, I'll ask Bill Robinson if he'd make one when doing my transmission.
It would be the same or better than the Triumph one.


A photo of the gear and key after a few thousand miles on the stroker engine, as I was going fitting all the supercharger & Carpenter bits;

 

[TURBO200R4]

I have 3500 miles done since the build, the gearbox was feeling a bit awkward and I became paranoid about something breaking, the titanium valve retainers need replacing and I was getting paranoid about how the pistons were doing with all the power and my tuning.
So decided it was high time to tear the engine apart and inspect most stuff, while doing the work above including transmission upgrade (before something broke).
Unlucky that it broke but lucky it was caught before serious damage.

It seems the crank pulley spigot might have held it together, after it fractured.
It might just be plain ol' bad luck and was a weak unit, seeing as nobody has had the issue before that I know of.
But I'm not really happy with just replacing it and hoping for the best.

I do have some very vague recollection of the key being a tight fit, but that was in the crank side rather than the sprocket side iirc.
Have to check my detailed files to see if the sprocket itself was tight going onto the crank nose.
If it was tight, maybe thermal related expansion might have been a factor.
E.g. crank swoll more under heat than the sprocket, and cracked it.

The key appears a bit damaged too (surface damage) so this might be a clue.

FYI Kev I use Nev's tensioner.
Before I buy a replacement timing gear, I'll ask Bill Robinson if he'd make one when doing my transmission.
It would be the same or better than the Triumph one.


A photo of the gear and key after a few thousand miles on the stroker engine, as I was going fitting all the supercharger & Carpenter bits;

maybe it is just the picture but that chain looks like it is fixing to roll over its close on the one side and wide on the other