Samurai Speed's Transmission Dissected! Options

[JohnTurbo]

We've been very busy with the renovations on our new shop that we hadn't had a chance to dig into our broken tranny. That and the fact that we ran into some problems with pulling the gears apart -- we had to send it out to someone to have it done as the gears are pressed on super tight.

Well, we finally were able to get it apart and take a closer look at it. Big thanks to Eddie, our head mechanic, for busting his butt on it.

Here are some photos where you can see the damage to the first gear itself as well as the gear shaft...











After closely examining the broken first gear, and seeing a pattern of hairline cracks in different places throughout the gear, it is our conclusion that the damage to the gear is most likely NOT from wheel hop. (Hence the reason there was no wheel hop on the launch that it broke.) It appears as if the residual damage is simply from LAUNCH CONTROL ITSELF.

The LC process seems to put so much pressure on the gear that over time it produces fractures and then ultimately the teeth break off. Using launch control then becomes like RUSSIAN ROULETTE... if the gear comes to a stop where you are about to perform another launch, and that position on the gears does not contain an existing fracture, then you'll most likely not experience breakage from that actual launch; however, that new launch could certainly produce new fractures of the gear near that position where most of the stress was placed from LC.

Remember how my car had over 100 launches on it? And yet others broke from 20 or less launches? It's literally called LUCK. It my case, the gears happened to not come to rest (before another LC was going to be performed) where previous fractures had occurred. So the pressure that new LC would put on the gears was being done just as if the car had never been launched before. It was literally like playing Russian Roulette. If the gear came to a stop directly on top of an existing fracture and you launched again, your odds were very high that the gear would break on that launch. Not always the case as some spots possibly took multiple launches with existing fractures, but it certainly appears that if you happened to stop the car with that pre-fractured area of the gear teeth lining up on the gear shaft and you went to launch the car that it was most likely causing the breakage.

So it certainly appears that it's not just wheel hop causing the damage and that it's the pure force of launch control itself that was putting the stress on whatever teeth were lined up on the shaft at the moment of impact. Bottom line... the gear materials don't seem to be strong enough to withstand the force of launch control.

We're now in the process of having a stronger first gear and shaft made... not only of stronger materials but also cryo-treated. Once we get this made my goal is to take the car out and do 100 LAUNCHES IN A ROW on the same day. We'll have to let the car cool down with temps, etc. when needed, but the goal is to bang the hell out of it to really test it. Then we'll open the tranny back up and analyze the condition of that 1st gear and shaft.

We'll post more news as it becomes available.

This post has been edited by JohnTurbo: Feb 23 2009, 10:59 PM

[Nitrouz]

John, the things you're doing for the community.....I wish there were more people/vendors like you.

Great job my man. Looking forward to your updates. And thanks for putting "wheel hop" to rest...(I was about to choke a chicken if I read that again...)

[Kris@GTRBlog]

Thanks for the update John. Subscribing to this thread.

[MindlessOath]

im not sure luck has a huge role. I was told by very informed informant that was also confirmed by someone else non related, that alot of the Nissan R35 Press cars had all had transmission issues (because obviously everyone that tested the cars for there own respective mags did launch control testing). There was a consistaincy to the madness but alot of them were random. most of them would die about 150 to 200 launch range. others were failing sooner like we have heard on the forums. The guy in russia and a few others out of country also did just under 200 launchs and damaged the gearssets like these (tho not as bad as yours for obvious reasons, power one of them).

Now take that what you will. im not saying your wrong. but i don't think your car is stock either.

i do belive your right in a few ways for sure! 4500rpm is simply violant. that will definatly be something that could cause damage from shear force. that combined with vdc being off, allowing for no traction control, causing the wheels to slip and in the right conditions cause wheel hop (as noted from many people including yourself that wheel hop does occour on these cars in the right environment).

The new launch control fixes the hard drop by reducing the rpm's and allows for traction to be controled better by having vdc on. This would help any traction slip (not eliminate obviously) reducing the possibilty of wheel hop.

really im just talking out of my butt, cause no one has all the parts from all the broken cars in front of them (except for a few). There is also silenoid problems which could also get gunked up and cause issues too. (which of course a few people have found out).

but what do you think of my arguement? is it wrong? i know its not 100% educated here, but im trying to help and give my opinion on it, plus share the info that i had. (again im not trying to sound like a know it all, or an ass).

This post has been edited by MindlessOath: Feb 23 2009, 11:31 PM

[JohnTurbo]

but what do you think of my arguement? is it wrong? i know its not 100% educated here, but im trying to help and give my opinion on it, plus share the info that i had. (again im not trying to sound like a know it all, or an ass).

Maybe I'm tired but I don't even see what your argument is. ???

And there IS a bit of luck involved, at least from the standpoint that you don't know which teeth are getting lined up at the moment the next launch control is done -- i.e. if an existing fracture exists, and you position that fracture at the moment of impact for the next launch, you are more likely to "finish the job" and break that tooth off (or that area of teeth which ends up happening like dominoes.)

[MindlessOath]

i guess what im trying to get at is, you dont know exactly if wheel hop caused those fractures and the force of launch control caused the damage to be more evident.

or you dont know if clogged silenodes caused any lubing issues causing more issues.

[rabenoja]

Great work John! What happened to the PPG set? Not available yet?

Also was there any other damage done or was it just isolated to the first gear and shaft?

Can't wait to see your progress!

[35R]

Outstanding that you guys are sharing all this invaluable info.

Nice work, and i can't wait to see how you go beefing the box up.

[JohnTurbo]

i guess what im trying to get at is, you dont know exactly if wheel hop caused those fractures and the force of launch control caused the damage to be more evident.

or you dont know if clogged silenodes caused any lubing issues causing more issues.

Of course we don't know exactly. For all we know vibration caused by the Bose back speaker when the radio volume is above '8' could have caused fractures to occur at the moment of launch control.

But what we CAN clearly see are several stress points on the gears. We can see residual damage that occurred from multiple launches. We can see certain 'wear' points that are worse than others.

All of this evidence leads us to believe that the blunt force of launch control produces residual damage to the 1st gear and when that damage "lines up" with the stress points where launch control occurs against the main shaft, it's a pretty safe assumption that's how the teeth are getting broken the rest of the way.

Great work John! What happened to the PPG set? Not available yet?

Also was there any other damage done or was it just isolated to the first gear and shaft?

Can't wait to see your progress!

The PPG set wasn't going to be released for awhile longer. So we just said, "we'll just do it ourselves."

All the damage was isolated to the 1st gear and on the shaft where 1st gear made contact.

This post has been edited by JohnTurbo: Feb 24 2009, 12:13 AM

[MindlessOath]

You have over 100hp more and u recived a similar failure as the press cars with about the same amount of average launches. It just doesn't add up compleatly.

You defiantly have a point about the lining up...

You said u had run into wheel hop and others I know defiantly have too. Doing a launch with a fractured gear set will cause more damage but what caused the initial fracture? I don't know if I would make such a claim with just this one case. It very well could have been from wheel hop. Obviously this case didn't take wheel hop to destroy the gear itself as u stated. But you did say that wheel hop occoured that day any many other times before it in your other posts. Martin also suggests the whole lube issues and silonoids issues could also contribute.

I guess I'm just looking for any possible way to confirm.

[35R]

At the end of the day there isnt going to be many stocker boxes that can run mid-10's and not blow up soon after. So in a sense i dont see how it matters if it's wheel hop or simple launch stress. The important thing is there will be stronger box options in the foreseeable future which is great

[tyndago]

Are you saying that the LC clutch release is doing the damage ? The slamming together of the teeth when the clutch is released ?

The LC itself can't put any more "pressure" than the engine can exert. The clutch release/dump and or wheel hop - the violent loading and unloading of the gear could do the same thing.

I have heard and felt wheel hop in a GT-R. I have seen the tell tale marks on the ground, of skid space, skid space. Its not something I made up just to start something as some people might think. Looks like someone might need to choke a chicken.

The stress risers are a normal type thing to see on a production gearbox. Its fairly normal for a standard gearbox gear finish to be less than optimal. Thats why when we prep a box for racing, we spend time on the gears , finishing them, eliminating the issues.

[R35_395]

John.

Are you guys going to look into clutch pack solutions?
That is going to be the next weak point.

[descartesfool]

John,

How do you plan to make the gear stronger? Are you going to make gear teeth wider? Change in type of steel? Shot peening or other stress relief? It seems to me from your evaluation that the first gear failed due to the steel being repeatedly taken past its elastic limit, so a replacement setup is going to have some pretty good metalurgy to keep the steel from fracturing. You need to balance strength, hardness, brittleness and wear properties. How much wider can the teeth be made?

[NickTO]

I look forward to having a stateside company engineer a stronger gearset. You guys certainly 'nurtured' a proper test bed with all those launches and you're able to analyze the weak points!

Great writeup of your findings.

[JohnTurbo]

John.

Are you guys going to look into clutch pack solutions?
That is going to be the next weak point.

Yes. We're doing some research into that right now.

John,

How do you plan to make the gear stronger? Are you going to make gear teeth wider? Change in type of steel? Shot peening or other stress relief? It seems to me from your evaluation that the first gear failed due to the steel being repeatedly taken past its elastic limit, so a replacement setup is going to have some pretty good metalurgy to keep the steel from fracturing. You need to balance strength, hardness, brittleness and wear properties. How much wider can the teeth be made?

We're exploring several options right now. The teeth can be made a bit wider but there's not a ton of extra room to work with. We'll just have to create some prototypes and test things out. That's the only way to create a solid solution.

[Chuck_H]

Nice work. Looking forward to testing day.

[mcduck]

Thanks for the research and the write up! Very interesting information.

The counterargument now, I would think... are there any cars that have been launched a LOT (stock or modded) that have not failed? There will always be wear, but if some transmissions are holding up better than others, is there a chance there was a bad/inferior run of gears during production? Is there any consistency to production date/vin ranges on the cars that we know of with 1st gear failure?

[nanokpsi]

Thanks for letting us see what you found.
However, I don't think you can eliminate wheel hop from the equation. Wheel hop will surely weaken the parts when it occurs, like the tiny stress cracks you observe. That would leave the gears vulnerable to break at any time, which is why some of the cars break days after being launched hard/repeatedly.

Does your car ever hop on the 18" mickey thompsans?

[RC777]

Awesome and good luck with this.. I can't wait to see the outcome.