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Discussion Starter #21
We're still moving along. The prototypes are in process. Once we confirm the prototype function, it will take time to get production done. We've learned alot on the C64, just looking where the OEM made their cost tradeoffs. We won't be making those. :) Fortunately we have a nice long-rod motor from BOE as a test mule when the protos get here.

Ironically, I had a transmission in for service last week with a popular close ratio set installed. The manufacturer had machined the 6th gear incorrectly, making it 0.040" too short. This meant that the range of snap rings from Toyota couldn't take up the slack in endplay. Ultimately the gears walked, the snap ring failed, and the 5/6 grenaded the top of the trans. These little fitment details matter. We're keeping the stack-up thickness same as OEM, though we are making a few gears wider where we can for a stronger product.
 

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Following g this with great interest. What kind of te frame do think it will be before something will be available to the public.
 

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Discussion Starter #23
Seems like a good time to discuss some of our findings for strengthening the gearbox.

Firstly, this isn't our first rodeo. We did custom input shafts for the Quaife Sequential gearbox. I've broken 2 of the stockers and Phil and another customer broke 1 each. More on that in a minute.

When speaking to materials science experts and knowledgeable racing gear and shaft suppliers, the common theme we heard was: "If you want to make your parts stronger, here is the order of importance: 1. Design 2. Heat Treatment 3. Material"

So rather than take a stock part and just throw 4340 or god-forbid 300M at it, it is better to fix some of the design deficiencies. This takes us back to the quaife sequential input shaft.

You can see where and why it broke. Quaife machined the molded 2nd gear with a square cut to the shaft. This creates a huge stress riser in the shaft. The shaft is held by bearings in the case(below 1st and above 4th.) This puts 2nd right in the middle of the shaft where the bending load is the greatest.

Our solution was to re-design the shaft with a proper fillet next to that gear. Additionally, we added a fillet on 1st and reverse! You'll notice because of bearings above the shaft, there is no fillet, however it is considerably thicker there AND much closer to bearing support above. The funny thing is that the OEM designed the stock input shaft with that fillet! Quaife apparently designed it out, likely because it made the machining easier!

That is not to say the OEM didn't make some poor choices which I'll go into in the future in more detail.

See the attached pics of broken shaft(1st pic), original shaft(2nd pic upper), and new BWR replacement shaft(2nd pic lower).
 

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Discussion Starter #24
Zen, We're looking at late fall/winter for release. Although US made, leadtimes are still long....
 

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because racecar
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to your knowledge is the input shaft issue relevant to quaife's sequential for the k20?
 

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Discussion Starter #26
Dallas,

I don't know. Different box and I haven't looked at one.
 

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That looks like a big step backwards from the OEM shaft...



The OEM shaft already has a huge chamfer where the Quaife shaft broke... that's probably why the OEM shaft has such a large chamfer there.

By making two medium sized fillets on both the reverse gear face and the 2nd gear face is probably not as good as having a large chamfer on the 2nd gear face alone. Your photo of a failure shows the failure at the 2nd gear face...right where the OEM chamfer is. Probably something to think about...
 

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^^^ If you look carefully, the fillet next to 2nd on the new design appears to be about the same size as the oem chamfer. If so, the fillet should be superior. A chamfer typically results in 10 to 20% higher Kt (bad) than a similar fillet. The fillet is the preferred approach.

Of course, a couple of guys taking guesses by looking at pictures don't produce any useful answers; I'm just saying I wouldn't discount the new design just because it looks different.

I ain't no engineer, just an interested bystander.
 

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Hi Fred,

I didn't notice this thread the first time. I'm very interested in knowing why you've decided to keep the stock synchros. My 2nd gear synchro is about to go, and it seems that the 2nd gear synchro is a pretty common failure point in these transmissions. Do you believe that the changes to gear spacing will put less stress on the synchro and keep it from failing?
 

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Hi Fred,

I didn't notice this thread the first time. I'm very interested in knowing why you've decided to keep the stock synchros. My 2nd gear synchro is about to go, and it seems that the 2nd gear synchro is a pretty common failure point in these transmissions. Do you believe that the changes to gear spacing will put less stress on the synchro and keep it from failing?
You've got a lot closer gear spacing with new set, so synco life should be much improved...

-Phil
 

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You've got a lot closer gear spacing with new set, so synco life should be much improved...

-Phil
Interestingly, I originally had a plan to go the opposite way to try to make a more reliable box. Through the installation of a shorter final drive, I was going to make 2nd top out a bit lower than where 1st would top out in the BWR set. My 3rd would be equivalent to the BWR 2nd, etc. etc. Of course, I was just building for myself and I don't ever autocross nor am I running higher than stock power. Regardless, I'll probably hold off on that for now and see where this goes.
 

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^^^ If you look carefully, the fillet next to 2nd on the new design appears to be about the same size as the oem chamfer. If so, the fillet should be superior. A chamfer typically results in 10 to 20% higher Kt (bad) than a similar fillet. The fillet is the preferred approach.

Of course, a couple of guys taking guesses by looking at pictures don't produce any useful answers; I'm just saying I wouldn't discount the new design just because it looks different.

I ain't no engineer, just an interested bystander.
A filet is the "standard" way to go...but theirs still looks smaller than the OEM in the photo. A fillet on either side of a chamfer would be even gooderer...
 

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Discussion Starter #33
Boxer, I guess that everyone on the interwebs is a critic.
1. The New Quaife shaft filet is about 0.100" smaller than the chamfer on stock. it looks much bigger on the stocker because the 2nd gear is smaller diameter than the Quaife.
2. The Filet spreads the stress better than the chamfer which is only as strong as the weakest part i.e. the stress riser at the angle at the start of the chamfer.
3. There are considerations for the shift forks etc that have to be dealt with in either case.

The stock input shaft is pretty robust as far as breaking in 2. However, that is usually because high-power cars just strip everyone of the tiny stock 2nd gear teeth off! Ask me how I know...... :evil::D

That said, chamfers and fillets all goodness. It needs to fit in the box and not hit the shift forks or reverse idler etc. etc. ;)

All this without discussing vastly superior steel and heat treat.....

Luxige, +1

LionZoo, the stock 2nd is BY FAR the biggest synchro in the box. It is the only 2 cone synchro in the box. However, since many people drive these cars as streetlight racers, the 1-2 shift gets rushed and crashes the dog teeth ultimately wearing out the syncho and gear hubs. Better oil like MT90 helps, not rushing the 1-2 helps more.

That said, yes, reducing the gear spread will significantly improve the wear since the RPM drop between gears is much reduced. This means the speed differential the synchro has to deal is less.

I drove our sequential, long-rod car on a brief "test" run on the street. This has close ratio gears. When you start rowing through those upper gears, it is just SICK!!! :drool: Always in the powerband, it significantly increases bloodflow! For drives lasting longer than 4 hours, consult a physician! rotfl Very similar setup in our new synchro gearset without all the herky-jerky of a sequential.:coolnana:
 

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LionZoo, the stock 2nd is BY FAR the biggest synchro in the box. It is the only 2 cone synchro in the box. However, since many people drive these cars as streetlight racers, the 1-2 shift gets rushed and crashes the dog teeth ultimately wearing out the syncho and gear hubs. Better oil like MT90 helps, not rushing the 1-2 helps more.

That said, yes, reducing the gear spread will significantly improve the wear since the RPM drop between gears is much reduced. This means the speed differential the synchro has to deal is less.
Fred,

I got my car with 95 miles on the clock. MT90 went into gearbox before the first trackday. I don't streetlight race and I shift rather slowly on the track (this has been mentioned to me multiple times by people in the car as well as those watching trackside). I short shift 1-2 (usually around 5,000 rpm) out of the pits and then never use 1st again. Yet, I still managed to wear out the 2nd gear synchros within 9,000 miles. That was partly why I'm exploring the idea of a very short final drive; so I could totally avoid 2nd gear altogether on the track.

Anyway, looking forward to hearing more on your solution. It's certainly a contender for when I plan to rebuild my tranny.
 

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Discussion Starter #35
Fred,

I got my car with 95 miles on the clock. MT90 went into gearbox before the first trackday. I don't streetlight race and I shift rather slowly on the track (this has been mentioned to me multiple times by people in the car as well as those watching trackside). I short shift 1-2 (usually around 5,000 rpm) out of the pits and then never use 1st again. Yet, I still managed to wear out the 2nd gear synchros within 9,000 miles. That was partly why I'm exploring the idea of a very short final drive; so I could totally avoid 2nd gear altogether on the track.

Anyway, looking forward to hearing more on your solution. It's certainly a contender for when I plan to rebuild my tranny.
LZ, that is nuts! Our 2nd lotus has 30k miles on the clock and I drive it like an ass-hat. :p Mostly it is streetlight driven. Maybe it is time to look at a fluid that has more friction than MT90 to help the synchros? Maybe you have a Monday or Friday transmission? I will say that when I rebuild the transmissions for our customers, usually 2nd looks pretty good and 3rd is just pummelled. Across the board 3rd gets hammered. That is because it is small and used alot. Again RPM to help here.
 

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Do you have a ballpark price range for the kit? Can we send you the trans? Do you a HP limit it will be recommended for?
 

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Discussion Starter #39
We should have the first protos of the gear set in Mid-September for testing. Really looking forward to it!
 

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LZ, that is nuts! Our 2nd lotus has 30k miles on the clock and I drive it like an ass-hat. :p Mostly it is streetlight driven. Maybe it is time to look at a fluid that has more friction than MT90 to help the synchros? Maybe you have a Monday or Friday transmission? I will say that when I rebuild the transmissions for our customers, usually 2nd looks pretty good and 3rd is just pummelled. Across the board 3rd gets hammered. That is because it is small and used alot. Again RPM to help here.
I stopped using MT90 after losing effective sync rods in a couple of boxes. It just seemed too slippery and easy to beat the syncros. Never again! Now back on good old Castrol and all has been fine in my modded E153.
 
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