SCCA Enterprises IB 001-2016 Transmission Reliability
Posted: Wed Apr 27, 2016 5:26 pm
SCCA Enterprises Information Bulletin 001-2016
Transmission Reliability
Lets start with a GEN3 1.6 / GEN2 1.9 comparison.
Both 1.6 / 1.9 are basically the same aero drag, suspension, tire, same basic grip potential, load placed on the gear box is close to the same. 1.2 G is 1.2 G, it really doesn’t matter which engine is providing the torque. The GEN3 weighs less, over-all load on the gear box is same or a touch less.
Both engines for all practical purposes have the same peak torque. How they make torque is different.
Lets draw a line across a dyno graph at peak torque for both engines, they are close, the 1.9 a tick higher. Now draw another line across 5 lb ft, down from peak, this tells the story. When you average the area under the curve, we see the difference. The 1.9 is around 1400 RPM, 1.6 is around 3100 RPM wide 5 down from peak. The GEN3 power band is a little over twice as wide.
Now, depending on how you shift, you can see why a GEN3 will out accelerate a GEN2. It weighs less and has a higher average torque output. We are not talking gross amounts of torque and shift points are the key, but it’s in the range of 1 or 2 lb ft of torque on average run through a gear.
Hmmm So why is the 1.6 so much harder on the transmission or is it ? Surely Mazda / Ford didn’t design the transaxle right on the edge of reliability .
Here are some reasons….
The clutch, The OEM 1.9 clutch can clamp the disc .25 to .4 tenths of a second under power. Tilton Clutch can clamp the disc in about .15 tenths of a second under power. The OEM disc has a dampened hub and the Tilton is solid and less forgiving.
Engine characteristics, the 1.9 is lethargic, the 1.6 is quick and free revving. Most drivers depress the clutch to shift at 6500 rpm…then free rev the 1.6 into the rev limiter around 7000 / 71000 rpm, release the clutch at a higher RPM than needed… more shock to the drivetrain on each up shift.
Wheel Spin, when you drop a wheel at corner exit or jump an apex curb without a lift…the 1.9 at 5300 RPM, torque is around 99 lb ft. The 1.6 at 6100 RPM torque is around 112 lb ft range. The 1.6 maintains torque much higher in the RPM range, wheel spin with your foot on the throttle creates more shock to the drive line when the tire regains traction suddenly.
Harmonic’s, destroyed the original starter solenoids. A dampened clutch disc will reduce this.
Transmission Temp, because of the higher tooth frequency, running temperature is up 15 to 20 Deg.
Transmission Oil, todays additive packages are much different than in the past, we could spend pages on this alone. "I’m going to way over simplify". A lot has changed with OEM’s since 1993, efficiency / long life are top of the list now days. This has pushed OEM’s to design very specific transmissions for many applications, along with very specific oil additive packages for each. This is where the problem starts for Petroleum company’s, retailers and racers….we all want to push the edge of efficiency as racers and Petroleum companies / retailers for profitability. There are more than 70 ATF / Transmission / Differential fluid specifications today. Gone are the days of Type F and Dexron ATF’s and 3 or 4 different gear oil’s in 2 or 3 viscosity’s. This is where the Petroleum companies run into a problem; they don’t want to blend each specific oil spec, retailers don’t want shelf 70 product types, so they cross blend and reduce the number of oil types they produce for the highest profit.
When our transaxle was new, Ford Spec’d 2.6 to 2.8 quarts of “Mercon” ATF and Mazda Spec’d (similar amount)of GL-4 gear oil / viscosity based on average temperatures where you drive the car. It’s important to understand ATF’s have different viscosity’s, even though they are not labeled as such.
You will need to do your own research, but choose the oil type wisely. It will help dissipate heat if you use 2.5 quarts, instead of 2 quarts.
How can SCCA Enterprises help,
The current Tilton clutch configuration we are using is about 60 lb ft less torque capacity or softer than the first 2 configurations. Tilton made a new diaphragm spring and organic disc just for our project, it’s the most forgiving clutch they have available.
For an example the 1.9 OEM clutch has around 145 to 160 lb ft of torque capacity. The current Tilton configuration we use is around 160 to 170 lb ft of torque capacity. We are very close to OEM, the rate it clamps the disc has to do with the design, Racing type vs OEM type.
We are working on a dampened clutch disc. The problem is there is not very much room under the clutch cover for the hub. I hope to have some samples by mid-summer to test.
Alternative gear manufacture, I talked with after-market gear manufactures, because the 3.62 final drive was obsolete. We now use the 3.85 final drive from the current “Mazda 2” we can service the final drive for the foreseeable future. Recently we reopened talks with an alternative gear manufacture to produce more durable 3rd though 5th gear sets at reasonable cost.
How can driver / owner help
Shift carefully and run little more oil in transmission…think about wheel spin and the sudden shock to the drive line when the tire regains traction, either from being bounced in the air or on and off the asphalt.
Keep some notes on the true amount of run time on the gear box / with the type and amount of oil used. Send the data to us…I will not share what you do…but give more of a “people have used a 70 / 30 mix of ATF and Gear lube” with good reliability.
One last note on the pre planning of the GEN3 kit :
The 5 SPD gear box that is paired with this engine, 2011 to current Fiesta was not a good fit for us. Gears are a little thinner (weaker) than our current gear box. Plus the ratio’s spacing is on the short side because of the 4.07 final drive ratio.
We would have also needed frame modification, it uses a cable shifter, which would feel just like a street car…that would have been a positive update. However one of the chassis tubes is in the way of the shifting mechanism on the gear box. We would also need a custom shifter & cables. The OEM ones are too short to reach and the shifter is plastic. Also new custom axles.
I’m not sure of the exact cost, it would have been in the additional 4500 to 5000 dollar range…plus labor for cutting and welding of the new frame mounts. We looked at this when the GEN3 project started rolling. The goal was and is to keep SRF running cost in check as much as possible. I think the gear box needs to reliable for 30 plus race weekends with a test day and that is the current goal.
Fords engine life forecast for the 1.6 is almost 2 times the life of the 1.9. The 1.6 needs conventional motor for 25 / 35 hours to reach peak performance. If you don’t over heat or rev, with proper oil & filter changes plus keep a clean oiled air filter in place. The 1.6 should provide many racing seasons of reliable performance.
In closing, the GEN3 conversion has been reasonably trouble free from the start, new issues do arise when you have 300 examples running across the county… It’s about the ratio of stress and expense vs smiles / good times. In my opinion the GEN3 raised the bar to a level, not many other SCCA classes can achieve.
Transmission Reliability
Lets start with a GEN3 1.6 / GEN2 1.9 comparison.
Both 1.6 / 1.9 are basically the same aero drag, suspension, tire, same basic grip potential, load placed on the gear box is close to the same. 1.2 G is 1.2 G, it really doesn’t matter which engine is providing the torque. The GEN3 weighs less, over-all load on the gear box is same or a touch less.
Both engines for all practical purposes have the same peak torque. How they make torque is different.
Lets draw a line across a dyno graph at peak torque for both engines, they are close, the 1.9 a tick higher. Now draw another line across 5 lb ft, down from peak, this tells the story. When you average the area under the curve, we see the difference. The 1.9 is around 1400 RPM, 1.6 is around 3100 RPM wide 5 down from peak. The GEN3 power band is a little over twice as wide.
Now, depending on how you shift, you can see why a GEN3 will out accelerate a GEN2. It weighs less and has a higher average torque output. We are not talking gross amounts of torque and shift points are the key, but it’s in the range of 1 or 2 lb ft of torque on average run through a gear.
Hmmm So why is the 1.6 so much harder on the transmission or is it ? Surely Mazda / Ford didn’t design the transaxle right on the edge of reliability .
Here are some reasons….
The clutch, The OEM 1.9 clutch can clamp the disc .25 to .4 tenths of a second under power. Tilton Clutch can clamp the disc in about .15 tenths of a second under power. The OEM disc has a dampened hub and the Tilton is solid and less forgiving.
Engine characteristics, the 1.9 is lethargic, the 1.6 is quick and free revving. Most drivers depress the clutch to shift at 6500 rpm…then free rev the 1.6 into the rev limiter around 7000 / 71000 rpm, release the clutch at a higher RPM than needed… more shock to the drivetrain on each up shift.
Wheel Spin, when you drop a wheel at corner exit or jump an apex curb without a lift…the 1.9 at 5300 RPM, torque is around 99 lb ft. The 1.6 at 6100 RPM torque is around 112 lb ft range. The 1.6 maintains torque much higher in the RPM range, wheel spin with your foot on the throttle creates more shock to the drive line when the tire regains traction suddenly.
Harmonic’s, destroyed the original starter solenoids. A dampened clutch disc will reduce this.
Transmission Temp, because of the higher tooth frequency, running temperature is up 15 to 20 Deg.
Transmission Oil, todays additive packages are much different than in the past, we could spend pages on this alone. "I’m going to way over simplify". A lot has changed with OEM’s since 1993, efficiency / long life are top of the list now days. This has pushed OEM’s to design very specific transmissions for many applications, along with very specific oil additive packages for each. This is where the problem starts for Petroleum company’s, retailers and racers….we all want to push the edge of efficiency as racers and Petroleum companies / retailers for profitability. There are more than 70 ATF / Transmission / Differential fluid specifications today. Gone are the days of Type F and Dexron ATF’s and 3 or 4 different gear oil’s in 2 or 3 viscosity’s. This is where the Petroleum companies run into a problem; they don’t want to blend each specific oil spec, retailers don’t want shelf 70 product types, so they cross blend and reduce the number of oil types they produce for the highest profit.
When our transaxle was new, Ford Spec’d 2.6 to 2.8 quarts of “Mercon” ATF and Mazda Spec’d (similar amount)of GL-4 gear oil / viscosity based on average temperatures where you drive the car. It’s important to understand ATF’s have different viscosity’s, even though they are not labeled as such.
You will need to do your own research, but choose the oil type wisely. It will help dissipate heat if you use 2.5 quarts, instead of 2 quarts.
How can SCCA Enterprises help,
The current Tilton clutch configuration we are using is about 60 lb ft less torque capacity or softer than the first 2 configurations. Tilton made a new diaphragm spring and organic disc just for our project, it’s the most forgiving clutch they have available.
For an example the 1.9 OEM clutch has around 145 to 160 lb ft of torque capacity. The current Tilton configuration we use is around 160 to 170 lb ft of torque capacity. We are very close to OEM, the rate it clamps the disc has to do with the design, Racing type vs OEM type.
We are working on a dampened clutch disc. The problem is there is not very much room under the clutch cover for the hub. I hope to have some samples by mid-summer to test.
Alternative gear manufacture, I talked with after-market gear manufactures, because the 3.62 final drive was obsolete. We now use the 3.85 final drive from the current “Mazda 2” we can service the final drive for the foreseeable future. Recently we reopened talks with an alternative gear manufacture to produce more durable 3rd though 5th gear sets at reasonable cost.
How can driver / owner help
Shift carefully and run little more oil in transmission…think about wheel spin and the sudden shock to the drive line when the tire regains traction, either from being bounced in the air or on and off the asphalt.
Keep some notes on the true amount of run time on the gear box / with the type and amount of oil used. Send the data to us…I will not share what you do…but give more of a “people have used a 70 / 30 mix of ATF and Gear lube” with good reliability.
One last note on the pre planning of the GEN3 kit :
The 5 SPD gear box that is paired with this engine, 2011 to current Fiesta was not a good fit for us. Gears are a little thinner (weaker) than our current gear box. Plus the ratio’s spacing is on the short side because of the 4.07 final drive ratio.
We would have also needed frame modification, it uses a cable shifter, which would feel just like a street car…that would have been a positive update. However one of the chassis tubes is in the way of the shifting mechanism on the gear box. We would also need a custom shifter & cables. The OEM ones are too short to reach and the shifter is plastic. Also new custom axles.
I’m not sure of the exact cost, it would have been in the additional 4500 to 5000 dollar range…plus labor for cutting and welding of the new frame mounts. We looked at this when the GEN3 project started rolling. The goal was and is to keep SRF running cost in check as much as possible. I think the gear box needs to reliable for 30 plus race weekends with a test day and that is the current goal.
Fords engine life forecast for the 1.6 is almost 2 times the life of the 1.9. The 1.6 needs conventional motor for 25 / 35 hours to reach peak performance. If you don’t over heat or rev, with proper oil & filter changes plus keep a clean oiled air filter in place. The 1.6 should provide many racing seasons of reliable performance.
In closing, the GEN3 conversion has been reasonably trouble free from the start, new issues do arise when you have 300 examples running across the county… It’s about the ratio of stress and expense vs smiles / good times. In my opinion the GEN3 raised the bar to a level, not many other SCCA classes can achieve.