Z1 Motorsport Driveshaft B4 / After Dyno G35
05-15-2012, 02:49 AM
#48
Administrator
Out of curiousity, what does an OEM drive shaft go for?
05-15-2012, 09:29 AM
#51
Administrator
So if the price is almost similar to OEM and the AL one is claimed to be stronger yet lighter, why would Nissan engineers ditch that option and go with a heavier, more complex steel drive shaft with an extra u-joint? 
Wouldn't the lower rotational mass help them achieve better performance, better mileage and emissions?
Wouldn't the lower rotational mass help them achieve better performance, better mileage and emissions?
05-15-2012, 09:57 AM
#52
Sam you well know that corporate level decisions are made on how cars are built with performance in mind, but never as a primary concern over profit except on some supercars. Cost and meeting a specific price point force compromise in every single aspect of design and construction of mass produced vehicles.
Why? There could be a number of different reasons. Their cost is probably cheaper for the steel shaft from their material and part suppliers. They aren't particularly concerned by the extra weight and rotational mass vs the cost savings.
The same reason our cars don't come with super lightweight forged wheels. Or carbon fiber body panels. Or dual clutch transmissions. Or...
Why? There could be a number of different reasons. Their cost is probably cheaper for the steel shaft from their material and part suppliers. They aren't particularly concerned by the extra weight and rotational mass vs the cost savings.
The same reason our cars don't come with super lightweight forged wheels. Or carbon fiber body panels. Or dual clutch transmissions. Or...
05-15-2012, 10:41 AM
#53
By removing one joint, you now increase the angle of the single joint.
Not something I would have, especially if I changed the geometry of the car by lowering it.
Thats the reason another poster has a noise, the u joint is taking too much stress.
Not for me!!!
05-15-2012, 11:32 AM
#54
Registered User
Join Date: Jun 2011
Location: Houston, Texas
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
BS, I disagree. Steel driveshafts have been made much longer in 1 piece for many many years. The only reason Infiniti or anyone else, would make a 2 piece shaft, is to minimize the angle of the u-joint. Halving the deflection of each joint.
By removing one joint, you now increase the angle of the single joint.
Not something I would have, especially if I changed the geometry of the car by lowering it.
Thats the reason another poster has a noise, the u joint is taking too much stress.
Not for me!!!
By removing one joint, you now increase the angle of the single joint.
Not something I would have, especially if I changed the geometry of the car by lowering it.
Thats the reason another poster has a noise, the u joint is taking too much stress.
Not for me!!!
The longer the driveshaft, the greater the tendency for whip (not sure if this is a linear correlation; may be greater than linear). Thus, two short shafts with a central U-joint may be preferable to a single shaft built strongly enough to withstand the whip.
This is also why the tendency toward carbon fiber driveshafts, which can be engineered for stiffness (to resist whip) along with torsional strength. Bearing all this in mind, I'd have to ask a lot of questions before taking this step.
As a separate issue I'm unclear as to why the apparent bump in horsepower/torque? The result of a reduction in driveline friction losses? If so, why isn't the increase uniform over the entire rpm range? Am I missing something?
05-15-2012, 11:45 AM
#55
The increase in power at the wheels is from less rotational mass that has to be spun by the engine's power. How much power does it take to spin a straw between your thumb and index finger? Now what about a rod of steel the same size, how much power would it take? Same principle. If every part of the drive train were half the weight it is now, engine output would be the exact same but how much of that power output would make it to the wheels would increase dramatically. Reducing the difference in the dyno number between engine HP and wheel HP for every pound of rotating mass saved.
05-15-2012, 01:13 PM
#56
Agree with TVPostSound. Geometry is an important consideration, but an additional concern relates to driveshaft "whip". Essentially, at very high rotational speeds the driveshaft has a tendency to bow outward from centrifugal force. As you can imagine, this would cause severe vibration and has the potential for catastrophic failure.
The longer the driveshaft, the greater the tendency for whip (not sure if this is a linear correlation; may be greater than linear). Thus, two short shafts with a central U-joint may be preferable to a single shaft built strongly enough to withstand the whip.
This is also why the tendency toward carbon fiber driveshafts, which can be engineered for stiffness (to resist whip) along with torsional strength. Bearing all this in mind, I'd have to ask a lot of questions before taking this step.
As a separate issue I'm unclear as to why the apparent bump in horsepower/torque? The result of a reduction in driveline friction losses? If so, why isn't the increase uniform over the entire rpm range? Am I missing something?
The longer the driveshaft, the greater the tendency for whip (not sure if this is a linear correlation; may be greater than linear). Thus, two short shafts with a central U-joint may be preferable to a single shaft built strongly enough to withstand the whip.
This is also why the tendency toward carbon fiber driveshafts, which can be engineered for stiffness (to resist whip) along with torsional strength. Bearing all this in mind, I'd have to ask a lot of questions before taking this step.
As a separate issue I'm unclear as to why the apparent bump in horsepower/torque? The result of a reduction in driveline friction losses? If so, why isn't the increase uniform over the entire rpm range? Am I missing something?
Yes, thats another factor.
The power gain was most likely the diminishing returns of the gains.
Once the weight was overcome, there was no more gain to be had.
Newton's first law of motion.
05-15-2012, 01:20 PM
#57
Dyno results could vary by > 10whp from run to run. The correct way to compare the dynos would be to take the averages of at least 3 runs.
05-15-2012, 02:09 PM
#59
got mine two weeks ago but couldn't install it because Z1 sent me a MT version instead of Auto. Even though it said 'g3<del>5</del> 7 Auto' on it The aluminum driveshaft is really light once its out of the cardboard tube, disappointed that it couldn't be installed. We had to take the exhaust and shields and saw that the flange was different.
lighter wheels and improving drivetrain losses such as the driveshaft do show up at the lower band of the rpm and these gains negate with accelaration, but even with 16 runs, looks like there is lot of power to be gained.
Someone at Z1 has been using this driveshaft on their supercharged/turbo G35 with no issues.
But don't 370z and R35 come with one piece driveshafts from factory? Even if 370z is not considered because of the shorter length of the car, the R35 is comparably similar in length to the g37. So the one piece driveshafts are doing fine with one less joint.
BTW, there is a centre bracket on the g37 driveshaft which is fixed to the underbody of the car, the whole shaft behaves like one piece so there is no outward bowing or change in angle.
lighter wheels and improving drivetrain losses such as the driveshaft do show up at the lower band of the rpm and these gains negate with accelaration, but even with 16 runs, looks like there is lot of power to be gained.
Someone at Z1 has been using this driveshaft on their supercharged/turbo G35 with no issues.
But don't 370z and R35 come with one piece driveshafts from factory? Even if 370z is not considered because of the shorter length of the car, the R35 is comparably similar in length to the g37. So the one piece driveshafts are doing fine with one less joint.
BTW, there is a centre bracket on the g37 driveshaft which is fixed to the underbody of the car, the whole shaft behaves like one piece so there is no outward bowing or change in angle.
newtons first law thats great. good ole middle school science books 