Aluminum driveshaft. WOW!

[Black_SS10]

I never noticed that big of a difference between the stock and aluminum shaft. The only thing I did notice was more noise, thats about it. I am currently using the factory shaft again. The DSS diff side spacer had a couple bolt holes strip on me.

[SquawkVFR]

Originally Posted by Black_SS10

I never noticed that big of a difference between the stock and aluminum shaft. The only thing I did notice was more noise, thats about it. I am currently using the factory shaft again. The DSS diff side spacer had a couple bolt holes strip on me.

Do you mind sharing the details? Brand, installation...etc...

[NEstyle]

Originally Posted by gtstorey

Think of a bicycle with you pedaling it (engine). If you go from heavy steel wheels to light weight carbon fiber wheels, you will accelerate faster (especially since it's rotating weight), but you as the engine will be the same (produce the same power).
I don't know how much quicker the aluminum driveshaft will make the car, but it will be quicker at the same power.

Well of course, but if a car can accelerate faster with an AL driveshaft, that means that more power is getting to the ground. On a dyno, that means that more power is getting to the roller which accelerates the roller faster which results in more measured power. Remember that a dyno measures power at the rear wheel after all of the losses. I am not talking about an engine dyno which is what your example is equivalent to.

[Black_SS10]

Originally Posted by SquawkVFR

Do you mind sharing the details? Brand, installation...etc...

It's a DSS aluminum one. I installed it, as with everything else for my car. It really didn't change the feel of the car, just added noise. If you're wondering about the spacer. The DSS shaft comes with two aluminum spacers that go on each end. Some of the holes on the diff side spacer stripped out and others I had to cut the bolts in order to remove the shaft.

[John_C]

My aluminum DSS shaft has more NVH, especially on deceleration.

I have a Tim King at TK Performance 1,000hp built CTSV 6L90, Circle D billet triple disc 3200-3400 stall and stock (for now) SS rear diff and axles.

Fwiw... Car made 723 rwhp 93 pump and 760 rwhp on E85.

[gtstorey]

Originally Posted by NEstyle

Well of course, but if a car can accelerate faster with an AL driveshaft, that means that more power is getting to the ground. On a dyno, that means that more power is getting to the roller which accelerates the roller faster which results in more measured power. Remember that a dyno measures power at the rear wheel after all of the losses. I am not talking about an engine dyno which is what your example is equivalent to.

I'm not sure that a dyno is sophisticated enough to pick up on that. The weight of the rotating mass isn't necessarily a " loss" from my quick read of how at least some dynos actually work since they use both the accel and decel time to calculate power. It would be interesting to see the math that is used for calculations to see how time/acceleration is factored into it.

[go_go_gadget88]

Most lighter drivetrain component swaps don't seem to effect dyno numbers much whatsoever from what I have seen, unless they involve reducing friction (where you lose power between the engine and the tires). So things like ceramic bearings and micropolishing gears I can see making minor changes in power readout. Things like a lighter driveshaft or throwing on a set of welds on it, less so. You aren't creating any more power, or freeing up any lost. You are just reducing weight, and thus creating less work for your horsepower to do, resulting in quicker acceleration (in theory). I don't see a lot of back to back 1/4 mile runs after a driveshaft swap so unsure of actual results.

Same can be said if I would lose the ~50lbs I want to. My car would be quicker, albeit by a small amount, but I would not expect it to dyno any differently. I'm with gtstorey though, I think it would be interesting to see the math the dyno uses for calculations

[SquawkVFR]

Originally Posted by Black_SS10

It's a DSS aluminum one. I installed it, as with everything else for my car. It really didn't change the feel of the car, just added noise. If you're wondering about the spacer. The DSS shaft comes with two aluminum spacers that go on each end. Some of the holes on the diff side spacer stripped out and others I had to cut the bolts in order to remove the shaft.

I’m not attacking your skills but could that be the difference? Mine was professionally installed and balanced?

[gtstorey]

The only thing I would add to go_go_gadget88 is that the loss of rotating weight is more important to acceleration than static weight so if you could loose 50 lbs from the rotating weight, your times would change a lot more than 50 lbs of static weight.

[Black_SS10]

Originally Posted by SquawkVFR

I’m not attacking your skills but could that be the difference? Mine was professionally installed and balanced?

All good. It comes from DSS already balanced. They mark it, mine was with yellow paint. It isn't hard to install. The instructions are clear and it is just some bolts. I measured the CV joint clearance and used a new torque wrench on the bolts. I know "pros" that can mess up an oil change. So I do 95% of my own work.

[NEstyle]

Originally Posted by gtstorey

The only thing I would add to go_go_gadget88 is that the loss of rotating weight is more important to acceleration than static weight so if you could loose 50 lbs from the rotating weight, your times would change a lot more than 50 lbs of static weight.

Yes, exactly. That is what I'm saying.

[go_go_gadget88]

Originally Posted by NEstyle

Yes, exactly. That is what I'm saying.

So you're saying thowing on a set of welds on would increase the dyno number, since it is freeing up rotating mass?

I would have to see this to believe it

[hammdo]

Originally Posted by NEstyle

I would love to see some before and after dyno results from a quick driveshaft swap.

I did just that with GPI, no hp or torque gain but, Got there quicker and all we noticed was how ‘smooth, quiet, and vib free’ it rolled on. I have the CF driveshaft. My suspension is a solid as one can get...


-Don

[SquawkVFR]

Originally Posted by hammdo

I did just that with GPI, no hp or torque gain but, Got there quicker and all we noticed was how ‘smooth, quiet, and vib free’ it rolled on. I have the CF driveshaft. My suspension is a solid as one can get...


-Don

The proofs in the puddin’.