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New rotors or driveshaft?

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Thank's for the replies. I wish I had waited instead of buying the factory rotors but at least I can run the stock ones while I save up some money for the Girodisc. I'm guessing they don't go on sale too often? I did save about 40lbs when I switched to the R350 wheels over my factory 20" wheels, so it would be nice to take off another 18lbs or so with the rotors.
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The human bodies and junk in the trunk with saggy springs don't apply to the S550 IRS.
Fair enough. But any time you go from a 2-piece d/s to a one-piece any angularity at the center support goes away. That changes the relationship between the d/s axis and the pinion axis at least a little.


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Neither of these mods will change your ET or autocross run times by much. Enough to win a close race or class where you'd have been only a close 2nd before, sure. Night-and-day difference and you improve from strictly mid-pack to winning, no.


Norm
Right. Do you just want to put checks in the modified box or do you want to make the car faster for a specific type of competition?

In drag racing, road racing, or autocross neither of them would be all that high in my list of cost effective mods.
 

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baer is 15.8 lbs total on the front, about 6 pounds on the rearas
 
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How much (if any) difference will saving a few lbs on front rotors make in 0-60 times?
 

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baer is 15.8 lbs total on the front, about 6 pounds on the rearas
so they make light weight discs for front and back?

thanks, So whats total weight saved if i were to change all four (if bear does make the rear)
 

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If you're buying rotors (and intend to track the car), slotted or blank should be your only consideration in that category.

I have a Shaftmasters 1-piece aluminum. I get vibration >80 mph and when I let off the gas. I've rotated it, I've adjusted the transmission mount spacing, I've talked to Shaftmasters. I've had the joints inspected by a professional (fine). I still get vibration. Currently, it's the best it's ever been and I will leave it. I suspect the fact that I have aftermarket engine mounts (at stock height) and I've solidified/through-bolted my differential doesn't help my case, though.

But, the only difference I felt from installing the 1-piece driveshaft was SLIGHT:Y increased snappiness in my application of power, which I do not feel is an absolute necessity on a road course. I'd rather the car be dead smooth in application of power (vibration free) so I can concentrate on lines and braking, not if the car is going to rattle apart.

My vote is for Steeda 2-piece rotors. Skip the drilled Baer stuff.

My even more vote is to not spend any money on either of the two, frankly.
 

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How much (if any) difference will saving a few lbs on front rotors make in 0-60 times?
Probably immeasurable. As they're on the front, they will act no different than a static mass relative to straight line acceleration.
 

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If you're buying rotors (and intend to track the car), slotted or blank should be your only consideration in that category.

I have a Shaftmasters 1-piece aluminum. I get vibration >80 mph and when I let off the gas. I've rotated it, I've adjusted the transmission mount spacing, I've talked to Shaftmasters. I've had the joints inspected by a professional (fine). I still get vibration. Currently, it's the best it's ever been and I will leave it. I suspect the fact that I have aftermarket engine mounts (at stock height) and I've solidified/through-bolted my differential doesn't help my case, though.

But, the only difference I felt from installing the 1-piece driveshaft was SLIGHT:Y increased snappiness in my application of power, which I do not feel is an absolute necessity on a road course. I'd rather the car be dead smooth in application of power (vibration free) so I can concentrate on lines and braking, not if the car is going to rattle apart.

My vote is for Steeda 2-piece rotors. Skip the drilled Baer stuff.

My even more vote is to not spend any money on either of the two, frankly.
Thank's. The blank would be nice since I only plan to do the front for now and it would match the stock rear rotors, that's if I decide to go with 2 piece rotors at all. I did see that Baer offers both blank and slotted options. I might run the factory rotors for now, since I have a brand new set, and eventually upgrade to the 2 piece later this year. I'm considering them due to the fact that I've finished updating my suspension and appearance stuff on the car, and don't want to risk losing the power-train warranty, so the next best option is to cut some weight. If I wasn't worried about the warranty I'd probably be adding a ported 18' manifold and tune.
 

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both will be rotating weight,
True, but since the rotational acceleration is much less than that of the engine in the case of the rotors and the radius is very small in the case of the driveshaft, the effect in either case is not as large as many people hope for. Smallish fractions of what taking a similar amount of weight off the flywheel and clutch assembly would give you.

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Thanks for mentioning Flywheels, I wondered when someone would interject this choice. I will do driveshaft & eventually rotors but, flywheels matter as well. I've done the driveshaft switch on my 14 Cyclone mustang and liked the increased shift response. I am one with my pony and feel a lot more than most novice drivers.
 
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It looks like if I go with Michelin 4s tires in 285/35/19 I can save about 3lbs a wheel over the A/S 3+ I currently run in 275/40/19, but it is nice having an all season tire, especially this time of year. Just with my R350 wheels, new tires, and rotors I could save about 22lbs a corner over the 20" factory setup. I wish there were cheaper options to save weight without gutting the car. My car came with the subwoofer, adaptive cruise control, and heated/cooled seats, which I'm sure add some significant weight.
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