72 replies to this topic

[OctaneNation]

SaulSpeedwalll,

 

I found this old post of yours on another thread. Does the same info apply to the Cusco unit??

 

 

 

Fresh install: ~15 ft-lbs.
After "break-in" with 75W-90 NS (no LSD additive): 9 +/- 2 ft-lbs
With LSD additive: <7 ft-lbs.
When hot: subtract 2 ft-lbs

If you are getting wheelspin and below 7 ft-lbs:
A. Change to 75W-90NS.
OR
B. Drain and "wash" diff out with brake cleaner or similar, then do A.
OR
C. Disassemble, clean everything, prove to yourself the clutches are completely unworn compared to your rebuild kit, and then do A.

[SaulSpeedwell]

SaulSpeedwalll,

 

I found this old post of yours on another thread. Does the same info apply to the Cusco unit??

 

Well, the effect of the fluid friction does affect both units, most similarly when the Cusco is set up as a 2-way.  One of the key differences is the Cusco supports MUCH higher breakaway torque - nominally 60 ft-lbs as received from MazdaSpeed.  The problem is you don't really want to be fighting 60 ft-lbs of clutch torque all the time.

 

As a crappy napkin math approximation with a host of assumptions, 60 ft-lbs divided by the 4.30 ring and pinion is 14 ft-lbs at the transmission output shaft, which in 4th gear would be 14 ft-lbs at the crank.

 

How much would you pay your engine builder for +14 ft-lbs???

[MPR22]

Well, the effect of the fluid friction does affect both units, most similarly when the Cusco is set up as a 2-way. One of the key differences is the Cusco supports MUCH higher breakaway torque - nominally 60 ft-lbs as received from MazdaSpeed. The problem is you don't really want to be fighting 60 ft-lbs of clutch torque all the time.

As a crappy napkin math approximation with a host of assumptions, 60 ft-lbs divided by the 4.30 ring and pinion is 14 ft-lbs at the transmission output shaft, which in 4th gear would be 14 ft-lbs at the crank.

How much would you pay your engine builder for +14 ft-lbs???

About $10,500 by my math. Or more as I would never lose if I have 14 ft/lbs over my competition.

[Bench Racer]

Take a look at your 1.6 torque under 5,000 rpm and compare to you 99. As the young crowd says, just saying.

[SaulSpeedwell]

Take a look at your 1.6 torque under 5,000 rpm and compare to you 99. As the young crowd says, just saying.

 

Dave, can we PLEASE not turn this thread into a 1.6 parity thread?  Under 5000 rpm is meaningless (and misleading) for SM - I don't have the chart in front of me, but all the shift points in a 1.6 should have you somewhere around 5700 rpm at worst?    

[SaulSpeedwell]

About $10,500 by my math. Or more as I would never lose if I have 14 ft/lbs over my competition.

 

Sounds about right.  The "assumptions" in my quickie napkin math overlook times when the inside wheel is light or skidding or in the air, or times when we are in 2nd or 3rd gear, or any time the car is running "free" down the straight and the clutches are NOT sliding against each other, but the point remains that for THIS class (where a few ft-lbs and a few tenths is a huge deal), you really only want as much "lockup" as you need. 

[Bench Racer]

Mark, fair enough. If the 1.6 had said 14 foot pound or somewhat equal torque under 5,700 rpm, we wouldn't have these discussions. I keep forgetting the folks moved to the 99 plus because the car handles so great, has nothing to do with what's under the hood. IIRC there are three 2nd gear corners at COTA.  How'd the 1.6 drivers fair there. Nope, that was not a question, it was a statement.

[SaulSpeedwell]

[SaulSpeedwell]

Mark, fair enough. If the 1.6 had said 14 foot pound or somewhat equal torque under 5,700 rpm, we wouldn't have these discussions. I keep forgetting the folks moved to the 99 plus because the car handles so great, has nothing to do with what's under the hood. IIRC there are three 2nd gear corners at COTA.  How'd the 1.6 drivers fair there. Nope, that was not a question, it was a statement.

 

Mark:  "Dave, can you please not pour mustard in the coffee?"

 

Dave:  "Fair enough!"   *proceeds to pour mustard in the coffee*

[Sphinx]

Can someone clarify something for me.  I was reading one of the Mazda Motorsports emails and I didn't understand this part:

 

Adds Mike Allen, MAZDASPEED specialist: “It’s pretty easy to open it up and change the discs and the plates to come up with a different bias ratio. You can buy different cams to change your lockup. It’s important, because in Spec Miata, there are only a couple of options for the 1.6-liter Miata.” - See more at: http://mazdamotorspo...h.SqnGwL0o.dpuf

 

Is this permitted by our rules?  Or is this one of those tech-shed legal deals?

[OctaneNation]

Well, the effect of the fluid friction does affect both units, most similarly when the Cusco is set up as a 2-way.  One of the key differences is the Cusco supports MUCH higher breakaway torque - nominally 60 ft-lbs as received from MazdaSpeed.  The problem is you don't really want to be fighting 60 ft-lbs of clutch torque all the time.

 

Hoping to put a unit in the car tonight. Recommend breaking in with Redline 75W-90 NS? Any thoughts on break in? 10 minutes of figure 8's? Can the car be run hard at practice with the NS fluid to see if additive is needed to bring down breakaway?

 

@Spinx: This may help http://www.cusco.co....pdf/p27_p29.pdf

[SaulSpeedwell]

Yes, you can can run it hard for a session and drain, as long as you do not have new gears.  New gears make a surprising amount of heat if taken to the track in anger with no break-in!

[Jim Drago]

http://youtu.be/bv7DTSvQNFg

Thank you for the ESA product placement

[SaulSpeedwell]

Got a question about what a current Type 2 Torsen from MazdaSpeed looks like brand new ...

 

In short, it looks similar but different than other T-2s made over the years ...

 

 

 

 

Compare to this old rerun .... (notice the black "coated" parts in the diff on the right are stock and unaltered parts)

 

[38bfast]

Well at the least the camera man has finally learned how to hold the camera.

[SaulSpeedwell]

LOL Ralph ...

 

This isn't directly SM relevant, but it is "Mazda Racer" relevant and the thread where I've been dumping anything notable that is differential-related ...

 

[SaulSpeedwell]

I have no lubrication sponsor, and I don't sell or profit from lubricants.  I'm not a fan of Shockproof for our LSDs. 

 

[SaulSpeedwell]

[Bench Racer]

Now that my friends (ya I know Danny, I don't have any friends) is a TRUE mentor.

 

Thanks Mark. ^

 

1.6 differential:

 

Mark/Justin, isn't the Cusco a heaver rotating mass? Why not a Mazda Comp LS? I know Mark, to many questions. 

[SaulSpeedwell]

Now that my friends (ya I know Danny, I don't have any friends) is a TRUE mentor.

 

Thanks Mark. ^

 

1.6 differential:

 

Mark/Justin, isn't the Cusco a heaver rotating mass? Why not a Mazda Comp LS? I know Mark, to many questions. 

 

Than the MazdaComp?  No.  A couple millimeters of rubber on those tall Continentals is a far greater factor than anything we could be doing in the center of the diff.  Weight near the axis of rotation of the "axle" is the last thing I would be worrying about.   However, you do have a point - we have proven time and time again that the 1.8 diff will slow down a 1.6 car measureably - not because of the Torsen, but because of the weight.  It is a good choice for rental cars and enduros.  Not a good choice for anyone trying to get up front in a 1.6.