72 replies to this topic

[SaulSpeedwell]

Has anyone used the Cusco yet and is it hard to set up ?

 

Sorry, meant Cusco

 

I moved this sub-discussion from the 1.6 Dead Horse thread

**This post generated too many emails, had to decontent it***

 

OK, that's enough for now.  I'll re-read it later and see if I goofed anything.

[Steve Scheifler]

Great stuff Mark! How about DIY instructions for measuring breakaway torque while still on the car? Better yet, a video!

[Jim Drago]

On the Tochi Fugi.. I have tested numerous times.. It is lighter than the torsen.. If you have any corners where you could possibly spin a wheel.. It will spin with this diff. Road Atlanta 7, Sebring Hairpin, Key Hole Mid Ohio, Carousel Mid Ohio and other places.. If you have a track where you really dont need it like Road America.. it is doable. However, I saw no advantage as you did have to baby it a little to avoid wheel spin. So after lots of testing.. I no longer test it..
 
 

[Brian129]

So I understand the difference in the 2 to 1.5 way thing, but if you say both can be adjusted to what you want, then I don't understand the issue.

Or is the adjustment that difficult?
I ponder putting a new one together, as my fatass is throwing me over weight, and that's one place I know I can improve upon.

[SaulSpeedwell]

Great stuff Mark! How about DIY instructions for measuring breakaway torque while still on the car? Better yet, a video!

 

It is pretty easy, except 99% of guys don't have a dial type torque wrench accurate in the 20 ft-lb range!  I HATE "clicker" torque wrenches!

 

You just put one wheel on the ground, one in the air, and measure cold and hot.  You can use the hub nut or even a lugnut and correct with a fudge factor to account for the extra "leverage" from being out on the bolt circle.

[SaulSpeedwell]

So I understand the difference in the 2 to 1.5 way thing, but if you say both can be adjusted to what you want, then I don't understand the issue.

Or is the adjustment that difficult?
I ponder putting a new one together, as my fatass is throwing me over weight, and that's one place I know I can improve upon.

 

They can be adjusted to whatever you want for INITIAL BREAKAWAY TORQUE, but the "way" involves different part numbers because you can only achieve 2 of the 3 different "ways" with one set of parts.

 

The adjustment isn't mechanically "difficult"  for someone with all the tools and that has done it before, but realize you are taking the entire rear carrier apart and taking the diff out of the ring gear and apart to "adjust" it - and thus, you don't really want to be "guessing" unless you plan to do it 10 or 20 more times in your life.

 

There IS a "Pro Adjust" version of the Cuscos with cam chips that can be swapped once the rear cover is off.  It would be a great option for a non-Spec-Miata, especially if you engineered in a quick-remove rear cover access plate.

[Steve Scheifler]

It is pretty easy, except 99% of guys don't have a dial type torque wrench accurate in the 20 ft-lb range! I HATE "clicker" torque wrenches!

You just put one wheel on the ground, one in the air, and measure cold and hot. You can use the hub nut or even a lugnut and correct with a fudge factor to account for the extra "leverage" from being out on the bolt circle.

Thanks Mark, I guess it was a "duh" question. In the past I've just grabbed both sides from below, tried to turn them in opposite directions and said "yep, that still takes about the same force as when installed". I let myself assume there was more to it than direct measure from the center nut, maybe something about accounting for the gear ratios or tire diameter, whatever. Stupid I know, but never really gave it enough thought.

So I'm buying a dial type wrench. Any suggestions?

This one maybe?
http://www.protorque...-300-in-lbs.htm

Or this one?
http://www.tooldisco...kup=PRED2F25CFK

[SaulSpeedwell]

http://youtu.be/73oFoWcK4hs

[SaulSpeedwell]

http://youtu.be/bv7DTSvQNFg

[SaulSpeedwell]

Thanks Mark, I guess it was a "duh" question. In the past I've just grabbed both sides from below, tried to turn them in opposite directions and said "yep, that still takes about the same force as when installed". I let myself assume there was more to it than direct measure from the center nut, maybe something about accounting for the gear ratios or tire diameter, whatever. Stupid I know, but never really gave it enough thought.

So I'm buying a dial type wrench. Any suggestions?

This one maybe?
http://www.protorque...-300-in-lbs.htm

Or this one?
http://www.tooldisco...kup=PRED2F25CFK

 

Consider what else you will use the wrench for -  Gravely cylinder head bolts, BMW glovebox screws, etc,  300 in-lbs is a good range for Miata diffs,

 

Never mind that I happen to show a 250 ft-lb wrench in my video, LOL

[B(Kuch)Kucera45]

Thanks Mark some cool stuff !

But I'm still going to pay you to do it !

[RazerX]

the second video is missing?

[Jason J Ball]

Given the information here what is the best option for someone who runs VIR the most? (Currently have original VLSD)

[SaulSpeedwell]

Given the information here what is the best option for someone who runs VIR the most? (Currently have original VLSD)

 

My opinion:

1.  If you can find a MazdaComp LSD installed and all ready-to-go for, say, $900-1100, you can look inside it and all seems OK, and you measure breakaway torque and it feels OK, then go that route.  I've never seen one "worn out".

 

2.  If you can't find a MazdaComp or you want a "better" LSD diff, or are trying to make a 1.6 fly, and you have $1600+ to pay for the diff and install parts and labor, go with the Cusco, but have it properly set up and installed.

 

3.  If you just never want any reliability problems (rental car, enduro car, or a diff you plan to take with you for an NB) then put in the '99+ Torsen.

 

I've run VIR, but not in an SM, so I don't know how hard you guys rock the curbs.  Do you get wheelspin with the VLSD after a few laps?

[SaulSpeedwell]

the second video is missing?

 

Yeah, dunno what happened?  I made a quick replacement vid. 

[OctaneNation]

I thought this was interesting:

http://mazdamotorspo...ev&uniqueId=846

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.”

GCR states:

1990 to 1993 Miatas may use the stock, unmodified viscous limited slip differential or the MAZDASPEED Motorsports Development limited slip differential

 

 

No where does it state you can muck with the Cusco unit....so technically can you?

 

Also where can one find VLSD stub axles as Mazdacomp is running out and are NLA.

[Steve Scheifler]

If I understood correctly, the Cusco requires the ones we tossed from our viscous units. Perhaps the only undamaged car parts I've ever thrown away.

[LarryKing]

 

No where does it state you can muck with the Cusco unit....so technically can you?

 

That's what's known around here as "tech shed legal."

[Tom Hampton]

The current rule is:
9.1.7.c.2.b. 1990 to 1993 Miatas may use the stock, unmodified viscous limited slip differential or the MAZDASPEED Motorsports Development limited slip differential, part number #QN1064-A00 (previously TOY1-27-200 & 0000-02- 5501). Alternate MAZDASPEED #0000-02-5500 limited slip differential is permitted.

That "alternate" #0000-02-5500 is the cusco unit.

So there no tech shed issue here.

[LarryKing]

 

So there no tech shed issue here.

 

I think we all know the Cusco unit is legal. 

 

I believe Octane was asking where does the GCR say you can adjust the breakaway torque.