28 replies to this topic

[mbican]

I believe my car has VLSD rear end. What would be my best option to change to a Torson, Thanks

[chris haldeman]

Call Jim Drago at east street racing and order one. That is your best option for a torsen. If it was me I would build a Cusco 1.6 diff. Torsen are heavy and slow in a 1.6. Hell I would run the 1.6 with Cusco in my nb car if I was allowed. Cusco is sourced by calling James at Mazda Motorsports

[gerglmuff2]

advanced claimed they couldnt tell a difference in speed between the torsen and the cusco .... that being said, i blew my mazdaspeed diff up last fall, and now my car has a cusco. the torsen is much more robust though. 

[Ron Alan]

advanced claimed they couldnt tell a difference in speed between the torsen and the cusco .... that being said, i blew my mazdaspeed diff up last fall, and now my car has a cusco. the torsen is much more robust though. 

I doubt your Mazdaspeed differential blew up...I'll bet your original stock ring an pinion failed! Salvaged many good Mazdaspeed differentials back into different original pumpkins. The Mazdaspeed clutch disks can wear and begin to not do there jobs...at that point parts to fix are non-existent and with the Mazdaspeed long out of production...Cusco it is. But the Cusco doesn't fix the inherent issue of the original 6" ring and pinions!

 

If we could run the Cusco in the 7" pumpkins(1.8), as Chris said, this would be the chose of many/most up front!

[Ron Alan]

I believe my car has VLSD rear end. What would be my best option to change to a Torson, Thanks

If you swap to a Torsen(only come in 94+ 1.8 cars)you will need the a 1.8 drive shaft and axles as well. If you consider the purchase of a Cusco to instill in your existing unit...you will need 1 more short stub axle I believe(someone correct me if I'm confused). The original VLSD comes with 1 long and 1 short stub axle. Dont confuse the equal length stub axles that come in a 1.6 open diff(and are what is needed in a Mazdaspeed diff)

 

If you order from Jim, he will send you every thing correct!(and this is the easy button!)

 

If you try and source yourself local...remember, the 94-97 cars come stock with a 4.1 ratio. These also come with either a Torsen 1 or a Torsen 2 depending on production year. These Torsens are fine but you would also have to source a 99+ open diff to obtain the 4.3 ratio needed...then install the early Torsen in the 4.3 ring and pinion! Or of course find a 99-02 4.3 Torsen complete. I believe in 03 was when the cars come stock with a Fuji LSD...Torsen no longer used. But this is legal.

[steveracer]

Actually you need the VLSD 2 size stubs for the Cusco.

 

The old Mazdaspeed diff needed both short stubs from an open diff.

[Jason J Ball]

Actually you need the VLSD 2 size stubs for the Cusco.

 

The old Mazdaspeed diff needed both short stubs from an open diff.

Steve is correct, the cusco is a direct replacement for the VLSD diff, same stub shafts. I did the swap myself with new bearings and had Rossini set the lash and adjust the bearing loads. I haven't noticed a significant difference between the cusco and the torsen yet. 

[Bench Racer]

Curious question, does the cusco open as non-worked on Torsen does on the unloaded side? 

[gerglmuff2]

the cusco is a clutch pack diff, not a torsen. 

https://auto.howstuf...fferential4.htm

[mbican]

 KIMG0026.jpg   54.23KB   3 downloads   The more I research it the more i'm confused. It has a two piece half shaft but no ears on flanges like I've seen pictures of 1.6 diff. It has no rubber damper on driveshaft side. Could it be a diff from a 94-95 ? 

 

 

P.S. Just got novice permit at Waterford Hills school last weekend, planning for first race at Mid Ohio this July. 

[Bench Racer]

mbican, Miata Differentials Spotters Guide. Miata and Torsen diffs. including Mazda Comp limited slip. https://www.miata.ne...rage/diffguide/

[mbican]

Appears according to pics in guide I have a 94-95 open diff. Guess I'll have to pull stub shafts to look into diff to be sure. I've had car for three years, it's been raced a bunch by a few different drivers. Seems odd they would have changed diff to an open. 

[Ron Alan]

Appears according to pics in guide I have a 94-95 open diff. Guess I'll have to pull stub shafts to look into diff to be sure. I've had car for three years, it's been raced a bunch by a few different drivers. Seems odd they would have changed diff to an open. 

Problem with the spotters guide is it has you looking at things that can be changed from diff to diff...once that is done you can throw that guide in the trash!

[Pat Mcg]

Just my 2 cents..  1.6 with cusco is a fantastic set up.   Set up properly it is better than the torsen IMO.   We are talking about tenths here not full seconds in the hands of a skilled driver.. Meaning... a skilled driver can be very competitive with any rear end in that car.   having said that.  You just highlighted that you got your novice permit.  Learn to drive it.  Don't spend to much time trying to navigate all these different possible options.  A 4.30 Limited Slip Torsen is the "LONG TERM" best and most cost effective option for 1.6.  About 900-12000 bucks for the full set up depending where you source.  East Street makes it easy by providing the entire package needed..  Thats axles, drive shaft etc. 

 

Cusco..  About 1500 bucks and you will need someone to do it correct. 

 

The current VSLD you have is fine.  They are not the best.. I would consider the VLSD "Sufficient" for just getting seat time and learning the car.    Again.  it will get you on track. 

 

Focus the dollars on wheel time.  Look at long term solution this winter... 

 

Run that car on the SVRA event at Road America... Mid Ohio..  Or wherever you can get on track for the least cost and learn to drive the car.  Regional SCCA events etc..   Low cost track time.  Good luck

[Brandon]

Appears according to pics in guide I have a 94-95 open diff. Guess I'll have to pull stub shafts to look into diff to be sure. I've had car for three years, it's been raced a bunch by a few different drivers. Seems odd they would have changed diff to an open. 

 

Verify specifically which differential you actually have installed before pursuing any changes. Additionally reconsider modification of the platform before you learn how to drive it as Pat notes.

 

Unfortunately, with the two different types of NA6-sized limited-slip differentials permitted in SM (Cusco or MSP), you may be better served to remove the pig (the differential component that holds the ring & pinion) to confirm what the innards actually are.

 

As others have noted, going to a Torsen will (nearly completely) alleviate any longevity concerns about your differential but there are trade-offs in going down that road (weight increase and no traction when one wheel is in the air).

 

To my knowledge, costs are comparable to going to a Cusco or a Torsen with a nod to the Torsen swap being easier for a shade tree mechanic to complete (no R & P lash adjustment experience).

 

HTH!

Brandon

[Steve Scheifler]

How important it is to have a limited slip diff is largely track dependent. These cars make so little power that short of hoping curbs at WOT in a low gear you won’t experience any inside/unloaded wheel-spin anywhere at some tracks. Do what you have the time and resources to do of course, but try to prioritize along the way. This may not be high on the list.

If starting with nothing I would go with the Cusco, absolutely. It is lighter, more mechanically efficient, bites even when a wheel lifts and is more tunable. The 1.6 ring & pinion is more fragile than the 1.8, but the Torsens do eventually wear out so they aren’t indestructible. Second choice is a good used 1.6 with the original comp LSD but I’d want it checked by an expert.

[mbican]

I have had the car for three years with over 50 hours seat time at HPDE's  I was wondering about diff because of some clunking noises coming from rear off car, will be checking things out this week. If I don't see anything will see if it gets worse

Hopefully it's not diff, sure could use more tires, just got my first set of stickers, or save up for new Penske shocks.

Installed fresh trans two years ago and rebuilt short block last Spring, It's always something isn't it

[Steve Scheifler]

Check drive shaft U-joints, half-shafts, bearings, all bushings back there etc. Diffs generally work till the break, or howl, but I haven’t heard them clunk.

[rusty]

Does anyone have an exploded view diagram of the 1.6 mazdaspeed clutch differential and any set up specs, disc thickness measurements etc.

[OrangeCrush86]

Does anyone have an exploded view diagram of the 1.6 mazdaspeed clutch differential and any set up specs, disc thickness measurements etc.

 

I think the 1.6 only had the viscous LSD which is non serviceable or if in more recent times the Cusco.