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PostPosted: December 17, 2023, 8:54 am 
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Joined: November 26, 2023, 6:37 pm
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Location: Southeast Michigan
I'm researching donor driveline options for a GBS Zero USA Miata build kit. I stumbled across this while searching for Mazda Miata NB LSD.

Anyone here with experience using a Speedmaster TorqueWorm LSD for Miata?
https://www.speedmaster79.com/Mazda-MX5 ... fferential

Sounds like the standard gear type torque biasing differential, aka, Torsen, Quaife and others. I figure they can't be too bad with applications for many other vehicles.

At that price it would be better to just buy an open diff and install this, compared to buying an NB differential unit with Torsen or other LSD.


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PostPosted: December 17, 2023, 2:29 pm 
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Location: Cornelius OR
There are different levels of anti-slip.

A locking diff will spin the inside tire, that is going to affect your overall grip, how much traction can you give up?
That would be a band aid for a really tight RWD car, I expect a Locost weight distribution would have to have some serious problems to push severely.
It seems to me that a locking diff would make a Locost very loose.
And the gear type limited slip may play right into what a Locost needs.

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PostPosted: December 18, 2023, 7:49 am 
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Bent Wrench wrote:
There are different levels of anti-slip.

A locking diff will spin the inside tire, that is going to affect your overall grip, how much traction can you give up?
That would be a band aid for a really tight RWD car, I expect a Locost weight distribution would have to have some serious problems to push severely.
It seems to me that a locking diff would make a Locost very loose.
And the gear type limited slip may play right into what a Locost needs.


The Speedmaster TorqueWorm isn't a locking diff, it's an automatic torque biasing differential (gear type), just like a Torsen or Quaife.

Anyone on this forum who has experience with this particular brand? Looks like a good alternative to a Torsen.


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PostPosted: December 18, 2023, 12:17 pm 
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I remember a Russian mfg for these. Speedmaster is just the name of the retailer. Looks like a solid product.

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PostPosted: December 18, 2023, 5:42 pm 
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They claim a torque bias ratio of 5:1, where a Torsen T-2R is 4:1, a standard Torsen T-2 is 2:1, and a Detroit TrueTrac is around 3:1. So it's a bit more aggressive about transferring power than the other common helical types.

Their ad seems to contradict itself, though:
Quote:
This is a preloaded unit allowing for a faster reacting unit.


but

Quote:
However, five times zero is still zero, so all of these helical LSDs work best when both wheels are 'planted' and some traction on the slipping wheel is still available.


Some helical differentials have springs that press the friction plates at all times, allowing some power to be transferred even with one tire lifted. Some Torsen units are like this, and the Wavetrac uses a cam system to ramp up friction pressure when the wheels have different traction levels.

Image

Their first quote states that it's a preloaded unit, but the second quote implies that it's not, and their blowout photo doesn't appear to show internal springs.

https://www.speedmaster79.com/Mazda-MX5 ... fferential

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PostPosted: December 19, 2023, 12:20 am 
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Location: Cornelius OR
What are you going to do with the car?
This is all just numbers and whammy zammy until you see what the car and you wants.
So many variables Tire size, compound, and pressure, different pavement (dirty or clean), temps, speed, venue.
Does your motor have excess torques to spare? Etc.

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PostPosted: December 19, 2023, 3:12 pm 
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Bent Wrench wrote:
So many variables Tire size, compound, and pressure, different pavement (dirty or clean), temps, speed, venue.
Does your motor have excess torques to spare? Etc.


^This needed to be repeated. Too many variables to say any particular LSD is the 'right' one. I will add though, Torsen style diffs do a better job of adjusting to the conditions than any other type.

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PostPosted: December 21, 2023, 5:47 pm 
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Joined: January 6, 2015, 4:42 am
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That looks like a solid choice with a great price! I have been running a mini spool for a while now but have a 4 pinion worm unit from this same company under the Christmas tree! Mine is going in a ford 8” rear end. Similar deal about $200+ off on Black Friday sale. I would have liked a 6 pinion one (about $100 more) but I think the jr. one will fit my needs.
Merry Christmas!
-Robert


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