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Hey Guys,

currently my blue turd NB has an OEM open diff (3.6 or 3.9?), when i dump the clutch i only get one wheel spinning, also when at wakefield the lean into the fish hook induces one wheel to spin, unsettles the car quite a bit & loss in time. i have been told that;

1. upgrading to an OEM torsen 4.1 diff will eliminate the single spin i.e. if i were to dump the clutch both wheels will spin off the mark
2. i will have shorter ratio's/better acceleration so to speak
3. if the car leans or is raised on one side at the fish hook as mentioned above, i will still get power to one wheel, but wont be as bad as current?

can someone who has swapped to this diff please clarify or confirm what the end result is? side note, it's been quite a while since i have performed doughnuts..& general sideways hooning, i cant bear it anymore, please help me help myself.

cheers,
J.

1) Yes, it'll spin both wheels when both are loaded against the ground.
2) Yes, a shorter final drive will give a larger torque multiplier at the cost of top end gearing
3) Kinda. If one wheel lifts off the ground it will give both wheels power, but IIRC torsen diffs essentially will deliver as much power as it takes to turn the lightest wheel at any given time. If that's only a tiny bit of torque to spin the unloaded wheel, that's all the torque the other side will get too. Not entirely coasting when driving in tripod mode, but not giving you much else either. Or so is my understanding, but I could be misremembering completely.

I had a 3.9 open diff in my NB and swapped it out for a 4.3 T2. It made the car feel much more planted when powering out, made it a little quicker getting up to speed, and did somewhere between 'absolutely nothing' and 'just a tiny bit more than absolutely nothing' to help when I was lifting my inside rear off the ground through Hungry corner at Lakeside. Turns out I just needed to improve my line a bit to prevent it from lifting so it wasn't a big weakness for me.

Get a 4.1 or 4.3 Tirsen. It will work fine most of the time. But both tyres need to be touching the ground. That's most of the time.

Torsen is great for the street.

If you're doing a lot of track time....I'd go for something more aggressive.

There are no magic bullets. Repeat after me - there are no magic bullets. Good.

A torsen will work fine. Modifying your suspension for better handling/grip works well. Getting more seat time/tuition works wonders. Place all ingredients in mixing bowl and mix well, tasting occasionally and adjusting as necessary. Enjoy.

A torsen needs a small amount of grip on the inside wheel to stop it 'going open' - this has never been an issue for me (even at the Fishhook), because I set my cars up to keep the inside rear on the ground by tweaking springs, shocks and roll bars, and adjusting driving style. A clutch pack lsd won't do that (go open) but it comes with its own set of compromises, I would put one in the racecar tomorrow if you gave it to me but I have never felt the need to bite that particular bullet.

This is a dual duty car right? In which case this is a slippery slope - the car becomes increasingly track focussed as you make track-oriented mods, ride suffers, big cams make traffic a pain, you have ripped the air and PS out, the (clutch pack) lsd is noisy and wears quickly ... and you don't want to drive it as daily, and the 'fun' car has gone missing. Ask me how I know this. Moral of this is to make your mods thoughtfully, mindful of the use(s) of the car.

The one mod you can make with NO long term ill-effects is to work on the nut holding the steering wheel. Great bang-for-the-buck, and does a lot to address (or at least work around) any car shortcomings.

Just my 2c

The Green Goblin wrote:OEM open diff (3.6 or 3.9?)

ADM NB8B OEM was 3.6: https://www.miata.net/garage/KnowYourCar/S8_Gears.html

thanks for the info guys..

A torsen will work fine. Modifying your suspension for better handling/grip works well. Getting more seat time/tuition works wonders. Place all ingredients in mixing bowl and mix well, tasting occasionally and adjusting as necessary. Enjoy.

car has relevant suspension bits, i've been tracking the car for quite some time & my line is on par as advised by instructors.. its come to a point where i noticeably & regularly experience the spin/lift & want to eliminate it as much as possible..

This is a dual duty car right?

its road registered but couldnt care how uncomfortable it is.. primarily track car dríven on weekends only.. to the track & back + royal nasho.

If you're doing a lot of track time....I'd go for something more aggressive.

what's something more agressive mate? keeping in mind that an OEM used 4.1 torsen is just over 1k shipped, not installed. trying to keep costs down where possible, so best bang for buck is preference.

Get a 4.1 or 4.3 Tirsen. It will work fine most of the time. But both tyres need to be touching the ground. That's most of the time

what is the difference between the 2? i've been told that the 4.1 works well for wakefield, i assume the 4.3 is slightly shorter in gearing? im honestly not too fussed about the ratio's, my main concern in order is traction (corner entry/exit) & skids..

Jas.

The Green Goblin wrote:thanks for the info guys..

If you're doing a lot of track time....I'd go for something more aggressive.

what's something more agressive mate? keeping in mind that an OEM used 4.1 torsen is just over 1k shipped, not installed. trying to keep costs down where possible, so best bang for buck is preference.



Jas.

Well I was saying more aggressive like a clutch type.....that still lock up even if 1 rear wheel lifts off off the ground. and perhaps locks up quicker
For sure the Torsen will last you for ever, as long as you have oil in it & install it properly. I wasn't considering price. If that's important.....for sure. Ive had a 4.1:1 Torsen in my NA6 for a good 12 years now. But it rarely sees track time nowdays.

The Green Goblin wrote:thanks for the info guys..

A torsen will work fine. Modifying your suspension for better handling/grip works well. Getting more seat time/tuition works wonders. Place all ingredients in mixing bowl and mix well, tasting occasionally and adjusting as necessary. Enjoy.

car has relevant suspension bits, i've been tracking the car for quite some time & my line is on par as advised by instructors.. its come to a point where i noticeably & regularly experience the spin/lift & want to eliminate it as much as possible.. .

Fair enough.

This is a dual duty car right?

its road registered but couldnt care how uncomfortable it is.. primarily track car dríven on weekends only.. to the track & back + royal nasho..

Ok, go for it.

If you're doing a lot of track time....I'd go for something more aggressive.

what's something more agressive mate? keeping in mind that an OEM used 4.1 torsen is just over 1k shipped, not installed. trying to keep costs down where possible, so best bang for buck is preference. .

A clutchpack LSD is more aggressive, or at least allows you to be more aggressive.

Get a 4.1 or 4.3 Tirsen. It will work fine most of the time. But both tyres need to be touching the ground. That's most of the time

what is the difference between the 2? i've been told that the 4.1 works well for wakefield, i assume the 4.3 is slightly shorter in gearing? im honestly not too fussed about the ratio's, my main concern in order is traction (corner entry/exit) & skids..

You should be fussed about ratios. You are fussed about losing traction in the fishhook, and therefore losing time. You are going to spend a $1k plus on an LSD to fix that. But you aren't worried about a mod that might be at no cost, or minimal cost, and which will gain you some more time ...