Tom1200
Tom1200 PowerDork
3/3/24 2:47 p.m.

So I may have a deal on a complete diff with lower gear ratio for my Datsun 1200.

The catch is it may be a Detroit Locker; it has been at least 20 years since I drove a car with one and my overriding memory is tit being abrupt and not as good as a proper LSD.

Understeer is the enemy of my 1200 and I have the car set up so that full throttle mid corner doesn't result in understeer.  I am concerned that the locker will aslo result in an initial push on corner entry.

Remember this car is extremely low power; if you unload the front end on a single corner entry you end up losing 2-3 tenths. 

So for those of you who have experience with both tell me what you do or don't like about either one.

Appleseed
Appleseed MegaDork
3/3/24 2:57 p.m.

Do they make a soft locker for a 1200?

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
3/3/24 3:10 p.m.

I have a Detroit locker in the back of my Samurai, which I've done plenty of offroading and street driving with and a couple laps around a track one time.

Like: Acts like a welded diff most of the time, which is great for offroad traction.

Dislike: Acts like a welded diff most of the time, which is a pain in some situations such as making tight turns at low speeds.

Similarly to a welded diff it can also cause some weird handling characteristics including abrupt changes between oversteer and understeer. In really slick mud for example it would cause the li'l truck to drive straight any time you're on the power and rotate sharply when you came off the power.
 

I also have the stock helical-gear torsen in my Toyobaru which I've done plenty of track and street driving with. Helical or 1-way clutch-type LSDs are my favorites for track use.

Like: Pretty good straight-line traction with no one-wheel-peeling, low maintenance, mostly feels like an open diff otherwise with no noticeable negative handling effects.

Dislike: None.

You should also check out this thread for some relevant experience: https://grassrootsmotorsports.com/forum/grm/track-only-welded-vs-open-diff-lsd-not-an-option-for-this-exercise/261995/page1/

Tom1200
Tom1200 PowerDork
3/3/24 5:38 p.m.

In reply to GameboyRMH :

My comment on that thread was welded diffs suck. I've run them on track and in all but extreme cases they ruin the handling.

If the locker truly behaves like a welded diff then no amount of discount will be worth it.

akylekoz
akylekoz UltraDork
3/4/24 6:47 a.m.

I had a locker in a CJ7.  On the street I had to coast through tight corners, click,click,click, then on the gas it would push or even wiggle a bit depending on how the cogs lined up.  In my current track cars I have an LSD and a High Bias Torsen, the LSD adds to understeer, the Torsen reduces understeer.  The Torsen alone took 2-4 seconds off my lap times.  I don't think I would want a locker for track use unless my style was lots of slip angle or drift.

TJL (Forum Supporter)
TJL (Forum Supporter) SuperDork
3/4/24 7:09 a.m.
akylekoz said:

I had a locker in a CJ7.  On the street I had to coast through tight corners, click,click,click, then on the gas it would push or even wiggle a bit depending on how the cogs lined up.  In my current track cars I have an LSD and a High Bias Torsen, the LSD adds to understeer, the Torsen reduces understeer.  The Torsen alone took 2-4 seconds off my lap times.  I don't think I would want a locker for track use unless my style was lots of slip angle or drift.

Agreed. I had a lockright in my truck. It was actually fine for street use. Coast on turns or give it gas and its locked. 
 

On a track car, I think going from open diff to locked diff in a corner would be terrible. 
 

Tom1200
Tom1200 PowerDork
3/4/24 11:15 a.m.

In reply to akylekoz :

I have a reputation of for being Mr Oversteer.........

wspohn
wspohn UltraDork
3/4/24 12:03 p.m.

I used lockers in my race cars and then switched to Quaife, which I found that I preferred

akylekoz
akylekoz UltraDork
3/4/24 12:17 p.m.

In reply to Tom1200 :

You will be fine then.  My very briefly owned Sunny race-car appeared to be locked.

This one.

Driven5
Driven5 PowerDork
3/4/24 12:27 p.m.
Tom1200 said:

If the locker truly behaves like a welded diff then no amount of discount will be worth it.

Apparently, it's even worse than that. It inconsistently alternates its behavior between welded diff and open diff as you modulate the throttle through the corner.

TJL (Forum Supporter)
TJL (Forum Supporter) SuperDork
3/4/24 12:49 p.m.

In reply to Driven5 :

Yes. If you are coasting, its open diff. You apply go pedal, it locks. Once you get used to it its not bad on the street, but it would suck on a track. I think a welded diff or spool would be better on track than a "selectable" just due to it bring consistent. 

Tom1200
Tom1200 PowerDork
3/4/24 1:28 p.m.

In reply to TJL (Forum Supporter) :

As you can tell from my replies I am reluctant to go to a locker.

rustomatic
rustomatic HalfDork
3/5/24 11:59 a.m.

LSD unless track-only.  My last experience with one (Yukon) was generally violent, but it was fine on track.  A newer project of mine has a Tru-trac, which I've heard lots of good things about, but I haven't actually driven with one yet . . .

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) PowerDork
3/6/24 12:32 a.m.

I've put a trutrac in my last three vehicles ('77 C10, V8 Pontiac Firefly (Chevy Sprint), and my '61 Apache).  I absolutely love them.

Tom1200
Tom1200 PowerDork
10/28/24 7:19 p.m.

UPDATE: So I bought said Detroit Locker and here are my experiences.

At Buttonwillow last month I only noticed under two circumstances; the first was backing out of the garage and the other was when I got the car really loose. I have this technique I carried over from motorcycles; when I get the car loose under braking I preload the throttle to settle the back end. When I did the there was a load thunk and the back end snapped back in line with the front. It's not pretty but it does the job.

At LVMS time trial yesterday I noticed this in tight corners. Anytime I overcooked a corner and I went back to the throttle rapidly there was a noticeable bang.  It didn't make the car unpredictable, it just made noise.

Here is the fun part; during my fastest laps it never made noise (hint hint be smooth) it was only when I'd arrived to fast and ended up really chucking the car into corners to make the apex did I hear the loud bang.

 

confuZion3
confuZion3 UltraDork
10/29/24 8:28 a.m.
akylekoz said:

The Torsen alone took 2-4 seconds off my lap times.

This is interesting. How did it help you? Was it about stopping the one-tire-fire coming out of corners, or controlling the cornering balance, or something else?

Tom1200, the fact that it's so noisy seems unsettling, but it sounds like the crowd says that's normal. I guess it just talks to you. Are you faster now with it?

Tom1200
Tom1200 PowerDork
10/29/24 11:34 a.m.
confuZion3 said:

Tom1200, the fact that it's so noisy seems unsettling, but it sounds like the crowd says that's normal. I guess it just talks to you. Are you faster now with it?

EDIT: I just looked and my times from January; while my average times are a bit faster my fastest laps from January and this past weekend are identical.  Worth noting in January the high was 60 and Sunday it was 85. I suspect if it was cooler this past weekend I would have gone a little faster.

 

There were two reasons I went with this; one was the fact that the LSD clutch plates were getting hard to come by, the other was the lower gearing eliminate the need for using 2nd in tight hairpins. There is a 2800 rpm drop on the 2-3 shift.  I went from a 4.38 to a 5.13 ring and pinion.

 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/29/24 1:18 p.m.
confuZion3 said:
akylekoz said:

The Torsen alone took 2-4 seconds off my lap times.

This is interesting. How did it help you? Was it about stopping the one-tire-fire coming out of corners, or controlling the cornering balance, or something else?

Tom1200, the fact that it's so noisy seems unsettling, but it sounds like the crowd says that's normal. I guess it just talks to you. Are you faster now with it?

Oh the Locker will talk to you a LOT.

 

I tried one hoping that I could get the turn in benefits of an open diff.  What I found was that Lockers do not like rallycross and it started disengaging under power.  All the little dogs inside the unit are kinda ugly looking now. 

I have a Traction-Lok now.  It's predictable and reliable.

akylekoz
akylekoz UberDork
10/30/24 7:12 a.m.

In reply to confuZion3 :

Two part, yes I can get on the power way harder and earlier coming out of corners.  Also the way the Torsen works when the inside tire loses traction it sends the power to the outside tire, this helps to rotate the car into the corner and significantly reduce under-steer.  

A locker or LSD connects both wheels together now the inside tire is rotating at the same speed as the outside tire.  This increases under-steer and causes torque lock like trying to turn a truck with the center diff locked, it just fights you. 

Most noticeable for me was the manner in which I opened my steering while coming out of a corner, it was more natural, lighter, and in general I was steering less with the wheel and more with the throttle.

This is on a RWD moderator powered car.  2008 Mustang 330 WHP 3400ish lbs.

I couldn't help but notice that the Laguna Seca, Miata, several performance models came with them prior to Ediffs.

 

Torsen® differentials use advanced helical gearing, produced on state-of-the-art gear cutting equipment. Patented Invex™, Equvex™ and Equvex II gearing give Torsen® the ability to deliver torque as needed to whichever tires can best use it, improving traction, stability, and vehicle dynamics.Torsen® differentials are torque-biasing, meaning they distribute torque between the tires – biasing more torque toward wherever it’s best used – without requiring a loss of traction to operate. They work by managing the friction which results when torque is applied to the helical gearing. This friction is what gives it the ability to prevent wheel spin and bias torque. By tuning and managing that friction level across the performance range, the differential has the ability to support imbalances in traction, allowing the tire with better traction to receive more torque while preventing unwanted wheel spin. The differential’s ability to bias more torque to the tire with better traction is characterized as the Torque Bias Ratio or “TBR” for short. This essentially represents the ratio of high traction to low traction that the differential can allow while remaining locked. The higher the TBR setting, the more aggressive the traction performance is.The friction itself comes from our unique helical gearing. When input torque is applied to a helical gear, it creates a series of thrust forces that push that gearing into the differential casing. When these forces push against the wall of the casing, that contact creates friction. As the torque load increases, so do the forces, and so friction increases in proportion to the amount of torque applied. That gives Torsen® the ability to support a lot of traction imbalance when under heavy throttle conditions, like exiting a corner. Yet, it still can differentiate freely and smoothly at low torque levels, so the car is docile and easy to drive and maneuver.When combined with brake-based traction control systems and other electronic chassis controls, Torsen® becomes even more effective, complementing these systems by reducing the amount of intervention needed and enhancing system response. This works in dry, wet, snowy, muddy, icy, even sandy conditions, giving your vehicle the best conceivable combination of traction performance.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/30/24 1:13 p.m.

In reply to akylekoz :

Torsens are just open diffs (helps turn in) that use the magic of the inability to backdrive a worm gear to send more torque to the wheel with the most traction.  They are a variable torque bias open diff.

Audis had Torsens that could transfer torque at up to a 2.5:1 ratio or up to a 4:1 ratio.  Neat stuff.  It's hell on fluid temperatures though.

akylekoz
akylekoz UberDork
10/30/24 1:40 p.m.

In reply to Pete. (l33t FS) :

Yup, mine is the high bias version.  For my HPDE heat isn't an issue, my buddy's GT500 has a pump and cooler attached to the diff.

If endurance racing with one a cooler may be needed.

confuZion3
confuZion3 UltraDork
10/30/24 1:47 p.m.

I guess I was more interested in exactly what it was about it that cut a lap time by that much, but you said it was on a Mustang, and that's some serious horsepower to throw into one semi-unloaded tire, so it makes sense.

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