Author Topic: Auto Locker Functionality Explained by John Zentmyer (Lock-Right inventor)  (Read 2605 times)

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When I built my 1989 4Runner (1985 front axle swap) in 2002 I chose a Detroit Locker for the rear and an Aussie Locker for the front.  Around that time I was able to hold a Lock-Right in my hands and was impressed by the stiffness of the springs. When my Aussie Locker arrived I was equally surprised at how soft the springs were in comparison.  Is there any correlation between the spring rate and how easily the locker can unlock?

Clearly, selectable lockers provide a lot of flexibility, especially on the street, but in my experience almost everyone that runs them ends up with a reliability issue sooner or later. I chose automatic lockers because I want both strong and reliable products.

I have never run a "lunchbox" style locker in the rear but would expect to hear a lot more ratcheting noise than with my Detroit Locker that I really don't hear at all other than the big bangs from time to time.

I love the value of the Aussie Locker in the front and they definitely seem to be strong enough for my application.  When I was making my selection it seemed that the Aussie Locker was stronger (i.e. less reported broken) on the forums compared to the Lock-Right. Clearly you're in a position to know the pros and cons of both. Any comment?

I read an article last night (and old one that referenced you) that indicated that the Lock-Right allowed the inner axle to go slower rather than the more common explanation that the outer axle is allowed to go faster. Did they describe it incorrectly or in a confusing way or does the Lock-Right really work the opposite way of the Aussie Locker?
RESPONSE 2 (from John Zentmyer)
Answering your questions in order:
1. Stiffness of the springs. This design of automatic locker will work with a wide range of spring pressures. Part of the design choice is the size of the locker(s). If a particular spring is going into a large locker, it should be stiffer than those going into a smaller locker because of the larger mass (cam gear) the springs have to move. To have one spring be used across a broad line requires that a stiffer spring go into the smaller lockers. That being said, a lighter spring will work with larger lockers until it gets too light. The choice depends on several factors, only one of which is the mass of the cam gear. The Spartan has fairly stiff springs operating inside small holes, but I havenít had any personal experience with them so Iím not familiar with the harshness thatís been reported.
2. Selectable lockers. While itís true that selectable lockers offer flexibility, they also offer a spool off road. While that might not seem to be too bad, it does tend to produce understeer on hard dirt and can put significant torsional strain on the axle shafts when turning on rock. Also, until thereís no torsion both axle shafts, even for a brief instant, they wonít release (nor will manual hubs). I view the Aussie-style locker as being the best of both worlds, tending toward the larger vehicles because the longer the wheelbase and the heavier the vehicle the less youíll notice a locker in the rear. As I was developing the Lock-Right I had a Lincoln MKVII that had a Ford 8.8 limited slip in the ass end. I machined a couple of special adapters to replace the clutch packs and ran the Lock-Right on the street (obviously) for about three years until I sold the car, when I put the limited slip back in. I never really went off-roading with it, but I do have the distinction of driving it right up to the base of the hill at Lionís Back in Moab. It looked like I would have ground clearance problems, so I didnít try climbing it. (Not to mention steepness problems?) I still have the adapters and probably the locker too. I should have taken a picture there, but I donít think I did.
3. Detroit Locker noises. The holdout ring prevents any engagement of the teeth while the vehicle is turning, so you wonít hear any ratcheting at all other than, as you point out, when it sometimes does its famous bang upon re-engaging. I realize that I canít be totally objective, but that being said, especially for larger vehicles, I donít think that an Aussie is all that objectionable in the rear. The L-R sure wasnít in the Lincoln, which I used for demos for potential customers. I couldnít hear it at all, and the only time I noticed it was getting on and off the gas in a turn, which tends to very slightly swerve the front end from side to side because power is being applied to the ground by the inside tire during acceleration and by the outside tire during deceleration (see below). Never had an issue with it, though, and it did get me out of a few tight spots (the trail to Lionís Back?).
4. Aussie v. Lock-Right quality. I do know that the Aussie is made right here in the U.S.A. from 9310 alloy steel because I helped set up the manufacturing here (they used to be made down underĖ-hence the name). I changed to 9310 from 8620 in about 1991 when I started to have chipping problems because 9310 has a higher nickel content that resists chipping. The industry seems to have attempted to follow suit until the last few years, but who knows what steel the Chinese are using? Also, heat treatment is a big issue. They may not now be heat treating the Lock-Right as well as was being done before. All I can say is that the Aussie is a first-rate product, and I can at least state my opinion that itís the best of the ďlunchboxĒ lockers out there. (That term originated in a magazine article about the Lock-Right in the early nineties, and it was thought up by the author.)
5. Axle rotation. An automatic locker will allow either wheel to rotate slower or faster than the ring gear. In a turn, power under acceleration is provided to the ground by the inside tire. This means that the outside tire has disconnected and is being ground-driven (rotating faster) than the inside tire, which is rotating at the same rate as is the ring gear. Less understood out there is deceleration. When getting off the gas in a turn, it turns out (pun intended) that deceleration is being provided by the OUTSIDE tire-Ėthat is, the outside tire is the one connected to the engine and is rotating at the same speed as is the ring gear. This means that because the tires are rotating at different rates that the inside tire has to be going slower than the outside tire. Thus, the cam gear connected to the inside tire is releasing and making the ďclick-click-clickingĒ in the turn. The locker is a black box that only knows differences in rotation as power or deceleration is being applied. It doesnít know forward or reverse or inside tire or outside tire.
1989 4Runner: Dual Ultimate (Inchworm front & Marlin 4.70 rear), Marlin Twin Stick, 1200-lb clutch, 4.88 R&P, Aussie Front, Detroit rear, 30-spline Longs, Long hub gears, ARP hub and knuckle studs & 35x12.50 Cooper STT PRO tires.  Marlin rear bumper & sliders.  FROR front bumper.  SAS with Alcan springs & Rancho 9000XL shocks.  Budbuilt Bolt-on traction bar.  Custom Interior Cage by Those Guys Rod and Customs.

Moab Tested & Rubicon Approved


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