To Lock, or Not to Lock... That is the Question

[ntsqd]

I put two ARB's in the 4rnnr. I wanted it to be a 'stealth' build and it worked extremely well. Far, Far better than I had any expectation of it doing. It was expensive and a bit complex. I used OTR Air switches instead of solenoids to switch them on and off, so that reduced the complexity a little.

For Snowball I wanted something different. It came to me with an unknown "Posi" in the front and an open in the rear. The first time that I had that 8.8 rebuilt I had a TruTrac put in it. Little did I know but the front is also a TruTrac. I didn't learn that until I tore the front end apart to put better beams in the TTB. That period where it had 2X TruTracs was awesome! It easily was as capable as the 4rnnr with it's 2X ARB's, but far less complex. It. Just. Flat. Went. Where. I. Pointed. It. When I'd had enough of that junk rear axle called an 8.8 I went with a D60 (mostly to match the 8 lug front brakes I put on the truck at the same time), and mostly because I wanted to try one it has an OX in it. That decision was a tough one, how well the truck worked with the 2X TruTracs was hard to give up.

 

[nvrstuk]

You said-
"Automatic lockers always unlock when one tire wants to go faster than the other. Period. They never stick or hang up. When you are going around a corner they will always freely allow the outside tire to go faster."

Not when power is applied... so if you are on the throttle around a corner BOTH tires will rotate at the same speed usually causing you to have fun on marginal traction surfacesespecially when letting off exemplified when towing like mentioned by both of us.

I have had this debate yrs ago about how a DL actually works b4 & the best explanation- (much better than my previous full page rambling on the previous post reference) but still the same- is here, which is why I saved this link a while back when trying to explain myself:

https://forums.autosport.com/topic/211396-detroit-lockers/

 

[ntsqd]

I lived with a Detroit in the rear of a truck for ~100k miles. NEVER again. Just no! I'd rather deal with an open diff. I foolishly even fixed it one when the side gears wore into the case. I was broke or I'd have put something else in there.

So yeah, a "spool" with power on and a funky sometimes ratcheting 'open' diff, sometimes still locked-up spool with the power off. Did not matter to it what direction you were going, power on and now it wanted to go straight. It sees compression braking the same as power on, and locks up. Yea! F__K! I came to hate cloverleaf fwy on and off ramps. It was great the rare times that I wanted to play at being John Buffum or Rod Millen, the rest of the time it sucked.

 

[Nothing Special]

.... Not when power is applied... so if you are on the throttle around a corner BOTH tires will rotate at the same speed usually causing you to have fun on marginal traction surfacesespecially when letting off exemplified when towing like mentioned by both of us....

With an automatic locker, as you get on the throttle in a corner you are only sending power to the inside tire. The outside tire is trying to go faster so it has unlocked the diff. With all of the power going to the inside tire it's likely that you will break it loose. It is the tire with the least loading, and if you are used to open diffs you are thinking you are sending torque to both tires.

When you break the inside tire loose it will catch up with the outside tire. Now that both tires are turning the same speed the diff will lock again. So yes, both tires will then rotate at the same speed. Was that caused by you applying power? Indirectly, because applying (too much) power is what made the inside tire catch up with the outside tire. But it's the inside tire catching up with the outside tire that directly makes it lock.

I get picky with that because when people say Detroits lock when you get on the power it leads people to do the wrong thing to try to keep it from locking, or worse yet, to get it to unlock. They think it you get off the power it will unlock, so they jump off the throttle and the compression braking breaks the one tire loose again and you're still spinning out.

As I said at the start, automatic lockers are completely predictable if you know how they work. Being able to predict what they will do makes it start to be possible to tolerate one on the road. But they DO have objectionable manners on the road (I said that at the start too). I don't mind living with one in the rear of my street and trail driven Bronco, and I was fine living with one in the back of my street and forest road driven F-150, even through 9 Minnesota winters. But I didn't want one in the back of my F-250 because I wanted it to be able to tow a heave trailer better. And I wouldn't want one if I was dealing with a lot of slippery sidehills.

Getting back to the original question, I kind of like an auto locker in the rear and a selectable in the front for the street and trail driving I do. The part about that setup that I like the least is the selectable in the front. Having said that, like I said before, I don't have much experience with an auto locker in the front, so I might like that even less. But I would like to try a front auto / rear selectable. And that's me. Others have different needs and/or different opinions and make different choices. They are right too.

 

[Broncobowsher]

What I find evil about an automatic (Detroit locker style) is what happens if you are in a turn and are going between on and off throttle, hovering around a coast.
While the locker will drive the slower tire when power is applied, fairly well known. It is what happens when you are off power. The faster tire will drive the engine. This is where the unpredictability comes in. It never bothered me, I knew what was going on. But for someone not knowing, especially at speed and in a turn, in a lifted rig, with floaty suspension...
The connection between the tire and the engine will shift side to side around the coasting point. A touch of throttle, inside tire is driving. Lift ever so slightly, locker swaps sides and the outside tire is now driving the engine.

 

[JeepGuy]

I think they were selling them as Detroit Soft Locks back when I put them in the CJ. Fun part about driving around on pavement was explaining the loud cracking around corners and the occasional slippage. Living in SoCal the wet pavement has never been too big a problem.

Technically... This Bronco is the wife's, so ease of drivability with the option to tackle some tough trails is when I'm going for.

Based on the feedback I think I'm going with my original thought of front and rear ARB. Now I just need a socal shop to install them. Any suggestions for the riverside area of socal?

 

[nvrstuk]

... below is what I stated:

I stated that ... "if you are on the throttle around a corner BOTH tires will rotate at the same speed". Meaning the diff is already locked before you go into the corner... this is asso when problems occur because some predictions don't come true when driving... especially when going down a twin track trail in marginal conditions or even multiple times a mile when in town something unexpected happens. (people, dogs, deer, slick patches, etc...) ALL these things make it impossible to predict what you need to do then the DL locks/ unlocks... like everyone agrees it is much more common when towing but the wheels are also locked when off the throttle (same as when on the throttle) also which I've referenced before and if you wheel like we do constantly on snow/ice then that's not a great feeling when pointing downhill with a DL doing it's "predictable, yet totally unpredictable thing" whether it's in frt or rear or both. Ask my best friend who has a DL up front in his Bronco. lol
.
When in town you can probably predict about a 100 other things when driving let's say a mile in town that are inconsequential but not that waaaay cool feeling you get when your DL does that on ice, gravel, pavement, etc. You might know it could occur at almost anytime but you will end up responding to what it's doing to prevent a potential issue.

Predict and response/respond are not the same

It's the response or reaction that you have to deal with constantly when driving with a DL. An open diff, a spool, a selectable NEVER puts you in that situation because they are predictable.

Detroits as you say, ... "do have objectional manners".... and it's the response that the driver has to use to correct those "objectional manners" that makes it "not predictable" because every surface, every slight difference in speed, every variable every time will be slightly different therefore causing you to have to adjust your response to the DL locking or unlocking for those conditions. If you were on a race track with the repetition of making laps then I could say the DL was "more predictable", but we aren't on a closed course so we have to react to the DL "bad habits".

Broncobowsher says it well above.

 

[ntsqd]

Yeah, that transition from Modulated Throttle to either compression braking or power was predictable in it's unpredictableness. You knew that it was going do to something sort-of, kind-of like this, but how much and how hard it hit were never exactly the same twice because the surrounding conditions were never exactly the same. I will say that I think it made me a better driver because it trained me to instantly adjust to unexpected changes in the way that the truck behaved. But! I'm really glad to not be driving one of those any more.

It used to be that I didn't really understand why some guys would suggest a spool for something that was going to be driven on the street, at least a little. I get it now. Far more predictable than a DL, that's for sure. With a DL you never really know when it's going to try to take you into the ditch. With a spool you know that's where it is going go immediately.

Both of the DL's that I've owned were the so-called "Soft Locker" version of the DL's. The one that I drove the most miles with, in Patch for a bit over 100k miles, was harsh in it's predictable unpredictableness. The one in the Suburbans (same 14bff axle) was far less harsh. The Subs were 129" WB and weighed about 6.5k lbs. Patch was a 112" WB and weighed ~4.5k lbs. I mention this because maybe the difference in the vehicles was the difference in how the DL's behaved?

 

[gnsteam]

I think they were selling them as Detroit Soft Locks back when I put them in the CJ. Fun part about driving around on pavement was explaining the loud cracking around corners and the occasional slippage. Living in SoCal the wet pavement has never been too big a problem.

Technically... This Bronco is the wife's, so ease of drivability with the option to tackle some tough trails is when I'm going for.

Based on the feedback I think I'm going with my original thought of front and rear ARB. Now I just need a socal shop to install them. Any suggestions for the riverside area of socal?

I think you're making the right choice. I debated this decision for months before ordering the front and rear ARB set ups. The biggest issue to get over is the cost, vs amount of usage. In the end I think you and I will like the street drive ability and the peace of mind. If you do get into a serious situation, the lockers are available. I rebuilt the front and rear axles (first time ever) and installed everything. The Dana 44 was the hardest of the two axles. So if you can afford it, having a professional would be the way to go. It literally took me a month to do both axles.A Doing a little at a time and as my patience grew thin. Just walk away and restart tomorrow. I have several photos in my build thread starting on page 12.
https://classicbroncos.com/forums/threads/project-76-orange-special-decor.239642/page-12

 

[Broncobowsher]

Based on the feedback I think I'm going with my original thought of front and rear ARB. Now I just need a socal shop to install them. Any suggestions for the riverside area of socal?

Good choice!

 

[Nothing Special]

I'd like this thread to be able to stay with its original point. So all I'll say is that I have a lot of years and miles with auto lockers in the rear and I've never been surprised by one. But I hear people with strong opinions on both sides. So I'll leave it bu saying auto lockers aren't for everyone. Some of us like them, some people don't. And I can't tell if "you" (whoever you are) will like them or not.

 

[Jakedog]

I haven't looked into it for quite a while (I went with Truetrac), but I remember Eaton was working on an electric locker, but they scrubbed the idea because of limited room inside the 9" housing.

If Toyota can fit an electric locker inside the Tacoma's small housing, why can't the 9" be designed to fit one?

Just curious.

 

[ntsqd]

Toyota had the freedom of designing a unique housing to work with the electric locker. Eaton could do that, but it probably isn't economically viable.

 

[jamesroney]

I haven't looked into it for quite a while (I went with Truetrac), but I remember Eaton was working on an electric locker, but they scrubbed the idea because of limited room inside the 9" housing.

If Toyota can fit an electric locker inside the Tacoma's small housing, why can't the 9" be designed to fit one?

Just curious.

Because the 9 inch is a straddle pinion design, and about 5-10 times stronger than anything Toyota ever put in a pickup. The Toyota's lack of the straddle pinion bearing support allows for a "normal" sized differential carrier to be utilized. This is also true of the Mopar 8-3/4 solution in the muscle car era...which necessitated the use of the Dana 60 as a performance axle. The Ford performance axle of the era was the 31 spline 9 inch "no-spin" which you know as the Detroit Locker.

So the thing that gives the 9 inch its r&p strength advantage is also the thing that prevents it from having adequate space for piston travel and gear engagement capability / strength.

There is insufficient market for an electric locker in a 9 inch that cannot be served (over-served?) by the existing ARB solutions. And the 35 spline Comp configuration has proven to be "good enough."

That and the fact that the eaton electromagnet ramp solution is junk...

 

[ntsqd]

For the record it isn't easy to kill a Toyota 8" diff. I won't argue that it is as strong as a 9" Ford, but I do question that 5x-10x factor. 1.5x-3x would be more my estimate. Stock the yota axle shaft splines are stouter (larger OD if only 30 spline) than the 31 spline 9" option, so I'm specifically referring to the diff assembly itself.

 

[Jakedog]

Obviously the Ford 9" is a stronger unit than the Toyota 8", but I definitely agree that the Toyota axle is stout.

 

[Johnnyb]

TrueTrack in back and ARB in front. I have found this to be a great combination in the sand, cinders and rocks, plus it drives great on the way to the trail as well, I have been on more than one slickrock trip where someone broke a front shaft because a non-selectable front locker or spool simply put too much on the axle shafts. I did ARB because it is supposed to be the best, but I think any selectable front locker could do the job.

-JB

 

[RuggedOverland]

The Eaton Truetrac front and rear have been amazing over the last 4 or 5 years and have survived a lot of stuff thrown at them. The drive-ability, traction and lower impact on components is really really hard to beat!

 

[Apogee]

I really like the ARB's my brother has in his '85 Yota...other than needing seals every so often, they've been solidly reliable performers, so I'm going the ARB route on my F150 HPD44/Ford 9 axle swap, knowing there were some compromises on the 31-spline 9" ARB application. I'm not a comp guy and I don't wheel my stuff like I hate it, so hopefully it works out well. Back to my comment about the seals though...I would suggest engaging the locker at least once a month, if not weekly, just to keep things cycling and lubed and happy. It sucks to flip on the lockers when you need or want them, only to hear them blowing air out the axle vent tubes.

 

[nvrstuk]

I really like the ARB's my brother has in his '85 Yota...other than needing seals every so often, they've been solidly reliable performers, so I'm going the ARB route on my F150 HPD44/Ford 9 axle swap, knowing there were some compromises on the 31-spline 9" ARB application. I'm not a comp guy and I don't wheel my stuff like I hate it, so hopefully it works out well. Back to my comment about the seals though...I would suggest engaging the locker at least once a month, if not weekly, just to keep things cycling and lubed and happy. It sucks to flip on the lockers when you need or want them, only to hear them blowing air out the axle vent tubes.

It's not the 31 spline ARB with issues, it's the 35 spline 9" ARB that has the issues. Brg caps & axle dia size compromise the integrity & they grenade.

I ran the 31 spline 9" ARB for decades and never had an issue. Everything around it failed but not the ARB.

However, I did twist a 35 spline ARB (non-competition model) into pcs.literally in half.

( Update: I should mention that my Feb 1986, D44 ARB never went thru a seal or ever had an issue in the 30yrs I had ran it. The 1st gen rear 9" never went thru a seal or had a maintenance issue of any kind.

I have heard that newer ARB 's have had a few issues. I have noticed that most seal issues seem to be with the newer recommendations of running the air pressure at 150psi instead of the old 85 to 105 psi that ARB recommended for decades. I asked ARB tech's about this and they said they have noticed more seal issues than years past... whatever that means. )