Spool vs. Detroit locker

[lax17]

What is the difference, and which would be better for a DD?
The axle would be a Chrysler 8.75".

[explorer]

A spool allows zero differentiation between axles. Very simple, and light, but unforgiving. The Detroit or any other auto locker, allow one side to overrun on turns. So, when you make a turn, the torque is being applied to the inner axle, and as the outer wheel speeds up around the turn, that side disengages and is allowed to freewheel. When the disengaged axle returns to the same speed as the other side, it locks back in. Still relatively simple, but heavier. More forgiving, but definitely different than driving with an open diff.

[lax17]

From the way people comment on the Detroit, I wasn't sure if there was any freewheeling involved.Thanks

[sidriptide]

From the way people comment on the Detroit, I wasn't sure if there was any freewheeling involved.Thanks

that is all dependant on whether power is being applied or not. a spool on the street in a DD is a poor choice IMHO. cheap and strong, but drivability suffers and you wear tires faster. occasional daily use i would not have a problem with but as your sole transportation i'd advise against it. you might not even find a spool made for the 8.25. i looked at lockers and such for mine last year, but never looked at spools.

[explorer]

you might not even find a spool made for the 8.25. i looked at lockers and such for mine last year, but never looked at spools.

He may have mistyped,but he said 8.75 or 8 3/4. Being that they were used in lots of full size Mopar stuff, I'm betting they have spools readily available.

Also, it doesn't matter if power is being applied or not with the Detroit. On or off the gas, it will allow one side or the other to unlock. If your on the gas hard enough to break loose the inside tire, then yes it will catch up to the outside and both will drive. The torque transfer reversing when you go from drive to coast while turning can give some interesting noises, as the sides that are locked and unlocked have to switch jobs. You have to look at coasting or engine braking the same as driving in reverse, then it will make sense.

[Bounty Hunter]

The Detroit is less streetable than a spool IMO, and I've driven both. The constant locking and unlocking of the Detroit can be unnerving, not to mention the sudden unintended lane changes it can cause.

I run Lincoln Lockers front and rear in my DD and love it. Tracks straight as an arrow, and very predictable in all types of driving conditions. Can't beat it offroad, and less stress on the axleshafts unlike an auto locker that suddenly locks during wheelspin.

[Wil Badger]

i have always driven with Detriots and i can say i have never had an unexpected lane change because of one.i would never install a spool on a DD.as for what axle he has i'm beating it was a mistype.they do not make a spool for the 8.25 i asked when i exploded my detriot a few months back.

[BrettM]

when discussing unexpected lane changes and unpredictable characteristics of auto lockers (like the Detroit) it would be best to mention whether you have an auto or manual tranny. It seems that the vast majority of these complaints come from people with manual trannies.

[Bounty Hunter]

i have always driven with Detriots and i can say i have never had an unexpected lane change because of one.i would never install a spool on a DD.as for what axle he has i'm beating it was a mistype.they do not make a spool for the 8.25 i asked when i exploded my detriot a few months back.
Ever run a spool on the road? I bet you'd be surprised, especially if you've had to ever put up with a Detroit.

[lax17]

Chrysler 8.75" w/dropout centersection, automatic transmission.

[explorer]

I ran an ARB for about a year. After running a auto locker, and switching to the ARB, I found myself running the ARB locked even on the street in low traction conditions. So in effect, I've run a spool on the street. I went back to an auto locker, which handles better in my opinion. I run a manual trans right now, and I've found that whenever it starts behaving odd on the street, it's been due to unequal tire circumference. I get exactly the same in pressure and have even gone so far as to measure their circumference if that doesn't do it. After checking and correcting the circum. with tire pressure, it is very well behaved.

[langer1]

Spools are definitely not for Street use, you literally have to slide the tires to turn.


Off Road they can also make in very hard to turn, that’s the reason for the ABR lockers you can lock and unlock as needed. The Detroit type lockers are automatic, they un-lock when you need to turn.

[90whitexj]

I would say go for the spool, and I AM SPEAKING FROM EXPIRIENCE. I DD mine and I spooled my rear 44 and dont mind it at all. YOur tires do wear a little faster, but I would not worry about it if I were you. And offroad, it is great too. While the Detroit and ARB boys are sitting there trying to decide why thier lockers wont engage. you can just drive right past them, with both tires spinning.

[langer1]

Well the check your state laws then also, as they are not street legal in most streets.

[Bounty Hunter]

Spools are definitely not for Street use.

I wish somebody had told me sooner, I've been driving this way for over 2 years :wierd:

Seriously, there's nothing I know of in this state's laws about running onroad with a spool.

[BrettM]

Well the check your state laws then also, as they are not street legal in most streets.
do you have a vehicle code for this? in any state?

[Roxtar]

I've used Detroits on DDs for a few years and love them.
Just let off the power in turns and it disappears. If you hit the gas in a turn it will want to head where it's pointed but not uncontrollably so. it doesn't matter if power is being applied or not with the Detroit. On or off the gas, it will allow one side or the other to unlock. I don't think so.
When power is applied it's locked, period. The locker doesn't have a brain that knows it's turning.
Power on=locked, power off=unlocked.
That's why people talk about the above mentioned unwanted lane changes.

[explorer]

When power is applied it's locked, period. The locker doesn't have a brain that knows it's turning.
Power on=locked, power off=unlocked.
That's why people talk about the above mentioned unwanted lane changes.

I disagree. Even under power, the detroit and other auto lockers will allow overrun. This is not the same as unlocking an ARB or similar. It just means that they will allow a wheel to travel faster than being driven, but not slower. When you say power off=unlocked, then does that mean that in reverse it doesn't lock as well? No brain also means it doesn't know which direction its spinning. To the locker, coast is the same as reverse. It reacts to torque. During forward driving, it will allow the outside wheel to spin faster around a turn. Same thing in reverse. The unwanted lane changes are more due to size diff. between tires in my experience related to pressure or just variance.

[ECU88XJ]

I disagree. Even under power, the detroit and other auto lockers will allow overrun.


By this theory, there would be no tire chirping when turning corners on the street because the inside wheel would be governing the 'slower turniong wheel and allow the outside tire to freespool. Every automatic locker i've ever witnessed will chirp when you gas it aroung a right hand turn from a stop. I'm going to have to agree with kid here; when you're on the throttle, the axle shafts are locked together, thus turning the same speed... Well as long as your locker is working properly...

[Roxtar]

The unwanted lane changes are more due to size diff. between tires in my experience related to pressure or just variance.When you coast into a turn it will disengage. If you apply the power halfway through the turn it will try to run in the direction it's pointed. In either direction. This has nothing to do with unequal tire pressure or anything other than the locker. Simply put, a real locker, when locked (power applied), is pretty much a spool.

[explorer]

By this theory, there would be no tire chirping when turning corners on the street because the inside wheel would be governing the 'slower turniong wheel and allow the outside tire to freespool. Every automatic locker i've ever witnessed will chirp when you gas it aroung a right hand turn from a stop. I'm going to have to agree with kid here; when you're on the throttle, the axle shafts are locked together, thus turning the same speed... Well as long as your locker is working properly...

The tire chirping is because your spinning the tire. It doesn't mean the axles are locked together. It spins easily because your only powereing one tire until it catches up to the other side at which point both will drive. I could drive my Lockright equipped TJ all day and not chirp a tire as long as I was very easy on the gas. The Detroits I've driven were the same way.

[old_man]

I have run Detroits for decades and have had no major issues with it on the street other than if you power through a sharp turn, it will chirp the tires.

[explorer]

When you coast into a turn it will disengage. If you apply the power halfway through the turn it will try to run in the direction it's pointed. In either direction. This has nothing to do with unequal tire pressure or anything other than the locker. Simply put, a real locker, when locked (power applied), is pretty much a spool.

I guess when your talking about unwanted lane changes I was assuming you meant in straight ahead driving. In that case, at least with my TJ, it is very sensitive to tire pressure differences. If one tire is low by even a couple of pounds, it will yaw toward that side every time you shift. I agree that when coasting through a turn and then getting on the throttle, it wants to understeer more than an open diff, but thats due to it only driving the inside tire. Lets forget about accelerating out of a turn for a second. Are you saying that if you drive very slowly around in a tight circle, that your Detroit doesn't disengage? Because I agree with you on the traits that they exhibit, just not the actual mechanical function. Is a Lockright a "real" locker in your eyes? To me it is, whatever reputation it has from the strength standpoint. And with that, I can make a slow turn under light throttle and here the coupler ratcheting. It did it when new, and was the same throughout its life.

[ECU88XJ]

The tire chirping is because your spinning the tire. It doesn't mean the axles are locked together. It spins easily because your only powereing one tire until it catches up to the other side at which point both will drive. I could drive my Lockright equipped TJ all day and not chirp a tire as long as I was very easy on the gas. The Detroits I've driven were the same way.

Yes, you're chirping the tire because both tires are spinning the same speed, exactly as a spool does., the inner tire will chirp as it spins to catch up with the outer's speed in the sharp corner

It is possible to feather/ go easy on the gas and not have this occur with an auto-locker. I'm not saying that this is a bad thing, just sayin that it happens.

I run a spool currently, i started ignoring tire noises long ago...

[explorer]

It is possible to feather/ go easy on the gas and not have this occur with an auto-locker. I'm not saying that this is a bad thing, just sayin that it happens.



This is exactly my point. You guys are claiming that when power is applied, its just like a spool. It isn't. What is it about being light on the throttle that makes the difference. Have you ever taken one apart and looked at the internals? It can lock one side or the other or both. It can also allow one side to uncouple, but only if that side is spinning faster.

[Roxtar]

I agree that when coasting through a turn and then getting on the throttle, it wants to understeer more than an open diff, but thats due to it only driving the inside tire.Completely wrong there.
It is because both tires are being powered equally.
That's why they are fighting the turn. The locker won't allow the tires to go different speeds and this is fighting the front end which is trying to force them to do so.
If you were only driving the inside tire it would just follow the front wheels (it would, essentially, be an open diff). There would be no binding, no trying to go straight, and no tire chirping.

[ECU88XJ]

This is exactly my point. You guys are claiming that when power is applied, its just like a spool. It isn't. What is it about being light on the throttle that makes the difference. Have you ever taken one apart and looked at the internals? It can lock one side or the other or both. It can also allow one side to uncouple, but only if that side is spinning faster.

because when you feather the gas you're accelerating and coasting alternately.

Anyways this debate is getting nitpicky; Automatic lockers are essentially acting as spools under acceleration and open differentials when coasting.


That being said, You can learn to drive them so they're virtually transparent on the street.

that's it, i'm done

[explorer]

I'll agree to disagree then. By the way, you can "un" soft lock a Detroit "soft" locker which lessens the torque required to disengage one side.

[Roxtar]

This is exactly my point. You guys are claiming that when power is applied, its just like a spool. It isn't. What is it about being light on the throttle that makes the difference. Have you ever taken one apart and looked at the internals? It can lock one side or the other or both. It can also allow one side to uncouple, but only if that side is spinning faster.By feathering the gas you are putting the locker on the edge of locking and releasing. You're just not accelerating hard enough to put it in a "full lock" situation. Under "full lock" it IS exactly like a spool.
Idling through a turn and completely letting off the gas are doing the same thing to the outside tire. The ground is making it spin (driving the tire) instead of the engine. This is what causes the locker to release. The engine speed being lower than the ground speed. As soon as enough gas is applied to make it accelerate (now the engine is driving the wheels instead of the ground) the locker goes into full lock and becomes a "spool".

edit: Sorry, was typing this when other posts came. Didn't mean to hasta

[Bounty Hunter]

A Detroit behaves exactly like a spool until you let off the gas and get back on it, it's the locking and unlocking that give the squirrelly characteristics. A spool does away with this, giving 100% predictability and no banging. hasta