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post #16 of 24 Old 07-15-2010, 08:02 AM
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1973 CJ5 
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Originally Posted by crzdmnky View Post
So tell me about spools. I am in the process of building a CJ5 mainly for the trails but am looking for some street driveability. I just got the Clutch in last night and took it out this morning.

It has a limited slip in the rear and it seemed tight up on the lift, but man when I tried to take it up my test course this jeep is the biggest dog of them all. It just sat there and spun its two passenger side tires (front and rear). I am a believer of the lunchbox lockers, but the price of the spools is very attractive.

I have read what I can on this subject, but everything I read was pretty old, just wondering if there is a new consensus.

Can you rebuild Limited slips?

IE. AMC20 rear Dana30 front
Factory Limited Slip rear diffs are pretty easy to rebuild, and they don't require you set the ring & pinion up again, which is a pain in the butt.

When properly clearanced, and you use the limited slip 'Friction Modifier' additive, there won't be much difference between a 'Lunch Box' locker and a tightly clearanced posi,
With the exception the posi will have MUCH better road manners since you still drive on the highway.


Spools are a REMARKABLY BAD idea on hard pack or highway!
You also should include in the time and/or cost of setting up the ring & pinion again when you switch carriers, which effects the 'Price'...

Spools keep BOTH WHEELS locked together at all times, that means you are twisting the crap out of the axles, loading the crap out of the ring & pinion, and you are beating the crap out of all bearings all the way through.

Spools have the WORST highway manners you have ever seen, and if you front wheels touch sand, gravel, ect, you WILL NOT be able to seer the vehicle, you will simply push the front wheels in the sand or whatever.


Lunch box lockers can be QUIRKY on highway/hard pack,
Tire chirping, popping, kicking in and out (locking/Unlocking at strange times),

But they DO NOT require you reset the ring/pinion, saving you money/aggravation on install,
And they are CHEAP & Easy to install.


If I had a 'Street/Trail' Jeep and I had a factory Posi in the rear, I'd rebuild it and keep it.
Remember to put the friction modifier in the rear gear lube!

I've seen guys with factory posi units set up 'Tight' with fresh clutches go about anywhere guys with rear lockers can go...

I'd put a 'Lunch Box' locker in the front if I had lockouts and part time transfer case (Dana anything) so I didn't have to fight the crappy/stiff steering you get from a locker in the front all the time.

Remember that Dana 30 up front isn't worth putting a ton of money in,
So if you can get away with $200 lunch box, that's acceptable.
But dumping money hand over fist into a Dana 30 is a real waste...

You don't have to set either ring and pinion back up saving you a TON of time and/or money,
And you will be able to keep up with anyone short of the selectable locker guys that have 10 times as much money in EACH end!

One word of caution,
I'd install a cross brace for the steering box if I were going to put a front locker in with larger than stock tires.
With a front locker, you are REALLY going to move that steering box around on the frame, an some support is a really good idea so you don't crack the frame around the steering box bolts.

A home made brace is just fine, doesn't have to be anything fancy, just keep that steering box from moving around when you go up in tire size or use a locker which makes steering effort much higher.

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post #17 of 24 Old 07-15-2010, 08:06 AM
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Spools are ok, but in my opinion if you get a ratcheting locker for the rear, and spool the front, you will maintain a better handling capability on asphault (gotta get to the trail somehow) I say this because with the lunchbox in the rear, it will allow you to turn on hard surfaces without the annoying (and costly) tire bark. also with a spool up front, you have the ability to lock and unlock the hubs, so there is no issue at all when streeting it.
Just my .02 but I have this setup and I like it!

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post #18 of 24 Old 07-15-2010, 01:25 PM
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Originally Posted by Truck633 View Post
Spools are ok, ....
also with a spool up front, you have the ability to lock and unlock the hubs, so there is no issue at all when streeting it.
Getting in and out all the time to lock/unlock the front hubs on the trail gets old QUICK...

One reason I use a 'Lunch Box' up front, so you CAN turn, just with increased effort when the front locker is 'Locked In'...

Spools are also going to cost extra for ring/pinion set up since the carrier is being replaced...

I use a 'TrueTrac' (Gear Type Posi) in the rear, and it works great,
No telling it's there on highway, hard pack, ect. until you start to slip a tire then it pulls like a locker without all the bad habits.
Best part is, you don't have to try and remember to lock in, lock out or deal with all the stupid stuff when highway driving.

And I use a 'Lunch Box' in the front, and it works great with the exception of increased steering effort and reduced turning radius when the hubs are locked in...
If I had to unlock more often, I'd upgrade to a Dana 44 front and use an OX selectable or something like so I didn't have to get out and lock/unlock hubs.
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post #19 of 24 Old 07-15-2010, 02:17 PM Thread Starter
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Hmmm, thanks guys for the info. Yeah I was reading up and thinking on the LSD in the rear. I think I can get away with tightening the clutches up and just driving it. I am going to go with a lunchbox locker in the front probably, I didnt know you had to reset your pinion when you put a spool in and I dont like that idea.

Yeah it is kinda nice this thing has a LSD, that saves me some money on buying another locker for the rear hopefully. Now I just gotta figure out a way to come up with this money. I still have an adapter to buy to stick a T-18 in this thing. Ugh

I will definitely re-enforce that steering box, I knew they had trouble but I didnt put it down on the to do list.Thanks for pointing that out to me Jeephammer.
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post #20 of 24 Old 07-15-2010, 04:14 PM
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the thing most people forget is that a lunch box locker is locked whenever power is applied, therefore still acting like a spool.

There really isn't much difference between the two everyday driving because you can't coast around most corners anyway.

The benefit of a lunchbox locker in the front is that if you have a twin-sticked transfer case, you can just shift into RWD and get your turning radius back because it will unlock. Turning with 4wd engaged and the hubs locked will be no different than turning with a spool.
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post #21 of 24 Old 07-15-2010, 04:20 PM
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JeepHammer, just curious. Have you ever driven a Jeep with a spool in the rear?

Spools are a REMARKABLY BAD idea on hard pack or highway!
You also should include in the time and/or cost of setting up the ring & pinion again when you switch carriers, which effects the 'Price'...

Spools keep BOTH WHEELS locked together at all times, that means you are twisting the crap out of the axles, loading the crap out of the ring & pinion, and you are beating the crap out of all bearings all the way through.

Spools have the WORST highway manners you have ever seen, and if you front wheels touch sand, gravel, ect, you WILL NOT be able to seer the vehicle, you will simply push the front wheels in the sand or whatever.
Actually, spreading the load out to both axle shafts decreases the individual load on the shafts. A spool has no additional effect on bearings, R&P, etc. No more than running a lunch box locker or Detroit (Detroit's actually are harder on R&P than spools.) As far as under steer from having a spool in the rear, all you need to do is drop out of the throttle. I've driven my CJ on the street with a spool since '98 and never had any issues. In fact, it actually helped the Jeep run straighter down the road.

Last edited by 82JeepCJ7; 07-15-2010 at 04:34 PM.
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post #22 of 24 Old 07-15-2010, 04:26 PM Thread Starter
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Well, Jeephammer made a point, I am not wanting to linkin lock either of my rearends because carriers are worth something to me, and I am not wanting to ruin any of them. Plus they do break, I have seen it since I am an implant from racing going into 4 wheel drives. If I was to do it, I would of bought a spool to keep things clean and able to be replaced, but they cost more than a locker! Plus I dont want to have to reset the pinion and all that stupid junk.

I am going to go with some type of Lunchbox locker up front, and tighten the crap out of my LSD in my rearend. hehe, no pun intended. This way I am only out the $250 for a locker unless I can find one used on Craigslist.

Spools still seem like the way to go on some rigs and what not, but I dont know if I want to make my CJ5 this way or not. I was hoping that I could make this CJ5 a little tame on the road, so if I needed to I could drive it to work incase something happens to the CJ7. I am reluctant to drive anything that has a top and doors now, its a disease I think. SO having two CJs is like a dream! lol
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post #23 of 24 Old 07-16-2010, 08:46 AM
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With 'Lunch Box' up front, you are down to $200 to $250 total.
Good time to replace the front diff seals, but you normally don't have to take the diff carrier out of the housing.
I usually do drop the front carrier when installing a 'Lunch Box' so I can replace seals, clean out the housing well,
Check pinion/install new seal, ect.
Makes working on the front carrier MUCH easier that trying to install the locker components in the carrier under a vehicle.

Even factory LSDs work pretty well, I've seen them set up 'Tight' and they will keep up with everything but a full on spool in a mud bog...
Don't forget to put the 'Friction Modifier' additive in the lube and drive about five tight circles IN REVERSE each direction to work the Lube/Friction Modifier (Posi-Lube) into the clutches or you will get 'Popping' when going around corners.

Posi-Lube (Friction Modifier) wears out fairly quickly, so you will have to add more every year or two,
You don't have to change the lube, just add the Additive when it starts popping or jerking and drive some backwards circles in both directions.

There are several places to get a rebuild kit for the factory posi units, and I've had REALLY good luck with them,
If one tire has NO TRACTION at all,
Off the ground or on muddy/'snotty' ground/ice, then the posi is useless where a locker WILL pull.
That's about the only difference.


As for a spool,
Some guys are REALLY misguided.

The axles are locked together at ALL TIMES,
When you go around a curve or turn, one, or both axles are being twisted because one tire is turning at a different rate than the other.

This is a CONSTANT stressing, loading & unloading of the axles, carrier, ring, pinion and all bearings involved.
We ran spools for several years drag racing, mud bogging, ect,
And I can tell you they are BRUTAL on the axle shafts.

When preparing an axle for spool, I paint stripe the axle shaft,
Or scratch the axle shafts long ways, so I know how twisted the axle shafts are when it comes back in for rebuild.
I've seen axles get twisted more than a FULL TURN in just one summer,
And Spools EAT BEARINGS, they are intensely hard on splines, and remember, you don't have side gears you can change, the entire spool has to be scrapped when you start finding twisted and worn splines in the spool.

There is a reason virtually NO ONE runs a spool except for drag racers and mud boggers or maybe sand drags...
They are just WAY TO HARD on the ring/pinion which is ALWAYS loaded unless the clutch is pushed in,
They twist the crap out of EVERYTHING, and the load the crap out of carrier and wheel bearings because the axles are ALWAYS loaded.

Often times when you jack up one side of a spool equipped vehicle, the tire will 'Bark' up to 1/4 turn because the energy of going around corners is stored in the axles even when the vehicle is NOT moving.
It's CONSTANT STRESS on the axles anytime the wheels are on the ground.


The reason for a 'Locker' is to UNLOCK the outside tire around corners and let the FASTER wheel FREE WHEEL around corners.
Some times it's a 'Ratchet' type locker, where you will hear an audible clicking as the outside tire freewheels since it's faster than the carrier is being turned,
Some times it's a 'Click' or 'Pop' as the carrier unlocks the faster tire,

And if you 'Goose' the throttle around a corner and turn the INSIDE tire faster than the OUTSIDE tire is being turned, then the locker will 'LOCK' again and you will turn BOTH tires
(The famous 'SIDEWAYS JUMP' that lockers under power are famous for!)

The point is, the axles are UNLOCKED as soon as you let off the power, and the axles are then allowed to UNLOAD the excess twist,
That takes the load off the splines, carrier, ring & pinion and bearings.

If you keep EVEN THROTTLE around corners, (Assuming you have proper clearances in the 'Locker'),
Only the INSIDE tire will be 'Driven' by the engine since the outside tire will be moving faster than the inside tire.
When you clearances are screwed up, the 'Locker' will stay 'Locked' too long, and you will get a big 'POP!' when it releases with pressure on it...

The 'Lunch Box' or 'Detroit' type lockers are UNPREDICTABLE when the clearances get out of tolerance...
Or you add a lot of power around a corner,

The biggest problem with the 'Ratcheting' type lockers is people don't keep up on center pin wear, or side gear tolerances...
The springs get worn/bent and pretty soon they are popping, banging, loading and unloading at every little movement...

There ARE rebuild kits out there, and they should be rebuilt REGULARLY if you are going to run a FULL TIME locker on the street!


Like I said before,
SPOOLS ARE A REMARKABLY BAD IDEA for anything but straight line racing where you don't have to steer or have the rear tires doing different speeds around corners.
They really shouldn't be considered for anything that is going to be used on the street or try and do 'Hard Pack' trails with,
Axle failure IS GUARANTEED if you drive a spool on the street,
Along with all the steering problems and handling problems they create.


FULL TIME lockers are a bad idea in the rear because they WILL push the front tires anytime you don't have traction in the front,
And they increase the steering effort quite a bit.

PART TIME or SELECTABLE LOCKERS are a MUCH better idea in the rear so you can TURN THEM OFF when on hard pack/highway and NOT have the steering issues that come along with a full time locker in the rear.


"Limited Slip" Differentials in the rear have their limitations, but are a MUCH better idea than using a locker in the rear if you are on the street or hard pack driving!

They don't require you 'Remember' to lock anything in, they allow you to go around corners easily,
They provide traction to the tire WITH traction,

And even the factory type clutch or forcing cone LSDs are better than nothing in the rear.


Gear driven LSDs, like the Detroit TrueTrac will deliver at least 30% of the power to the tire WITH traction,
Have NO issues around corners, don't effect you even on ice or gravel,
And will split the power 70%/30% in most cases.
They DO NOT reqire new clutches every couple of years, they DO NOT require any 'Friction Modifier' additives, and they are always 'ON', you don't have to remember to 'Lock' or 'Unlock' anything.

I didn't have a factory LSD in the rear, so I put in a Detroit TrueTrac, and I couldn't be happier with it.
SO MUCH SMOOTHER than any of the lockers I've used down though the years,
Never get hung up unless I 'High Center' and NO TIRE is getting traction,
And I don't have to remember to 'Lock In' and 'Lock Out', it's done automatically.


You can acquire, modify and have installed a D-44 front for somewhere between $500 & $1,000.

With a Dana 30,
You can change ring & pinion, change carrier, change axles, change U-joints, change hubs, ect.
Have well over $3,000 in a Dana 30, and STILL NOT HAVE THE STRENGTH OF A FACTORY DANA 44.
It simply doesn't make sense to polish a 'Turd', since it's still going to be a 'Turd'...

If you are going to spend money on a factory Dana 30,
As long as you don't have a 'Q-Track' transfer case,

The $200 or $250 for Dana 30 diff seals, pinion seals, and 'Lunch Box' locker is a pretty good investment.
You can do it yourself with basic hand tools,
You can UNLOCK the hubs and Shift the transfer case to Two wheel drive and completely elminate any steering or fuel mileage issues,

While it only takes a few seconds to lock in the hubs, shift the transfer to 4 wheel drive, and have a VERY capable vehicle off road.

I don't see anything wrong with the 'Lunch Box' lockers in the front if you have a 'Dana' transfer case and lockouts on the front hubs.
This makes for a VERY capable On/Off Road Vehicle that isn't going to beat you to death on maintenance, parts or build costs, and it's going to steer and go around corners like it's supposed to.



Then you won't be the idiot running a Dana 30 in mud bog races, rock climbing, ect.

If you have a true HARD CORE rig, then selectable lockers, twin sticks, Dana 44 or Dana 60 axles front and rear are a requirement.
You will probably NOT be street legal anymore,
And you will probably TOW the vehicle to off road sites...

That eliminates any 'Street Driven' issues for you, so SELECTABLE LOCKERS or even Spools will make sense for you.

HARD CORE OFF ROADERS KNOW THAT BROKEN AXLES, U-JOINTS, STEERING KNUCKLES, ect. are a fact of life and you live with it.


Since we are talking Street/Trail vehicles here mostly,
Then I can't recommend Full Time lockers in the rear, Or Spools at any time.
Too many 'Driveability' and Maintenance concerns,
Plus the cost of ring/pinion set up and wear & tear on all the drive line parts with full time lockers in the rear or especially spools.

If you have different opinions, that is fine.
If you are running full time lockers in the rear, or spools anywhere on the street, that is fine with me.
I just don't recommend it for any street driven vehicle for reasons stated above.
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post #24 of 24 Old 07-16-2010, 11:03 AM
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^^^ Gotta agree.

I installed dual ARB's on my CJ5 build with stock D30 and Moser equiped AMC20 and 4.56 gears. I know the limitations of the 30/20 combo, and will not press them. Driver input (along with tire size), has a great deal to do with lifespan of the 30/20.

Spools work great in the sand/mud, just about every quad out there has a 'fixed' rear axle. And they have their place on the drag strip. I don't see their value on slick trails where you need to maneuver around trees, etc.

But to each their own.

"In the end...It's all Hack."
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