Technical The pros and cons of a locked rear from those who have or want to

OK an argument has ensued between me and a long time friend. While he has never run one he insists that you cannot run a spool on the street.

I have done it and while I prefer to run a Locker I have not experienced anything really bad with one. I do know that a spool can put extra pressure on the axle flanges that becomes more pronounced with wider stickier tires but most of us him included do not run ultra wide sticky tires on our old heaps.

So voice your opinions (preferable backed up with logic or fact) or experiences and lets see where we can end this age old argument.

Please no name calling unless it is absolutely necessary or you are calling me a bad name just because you can.

 

Of course you can but why would you want to. Could get dicey in rain and snow.

 

never done it, but I know a bunch of guys who run Drag Week with spools. They're all still alive.

 

Before haunting the H.A.M.B., I thought a locked rear end was another term for constipation. I'm learning . . .

 

I've run a spool, a welded rear, and various different lockers. A fully locked rear will let you know it's back there more than other types (more chirping of the tires IMO) and it wears tires more. The first time I accelerated on wet asphalt I looped around. Lockers make more of a racket because when they unload it sounds like something has broken. After a while, I was pretty fond of the tire chirp.

If the rear was set up to handle a fully locked rear, I don't see a problem other than adjusting to the wet road mannerism and tire wear.

 

I run a spool on the street in my roadster. No problems. I try to stay out of snow (not very successful) and rain most of the time. When I get caught, I don't drive like an idiot, so no problems.
r

 

Never could afford a real spool when I was in the market so we just welded up the Spider gears and made our own. It was OK in normal operation but was a handful cornering in the rain. We're talking teenage kid with '48 Chevy, bad shocks and "maypop" tires so just my opinion.

 

We run one in the roadster no problems. But it seldom gets driven more then 150-200 miles at a stretch.

I have run them in the past in heavy and light cars, they chirp on a street corner some times but that is all I have really noticed.

@aaggie I have run spools because I couldn't afford a locker before. had a spool under the bench, had gears and a locker was going to be several hundred dollars down the road.

 

I ran one in a 409 (421 inch) powered 61 Impala with 3.70 gears for years.
It was actually highly modified Dana posi from back in the 60's. The clutch packs were restacked with a different combination of disc's. Then the housing was bolted back together, and all of the fasteners were welded in place. The unit came out of a 62 Impala, 409 powered drag (only) racer after he went to a Pontiac axle, after spitting the Chevy pinion gear out of the housing and onto the Irwindale track surface.

The inside tire would "always" squeal through out the entire corner in slower corners. The cars was a bit of a challenge in the rain/water. Much more so than a "normal" positraction unit.
At the drag strip (mostly Orange County), there was very equal tire marks, side to side. Each being exactly the same length.
Yes...it "WAS"...a locked posi unit...

Why did I run this thing on the street, I was poor and the only way to put some sort of "posi." unit into my big 61 and I had it in the corner of the garage.
This was not my daily driver, but it did get a lot of miles put on it. I had no axle, housing or bearing problems. My guess why, is that I never ran slicks. Just semi high dollar radial street tires (Good Year, NCT) for the time. These tire's had marginal straight line traction, but incredible side/slip traction.

The guy I eventually sold the car to hated it. He called me after about a week of owning the car, and asked what was "wrong" with the rear end. I had forgotten to tell him about it.

Mike

P.s. - Would I do it again...no.

 

The only time i've driven a spooled street car was my 32 for a few weeks when i first put it on the road.
Ran 4:30 spool in a 9" and old goodyear slicks...yes slicks. Lol

Never drove in rain but i know how it would have reacted.
Biggest issue i had was in slow, tighter turns the car wanted to go straight so i had to put serious effort on the wheel. It pushed hard.
That was with 5.60x15 up front and 16x10 slicks though so there was very little "slip" out back to the inside wheel. And when it did finally slip, it was like driving a 4x4 on dry pavement with the dry hop/chucking out back.

I swapped to a 4:10 trac lock now so its all better hahaha

Fun times.

Tony

 

Ive never run a spool on the street but I ran a Lincoln {welded spider gears}locker in my street 57 ford 427 4 speed car back in 1965. Kind of chirps the tires going around corners but back then there weren't many options for street racing. Now you can get strong positraction type rears so theres no need to weld spider gears any more. It really makes them howl like hell too

 

I have built and owned a wide variety of 4x4 vehicles, all with numerous and various types of locking differentials, and with limited-slip differentials.

I don't recommend clutch style limited slips. They have no active function, and when they wear out, they are open, and your gear lube is full of friction material.

I do not recommend cam or ratchet type locking differentials on the street. They can make for disconcerting and downright dangerous handling on the street. They can cause on/off throttle involuntary lane changes, and an under-short-soiling surprise for the person behind you.

Fully-locked, permanently locked (welded, spool, whatever), can be more predictable in the handling department, but but by no means ideal (they can suck, but always to the same level). You can end up the wrong way 'round in a hurry.

I have heard countless guys on the CB on the trail complaining "I am trying to turn, but the locker (or spool) won't let me." If you have a light car, this can cause you to plow right off the road in a turn, so be prepared.

What I favor for the street, and for everything but the most hardcore offroad rig is a torque-biasing limited slip. They have an active function, have no associated handling issues, and don't wear like other systems.

I have one in every single vehicle I own (including the Wife's DSG VW), and at both ends of my Jeep (D44/D60). My 1960 Falcon, running a Ranger 8.8 has one too. All but the VW are Eaton TruTrac's.

The one in the rear of the Jeep is a rare one that switches from a torque biasing limited slip, to a ratcheting locker, electrically. It engages, for reasons I cannot explain, every so often. When it does, it almost takes the rig off of the road. Not good. Next time I have the cover off, might weld-defeat that feature.

My advice: A fully locked rear can be fun, but if there is wet weather in the forecast, leave the car at home, or better yet, don't run one.

 

What about using one of those air operated lockers? Normally it's unlocked, when you want to lock it, flip a switch and air pressure locks it like a spool. Never ran one myself, but seems like it would be the best of both worlds, unlocked for the street, locked when you want maximum traction.

 

My flat fender jeep Is more predictable with a spool than it was with a locker. I like it much better on street.even in the rain and snow. Selectable lockers are unreliable.

 

I have an ez locker in the back of my old 4x4. It's supposed to disengage in the corners and lock when throttle is applied. Works well except during a real hard stop it would clank pretty bad and stall the engine now and then. My truck is a stick maybe that's got something to do with it. Also happened one time on the snow and didn't want to go around a corner. Clanked and stalled and wouldn't turn the corner. Thank god it stopped short of the steep drop. Be careful if you get one. Do weird stuff sometimes.

 

The devil hates a coward Pork and beaner!....

 

Not in my experience. I have installed ARB, OX, Detroit Electrac, Eaton E-Lockers. Zero callbacks.

 

Not a spool, but I had welded spider gears. Like most things, after a while, you can get used to it. They are not fun in the snow, when you want to make a low speed turn, and you have to be pretty careful accelerating from a turn on wet pavement. One can find himself going the wrong direction pretty quickly if he is not careful. It was a little rough on tires, more often the front tires rather then the rear tires. I remember having really good front tires and nearly bald rear tires so I could turn the car when I wanted to (66 Coronet 383 4 speed). I ran a Mopar 8 3/4 and had one center section with 3:55 gears and welded spiders. I would swap it in and out pretty often, it was probably in the car a couple months each summer for a few years. I think when the car went away, the welded center section went with it. Gene

 

In 1986 I had a 47 Ford business coupe. Small block Chevy etc,etc. A locked 9" rear..
While I was at work, my wife at the time needed to go into town to get something. A two mile trip.. The coupe was last in line in the driveway. It was lightly misting rain, like a heavy dew. So rather than jockying the vehicles around. She used the Ford..
About 1/2 the way into town, the road goes into a lazy "S" curve between two lakes with houses on the perimeter. She gets into the first curve, the Ford starts to slide, due to no differential action in the rear end. She over compensates and losses it.. Goes across the on coming traffic thru a shallow ditch, takes out a mail box and smacks a new Buick, setting in its driveway, in the left rear quarter, at the wheel.
On impact She, being 4'11", hits her mouth on the steering wheel..

The cops arrive. She is taken to hospital. As the coupe is being removed from the Buick and loaded on the tow truck. The state police officer noticed that the rear axle/tires just slide on the ground as the car is turned and loaded. He notes a defective equipment statement on the ticket..
A very long and expensive story, short.
Insurance company would not cover anything. "Knowingly operating defective vehicle, leading to injury and property damage" then cancelled policy.
I had to pay out of pocket.. Mail box, ticket cost. Tow cost and storage (legal thievery), Repair of the Buick, rental car for owner. All ambulance, hospital costs for wife, plus Orthodontic care and mouth rebuild for two years (they should have sewn it shut).
Plus bumper, fender, paint, custom radiator , tire and steering wheel on the Ford.. Then had to remove the spool so it would pass "equipment repaired" inspection.
NEVER use a locked rear on the street!!

 

I've got air lockers front and rear (Dana Difs) in my daily and they have been reliable through heavy abuse for ten years now. No problems. Love 'em. With just the rear axle in total lock mode it will certainly make you go straight when you don't want to, even on dry pavement. I suppose a longer wheelbase vehicle would have more steering leverage than my short WB but I think a spool or Lincoln Locker on the street is dangerous and I'm no pansy ass. I'm known for danger rides.

 

I run one in an OT vehicle, in the rear, I love it. I do think, however, they would be out of place in most hot rods.

 

I ran a full spool in a non Hamb hillclimb car. Because the class I ran in meant the car had to have full road registration I used to drive it a lot ( Who wouldn't want to drive a race car on the street). I found if you keep on the gas pedal just a little bit it was OK around slow corners. Most tracks I ran at were over 60 miles away and I had plenty of wet trips on semi slick tyres with no trouble if I took it easy.
Most hot rods wouldn't need any more than a LSD or Tru-trac. They will hook up fine.
Tru-Trac's are great. They will not slip but don't behave like a tight LSD.

 

Set the roll couple of the suspension up correctly [and rear shock rebound] ,and it won't matter whether it is wet or dry
you won't get any unpredictable understeer
A spool will always chirp the inside tyre when turning tight [this is unavoidable]

I've ran locked rears in my road race cars since day one because they are more predictable


If you're faint hearted run a torsen

 

I'm not sure I'm taking this "predictable" comment in a positive context. All you can predict is that in a normal car (racers and 4X4s not included) it's not going to steer easily. Try getting into a tight spot with one and it feels like it wants to break an axle. I've had 2, one was an old welded spider 9" in a short 62 uni pickup, the other was a real deal spool in my street (turned track only) racer. Once you do get it turned watch your fingers as the wheel whips back to straight if you're on the road (!) as it'll come back with a vengeance. At my age, no thanks. Was it fun? Yes and no, yes being when you're WFO, no being when you need to park the damn thing in close quarters. As to the original question, yes you can run one on the street and it'll behave poorly in the driveability dept. Still, much like mid 60s kustoms, just because you can doesn't mean you should.

 

I had an OT Mustang with a 3.91 Detroit Locker, that car was light in the ass so I had to be careful even with that in the rain. But, otherwise it was great.

I ran spools in the stock cars since they were so cheap and easy to install. That would chirp the inside tire on tight turns in the pits. With the stagger in the rear tires, left-turn only springs, I could easily push the car in the pits to the left. To get it pushed to the right took 4 strong guys.

With my Ford, I'm going with a posi rear of some sort.

 

The slip angle of a tyre is usually greater than the differential difference between L&R [except in very tight turns]
You need to increase the roll stiffness in the rear to induce a slight amount of oversteer [loose] and sometimes you need to soften the front roll stiffness

Either with stiffer rear springs or better still a rear anti roll bar.
If you are a "drag racer" you'll probably prefer softer rear springs for straight line weight transfer so the rear anti roll bar is a better choice.
When a car bodyrolls [the same amount Fr & Rr] the outside rear will support the larger share of weight transfer because of the rear anti roll bar.[ this will make the rear loose ]

If you have 2 way adjustable shocks on the rear, soften the compression and stiffen the rebound. This help load up the outside rear tyre and unload the inside rear during body-roll. Adjusting the shocks this way also helps forward bite [rear weight transfer]

To correctly set up a spool on the street costs a bit of $$$ , if this is out of the grasp of the average hotrodder they could save money by simply buying a Detroit locker or torsen [ tuning the suspension will cost more ]

Done correctly, the car is quite predictable and fun to drive

 

one of my cars has a spool... gota drive it knowing what will happen (downside) spin outs...
(up side) kinda gets there attention (corner cherpin the tires )

 

I have run three spools on the street.
The first was a full size Chevy Truck that was raced in Pro Rally. That means it had to be street legal and we did thousands of miles of paved road both on stages (race speeds) and transits (Regular street driving). It ALWAYS squealed the inside tire on the pavement. When racing, no problem, but it did cause the truck to understeer so I had to adapt the driving style to flick it into every corner that wasn't a sweeper. On the street it was just a pain in the ass, between the noise and the way it "Hunted" going down the freeway.
The second was a Ford Ranger pickup - also used for Rally racing - same as the big chevy
The third was a Sunbeam Tiger. Short wheel base high horsepower car with big tires - absolutely ruined the handling of this car, it "Pushed" in every corner like a PIG.
I also drove a friends 32 roadster with a 286" flatty and a spool with 7.60's on the rear. To me it was twitchy and when he took it out the car was much more fun to drive.
In my opinion, from experience, spools have no place on the street.
Oh, and asked the guys who help position the Anglia at SEMA this year what they thought about the spool, with slicks, when trying to turn the car It binds up so much you can tun the steering wheel to act like a parking brake!

 

Most folks are stuck with the suspension they have. No adjustments possible, aside from basic alignment.

Chirping the tires, for any reason, in many jurisdictions, will get you a ticket.

Running a Torsen (nearly same as a TruTrac), is not for the faint of heart, it is for the realistic, who have to drive their cars on public roads, on irregular surfaces, in inclement weather, around other cars, and the property of other people.

Scroll back up and read about how your insurance can be voided. It is a good read, and a stark reminder of what happens when you get caught.

 

We ran welded rears on dirt tracks and it was sometimes difficult to line one up to get it on a truck or trailer with the stagger in the tires.