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

Ran a powertrax locker with the ratcheting gears to replace the spiders. Went in easy and worked fine for me other than being noisy on slow sharp turns.

 

My brother ran a 57 Pontiac with a 4:88 gear with a pair of those old spider-locks that locked the rear end with slicks on the street. He called me one day to say his car pulled super hard to one side. I rode with him for a test drive. He had both hands on one side of the little foam 10 inch steering wheel trying to keep it straight. Had a low rear tire...
He really got a work-out driving that 3300 lb car set up like that.
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I have towed about 7 or 8 guys off of the trail when one of those failed.

 

Oh, the ol' locked rear end memories!
1958, my friend Donahue traded me his cool red '34 Five window for my '49 Harley, the '34 had a 5/16 X 1/4 flathead (274 cubes) and burned up wires and fuel hoses, from a recent Stromberg blaze.
Fixed everything, but Donahue didn't say anything about a 'locked rear'...
Didn't notice anything 'til I drove it, got on it in low gear, "BAM!" about 10 MPH, no power, so I pulled it
over to the curb, popped the hub caps, and idling in low gear the axle stub was turning in the hub.
Replaced the left axle key, checked the right side. Axle key sheared there, also.
Installed 2 Moon soft keys...
Fired it up, pulled out of my driveway and turned, Holy Hannah! Extreme 'stiffness' in steering 5 degrees off center, then when straightening it out, the 3 spoke Bell nearly slashed fingers!
Not to mention the Santa Clara cop standing on the corner, gave me the whistle and wave, so I pulled over and got a ticket for 'breaking traction around a corner'!
Welded spiders. Sure came out of the hole quick, though...4.44 rear with 25 tooth Lincoln gears.

Fast forward 20 years... My '55 F100 still had the old Dana rear in it, 3.78s, but the spiders were worn so bad it 'crunched' on corners, 'clunked', just worn out.
I needed the truck for 2 days, so in haste (and efficiency) removed the rear plate from the diff, flushed out the oil and teeth fragments, and gave it a pressurized spray of lacquer thinner.
Arc welded the spiders solid, replaced cover, and filled it up with Swepco non-foaming 80w, that I used on Porsches.
Not as bad as the '34, (truck has more wheelbase, and frontal weight) but that little trick shot it out of the gate like nobody's business!
It was like that for 2 months, and on a rainy night I spun it around (360*) on Winchester, in front of Century 23...People were lined up outside for the movie ("THE CAR!") and got a hell of a preview.
Rattled me a little...Drove it back to the shop and locked it up.
The 9" went in that weekend!

 

Oh man, this is something I've forgotten about. It's happened to me, too. Yes, uneven pressure will teach you a lesson, for sure.

 

Beaner,?

Why you want to stir that pot?

 

Try pushing a car around a corner that isn't running with a spool or lock rear end.

It's a great workout!

 

I have a Detroit in my daily jeep. Works fine. Little noise but the four link is set to roll steer correctly.

I had an All Trac in my 54 M37. It also worked flawlessly, but was a lot noisier.

Had an old crash box Detroit in my 68 bronco. Worked fine but was a hand full on ice or snow.

Learn to drive them and you won't have any problems. Stay off the throttle around corners.

 

My '03 Tacoma has a electric locker rear axle for off road use. On dry pavement it is terrible, hops around corners and doesn't track straight, on wet roads it will come right on around for a 360 if I'am not careful. My race car had 14x32 drag slicks with a Dana 60, 4.11 gear and a spool. It would really struggle going around corners, and you couldn't push it if you had to.

 

Guess I wont use one if I ever build an off-road vehicle, but it worked fine for me on the street.

 

Yeah, torque multiplication is a harsh mistress. Some of these guys have transfer case low ranges of 10.44.1. Even a little six-cylinder with just 200lb.-ft. of torque turns out 2088lb.-ft. at the pinion through one of those, with 1:1 gear in the transmission. With a first gear like 3.83:1, that's 7997.04lb.-ft. at the pinion. It is a wonder anything survives at-all.

 

Listening carefully here - the 9er in my Chevy is equipped with an Auburn Detroit Locker. Very little road time yet, the tire pressure issue is good to know about in advance.

 

Someone has got to. LOL

I figured it would make for good stories to start the weekend. Its funny the only one I ever spun in the bad weather at least by accident was one with a posi. I usually run lockers if I can and a posi (limited slip?) is open until it locks, instead of locked until it opens. left a light in the rain, short wheelbase truck and a little nose heavy, when it went from open to twin drive one tire was trying to catch up with the other and around it went. I would much ruther have both tires digging then one and then two anyday. But as rocky pointed out you do have to mind your tire pressures.

 

I run a spool in my Nova on drag radials and its straight up dangerous in the rain. Anyone who says otherwise is full of shit.

 

I have had some seat time in a friends car with a spool, I wouldn't try to drive it in the rain. I have a Detroit Locker in my daily, works pretty good in the dry. You can skate by with a Detroit in the rain, but you have to pay attention ALL the time, and I have had Detroit lockers in a lot of cars over the years. I wouldn't let ANYONE else drive my vehicle in the wet. If the vehicle is nose heavy and has a lot of power/gear, its pretty evil in the wet. Dumprat says "stay off the throttle around corners" hell, if its raining, I stay off the throttle around corners, changing lanes, crossing painted lines in the intersection...you get the idea...
Both the spool and the Detroit locker will push very hard in the dry, just as Tony says. If good all-around handling was in the agenda, I wouldn't run either, but I like detroits in street cars with a drag race focused intent, they are pretty bulletproof.
Personally, I wouldn't run a spool in a street driven car unless I had no other choice. They arent "unsafe" in the dry, but fairly unpleasant to drive around corners even throttle off. I am just not abig fan.

 

My wife drives the jeep with the Detroit. I don't really think it is that big of a deal. But having said that suspension design with a locked or spooled rear makes a HUGE difference.

A car that wants to push or under steer through corners with an open diff will suck badly with a locker.

 

I mentioned nose heavy, but I notice I didnt really spell it out. The vehicle I am discussing here is pretty nose heavy (58/42). Its flat out evil in the wet, in heavy rain, I have had the ass-end come around changing lanes and gently rolling the throttle on at 30 mph. And yes, even in the dry, it plows like an Oshkosh.
That was with M/T 275/60 ST's, not drag radials. No way IN HELL would I let my wife drive it in the wet. Hell, she wont even drive it in dry!

 

My opinion is if you don't want to put an emergency brake on the car just run a spool. Turn the steering wheel 1/2 turn when you park and the Hulk can't push that sucker.

 

Yeah, i forgot all about that!
Once i got to the roller stage on my coupe, moving it around was a flat out bitch unless you were going in a straight line!
Tony

 

Beaner with a locked rear yikes. I've driven with you in a new car and all I've gotta say is if your thinking about that in the model A you'd better call modot and have them put the bumpers in the gutters!

 

You need to be more specific here with that statement. Drag Radials are straight up dangerous in the rain... not the spool.

I ran a locked rear in my Lotus Cortina and it was absolutely predictable in the rain. The suspension was set up correctly .
Just locking the rear end without any consideration to the rest of the set-up is hackjob engineering at its best.

 

I hate late models. The Silverado is a limited slip and it locks when you east expect it.

I like knowing that both wheels are locked and nailing it way better then nailing it with it open and not knowing for sure when the second wheels is going to get snagged and be turning slower then the one that is already spinning.

By the way I wouldn't run drag radials in the rain with an open rear or any other rear unless I just got caught out in the rain with them and had to limp it home. They like cheater slicks or any other slick are not wet weather tires, tires make as much difference as any other thing with a locked rear. Perhaps there is the rub, most of the fellas saying that they are hard to drive in the rain are trying to drive them with tires that have no tread.

 

Per the original question...of course it can be done but why? Makes absolutely no sense! I had pretty good luck with the old "positrac" (clutch discs and plates). I used the recommended GM oil and made lots of tight right and left hand turns...seemed to help. I raced almost every weekend somewhere...75% street 25% strip. However, I tried to run one in my 1st gas dragster...big mistake! Violent right turn every run. Replaced it with a Getz "locker" cheapest locker available, about 65.00

 

Word on the street is the Nitto 555's and Toyo Proxes TQ's are fairly rain friendly, as well as the new M/T ET Street S/S drag radials.
I haven't tried any of these yet, so I cant speak to this first-hand, but I will be trying a set of the new M/T's this spring, and I will be trying them in the wet.
http://www.mickeythompsontires.com/strip.php?item=ETStreetSS
The Proxes also work pretty well at the track, but HAMB friendly sizes are limited to non-existant. Most guys that run the Nittos compare the track performance to the BF Goodridge drag radials, which are pretty so-so.

 

There is the rub. A posi unit or a locker that is not a true locker will spin you around every time. With a locker or a spool you have reproducible driving all the time, when you drive a rear that is open until you loose traction you don't.

I think that there are more than one reason to run a spool on the street or a locked rear if you prefer. one is cost, I have reached a point in life for example that I either normally know where I can snag a locker pretty economically or I have one on hand. Gene and I both have contacts now that only come from 40+ years of racing and rodding, if I were a young man today and had to purchase new it would be an entirely different story. A new locker runs in the 400+ dollar range, a new lightweight spool can be had for about 150. Another reason to run a spool has to do with again cost, we sometimes find the perfect rear and it comes with a spool already installed, a locker or a posi unit again would be another 400 or so investment.

 

Ya you're right, a 100hp foreign tin can with a spool is nothing like driving a 700 hp 3,700lb car with a drag race suspension setup.

 

You actually need to read what you wrote, especially the words "with a drag race suspension setup"
Which is the point I'm trying to explain all along.

My old road-racing Corvette might not have your chest thumping 700hp [it only had 612hp] but it weighed only 2600lbs and was OKish in the wet.
The main issue was the weight of the BBC up front not the locked rear end.
[I had never driven it on the road when wet, only the track]

The Cortina was driven on the road in the rain.

 

Its the combination of "weight up front" HP (more accurately, torque at the wheels, so gearing plays a HUUUUGE role here as well) and a locked rear that is evil in the wet. I am not at all surprised that a Cortina would be perfectly manageable in the rain with a locked rear. As far as that goes, if Benno is running this in his Model A (probably in the 53/47 range?) with a 350hp small block and a 3.08 rear gear, it might be "livable", MIGHT BE. Another factor with my particular combo that I have mentioned to Dumprat off forum but wasn't thinking of when I posted, is that most of the weight on the back end of my vehicle is unsprung, if I looked only at sprung weight, the bias is probably more like 70/30.
I have run lockers in a number of cars over the years, all with mid four series gearing and 400+hp, and I have had a couple with limited slips with the same sort of gearing and hp. The cars with lockers were touchier in the rain than the cars with limited slips, and the cars with lockers and a front bias of more than 55/56% were downright evil in the wet. The locker/front bias combo plays a bigger role than hp/torque at the wheels.
On my present combo, I have also been thinking that Cal-Tracs might exacerbate the spooky wet weather behavior with a locker relative to slapper bars. I don't have any A-B-A testing to back this, its just a hunch.

 

That's odd, unless it's a newer model rear end?

The Dana's I set up use a set of clutches, takes about 60-70 ft/lbs to break one side loose...in effect it's a somewhat locked going straight, the slips as you round a corner.

What kind of rear end are you referring too?

 

The Corvette had mid corner understeer due to heavy weight [only on hairpin bends]. It was neutral on corner entry and with 600 ft/lbs + torque I could induce a nice corner exit throttle oversteer.

Most people here running drag racing set-ups will be getting oversteer in the wet [ in road racing this is known as "snap oversteer"]
A car with too much roll stiffness in the rear [or too much rear weight] FOR THE AVAILABLE TRACTION will get snap oversteer because the front will turn in easy but the rear keeps wanting to go straight ahead.
In road-racing with a well dialled in car, snap oversteer is caused by poor driving skills [ usually the driver lifting off mid-corner and compromising the traction]

This is a tyre spring combo issue, not a locked rear problem