Several months ago driving down a hill in the rain, my '97 f-250 ld, 3.73ls equipped truck, slid around from the rear-two 360 degree spins before coming to a (thank God), safe stop on the highway. I couldn't figure out, at the time, the cause. I was not turning, accellerating, coasting or braking. I just read on the TDR site about many members with Dodge limited slip axles, loosing control in snow and rain, with the rear breaking away. Is this a problem under these circumstances with these axles. Some Dodge members have said that with past similar trucks without these axles, they have not had these skid problems. I would appreciate any experiences or thoughts on this subject. Thanks

 

I have the limited slip rear axle.. to be honest... I have a 150 pound weight in the bed of my truck... and that truck still breaks lose on wet roads like I was on ice... I'm not driving crazy either normal acceleration is causing it... maybe I've got too much truck...

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99' Ford F150 XL Sport
(Black) V-6 3.55 manual
Mods:
Airaid, Bosch +4 Plat.
Dynomax Ultraflow SI/DO
Color Keyed Carpet
AVS Headlight covers
AVS Bugdeflector II
Lund Wiper Cowl
Lund Tinted Glass
Lund Soft Bed Cover
V-tech Taillight covers

 

Tires play a good part in this. when I had my Goodyears they would slide all the time
since I've had my BFG's I haven't slid once.



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Y2K F150 4x4 XL Med Torredor Red
4.2 5 speed,AIRAID, SuperCHIP,
3.55 LS, Leer camper shell, bedrug,
Ranchhand Rover Brushguard with 6 LIGHTS and
Wireless remote switch Tint/alarm/ aftermarket keyless entry/locks
2m/10m/11m/12m radios, Scanner
LT285/75/16 BFG All Terrains
regulator@f150driver.com

 

The limited slip will force the truck to fish tail in slippery conditions alot easier then a regular universal differential. But in a 4wd, it's very controllable, with under steer being more of the problem. But your going to benefit more from the LS in snow and mud, having both tires spinning. When I was looking at buying a truck, I could of purchased a 99 F-150 with all the options I was looking for, except the LS wasn't available at the time, so I went with a 98 that had it.

 

I drove my '98 with an LSD through the big ice storm two years ago and never had a problem fish-tailing. With no winter tires, either, just the stock F-stones.

Where I've heard it can spook you is if you are going fast on ice and it starts to slide and you keep gassing it. That can sometimes get the power going back and forth from left to right, looking for grip and send you for a loop. I've never experienced that, however.

In a Canadian winter, I swear by my limited-slip.

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Black 2000 SC short-box XLT. 4.2 V-6, 5-speed, 3.55 limited-slip. CD, remote entry, factory side steps, rear fender inner splash shields (TSB 00-09-05), FORD box liner.

My third F-series. The other two: '73 F-100 Custom, 240 cube 6, 3 on the tree, tan, "West Coast" mirrors, step bumper, knitted vinyl seat, AM radio; and '98 F-150 XL-SC, XLS package, Pacific Green, 4.2 5-speed, 3.55 ls, FM-cassette.

GREAT trucks!

 

As you've learned first-hand, LS can cause some real sphincter-puckering for the uninitiated.

My '97 4x2 5.4 3.55 LS got sideways on a freeway entrance ramp in the rain while fully loaded and towing a 20' travel trailer.

Undertaking 'black-ice'-covered overpasses while still on cruise control will cause the best of drivers to prove their worth.

Starting on ice-covered highly-crowned roads frequently cause rear-end slides into curbs (or parked cars).

Antilock braking gets confused due to left/right wheels acting in unison.

Lastly -- Running in 4x4 can offer even more pucker-power since lockup of the rear is usually accompanied by lockup of the front -- which is a plausible reason why so many 4x4's end up blazing sideways trails off the freeways and being listed in the Trader magazine with "Some Rollover Damage" underneath the picture.


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Y2K™ Jim - N8JG@Hotmail.com

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"

 

I have a 3:55 LS on my 98. I never knew I
had it until one day on a gravel covered paved road. I floored it and the right side started spinning(heard the gravel flying)
Then it started switching sides(left side,right side) It was a cool way to find out though..Never has tried to slide out on me,either. Not even that time,,,,98

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98 F-150 4.6 Litre XLT2wd Ext. cab
Yokahama AVS/ST's
prarie tan/tan int.
K/N gen.II fipk
custom dual exh/gibson rectangle tips/rear exiting.
color matched snuglid
Superchip!!!
Westin nerfs blk .powdercoat
Clear front corners
Euro tails(Altezza style)
Cobra 75WXST cb w/weather alert
[b]Kenwood cd w/Radio Shack speakers,don't laugh it sounds pretty good]
Viper 500HF Security system
On the way/wheels,tires,air dam, etc..etc.......
doin the monochromatic boogie
on the front end.Billet grilles on order
www.my-f150.com Still want to lift it,YESSS!
FENDER GUITARS,ROCK!!!
http://www.bigsandy.net
officialtomwaits.com
reverendhortonheat.com

WOW,what a cool site!

 

Y2K 7700: How does the front lock up? I thought it was an open differential up front..

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2000 F150 XLT 4x4 Short Bed. Amazon Green, 5.4L, SuperCab, ORP, Tow Package, Sliding Rear Window, Electronic Shift, Keyless Entry, LT265-70-17 Tires, Clarion Pro Audio, Herculiner Bedliner, Air Silencer Removed.

1994 SVT Mustang Cobra. #1032 of 6009. Black coupe with black leather int., 3.73 rear, Bassani Exhaust, Aluminum D/S, Bridgestone RE-71 255-45-ZR17

My Home Page

 

Well, your thinking is right -- but are you assuming that one tire is skidding (stopped) on the front and the other three are going the same speed? Can't happen.

Since the rear is gearlocked to the front -- if you lock up the rear, the fronts will lock too.

Assume that the two rear (LS effectively 'friction-locked' together) are turning at one rpm. The fronts ([Fleft + Fright] / 2) MUST be going the same speed as the rears ([Rleft + Rright] / 2) -- since the front and back are gear-locked together by way of the gears in the transfer case.

If you're moving at 25 mph and the road surface is such that when you hit your brake you lock up (stop) one tire -- the tire on the other end of the axle SPEEDS UP to 50 mph (due to differential 'differentiating') while the two tires on the other axle (and the engine) remain at 25 mph. That sends your ABS into action -- since it sees one tire accelerating and the other tire decelerating and the two on the other axle forcing the whole mess since, again, the front is locked to the rear via the transfer case -- which does not differentiate the front with the rear.

Of course, the vehicle is decelerating which means that the rear wheels are slowing down -- but the relationship formula still stands as the speeds decrease.

When you gear-lock the front and rear together -- plus friction-lock the left rear to the right rear -- you get superior off-road performance (compared to fully-differentiated all-wheel-drive passenger-car type geartrains) -- but you get very squirrely slippery-road handling.

Summary: Don't let your wife drive in 4x4 on icy roads at anything but crawl speeds -- and NEVER use cruise control on slippery roads if you have an LS rear differential.

You get the best lateral stability with an AWD (Non-LS differential in front axle; differential in transfer case; Non-LS differential in rear axle) -- but you get the best off-road "go-motion" with non-differentiated front/xfer/rear gearboxes.



[This message has been edited by Y2K 7700 4x4 (edited 11-23-2000).]

 

First of all, the bottom line is don't use the cruise in slippery conditions. Puckered my rear on the DC beltway this summer in a downpour when my Explorer fishtailed at speed (due to hydroplaning). Second, using 4wd and ABS does not present a problem. If the single wheel locks up as in the situation you described, or if two do also, regardless of whether or not the others accelerate because of it, the modules still sense that wheel(s) are locking, and it modulates it the brakes. I've NEVER had all 4 lock up on me on either my 97 F-150 or my 98 Explorer, except right at the end of a long panic stop in loose gravel/deep snow. The fallicy lies in the operator getting overconfident in his/her ability to STOP in 4wd being better than in 2wd. It just doesn't work that way. ABS and 4WD don't rewrite the laws of physics, they just help to more fully utilize them. As for my thoughts on the limited slip, in my experience on my last f-150, my "limited" didn't seem to have a limit. I got stuck backing into my parking space (only a VERY slight uphill) when the left rear came to rest on an ice patch. The left rear would spin to no end, but the right side refused to drive it at all (as though I had an open diff). I even gave it a little gas, and it never moved the truck an inch. Even after the LS got fixed, it never seemed to limit the inside wheelspin much at all. I think I'd like to get a detroit locker or other "true locking diff" eventually, but the LS is fine for now.

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98 Explorer (Lemon Law Case in Progress)

'00 F-150, X-cab, 4x4, Lariat, Off-road, Trailer Tow, Holandia Sunroof, built 11/99 picked up 10/00!
List of planned mods: Clear corners and tails, CB wiring, Stainless brush guard, at least 1 set of KCs (probably more!), custom radar detector mount, color matched trailer hitch with stainless steel ball, torsion bar tweak, bug deflector, spray in liner, and a tonneau of some sort...

 

The bottom line on LS rear ends is that they want to go straight when they lock. So, when you're driving on slick roads, go easy on the gas. The left and right sides will slip and you'll go around turns nice and safe. You hit the gas too hard and the rear end will try to lock up and make the truck go straight and since the front tires are turned, you'll end up with the rear end slipping sideways. In this case, an open rear end is safer because one tire gets no power and it helps in keeping the truck from sliding sideways.

If you use 4WD and you have LS rear end, your vehicle will want to go straight even more. Any turning makes the front and rear axles want to work against each other. It's something you have to be aware of when in 4WD. There's a road that I drive with a hairpin curve. I can't make it around without backing up when in 4WD, but I can easily make the turn when in 2WD.

On icy roads, I don't think I'd use 4WD unless I was going absolutely straight and on level ground. Actually, I don't think I'd use it at all.

As for gdblake's problem, I can only guess. Since the truck was going straight, the only thing I can think of is the rear tires hydroplaned, lost traction and swapped ends.

I really can't see how a properly functioning LS rear end would cause a problem when going straight unless the LS is super super tight. In that case, any slight turn would cause a difference in speed between the two sides of the axle and cause slippage. The other possibility is that the two tires are of different enough diameters that it would cause slippage with a locked up rear end.

Anyway, I'd check that rear end to see if it's too tight. Maybe somebody changed the oil and forgot to put the friction modifier in? Just a guess.

Had an International Scout II with LS rear end and if we didn't use a particular oil, the rear end would lock and it would make turning very difficult. It would bind, then finally slip with a clunk when going around turns.

 

98SCREAMER, your description of power going from one wheel to the other more aptly describes the operation of an open differential. In an open rear end, power tends to go to the side with the least resistance. One side slips, then grabs. This then causes power to be sent to the other side and causes that side to slip.

When I floor it on gravel, both rear wheels spin. There isn't any transfer of power from one side to the other. Actually, one side spins first, then the other side starts spinning too.

 

I wish I had the LS rear end instead of regular slip like I have because all I do in the rain is spin tire and not go anywhere unless I take off real easy and take forever to get up to speed instead of my normal WOT when taking off from traffic lights.

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2000 F150 XLT Reg. cab
4.6 Triton Engine
4x2 3.55 rear end gear
sliding rear window
automatic keyless entry
white styleside short box

 

hmustang, I have the 3.55 LS rear and the 5.4L engine and believe me. It spins both wheels real easy when it's raining.

If you have an auto tranny, start off in second and manually shift into drive. Starting in second reduces torque to the rear wheel(s).

 

The only way I have ever been able to get an LS rear end to lock is to hold the brakes, ease on the gas and then let off the brake. Otherwise all I get is the tractionless wheel spinning like an open diff no matter how much gas it gets. I have had two Ford Trucks and they both behaved this way, the owners manuals say nada about how to get it to lock.