posi-trac in the rain

[maxkillz]

two tires putting power down = more traction than just one.

Lay off the gas, man! I have a 300whp supercharged/nitroused (thats 300hp without the nitrous... btw) thunderbird with 'posi' (positraction is actually just GM's term for limited slip differential) and it does fine in the rain. It also has tires on it that are not meant for rain whatsoever...

i do lay off the gas ;D only 1/4 down and my tires loose all grip :-/ my engine has a lot of torque. but it's not lacking in hp either. 460cu in V8 has a little power ;D

 

[john_lawson]

my first real powered v-8 1975 pontiac trans am -wait before you guys start talking crap it had a 400 cu-in bored 40 over with aftermarket pistons trw flat tops lunati cam 6x heads yea 6x the best well almost
the best -i put 373 gears posi / aka limited slip i also put a rock crusher m22 muncie 4 speed i love the way they sound around 375 horses did it all myself man i miss that car torque ouchi mama did that have torque
oh steel crank all the goodies but i almost wrecked it a lot of times you have to get the feel of a car with a posi it takes a while but once you got it thats it your hooked --i know a lot of you ,might say my car will beat your car but its not about that its about having fun building your own ride
oh and i always have cars with either a 4 or 5 speed manditory

 

[maxkillz]

yea almost wrecked the truck a few times in the rain from the oil and stuff on the road right when the rain first started. It's all about having fun with your ride in the end ;D

 

[sad_sagi]

you'd think posi would be better in rain... with a cheap diff one wheel would just spin and then you'd get no traction...
the cheap ass tires i bought for my camry have no traction in the rain... not fun when your moving sideways on an on ramp going 40 lol
tires make a bit of difference in lateral movement

 

[GooeyGus]

you'd think posi would be better in rain... with a cheap diff one wheel would just spin and then you'd get no traction...  

Thats what I was getting at


And 1/4 of the way down... maybe thats your problem! hehe... With a truck with absolutely no weight in the back 25% throttle will spin you around in a corner. I probably dont ever go above 15 or 20% throttle in my cars when driving normally (and I'm not just guessing... I have an Apexi SAFC in both cars which has a readout telling you how much pedal you're giving it ) Heck, it only takes less than 10% to maintain cruise control on the freeway.

 

[maxkillz]

[quote author=sad_sagi link=1224109265/0#19 date=1224324288]you'd think posi would be better in rain... with a cheap diff one wheel would just spin and then you'd get no traction...

Thats what I was getting at


And 1/4 of the way down... maybe thats your problem! hehe... With a truck with absolutely no weight in the back 25% throttle will spin you around in a corner. I probably dont ever go above 15 or 20% throttle in my cars when driving normally (and I'm not just guessing... I have an Apexi SAFC in both cars which has a readout telling you how much pedal you're giving it ) Heck, it only takes less than 10% to maintain cruise control on the freeway.[/quote]
1/4 is a rough guess just push it down enough to get moving but even just a tiny touch spins the tires in rain, 1/3 down on dry pavement spins the tires for a few feet-30ft depending on the pavement and where did you get the readout? how much was it?

 

[maxkillz]

well it started sprinkling here so I went out and took a drive, and this video was with the gas about 1/5 down, the tires spin like they are off the ground :-/

 

[maxkillz]

heres a pic of the truck I was driving

 

[Chicxulub]

First of all, I haven't read the thread.

Most cars that are nowadays called "posi" are actually LSD rears. Posi rearends suck unless you're drag racing and not doing much else.

That being said, my Cobra had an LSD, and it was nice. Most rear drive vehicles with a v8 nowadays have an LSD and they do very nicely in the rain, if you know how to drive it. Personally, I prefer oversteer to understeer anyway.

 

[maxkillz]

mine not limited slip, the tire bounces as I turn, even at slight angles :-/ no grip in the rain either even with those tires (i don't think they help in the rain though)

 

[JLSE]

Posi track on a vehicle that is for daily driving is not an ideal one. There is a company based out of AU called ARB which (I think) still makes an air locking diff assemby. I have this on my 1982 Toyota Landcruiser BJ-42 Diesel, front and rear. They are perfect for rock crawling and general off-roading, when the diff starts to give. Flick of a switch, press of a button and the compressor engages the posi. When you are done, simply shut it off and your back to normal.

The reason posi is not a good idea for daily driving is the equal tire speeds on left and right when cornering. When you make a right hand turn at speed with LSD or a reg. diff, the rear left tire will spin faster than the right. When posi is involved, both tires spin equal, and can spell disaster by way of flipping the truck. On a car its not so bad as the center of gravity is lower, and the worst case scenario is usually some fun fish tailing. But on a top heavy truck, watch out :-/

On my 2nd gen twinnie Supra, it comes stock with a limited slip, and it performs like magic giving serious traction, and the ability to corner at high speed without the dangerous equally spinning rear tires.

When I bought my locker kit for the cruiser, it cost me approx 1200 US for the rear locker, compressor, and switch gear + mounts. The front end cost approx 500., but that was a few years back, and im sure there is some reduction in cost

 

[maxkillz]

it fish tails more than I would want :'( even when I go slow on some of these roads the back end just starts to swing. a lot of these roads are just smooth concrete or worn down asphalt :-/




[smiley=smiley_down.gif] thats kicking it down to about a 1/3 on a good road

 

[JLSE]

Your fishtailing with an empty bed yes? With my truck, its built like a tank, 5000lbs and is the japanese version of a jeep, just much better .  The short wheelbase and high center  makes posi a really bad idea in these. In your case, you have a nice long wheel base, and your center is lower.

Now if you have the rear full of firewood, it would change the situation a little by making those tires stick, thus more prone to flipping. But thats a fairly long truck, and I dont think anyone in their right mind would be driving like Schumacher with a full load.

Is the posi factory?  Aftermarket can be iffy, as the truck may not be a good match for posi. But there are many AM companies that make posi for ford rear ends, in that the same diff may be found in a Mustang (Example), but designed for a lower center and not for a truck.

If you have the space, put some ballast in the rear by way of secured sand bags, one over each tire. Just be very careful with ANY corners or bends on dry ashfalt


In the Toyota Landcruiser Assoc. we have a popular bumper sticker ' Friends Dont Let Friends Drive Jeeps ' :

 

[maxkillz]

Your fishtailing with an empty bed yes? With my truck, its built like a tank, 5000lbs and is the japanese version of a jeep, just much better . The short wheelbase and high center makes posi a really bad idea in these. In your case, you have a nice long wheel base, and your center is lower.

Now if you have the rear full of firewood, it would change the situation a little by making those tires stick, thus more prone to flipping. But thats a fairly long truck, and I dont think anyone in their right mind would be driving like Schumacher with a full load.

Is the posi factory? Aftermarket can be iffy, as the truck may not be a good match for posi. But there are many AM companies that make posi for ford rear ends, in that the same diff may be found in a Mustang (Example), but designed for a lower center and not for a truck.

If you have the space, put some ballast in the rear by way of secured sand bags, one over each tire. Just be very careful with ANY corners or bends on dry ashfalt


In the Toyota Landcruiser Assoc. we have a popular bumper sticker ' Friends Dont Let Friends Drive Jeeps ' :

all factory except the engine and transmission. I would rather fishtail a bit over flipping. also I don't want to load down my truck very much, it gets horrid gas milage as it is. it weighs a lot more than most trucks now a days

 

[JLSE]

This is where an ARB Air Locker comes in handy

Not my truck BTW, thats a FJ orBJ 70 pickup, very poular in the Outback and abroad.

 

[sad_sagi]

now that i think about it, there is probably a billion of those fords out there, so someones gotta make a fancy rear diff that will help.