Rear Posi (is it worth the money)

[novaX522]

I went down to Quick Performance this morning and picked up this kit. My buddy is gonna help me set it up. Looking forward to the new setup.

[LT7A]

If you and your truck are performance oriented: yes. If not: probably not. If you have a stock 350 or smaller and aren't going to drive in the rain or go off road, it's probably an unnecessary expense. The way I see it, if I'm going to modify my truck for more power, I'm going to include making that power usable as part of the plan. Good power + posi = fun. Good power, no posi = noise. Think of it like this. A guy who works out can't skip leg day or he starts to look funny with only a strong upper physique. All that strength is hardly usable without having the strength in your legs as a basis, foundation to push from. So now that you're not gonna skip leg day, how good is it if you only work one leg, the same leg every time? Having one strong leg isn't useless, it just doesn't give you the same range of abilities having two strong legs does.

[MikeB]

Originally Posted by novaX522

I went down to Quick Performance this morning and picked up this kit. My buddy is gonna help me set it up. Looking forward to the new setup.

That's some quality stuff you have there. Nice that you can get it all locally.

[3drburb]

Originally Posted by LT7A

If you and your truck are performance oriented: yes. If not: probably not. If you have a stock 350 or smaller and aren't going to drive in the rain or go off road, it's probably an unnecessary expense. The way I see it, if I'm going to modify my truck for more power, I'm going to include making that power usable as part of the plan. Good power + posi = fun. Good power, no posi = noise. Think of it like this. A guy who works out can't skip leg day or he starts to look funny with only a strong upper physique. All that strength is hardly usable without having the strength in your legs as a basis, foundation to push from. So now that you're not gonna skip leg day, how good is it if you only work one leg, the same leg every time? Having one strong leg isn't useless, it just doesn't give you the same range of abilities having two strong legs does.

As funny as this may intend to be I personally find it to be incorrect. Posi may be great on dirt, off road, drag racing or burnouts but not so great in the rain and even worse in the rain or heavy rain with a lot of added horsepower.

This is just what I have experienced driving and riding in cars and trucks with and without a Posi.

I guess to each their own.
Have fun, happy rodding and be safe.

[LT7A]

Originally Posted by 3drburb

As funny as this may intend to be I personally find it to be incorrect. Posi may be great on dirt, off road, drag racing or burnouts but not so great in the rain and even worse in the rain or heavy rain with a lot of added horsepower.

This is just what I have experienced driving and riding in cars and trucks with and without a Posi.

I guess to each their own.
Have fun, happy rodding and be safe.

Well, we're certainly experiencing it within a short distance of each other. I think you can say that it's not your experience but I don't think you can say that it is not correct. The stakes are higher if you have a posi car get away from you than if you sit and spin one tire in place. However, with our weather and especially in the rain after it's been dry, I would not want to drive a non posi rig. I drive pickups all day for work and posi is necessary to avoid excessive wheelspin with moderate horsepower (and moderate throttle). Wheelspin going uphill from a traffic light or stop sign is not a good look for a company rig. And not what I want in a personal rig either. And with an empty bed you have nothing usable on tap if you need to accelerate quickly for any reason. I don't think a high horsepower rig has any business being out in the rain unless it's all wheel drive, so in that case a one-legger could be better because you can't go anywhere.

[3drburb]

Originally Posted by LT7A

Well, we're certainly experiencing it within a short distance of each other. I think you can say that it's not your experience but I don't think you can say that it is not correct. The stakes are higher if you have a posi car get away from you than if you sit and spin one tire in place. However, with our weather and especially in the rain after it's been dry, I would not want to drive a non posi rig. I drive pickups all day for work and posi is necessary to avoid excessive wheelspin with moderate horsepower (and moderate throttle). Wheelspin going uphill from a traffic light or stop sign is not a good look for a company rig. And not what I want in a personal rig either. And with an empty bed you have nothing usable on tap if you need to accelerate quickly for any reason. I don't think a high horsepower rig has any business being out in the rain unless it's all wheel drive, so in that case a one-legger could be better because you can't go anywhere.

I guess I will agree to disagree with all that, as I drive in the same weather with no Posi without spinning from stop to start and I live on one of the biggest hills in Kent driving a Chevy Express about 5 days a week for work.

Thanks for the education.

Wow! All the trucks and cars that made it building the world and farming and daily use along with being enjoyed with the non Posi all these decades while spinning tires not being able to move when it's not sunny and they are still building millions of them, Even the OP truck made it this long without.

Btw, I also have classic cars with a Posi.

[3drburb]

I hope to see you out and about sometime enjoying your Square body.

[1969stepside]

i have a mild small block 327 in it. i will get the specs on it later and see what you all think

[72SB]

For me going from 3:73 to 3:08 required a new carrier....so it was a no brainer to go posi aka Limited Slip.

While just driving around on streets its not "necessary" to have LS unless 1/4 mi use is intended....but when you need it....you need it.

[LS short box]

Hey you two from Seattle and Kent WA area when is it ever dry. Two kinds of weather in the Seattle area rain and going to rain. The reason I say that I spent 18 months stationed a Fort Lewis. LOL.
Sorry for the highjack but I couldn't resist.

[weq92f]

.

Some truth here...case in point:

Drove a V8/6 speed manual 94 Trans Am for over 20 years and learned that LSD (posi) diff can and will cause issues. Aside from having to be careful in inclement weather as mentioned here, there's another concern when the cruise control system is not smart and there's no stability or traction control: On wet slippery roads, even at freeway speed, the cruise will spin both rear tires all the way to redline which causes fishtailing and, if you don't know how to drive...accidents/possibly death. The car was/is dangerous in these conditions!

-klb

[72SB]

right foot control is the most crucial component in vehicle control under any driving condition. Posi or not.

[MikeB]

Originally Posted by 3drburb

Posi may be great on dirt, off road, drag racing or burnouts but not so great in the rain and even worse in the rain or heavy rain with a lot of added horsepower.

This is just what I have experienced driving and riding in cars and trucks with and without a Posi.

I guess to each their own.
Have fun, happy rodding and be safe.

I had a friend who told me the same thing -- great for straight line or off-road, but not around wet corners on paved roads.

I assume that's a friction modifier in the small jar. Be sure to use it to prevent the outside tire from chirping during turns. And don't fill the diff to overflowing, so you'll have a little room to add more later. I had that exact problem--chirping during turns. I resolved it years later by adding a little more than the posi manufacturer recommended when I changed the gear lube.

[MikeB]

Originally Posted by weq92f

On wet slippery roads, even at freeway speed, the cruise will spin both rear tires all the way to redline which causes fishtailing and, if you don't know how to drive...accidents/possibly death. The car was/is dangerous in these conditions!

Cruise control + wet slippery roads + redline does not compute.

[chevmn]

About 40 years ago I had a big block Chevelle with a one legged open diff and I was going to work one morning on slightly wet pavement. When the light turned green, and like i often did, I opened it up (not best decision). Needless to say, the rear never hooked up, and several blocks later apparently one side decided to grab, and at fairly high rate of speed it took a hard left turn. Letting off the gas was fruitless, and I broadsided a concrete culvert on the opposite side of the road, bending the right axle, wheel, and tweaking the frame. To this day I will still say if I had a posi, it would have acted much differently, most likely gaining traction vs. spinning one tire until it reached such a high speed ultimately causing loss of control. Should I have known better? Probably, but I was in my early 20's so brain had not fully developed yet :-), and I had just gone through the engine, adding more cam, etc. But, it all depends on how you drive, conditions, etc. An open diff is perfectly fine on dry roads and sensible driving. But a 4x4 with at least a posi in the rear and the right tires is sure nice when road conditions are less than ideal. In those conditions, every additional driven wheel makes all the difference.

[weq92f]

Originally Posted by MikeB

I had a friend who told me the same thing -- great for straight line or off-road, but not around wet corners on paved roads.

I assume that's a friction modifier in the small jar. Be sure to use it to prevent the outside tire from chirping during turns. And don't fill the diff to overflowing, so you'll have a little room to add more later. I had that exact problem--chirping during turns. I resolved it years later by adding a little more than the posi manufacturer recommended when I changed the gear lube.

.

I don't have issues with chirping of the tires but the diff itself would make a very odd sound during sharp turns after long straight highway cruise. This happened only when the fluid was needing changing. Adding a LSD additive to the diff kept this from occurring when fresh and for many miles thereafter.

-klb

[Accelo]

Interesting thread. I just figured the posi argument was just going to be "in favor of".
I am in this camp but some interesting posts for the "none posi" side also.

Over 50 Years ago when dumb kids used to race while cruising I was with a fella in a V8 powered Rambler Rebel, without posi. It was raining and he got into a stop light race with a VW bug.
He didn't let up on the gas, to possible gain some traction, all the while one tire spun and one didn't. The VW beetle beat us to the next light.
I still laugh about that one.
Cheers.

Cruise control + wet slippery roads + redline does not compute here either.
Bad idea. Any modern car, with traction control, would shut off the cruise control if the driver tried something this silly.

[weq92f]

Originally Posted by Accelo

...<snip>...
Cruise control + wet slippery roads + redline does not compute here either.
Bad idea. Any modern car, with traction control, would shut off the cruise control if the driver tried something this silly.

.

Yes well...the owners manual did not warn against using cruise in inclement weather. The system was/is very basic. If the wheels broke traction with cruise control engaged, the system just keeps trying to make the car go faster not knowing that the wheels were spinning and so it just keeps applying more throttle in an attempt to maintain the set speed!!!! All the way to redline and the rev limiter...DANGEROUS.


-klb

[3drburb]

I am not against Posi or for none Posi, as I have both.
I was just stating fact as to what I know from my own experience and others to a particular post.
Whatever makes the OP happy is the side I am on, as I believe most of what we do with our hobbies is based on want, so if you want it and can afford it, just do, it shouldn't matter what engine, trans even if it doesn't run and you want a Posi to sit in the bed of the truck (may not make sense to most) go for it but now you have some pros and cons if that helps.

[truckster]

Originally Posted by 3drburb

As funny as this may intend to be I personally find it to be incorrect. Posi may be great on dirt, off road, drag racing or burnouts but not so great in the rain and even worse in the rain or heavy rain with a lot of added horsepower.

I found out the downside of a posi the when I built a sleeper with an Olds 455. I had just finished buttoning it up and decided to take it out for a test drive. There was a light rain, and the first time I goosed it I did a 180. After that I learned to be more judicious with the fun pedal and I haven't had problems since... until I bought my Z/28 and took my wife out for a drive. That's another story... one she won't ever forget.

[3drburb]

Originally Posted by truckster

I found out the downside of a posi the when I built a sleeper with an Olds 455. I had just finished buttoning it up and decided to take it out for a test drive. There was a light rain, and the first time I goosed it I did a 180. After that I learned to be more judicious with the fun pedal and I haven't had problems since... until I bought my Z/28 and took my wife out for a drive. That's another story... one she won't ever forget.

What was the built Olds 455 in?

[truckster]

Originally Posted by 3drburb

What was the built Olds 455 in?

I put in a 1981 Buick Estate Wagon that had previously been home to an Olds diesel. Just for fun I left the diesel badges on it. It's one of the ones I kind of wish I still had.

[3drburb]

Originally Posted by truckster

I put in a 1981 Buick Estate Wagon that had previously been home to an Olds diesel. Just for fun I left the diesel badges on it. It's one of the ones I kind of wish I still had.

Breaking that loose would give you the jitters for a few minutes afterwards, at least you were in something big and hopefully didn't hurt anything. 60s 425 and 455 are a beast of an engine stock so built up can be fun and very scary.

[67 twins]

Originally Posted by weq92f

.

Some truth here...case in point:

Drove a V8/6 speed manual 94 Trans Am for over 20 years and learned that LSD (posi) diff can and will cause issues. Aside from having to be careful in inclement weather as mentioned here, there's another concern when the cruise control system is not smart and there's no stability or traction control: On wet slippery roads, even at freeway speed, the cruise will spin both rear tires all the way to redline which causes fishtailing and, if you don't know how to drive...accidents/possibly death. The car was/is dangerous in these conditions!

-klb

No the vehicle is not dangerous. The operator is. You should NEVER use cruise control on wet slippery roads. This is a case of operating the vehicle wrong & then blaming said vehicle.

[oneshotkyle]

The old inline 6 almost got away from me today with the one tire fire