Rear Posi (is it worth the money)
 

i have a 308 gear i think in my 69. the rear end is from a 72 v8 2wd truck. my question is would it be worth putting a posi unit in it? should i leave it alone? what would be the price to put a posi unit in it? pros and cons? i will not be dd the truck it will just be a fun truck. any and all opinions are welcome

Re: Rear Posi (is it worth the money)
 

I feel like it's completely worth it.

No one wheel peel. Better yet, less likelyhood of any peel, and both wheels are putting the power down and not spinning.

Re: Rear Posi (is it worth the money)
 

Basic answer: rarely is it worth it.

Unless, you use your truck as a truck: towing/hauling, driving in various roadway surfaces other than pavement, weather conditions, or you're using the truck competitively like racing. The only time that you'll know you have posi is in these types of conditions...there may be a few more.

Other than that, I find most people think it's just cool to say "I have posi"

Re: Rear Posi (is it worth the money)
 

How often do you get wheelspin? If you're having problems hooking up, it can be worth it.

I just put a Detroit TrueTrac in my Blazer. My total cost was under $600. It's worth it to me.

That's really the question: Is it worth it to you?

Re: Rear Posi (is it worth the money)
 

i am not sure the truck is just a driver weekend truck so is the price of the posi worth it or is it just a waste of money?

Re: Rear Posi (is it worth the money)
 

I would say not worth it unless you have a heavy foot. Which don’t matter much for us inline 6 guys with 150hp����

Re: Rear Posi (is it worth the money)
 

Also, consider weather....ice, mud, rain, etc...easily worth it to me.

Re: Rear Posi (is it worth the money)
 

The vast majority of vehicles don't have an Limited Slip Differential (Commonly referred to as an LSD.) and their owners don't even realize it. If you haven't had problems with getting stuck in mud, dirt, snow and such and your not racing your truck I'd recommend putting the money elsewhere in the truck.

For me it was worth the money as missing work due to weather isn't a option.

Re: Rear Posi (is it worth the money)
 

oh! extra height roof! nice! musta been ordered as an ambulance. LOL

Re: Rear Posi (is it worth the money)
 

Had a 400 HP C10 shortbed with posi. Almost as much fun as a roll in the hay with the ol lady. I said almost.
The truck was not much fun in the rain.

Re: Rear Posi (is it worth the money)
 

Again depends on the HP of the truck and it's usage. I like and use the Tru Track. But today the posi itself is sneaking up on $700 from Summit. Then comes the maybe new lower gears? Bearing kit? Install and setup $500? unless you have tools and skills to do it your self.
New axles from Moser?
Could be some serious scope creep here but that's what hot rodding is all about. LOL.

Re: Rear Posi (is it worth the money)
 

Eaton LSD $450 ish
Master Install Kit $200
Labor $400 ish
Seals/Gaskets/oil $50

If you want a gear change also, no additional labor but $250 for gears and $10 for a new speedo driven gear

Shop may "discover" axle is worn so new axles and bearings $300

Re: Rear Posi (is it worth the money)
 

One tire fryer I call them.
If you keep the gears and just change the carrier it's the price of the Differential and bearings plus labor. Not many can do this job themselves.
With the light rear ends on our trucks their is a lot of tire spin.
You didn't give your motor information.
However, with this high a ratio it's not as bad as if you had 3.73's.

Re: Rear Posi (is it worth the money)
 

I took one (373 hooked to a 400 trans behind a 402 ) out of a 2 wheel Burb in my short stepper 327m20 and I love the 11s it leaves in front of my neighbors houses ....I don't drive in the rain or snow anyway.....:devil: I have another I bought for short money when you could in my next build too and one drum to drum 6 lug 373 sitting on the side of my garage just because I like them if your a parts changer like me buying a good used one drum to drum is a real easy instal good luck on whichever way you go

Re: Rear Posi (is it worth the money)
 

I got an estimate from a local shop about two months ago to change an open 4.56 to a posi 3.54 in a D60 (so the estimate included the gear change also) ~$2200. I decided it was not worth it, right then and there, ha...

The ONLY reason I was considering the posi was because everything was already going to be torn apart for the gear change. If you're not racing - and if you're not going off-roading or intentionally driving in poor weather conditions (you did say it was only a weekend driver), there's really no reason to dump the money into a posi "just to have one" even if you installed it yourself to save a few bucks (especially with 3.08s).

Re: Rear Posi (is it worth the money)
 

Don’t undervalue just how dumb you’ll look, when all the kids and ricers are watching and you lay down an endless burnout……



…..with 1 lonely tire 😔



You don’t want to be that guy. Save your pennies.

Re: Rear Posi (is it worth the money)
 

I’m driving down to Quick Performance this Thursday. They have a great deal. Posi center, gears, and bearing kit for $525. I set up 12 bolt gears in my elCamino years ago, it wasn’t too bad. I’m going to borrow my friends set up tool. Obviously it gets a little more costly to hire it done.
I’m also replacing the axle bearings and seals while I’m at it. My axles weren’t too bad, but the passenger axle was a little worn , so I’ll use a repair bearing for it. Those were really reasonable from rock auto.
I plan to do some towing and I do occasionally goose it for my own enjoyment. For me, a posi was a must.
P.s. I did run it at the dragstrip right after I bought it, so I’ll have to try that again.

Re: Rear Posi (is it worth the money)
 

love this comment LOL

Re: Rear Posi (is it worth the money)
 

Just put it in my 81, drove it two miles then parked it for the winter. I can confidently state based upon those two miles: totally worth it!

Completely different driving experience, completely different truck. Lots of fun. I have 400hp, 400tq and a 700r4… but I think you’d feel the difference with any V8.

My two cents is that I do think that it’s a decision you should make when you are happy with the rest of the drivetrain. Get the engine and trans where you want them, first.

Re: Rear Posi (is it worth the money)
 

Other than being cool to say you have one, they are well worth it for two purposes. If you use the truck regularly in all conditions on and off the road a posi is a great improvement to your truck's abilities. The second purpose is for hi-performance. You won't have a truly hi-performance truck, street or off road, until you install a limited slip or locker.

Just to drive and enjoy occasionally, I'd say it would be just a cool thing to say you have. So basically you'd be doing it for others, not yourself. I put LSDs or lockers in all my trucks, if they don't already have it, because I am about better function and utility when it comes to my trucks. foe my '67 2wd shortbed the posi is to go with the hi-performance 327 and Muncie M22. My '72 K2500 has the factory Trac-Lok for obvious reasons. I hope to hand-build from scratch a third truck for off road. That will have a No-Spin (Detroit Locker) rear and a Tru Trac front for optimum utility

Re: Rear Posi (is it worth the money)
 

Do you like doing burnouts? If so then yes

Re: Rear Posi (is it worth the money)
 

If I did a one wheel squeal with my truck I'd be laughed out of the club.
But that's just my truck ;)

Re: Rear Posi (is it worth the money)
 

Are you saying you're not sure how the truck will be used?

Mud, sand, driving uphills on dirt roads, or exhibition of speed? Yes, a posi will make a difference.

Driving to Dairy Queen or Home Depot? No, it won't.

Re: Rear Posi (is it worth the money)
 

I guess I’d equate it to throwing a baseball. If you feel that someday you’ll be in a situation where you’ll need to hurl an object at speed with accuracy….OR if you just plain old got a Hose and want to put it on display for StreetCred, (like hanging out at the DrownTheClown booth at the fair)…..you’d invest in the ability to throw the heat.

If you’re quite confident you’ll never need to throw an object….or even more confident you’ll never need to publicly display your (lack of) skills, then forego the effort and hope the odds land in your favor.




If you choose path 2 and someday are forced to hurl an object at a charging bear, or get asked to throw out the first pitch at a Little Leage game…..don’t say you weren’t forewarned. It’s ok to have a limp-wristed-noodle-arm, so long as you never need to show it, and nobody ever needs you to use it.

Re: Rear Posi (is it worth the money)
 

haha. how old are you? I'm 56 an never, ever been one of those - "oh look at me, see what I can do".

LOL

But, whatever you enjoy. I think it's childish, always have.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

That's some quality stuff you have there.http://67-72chevytrucks.com/vboard/i...ons/icon14.gif Nice that you can get it all locally.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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

Re: Rear Posi (is it worth the money)
 

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

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

.

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

Re: Rear Posi (is it worth the money)
 

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

Re: Rear Posi (is it worth the money)
 

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.

Re: Rear Posi (is it worth the money)
 

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

Re: Rear Posi (is it worth the money)
 

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.