question about posi unit and gears

[jojoman]

ok im on process of installing or wanting to install 4:10 gears which i thought was a posi but the guy doing it. is saying that putting 4:10 gears and putting a posi unit is 2 different thing. any help?????

[ont_guy_38]

Yes the posi unit is totally separate from the gears themselves. If you don't have posi now then you will need a carrier also.

[86c20]

4.10 are just gears. a posi is diff altogether. you can put gears in and not a posi adnd vis versea

[jojoman]

i got a 383 stroker with a 350 wat would be the best gears that ya think for getting the most and best power

[Car'n'Guitars]

Originally Posted by jojoman

i got a 383 stroker with a 350 wat would be the best gears that ya think for getting the most and best power

It depends on if you want speed or acceleration.

[jojoman]

i mean i would like a lil of both world but i guess wen it comes to shutting peolpe mouth i want take off but... still not really decided

[Car'n'Guitars]

With a higher numerical value you will accelerate quicker, with lower you will not accelerate quick but gain top speed and continuously accelerate but not quickly.

[jojoman]

well thanks alot man im going to make some more research see wat can get me around wat i want. i thought there was only 373 and 410 so i guess i didnt do my home work

[INSIDIOUS '86]

Put 373s in that will do the job if your engine don't have enough piss those 411s will make you slower. Gett rid of the th350 and get a built overdrive transmission, not one of those high hp corvette build stuff either
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[86c20]

? to ask here is what size tires are you running?

[spencer_41188]

you can talk about gears all day long but whos talking after i pass you doing 150 and yes i said 150 in a crew cab square! what you need is more gears like a 700r4, t5, or a t56 there all a easy swop. with a o/d you will get better mpg's ... when you dont mash on it lol and more top end ... but if its fast now i wouldnt worry about rearend inless its a 1 wheel wonder. lol

[INSIDIOUS '86]

Originally Posted by spencer_41188

you can talk about gears all day long but whos talking after i pass you doing 150 and yes i said 150 in a crew cab square! what you need is more gears like a 700r4, t5, or a t56 there all a easy swop. with a o/d you will get better mpg's ... when you dont mash on it lol and more top end ... but if its fast now i wouldnt worry about rearend inless its a 1 wheel wonder. lol

I have done only 140 in my shortbed with 3.08 gears and that was with it lowered and a 400hp small block. And I can tell you it took a while after 120 to get to that speed. So I'm sure a crew can is going to need a VERY strong motor to get to 150 not to mention exceptional steering
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[Firebirdjones]

High speed like that doesn't interest me unless it's done in the 1/4 mile

First one to the next stop light wins....

[jojoman]

Well it has a pretty nice 350 Trans on it . And im riding on 15s for now 275/60/15 to be exact but im wanting to put some 18s and im not concered about the mpg. Either is more like a street beater truck every blue moon I take it for Lil cruise. Is there any gears that would be in between those 3 73 and 410. Ya really a big help thanks ya
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[Firebirdjones]

You might want to consider what cruise rpm you are comfortable with. That might help you decide.

I can tell you I have a car here with 3.73's (no overdrive) and those same sized tires you have (28" tall) and it will cruise 65 mph at 2800 rpms.

I also have 4.10's in another car with that exact same tire (28") and no overdrive and it goes 55 mph at the same 2800 rpm.

It's really up to the user and all personal preference. I personally feel the 3.73's are a great gear with the 28" tire. I've driven accross county a few times with this setup and it's great.

Just depends on how much of a hurry you are in

[clinebarger]

Originally Posted by spencer_41188

you can talk about gears all day long but whos talking after i pass you doing 150 and yes i said 150 in a crew cab square! what you need is more gears like a 700r4, t5, or a t56 there all a easy swop. with a o/d you will get better mpg's ... when you dont mash on it lol and more top end ... but if its fast now i wouldnt worry about rearend inless its a 1 wheel wonder. lol

Really?? Even if your truck would run that fast.......Your tires are most likely not rated for anything over 100mph

[jojoman]

and wat about posi units how good are those. at crusin and doing quick take offs. also with gears only one tire would burn out right? sorry im askin so many questions im just trying to get my chips right before i move foward thanks

[INSIDIOUS '86]

What kind of diffrential do you have? 10bokt 12?
Eaton makes a good clutch posi unit. I have the Detroit true track which I love!
Auburn makes a decent one but it has to be replaced when worn down
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[clinebarger]

Posi's are a good thing & can be a bad thing.

Pro's.
Better straight line traction.
You can leave 2 tires marks now!
Burnout friendly....No more exploding spider gears.

Con's.
Breaking traction will pitch the rear of the vehicle to one side.
Can understeer in wet/ice conditions. (turning the wheel, Truck still goes straight)

Having a Posi & Power is alot of fun once you learn to "Stab & Steer"

[Firebirdjones]

Quite a few to choose from. For me, a street and track car/truck I prefer the clutch style posi units from Eaton. Original supplier of positractions for most of the muscle cars in the 50's/60's on up.

I like the fact that they are rebuildable, and the preload can be set to your liking, better clutch packs, springs, shims etc...and can be built stout enough for even a more serious track car. Wear really isn't a problem either, I have a couple of them here (one going on 25 years old and the other 43 years old) with thousands of street miles and hundreds of drag strip passes, still working fine. One is a Moroso Brute Strength unit that's been in use since 1987 and another is an original 69 date coded GM/Eaton unit. If they ever do show signs of wear, rebuild kits are about $150.

They are also very street friendly, no noise or chatter if the right additive is used, no pulling or unruly driving characteristics you'll find in some lockers and spools.

About $500 for a good one. Some of your lockers are slightly cheaper. Just depends on how much you want to spend and what you want to put up with on the street.

[jojoman]

Wat im im trying to do is not at all a daily driver,
Yes on a cruzer
And wen ever some one decides to rev their motor up have something to put my power to the floor. But I do have a 350 Trans and that something I wanna keep. My motor is a 383 Stroker. So maybe a posi unit is best optio. Do posi units help u get a close enough launch as da 4:10 gears. Wat about hwy wise do they move pretty good . Lets say im rolin at 60 and gun it are they ok with that. I really do appreciate all ya help
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[kalbert]

As a guy who did all the wrong things and went with 28" tires and 4:10 gears on a crummy Gov-lock carrier with a 700r4 and a pretty much stock 350 that regularly gets 8 MPG on the highway and 10 in town and is almost never within the power band of the motor because the poor thing runs out of legs at about 4000 RPM let me offer some advice...

If you're interested in 1/4 mile racing, figure out where your motor makes power. 500-3000 RPM or 3000-9000 RPM or whatever it is. Then figure out the diameter of the tires you want to run (this may be dictated by what class or series you will be in). Then calculate what rear gear ratio it will take to put you at the peak of your power band just after you would have crossed the finish line. This will be best for racing, a noisy bear on the highway, and probably have a relatively low top speed.

If you're interested in a cruiser for heading to the car show or taking on a tour or something it's a little different. Figure out where your motor makes power, then figure out what diameter tire you will run. Now calculate what gear ratio puts you in the mid to low range of your power band when cruising 70 MPH on the freeway in high gear. This will be a nice all around performer, especially if you have overdrive.

If you're going for top speed figure out the engine's power band, the diameter of the tire you want to run, and the top speed you want to achieve. Then calculate what gear you need to get the motor at the peak of it's power band at your desired speed in high gear. Gearing here will probably be very high, not fun to drive. It could take miles to accelerate to your desired top speed, if you're able to achieve it at all. There's many factors involved in top speed that simple math like this doesn't include.

If you're going to cruise around town street racing, smoking tires, trying to challenge people at speed, etc I encourage you to think twice and not.

A limited slip or even locking differential will certainly help launching, and not just at the track, but won't really offer anything at speed like when pulling out to pass a slower car on the highway. Even modest every day take offs from a stop sign can break the right rear tire loose though, particularly when wet or sandy. Snow and wet grass performance will be greatly improved. Always sad to see a really nice pickup one leggin it in wet grass looking for a spot to park at a car show.

The factory Gov-Lock is a modest performer under normal use, but not much for heavy duty applications. Other limited slip units from Eaton or Auburn or Moroso are generally pretty tough, but also offer nice streetable performance. If you intend to race competitively go with a locker or if you're really serious a spool. Don't be the guy with a spool on the street, it's not fun to drive and it's not safe either.

[86c20]

ok a pose is ONLY going to help with traction not speed. insted of one tire getting the power both do. now if this was me a 383 350 trans and looking for more of a stop light to stop light i would go 4.10 but if i am going to do both highway and stop light i would go 3.73 more of a little bit of both gears.

[spencer_41188]

Originally Posted by INSIDIOUS '86

I have done only 140 in my shortbed with 3.08 gears and that was with it lowered and a 400hp small block. And I can tell you it took a while after 120 to get to that speed. So I'm sure a crew can is going to need a VERY strong motor to get to 150 not to mention exceptional steering
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so how far did your speedo wrap around

and if you dont beleave me i will just have to post a copple videos and post the dyno numbers

[clinebarger]

Originally Posted by spencer_41188

so how far did your speedo wrap around

and if you dont beleave me i will just have to post a copple videos and post the dyno numbers

Doing 150 on a Dyno is a different story than on the highway.
I would like to see those dyno numbers of a 383 sbc that can get a 1-ton 4x4 to a buck-fifty.