Anonymous-0
Well-known Member
I need some opinions on the good and the bad of postive traction rears. Is it better to go with posi for a 1971 nova with a 350-375hp engine with 350 tranny. As long as it can break the tires loose!
Anonymous-0
Well-known Member
That very true, i want to leave my mark every where I go!
glennster
Well-known Member
from a performance standpoint, the posi is the way to go. you also will need to select your ring and pinion gear ratio and rear tire size. red line rpms on the motor are another factor. you will prolly run somewere around a 3:73 to 4:11 gear ratio for a street car. decent driveability, good off the line, decent top end. higher ratio will get you rolling quicker but you will cut your top speed.
ahh... take it from a old hot rod driver, cops just love folks who "leave their mark wherever they go" back in the day i fried the tires off a "68 z-28 camaro, a 69 mustang gt, and a corvette powered 38 chevy coupe, the cops just didnt like any of them! and, if your racing for real, remember while your meltin the tires and lookin cool, the other guy is hooked and winning the race
Anonymous-0
Well-known Member
Posi is better for doing "donuts" too.
Chuck (CA)
Well-known Member
Well, back in the day (the "60"s) I ran 4:56 posi in my "57 Chevy. Maybe a little too low for street use, but it sure would light "em up on demand.
The problem was, whenever I turned a corner or was on a windy road, the rear would howl and the tires would protest. Seemed the positraction really preferred going in a straight line.
Chuck (CA)
The problem was, whenever I turned a corner or was on a windy road, the rear would howl and the tires would protest. Seemed the positraction really preferred going in a straight line.
Chuck (CA)
dieselpaul
Member
knew a guy in the 60's that blocked off rear brakes. [remember that dumb trick?] back out from drive-in, get a burn-out going, ride brakes, make smoke---
Nolan (foxtrapper)
Member
A posi essentially ties the two rear tires together. With a posi you'd need to break both tires free to spin, not just one. That's good for performance, particularly accelleration. That's bad if you just want to smoke a tire.
A posi makes life much more interesting in the rain and snow and ice. With an open differential too much throttle spins just one tire. With a posi, you spin both rear tires, and the entire car spins around very easily. It's fun and you go "wee" when you do this at a stop sign. It's not so fun when you snap into a spin on the exit ramp or a turn on the backroads.
A posi gives better overall traction and holds it longer than an open differential. But when a posi rear loses that traction, it loses all of it, instantly. This makes a posi type rear more demanding of your driving skills.
A posi makes life much more interesting in the rain and snow and ice. With an open differential too much throttle spins just one tire. With a posi, you spin both rear tires, and the entire car spins around very easily. It's fun and you go "wee" when you do this at a stop sign. It's not so fun when you snap into a spin on the exit ramp or a turn on the backroads.
A posi gives better overall traction and holds it longer than an open differential. But when a posi rear loses that traction, it loses all of it, instantly. This makes a posi type rear more demanding of your driving skills.
Anonymous-0
Well-known Member
Funnily enough my dog has the same habit.Out here in Oz we have hoon laws,first offence car impounded for 2 days,you pay the hundreds to get it out of the pound,plus fine. 3rd offence is loss of car[that hurts but won't do it a 4th time]so your pride and joy will be sold,proceeds to the Govertment.
Anonymous-0
Well-known Member
Funnily enough my dog has the same habit.Out here in Oz we have hoon laws,first offence car impounded for 2 days,you pay the hundreds to get it out of the pound,plus fine. 3rd offence is loss of car[that hurts but won't do it a 4th time]so your pride and joy will be sold,proceeds to the Govertment.
jose bagge
Well-known Member
It's a no brainer- you'll want the posi. But- you'll want a 12 bolt rear as opposed to a 10 bolt that's probably stuck up under the car right now. What you REALLY want is a Ford 9 inch rear to stick up under it...much stronger, and it has a removable 3rd member that you can swap out in 45 minutes.(plus no c-clip axles and a lot more available ratios) I had 2 3rd members for my Nova w/ 9"- one with 3.73s and an open diff for just stroking around, and another with 4.33s and a mini spool for weekend fun. Mini Spool is about $95 for these ford rears and positively locks both axles. Now, let's talk converters....
You are far less likely to break anything in the driveline with a pegleg cause the power is going to the tire with the least amount of traction. Posi will sent the power to the street. I would definitely go with the posi. A 12 bolt while giving up some convenience to the 9" does actually weigh less and will ride marginally better and will be a GM part, cause to some folks that is important.
Don't mind the grammar,
Aaron
Don't mind the grammar,
Aaron
jose bagge
Well-known Member
hey John- while you're junk yard shopping for a rear, look at rear springs as well if you currently have the "mono leaf" (single leaf on each side rather than stacked leaves). The "mono-leaf" springs really wind up on launch, changing pinion angle and causing wheel hop and breakage. The multi leafs, while heavier, are much better at wheel control- and generally will give a little bit more ride height in the rear with a less sloppy ride.
buickanddeere
Well-known Member
Friction disk limited slips diffs without the centrifugal engagement soon wear out and become an open diff.
Best positive drive diff is a Detroit Locker or the Torsen.
You have to aware that a limited slip diff can make the vehicle suddenly steer left or right when one tire gets good grip.
Geared Torque-Sensitive Differential
Geared, torque-sensitive mechanical limited slip differentials utilize worm gears to "sense" torque on one shaft. The most famous versions are:
* Torsen differential invented by Vernon Gleasman in 1958, then sold to Gleason Corporation, who started marketing it in 1982;
* Quaife differential, sold under the name Automatic Torque Biasing Differential (ATB), covered by European Patent No. 130806A2.
Geared LSDs are less prone to wear than the clutch type, but both output shafts have to be loaded to keep the proper torque distribution characteristics. Once an output shaft becomes free (e.g. one driven wheel lifts off the ground; or a summer tire comes over ice while another is on dry tarmac when the car goes uphill), no torque is transmitted to the second shaft and the torque-sensitive differential behaves like an open differential.
Geared LSDs are dependent on the torque and not on the speed difference between the output shafts. Such differentials may be acceptable on dry pavement, but are not adequate on slippery surface[3].
Geared LSDs may be used:
* to reduce torque steer in front-wheel drive vehicles;
* as a center differential in four-wheel drive (e.g. on Audi Quattro);
* in rear-wheel drive vehicles, to maximize traction and make oversteer easier to manage (as in Drifting). Although, for professional drifting, a geared LSD is less effective compared to a clutch type LSD.
Best positive drive diff is a Detroit Locker or the Torsen.
You have to aware that a limited slip diff can make the vehicle suddenly steer left or right when one tire gets good grip.
Geared Torque-Sensitive Differential
Geared, torque-sensitive mechanical limited slip differentials utilize worm gears to "sense" torque on one shaft. The most famous versions are:
* Torsen differential invented by Vernon Gleasman in 1958, then sold to Gleason Corporation, who started marketing it in 1982;
* Quaife differential, sold under the name Automatic Torque Biasing Differential (ATB), covered by European Patent No. 130806A2.
Geared LSDs are less prone to wear than the clutch type, but both output shafts have to be loaded to keep the proper torque distribution characteristics. Once an output shaft becomes free (e.g. one driven wheel lifts off the ground; or a summer tire comes over ice while another is on dry tarmac when the car goes uphill), no torque is transmitted to the second shaft and the torque-sensitive differential behaves like an open differential.
Geared LSDs are dependent on the torque and not on the speed difference between the output shafts. Such differentials may be acceptable on dry pavement, but are not adequate on slippery surface[3].
Geared LSDs may be used:
* to reduce torque steer in front-wheel drive vehicles;
* as a center differential in four-wheel drive (e.g. on Audi Quattro);
* in rear-wheel drive vehicles, to maximize traction and make oversteer easier to manage (as in Drifting). Although, for professional drifting, a geared LSD is less effective compared to a clutch type LSD.
dave guest
Well-known Member
Supposed to weld the spider gears together. Least that's what I heard. Never did it. Couldn't weld back then. Never had no money either. Used to climb over or under fence at Detroit dragway on Sibley in Riverview, Mich. to catch the action. One time a dragster burned up. Ambulance came and left empty. Never heard anything about poor driver. Twenty years ago my son run a Nova with a 400 there. Now it is gone.
Anonymous-0
Well-known Member
I would look into the new electric locker that I think is offered by Auburn Gear. If it is made for your rear end, it might be a good solution to traction when you need it for a quick takeoff, but normal driving most of the time.
When the cars like that were fairly new, it wasn't hard to find a posi rear end in a wrecking yard fairly cheap. But 40 years later, I doubt you will find a GOOD original factory unit, at least for decent money. If you have a good rear end now, with an appropriate gear ratio, you probably could get it set up with an aftermarket limited slip differential or a locker for around $1000.
If you need a different ring and pinion, this would be the time to do it, since the set up is more or less the same with new or used gears.
I have driven cars with both open differentials and limited slips, and a couple of trucks with lockers. In general, I would say it is easier to drive a car with an open differential than one with a tight limited slip. On the other hand, if you are fooling around with drag racing (or other straight line acceleration contests!, it just doesn't work well to only spin one tire. I think the electric locker would be a super compromise--an open differential most of the time, but a locked rear end when you throw the switch.
If you have a lot of power, you probably should worry about breaking the stock axles. And with C clip axles, when they break, they often come out of the axle housing. BE CAREFUL and good luck!
When the cars like that were fairly new, it wasn't hard to find a posi rear end in a wrecking yard fairly cheap. But 40 years later, I doubt you will find a GOOD original factory unit, at least for decent money. If you have a good rear end now, with an appropriate gear ratio, you probably could get it set up with an aftermarket limited slip differential or a locker for around $1000.
If you need a different ring and pinion, this would be the time to do it, since the set up is more or less the same with new or used gears.
I have driven cars with both open differentials and limited slips, and a couple of trucks with lockers. In general, I would say it is easier to drive a car with an open differential than one with a tight limited slip. On the other hand, if you are fooling around with drag racing (or other straight line acceleration contests!, it just doesn't work well to only spin one tire. I think the electric locker would be a super compromise--an open differential most of the time, but a locked rear end when you throw the switch.
If you have a lot of power, you probably should worry about breaking the stock axles. And with C clip axles, when they break, they often come out of the axle housing. BE CAREFUL and good luck!
Anonymous-0
Well-known Member
I was wrong about the manufacturer. It is actually Eaton Gear, and they call it an E Locker. Good luck!
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