D60/4:10 locker in a street car?

[71 Duster 440]

Hey all, my name's Chris and I'm new to the forum. Some of you may have seen me post on moparforums.com. I have a question about the A body that'll be parked in my driveway sometime next week. The car is a 1971 Duster with 25k original miles, originally a /6, now a 440 with a 4 speed trans from a Hemi application (seller was unclear on what Hemi car it came from), 8 point cage, narrowed rear end, mini tubbed, ladder bars, full subframe connectors, Dana 60 with 4:10s and a locker, etc.

The problem is, I've never driven a car with a locker on the street (or anywhere for that matter). How are the manners of a locker on the street? I've heard some horror stories. Will it be impossible to cruise in this thing with a dana 60 locker and 4:10s? I was told to switch to a sure grip unit and some 3:54s or 3:73s if I want to cruise, but curious to get some opinions of guys on here first. Some of you may think I'm being impatient, but I haven't driven the car yet and won't be able to for about a week. Thanks in advance for any advice/insight. Pics coming soon!

Chris

 

[Orv Grote]

71 Duster 440. I run a Richmond full locker on the street. No big deal. As
far as driveability with 4.10 you left out an important part of info. How tall
are your tires? I assume fairly tall if it is tubbed. Here's the deal: a 28" tall
tire turns approx. 713 revolutions per mile x 4.10 (gear ratio)=2923 rpm @ 60mph.
A 29" turns approx 698 revs permile x 4.10 = 2861 rpm @ 60mph.

 

[1968FormulaS340]

If locking differentials were good on the street lots of people would run one.

Very few run one on the street.

End of story.

 

[71 Duster 440]

71 Duster 440. I run a Richmond full locker on the street. No big deal. As
far as driveability with 4.10 you left out an important part of info. How tall
are your tires? I assume fairly tall if it is tubbed. Here's the deal: a 28" tall
tire turns approx. 713 revolutions per mile x 4.10 (gear ratio)=2923 rpm @ 60mph.
A 29" turns approx 698 revs permile x 4.10 = 2861 rpm @ 60mph.

The car isn't actually in my possession yet, picking it up some time this week. I can't physically go out and measure the tires but I believe they're 29" if I remember correctly. Thanks for the info! Wouldn't the gearing of the transmission also come into play in how many RPM I'm turning at 60 mph. What 4 speeds were available in "HEMI applications" and what was their 4th gear ratio? Were they all A-833s?

If locking differentials were good on the street lots of people would run one.

Very few run one on the street.

End of story.

Yeah, I understand lockers are uncommon on street cars for a reason, but it's what I have to live with until I can change it out (if I decide to do so). I was just looking for some information/opinions/experiences from guys who run them on the street. Thanks for the input. I guess I'll wait and judge by how the car performs.:thumbrig:

 

[Orv Grote]

1968FromulaS340. Nice reply. Full of all kinds of useful info. Keep it up!

 

[1968FormulaS340]

1968FromulaS340. Nice reply. Full of all kinds of useful info. Keep it up!

No problem... I have ran one on the street.

The thing you can get is some strange uncomfortable rear movements from time to time.

These odd feelings can happen both when going straight and/or when turning.

Some things just aren't that great for the street. This is one of those things.

 

[crackedback]

I've run lockers and don't find them terrible on the street. No worse than the quirks of running an 8" converter, a big roller cam or a spool.

IMO, cost is one of the biggest reasons you don't see detroit lockers running much on the street.

To me it depends on the car whether I'd run a powerlock or a locker or even a spool. God forbid, I've driven with a spool on the street too. I'm probably doomed to hell at this point. :-D

If you can live with the nuances of each set up, don't drive in the rain a lot, then no biggie. If not, run a powerlock.

 

[71 Duster 440]

I've run lockers and don't find them terrible on the street. No worse than the quirks of running an 8" converter, a big roller cam or a spool.

IMO, cost is one of the biggest reasons you don't see detroit lockers running much on the street.

To me it depends on the car whether I'd run a powerlock or a locker or even a spool. God forbid, I've driven with a spool on the street too. I'm probably doomed to hell at this point. :-D

If you can live with the nuances of each set up, don't drive in the rain a lot, then no biggie. If not, run a powerlock.

That's good to know, thanks for the info/encouragement. I suppose I'll just have to get a true feel for what I'm going to do by driving the car and seeing its temperament on the street.

 

[MY340]

That's good to know, thanks for the info/encouragement. I suppose I'll just have to get a true feel for what I'm going to do by driving the car and seeing its temperament on the street.

My Duster has 3.91's and and Powertrax locker in the 8.75 rear. Other than a slight clicking when I turn a corner it works fine on the street. The previous owner was going to use it as a street/strip car and wanted a strong locker in the rear.

 

[Bogie]

The big issue with lockers and street driving is going around corners. if you load and unload the drive train via the throttle it gets jumpy. I have lockers in my pickup and going around a corner either on the gas or coasting is no problem but jump on the gas half way throu and it will let you know its back there do it in the rain or snow and its likely to switch ends on you.

 

[Coyote Jack]

I run a spool on the street and it's no big deal as crackedback said. It just took a little getting used to. The locker won't be to much different than the spool. I don't drive in the rain much at all though.

Jack

 

[Outsider]

Detroit Lockers were factory equipent in go-fast Mercurys and Fords. They work just fine on the street. (Fantastic in my opinion.) They are nothing like a spool. (which I am running now) And they are a superior diff with the only issues being noise, weight, and cost.
You bought a car that is tubbed, narrowed, and caged...why would you even consider a suregrip with 3.54?