what rear would you go with

-
trudysduster

trudysduster

FABO Gold Member
FABO Gold Member
Joined
Aug 24, 2009
Messages
5,033
Reaction score
224
Location
Corinth, Ky.
I need some input on what rear to stay with in my Duster. here is what I have:

440 .030 over
509/292 purple cam
keith black pistons
3000 hughes stall
727 tranny
8.75 rear with 489 case currently 3:91 clutch type
245/60/15 tires

I want something that can cruise a little bit and something that if I want to get in it will stand up and talk. I was leaning on a 3:55 but not sure. I have someone who has a 3:55 489 but it is a cone type. I don't know anything about a cone type. I heard to stay away from them. The 3:91 seems a little high to me. Maybe it is just the exhaust I have on it. Let me know what one you would go with and whether or not to trade a clutch type 4:10 I have here for a 489 cone type 3:55. thanks,Bill
 
Keep your 3.91s and find (or build) yourself a center section with 3.23 gears in it. Takes about 30 minutes to swap center sections and you'll have a car with a dual setup.
 
I have a set of 3:23 gears here also but I didnt know how my car would do with them in it with a 3000 stall and my tires. they are not in a punkin. Any thoughts.
 
3.23 is better for highway driving (going to the beach)
3.91's is for high speed takeoffs (drag racing)

some people have two pumkins, if they are the same same model you can swap them out on track days to the racing gears... then keep the others in for normal use
 
This is a show car only. It will never see a strip. It is mainly for cruise ins, car shows, maybe wiping a chevy or fords a*s once in awhile. I just wanted to know if I went and put a 3:55 or maybe my 3:23 in it if it would serve as toilet paper. I am not too familiar with these gears. I can tell you that the 3:91 I have in it will just light up the street.I am just looking for an all around good rear to maybe get on the interstate if I wanted and travel a little without being drounded out inside the car.
 
Youll be slower off the line but you're Rpms songs be screamin down the road at freeway speeds. Id have that second pumpkin with the 323 in it. Besides if you opt to beat on a Chevy or ford, take it to the track and swap in the 391s. The 355 will still suck gas like the 391 but won't have that plant you in the seat type of feel to it. Even with that converter, I'd go for the 323s because you tires aren't that very big
 
my usual get around driver/highway use 440/auto worked really well with a 323 and was ok out of the hole. if you are set on replacing the 391, get yourself a drop in 355 gear. i have used these in a regular street driven setting and they are very nice for daily use and the occasional light to light. i find them to be a nice happy medium between street and strip use. keeeep the 391s so that you have options. hell, at one time i had a set of 323,355,391,410 all ready to go whenever i decided to change anything else up. those were the days lol
 
73AbodEE said:
my usual get around driver/highway use 440/auto worked really well with a 323 and was ok out of the hole. if you are set on replacing the 391, get yourself a drop in 355 gear. i have used these in a regular street driven setting and they are very nice for daily use and the occasional light to light. i find them to be a nice happy medium between street and strip use. keeeep the 391s so that you have options. hell, at one time i had a set of 323,355,391,410 all ready to go whenever i decided to change anything else up. those were the days lol
Click to expand...

Your forgetting one of the greatest gears out there. Good old 373s which you can now get for Mopar (always wondered why Mopar never used those).
X2 on the different gears, I got 323s and 391s and will eventually locate a 489 with 276 in it (which is get a clutch type suregrip) for pure highway gears and maybe the silver state race.:cheers:
 
well the 3:91 is going in my sons Dart 340/4 speed when he gets it done. I just swapped it into mine to get away from the 4:10. I didnt see a whole lot of difference. That is why I was thinking about going to a 3:55 but I am now leaning on putting the 3:23 in replacing the 4:10 and selling the 4:10 gears. They don't even have 500 miles on them. I still have the box and packing stuff from them. But I am a little older now since I had 4:10's in my 64 Chevelle.
 
Since it's not going to be a strip car I would say go with the 3.23. Unless your running drag radials 1st gear will be a total burn through and most likely most of second too. I had a 70 roadrunner with the 335 HP 383 that had a 780 holley and turbo muflers and was well tuned, but it was just a stock magnum engine. Had a 727 that was beefed up a bit, good shift kit , extra clutches and such, stock converter. It would melt the tires in first and get alot of rubber in second if you held it down and on warm days get rubber on the shift to third. Car would run 14.0 at 100mph at the track using small slicks. Nothing but a well tuned muscle car realy. It got 16.7 mpg on highway at 55 mph. 0 to 130 in about a mile from a dead stop, with top end of 144. Your not going to drive like that I hope, lol. Point being a built 440 in a duster that you want to be able to drive anywhere go with the 3.23's you will have plenty of trouble hooking it on the street. Should be able to lay rubber in first as long as you keep the pedal down unles your going to do alot of traction mods.
 
Well its alot of work but you can get the best of both worlds if you're willing to install an overdrive. I'm putting an A-518 overdrive behind a 440 for my Duster. The A-518 is basically a 727 with another planetary gearset added on which is a .69 OD. With 3.91 gears when you shift into OD it drops your final drive to 2.70. I got all the info I needed to do the intall right here on FABO and while talking to people I came across a deal on the JW ultra bell bell housing that will enable the A-518 to mate to the 440 (A-518 has a small block bell housing pattern and won't bolt to a big block without an adapter or the aftermarket bell housing. Its pretty involved but to me its well worth it.
 
I've used the 3.23 gear set and the 3.91 hear set.

The 3.23 is a great all around gear which may not be slammin you in the seat off the line but it's still a good gear that you can still blow people off the line with, and your highway rpms are much more friendly with the 3.23s.

I currently have a borrowed 3.91 set in the car which is fantastic off the line and burn outs, but the gears just plain suck on the highways especially when a mustang passes you and wants you to give chase but you can't because you are already turning 3500 rpm cruising at 70 and you don't want to blow the motor up just trying to see who has the biggest balls.

If I had a choice I would go with a 3.73 gear or a 3.55, but For highway cruising and and all around great gear the 3.23 is hard to beat especially if you want to get up to 90 mph in a hurry to show the mustang who's boss without redlining the motor.

I have a 742 case 3.23 set with the clutch style sure grip in excellent condition that is dry, quiet and not sloppy that I would trade even swap for that 3.91 if it's in great condition as well.
Just something to think about.
 
Bill, considering the torque of a 440 big block I don't see why 3:23's wont's work real good with your 245/60 tires. They'll lower the hwy. rpm cruising rpm a lot over the 3:91's you have now and still take off decent. One thing you might try to get an idea how taller gears will feel is to slow way down to 10 mph, click it into 2nd gear then nearly floor the throttle but not so much that it kicks down to 1st gear and see how it feels. I have a mild 408 in my Cuda with 3:55 gears and when I slow down to 10 mph and floor it it still roasts the 275/60/15 drag radials cause it's torquey like a big block. Getting ready to put some 3:23's in it for more pleasant hwy cruising.
 
1970Duster said:
Your forgetting one of the greatest gears out there. Good old 373s which you can now get for Mopar (always wondered why Mopar never used those).
X2 on the different gears, I got 323s and 391s and will eventually locate a 489 with 276 in it (which is get a clutch type suregrip) for pure highway gears and maybe the silver state race.:cheers:
Click to expand...

X2 3:73 are in my opinion, the best of both worlds, I am switching my 3:23 out right now for them. My Father Inlaw run's them in his cheby II, and I love them!
 
Yeah Fishy, I think I have just about come to the conclusion that I am gonna put the 3:23's in it and sell the 4:10 gears. The 3:91 is going in my sons Dart behind a 340/4 speed but he is wanting to see what the 3:23 acts like. With the gas prices the way they are it was costing me about $50.00 to take this up to the car shows that as about 60 miles round trip. If you know anyone who needs a good 4:10 with about 300 miles on it,let me know. I will probably be listing it on here in a week or so. Thanks for the info and thanks to all of you guys for the info. Bill
 
that cam is going to want the 3.91 gear. may be able to highway cruise with a 3.23 but i don't think it will be a fun car around town with a 3.23. maybe a 3.55 as a compromise but depending on the converter it may slip too much.

if its just a show car i would be pulling that damn cam and sticking something mild in it along with a 2.94 - 3.23 gear.
 
well, I am gonna try it and see what it does. I can always change the punkin and go either 3:91,3;55 or the 3:23 a hell of a lot easier than changing the cam. besides, I like the car shaking when it idles. sounds goooooooood.thanks for the info. I will keep an eye on it. I may have to settle with the 3:55. But the 3:91 Is a little steep for the interstate. I also have a set of Richmond 4:10 gears I am gonna be selling. They probably dont have 300 miles on them. keep an ear out if you know someone who needs them. I may list them here next week or so.
 
This looks like a good rear to go with.
 

Attachments

  • denise-milani.jpg
    134.4 KB · Views: 281
I would go with the 3.23's for a street cruiser. Would also try and stick some wider tires on it and may even want to go a little taller too. You should get on one of the RPM calculators and play around with it. Try different gears and tire heights and see what you come up with and what you can live with for the driving you are going to be doing.
 
You must log in or register to reply here.
-

Back
Top