Living with 3.91's

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TimDart

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Hi guys,
Ive come across aset of 3.91s for my Dart. Currently have 3.23s, but wanting to go faster and get into the 13's.

motor is 360/727trans with good parts/2400 stall convertor

Just like to know what it is like living with these gears on the street

Not much worried about mileage cos the gas is so expensive anyway!
 
I have 3.91 gears and am wanting to go 4.30. The 3.91 are a great all around gear.Street or strip.Kevin.
 
Depends on tire height whether you can live with them.

I have a set in my Dart with 25" tall tires and they are murder in the highway. Around town it's great. I can go from 1st to 4th gear without much problem.
 
I used 3.91s for awhile. Got the Duster well into the 13s.
I currently have a set of 4.30 that got me into the 12s.
If any one is interested, I would trade them for a set of
3.91s This is a complete center. 742 casting. With a small
yoke. Anyone? PM me.
 
Hmmm, mixed views then, tyres are 26" and its a 727 3 speed. Truth is, the gears were cheap (whole pig) so i think i'll give it a go.
I fancy being the fastest car here in Euro rice town!=P~
 
I have 3.90's in a Dakota. It turns 3000 rpms at 60 mph and a 27.7" tire. If you don't do a lot of freeway driving, you should be fine.
 
Thrashard340 said:
I have 3.90's in a Dakota. It turns 3000 rpms at 60 mph and a 27.7" tire. If you don't do a lot of freeway driving, you should be fine.
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Agree. I have 3:91 gears with 26" tires and its great around town. I can cruise at 70 MPH on the highway for long distances but it revs pretty high and its not something you really want to do very often. So if you aren't going to do a lot of highway driving they are great street/strip gears.
 
518 AOD will fix that highway RPM thing. :cheers:

I'll have mine all wired up and operating as a 4spd this winter once I get the 2.45s out of my axle. I'm going to 3.55s because they were more or less free.

I could go higher, but I'll be running 26x10s on the back, and around here "highway" means 80mph+...so the 3.55s will be fine.

Our Swinger 340 had 14" wheels and 3.91s and it was great around town. We didn't do lots of highway driving, so it wasn't a big deal.
 
Mmm, suspect I could be compromising the car inthe long term. That said, i've borrowed the 3.23 gears off of one of our Mopar guys for 4 years now, so i guess i'll be due to hand those back and fit the 3.91s regardless!
 
i hated the 3:91 gears in my dart.


around town it isn't bad but as soon as i get on the freeway they suck. i can't stand turning 3500 rpm and having to cruise the slow lane. and i have a 28" tire on the car. at the track they were great with a 26" tire. would go through the traps at 5900 and turn low 12's .
 
I run 3.91s. They were great in vegas, i hardly drove highway, tears up to 100mph from a cruise...now im in florida. all the shows and cruises are 30mins to an hour down the highway. I hate them! But...im moving back to vegas, :D lol
 
4.10's in my 69 Dart. Great around town, but not good for more than 15 minutes on the highway. 3000 RPM at 60 mph 9 - 13 MPG

It does get out of the hole in a hurry.
 
abodyjoe said:
i hated the 3:91 gears in my dart.


around town it isn't bad but as soon as i get on the freeway they suck. i can't stand turning 3500 rpm and having to cruise the slow lane. and i have a 28" tire on the car. at the track they were great with a 26" tire. would go through the traps at 5900 and turn low 12's .
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What are you running now joe?
 
sublimeswinger said:
What are you running now joe?
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nothing .. the motor is apart.. lol.

i'm doing a 408 for the car if the parts ever come in and i'm gonna stick a set of 2.94 gears in the car.. setting it up for cruising like i should have in the firsat place.lol. i do alot of flying up and down the freeway and with the 3.91 gears i had points that i was turning 3800 rpm. lets see, i took three trips to the pocono's last year at 2 hours each way all freeway, did carlisle wich is 2 hours all freeway and an all day poker run that i ended up on the parkway for a long distance. plus i want to be able to cruise the car the 7 hours to ohio for the nats in the next few years. hopefully it will still be decent at the track. if i can get it to low to mid 13's with the 2.94 gears, idle with a/c and not overheat and be able to cruise anywhere i'll be happy. i'm not asking too much am i? lol
 
abodyjoe said:
nothing .. the motor is apart.. lol.

i'm doing a 408 for the car if the parts ever come in and i'm gonna stick a set of 2.94 gears in the car.. setting it up for cruising like i should have in the firsat place.lol. i do alot of flying up and down the freeway and with the 3.91 gears i had points that i was turning 3800 rpm. lets see, i took three trips to the pocono's last year at 2 hours each way all freeway, did carlisle wich is 2 hours all freeway and an all day poker run that i ended up on the parkway for a long distance. plus i want to be able to cruise the car the 7 hours to ohio for the nats in the next few years. hopefully it will still be decent at the track. if i can get it to low to mid 13's with the 2.94 gears, idle with a/c and not overheat and be able to cruise anywhere i'll be happy. i'm not asking too much am i? lol
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Overdrive an option? the Gear vendors in my dads car is pretty nice, i'd think you would have to go with another converter too, to go down to 2.94.

Someday ill live happier with the 3.91s and get a stinkin 5spd manual in the thing!
 
simple solution, use the 3.90s at the track and cruisin around town ,then install the 3.23s when you feel the need.
 
I had 391 gear in my Coronet drove all the way from Central Illinois to Columbus OH to the Nats.Didn't bother me a bit...Drove from MI to IL in a 69 1/2 with 410 drove it 65-70 all the way home.
 
No thanks I have a 383 Dart I took out the 456's and put in 391's so I can drive it on the street..
 
What it comes down to is personal prefference. Some guys don't seem to mind buzzing their engine at 3600-3800 rpm all day and others (like me) don't like abusing the engine like that. My Cuda had 4:10's in it with 27" tires when I got it. At 65 mph it was turning 3700 rpm. That'll wear on an engine fast. I rebuild another center and installed 3:73 gears. Much better!! Now at 65 it's only 3100 rpm so driving down the hwy is much more pleasant. Still runs good too. Probably lost a little out of the hole but it was worth it.
 
I have 2.76's in my Duster and I feel like it's turning fast on the highway. I guess I'm just used to our '03 Town & Country turning 2000 RPM at 75 mph.

If you're in the UK, I doubt you have to worry about running at 75 mph for longer than a couple minutes, so go ahead and toss in those 3.91's!
 
3.9 gears in a Dart 360/727 ,used to have 3.7's .I a lot of country driving here in Western Australia as well as city holeshots at the light to amuse myself.

Do not have a problem with them.

Benton

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GoodysGotaCuda said:
Overdrive an option? the Gear vendors in my dads car is pretty nice, i'd think you would have to go with another converter too, to go down to 2.94.

Someday ill live happier with the 3.91s and get a stinkin 5spd manual in the thing!
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ahh maybe down the road but right now the motor is gonna tap me out money wise. weather i go with a 2.94 or gear vendors i'll have to tighten the converter so thats a wash.
 
I ran 391s in my 70 440 cuda with a 26" tire but I didnt drive it very much. I also ran them in my 69 Barracuda with a 28" tire and tight 8" converter. I had it on the highway a few times, I wouldnt go very far with it though.

The Barracuda at one time had 4.30s and a 27" tire, I drove that combination 1hr down Sunrise highway on L.I. to a cruise night. Didnt bother me then but Im not 21 anymore either.
 
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