rear gears make a difference

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dartsteve

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Opinions and feed back appreciated.
I have a strong fresh 340 in a 69 dart.
With the original rear end that came with the 6 cylinder the car it
ain't got the get up and go it should.
Shift kit in the trainy and 2200-2800 convertor.
Will gears get me out of the hole like this 340 should , for the street 4:56 ?

Thanks,
 
if your not going to do alot of freeway driving 3.91 are a blast around town and will really wake up that 340, yet they will still let ya squeak by on the freeway. If your going to do alot of freeway driving 3.55's might work out better for ya.
 
I presume you have a 7.25" rear end if it came behind the original /6 engine. If so, don't waste your money putting gears in there because it probably won't last very long behind a strong 340. You should start looking around for an 8.25" or 8.75" rear end, both of which have their pros and cons. The 8.75" has the removable carrier, so it's easy to get two chunks with different gear sets for different applications, but the A body ones also come with the 5 x 4" small bolt pattern which you have now. The 8.25" isn't as easy to change gear sets, but they generally have the 5 x 4.5" large bolt pattern. Decisions - decisions. :) And as ProStreet said, either 3.55 gears for the street/highway, or 3.91 gears if you're not spending too much time on the freeway.
 
I put 323's in my built 318, if I change them I might go to 355's. It used to be a race car with 456 or 486?, definitely not for the street. The good thing is I can cruise 75-85 mph and only push 2500-3000 rpm's, over a 100 mph at 4000 rpm's. For the street I'm happy but with the 355's could be a little quicker off the stop. Peace
 
I have a 69 Dart GTS, mild 340, 727, 3000 stall, 3.91's , Drag Radials.
I drive it to the track and run low 8's in the 1/8 mile. More gear would be nice
at the track but I drive on the street. :thumblef:
 
I'm with Goody and almost everybody else. 3.91's are great on the street, haven't had mine on the highway yet though. :D Upgraded from 3.55's (gears are for sale! ;) ) and I'll never go back!! :)
 
I'll go along with everone else. 3.91 tops for the street. 3.55 is a good all
around gear. I got a set of 3.23s for the street for mileage. Also a set of
4.30s for the strip. 8 3/4s are great to swap the gears out quick.
 
OldVart makes a good point about the bolt pattern. One way to address that issue is to narrow a c-bod rear and go with aftermarket axels. The price starts adding up, but as always you only get what you pay for. A-bod 8.75s are getting rare and pricey. You can end up ahead with a re-done c-bod or old truck rear depending on what you can find and the total cost after it's all said and done (brakes, diff, you name it). The truck rears usually already have tall gears in them. Gotta consider all the details. :salut:
 
i have run up to 4 56 gears on the street, they are not good out on the hiway . but great fun around town, i have also run 4.30 s still fun in town , rough on the high way... 410 s i have run many times and feel they are the better of the choices, they are not to bad on the hiway and still get up and go in town, none of them are good on fuel...tire size matters also, the taller the tires, the taller the gears need to be .. i.e a set of short tires with 391s will act about the same as a set of taller tires with 410s
 
I'm going to stick with my original plan and put 3.55s in my 8.25 axle. We had 3.91s in my Dads Swinger, and it was fun, but on the open highway that 340 was turning a lot of RPMs.
 

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