Swap 3.23 to 3.55 rear end... Is it worth it? - Moparts Forums

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Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: feets] #1633535 06/14/14 08:44 PM 06/14/14 08:44 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: 3.91s on a driver is a bad idea. It's even worse if you're used to driving around with 3.23s. You keep waiting for the transmission to shift into a higher gear it doesn't have. I punted my 4.30s long ago. I hated those things. It made a drag racer very happy that I swapped straight across for his 3.23 set. I've thought about doing a 3.55 in the Imperial to help it get around town but I will ONLY do that after an overdrive swap. I disagree, I swapped a set of 4.10's in place of the 3.23's in m 64 300. Then proceeded to drive it from Memphis to Tucson. Never waited for the trans to find another gear it didn't have. Of course it was a three speed stick though so I kinda knew what gear I was in at all times. Nonetheless, the rpm never bothered me. At the time it was the only car I had so it was my DD as well. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Supercuda] #1633536 06/14/14 09:08 PM 06/14/14 09:08 PM
Joined: Jan 2003 Posts: 3,575 The Netherlands BigBlockMopar master
BigBlockMopar master Joined: Jan 2003 Posts: 3,575 The Netherlands	I agree with Feets here; If one drives a 'modern' car everyday, once you get into an 'old' car with 3.+ gears, you'll notice the increased (and seemingly unnecessary) higher highway rpm's. If you're used to a car with 3.23 gears, going to 3.91 gears will indeed feel as if the car is still missing a gear to shift into. I've pretty much had all available gear-ratios in my Mopars at one time or another, and the 3.23's, a just maybe the 3.55's (in a car with a small engine) is pretty much the highest ratio one can feel 'good' about on highway speeds. I've been doing some 2.5 hour trips with 3.91 gears a few times with a well built 440 and a 500" stroker under the hood, and I can't say those rides were very enjoyable. The torqier the engine, the less gear you need in the rear-axle. BigBlockMopar.com

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Supercuda] #1633537 06/14/14 09:24 PM 06/14/14 09:24 PM
Joined: Dec 2013 Posts: 4,674 Wichita G GY3 master
GY3 master G Joined: Dec 2013 Posts: 4,674 Wichita	A lot of hassle for not much gain (if any). I had a very similar combo in a 71 Cuda and the the deep 1st gear swap along with all kinds of gears going as deep as 4.56. In the end I really liked the 3.23 rear gearset and the standard 2.45 first gear in the 904. It was the best of both worlds (drag and street). As an aside, I built my current '63 Dodge 330 with 3.55's because I knew it would see long runs and lots of street duty. I'd never go deeper than that on a street car with no overdrive. The 440 has more than enough torque so deep gears are not needed..

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: BigBlockMopar] #1633538 06/14/14 09:29 PM 06/14/14 09:29 PM
Joined: Sep 2013 Posts: 464 KY Telvis OP mopar
Telvis OP mopar Joined: Sep 2013 Posts: 464 KY	Maybe I will just add the 904 lower gearset and keep the 3:23. It will be the lowest cost option for sure That's King Weenie to you!

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633539 06/14/14 10:35 PM 06/14/14 10:35 PM
Joined: Jan 2003 Posts: 1,883 Northern OH R rapom top fuel
rapom top fuel R Joined: Jan 2003 Posts: 1,883 Northern OH	I got the lower 1st. gear set and 2.94's. Love the gear set but sometimes I wish I had overdrive. I can't imagine running 3.23's or 3.55's.

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: rapom] #1633540 06/14/14 10:38 PM 06/14/14 10:38 PM
Joined: Jan 2003 Posts: 949 Indiana 6 68_661charger super stock
68_661charger super stock 6 Joined: Jan 2003 Posts: 949 Indiana	Id say it worth it. I went from 276 to 323 in one Charger long ago and 323 to 355 in another and I thought the 355 switch was more noticeably better but yeah depends on tires and etc etc.

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: 68_661charger] #1633541 06/14/14 11:13 PM 06/14/14 11:13 PM
Joined: Jan 2003 Posts: 1,760 Windsor, ON, Canada D Diplomat360 top fuel
Diplomat360 top fuel D Joined: Jan 2003 Posts: 1,760 Windsor, ON, Canada	Go for it... I experienced the following combinations: 1) 2.7x (with low gear ratio 904) 2) 2.94 (with low gear ratio 904) 3) 3.55 (with 727, 2300 stall converter) 4) 3.91 (with 727, 2800 stall converter, but moved to a 4000 Dynamic right now due to the powertrain combo) A 'day-night' difference between 2 & 3 and again between 3 & 4. If you can tollerate the higher RPM on the highway (c'mon...not that bad either...) you'll be fine, because when you're in town there just ain't no greater feeling that literally leaving just about anything else behind you...should the need arise... Now...if you want to cruise as much as you can, and want the motor to just purr along then 3.55 is probably as low as you want to go.

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633542 06/14/14 11:35 PM 06/14/14 11:35 PM
Joined: Aug 2007 Posts: 2,356 Kentucky D dfsmopars top fuel
dfsmopars top fuel D Joined: Aug 2007 Posts: 2,356 Kentucky	It's difficult for most of us to have it all. I think the 3.23.is a great gear. Right now I have 3.55s behind an OD trans and it is a nice combo for the street. 3.91s are too low without an OD. I've had all of them for the street and if the motor is strong 3.23 sure grip is hard to beat. I've never modded the trans gears but that sounds like a nice option to start with. With a 3.55/904 combo you'll be somewhere around 2700-2800 rpm at 70 mph. My 3.55/A500 combo is 2000-2100 rpm at 70. BTW my tires are 28.5" tall. Last edited by dfsmopars; 06/14/14 11:39 PM. ‘72 Charger, 5.9 Magnum, Tremec 5 spd., Pro-Touring ‘14 Big Horn, Quad Cab, 4x4, 1500

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: dfsmopars] #1633543 06/14/14 11:45 PM 06/14/14 11:45 PM
Joined: Sep 2013 Posts: 464 KY Telvis OP mopar
Telvis OP mopar Joined: Sep 2013 Posts: 464 KY	Quote: It's difficult for most of us to have it all. I think the 3.23.is a great gear. Right now I have 3.55s behind an OD trans and it is a nice combo for the street. 3.91s are too low without an OD. I've had all of them for the street and if the motor is strong 3.23 sure grip is hard to beat. I've never modded the trans gears but that sounds like a nice option to start with. With a 3.55/904 combo you'll be somewhere around 2700-2800 rpm at 70 mph. My 3.55/A500 combo is 2000-2100 rpm at 70. I would like to do the A500 if I can find one. I think one of the earlier posters is correct. I will have to tear down a transmission install the gear set and swap transmissions. It wouldn't be that much more of a hassle to just swap for the A500...I started looking for them online. It looks like it might be hard to find a decent one. I need to find a comprehensive list of cars and trucks that had the one I need. I don't want to get something and find it;s the wrong one. I have been reading some of the threads on the conversion. It doesn't look that bad. The solenoids and transmission mount crossmember seem to be the only hard parts. If I can find a decent one I will return the 904 gear set and just swap the transmission. That's King Weenie to you!

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633544 06/14/14 11:50 PM 06/14/14 11:50 PM
Joined: Aug 2003 Posts: 43,185 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,185 Bend,OR USA	If you do the math on the low gear sets, stock and low low gear sets, you sould probally have much more low gear multiplication of torque in 1st gear with the 3.23 and the low gear than with the standard ratio low gear set and the 3.55. My calculator batterys just went tents up just now so I can't , won't, do the math for you. Multiply the low gear ratio times the rear gear ratio to get the starting line ratio I borrowed the house solar powered calcultor, the 3.23 with a 2.44 low gear ratio, standard 727 gears equals 7.88 in first gear, the same low gear set and the 3.55 rear gears equals 8.66. The low gear set in the 727 is 2.77 if my memory is correct so the 3.23 with them is 8.947 or rounded up is 8.95 The low gear set with the 3.55 would be 9.83 I like using a 1st gear low gear set like that I use to use them in my 1963 M.W. stocker in NHRA stock class racing I'm building a new 4 speed street car, it wll have a NP833 O.D stick tranny in it, they come with a 3.09 low gear set with .64 O.D. in overdrive, I'm going to use a set of 3.54 gears in the Dana 60 with a short set of rear tires, hopefully 275x60x15, or what ever will fit in a 1966 Dodge Coronet Deluxe It pays to think before acting Especially on car parts and combinations Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Cab_Burge] #1633545 06/14/14 11:59 PM 06/14/14 11:59 PM
Joined: Sep 2013 Posts: 464 KY Telvis OP mopar
Telvis OP mopar Joined: Sep 2013 Posts: 464 KY	Quote: If you do the math on the low gear sets, stock and low low gear sets, you sould probally have much more low gear multiplication of torque in 1st gear with the 3.23 and the low gear than with the standard ratio low gear set and the 3.55. My calculator batterys just went tents up just now so I can't , won't, do the math for you. Multiply the low gear ratio times the rear gear ratio to get the starting line ratio I borrowed the house solar powered calcultor, the 3.23 with a 2.44 low gear ratio, standard 727 gears equals 7.88 in first gear, the same low gear set and the 3.55 rear gears equals 8.66. The low gear set in the 727 is 2.77 if my memory is correct so the 3.23 with them is 8.947 or rounded up is 8.95 The low gear set with the 3.55 would be 9.83 I like using a 1st gear low gear set like that I use to use them in my 1963 M.W. stocker in NHRA stock class racing I'm building a new 4 speed street car, it wll have a NP833 O.D stick tranny in it, they come with a 3.09 low gear set with .64 O.D. in overdrive, I'm going to use a set of 3.54 gears in the Dana 60 with a short set of rear tires, hopefully 275x60x15, or what ever will fit in a 1966 Dodge Coronet Deluxe It pays to think before acting Especially on car parts and combinations Great information! It confirms that the lower transmission gear set is definitely the way to go. Now, if I could find an A500 to swap out I could get the lower low gear and an overdrive. I could have the 3:55 or even the 3:91 gears and still have great highway manners. Even if I don't find an A500 I can still swap the 904 gears and keep the 3:23 set I have and do pretty well on takeoff. Those aren't bad options either way. Thanks for the info! I think this is what the guy from Turbo Action was trying to explain. It makes a lot of sense. That's King Weenie to you!

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633546 06/15/14 02:48 AM 06/15/14 02:48 AM
Joined: Aug 2007 Posts: 6,095 Valencia, España NachoRT74 master
NachoRT74 master Joined: Aug 2007 Posts: 6,095 Valencia, España	Can't talk about maths, but I did it at the same time went with SG replacing open differential and I'm enjoining it without loose on daily driving on streets Did it with still stock 400 engine and 727 on 255/60-15, now stroked with 175K MP converter and even more fun. I bet with a better TC will be way better, but not funds for that now. With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: NachoRT74] #1633547 06/15/14 03:57 PM 06/15/14 03:57 PM
Joined: Jan 2003 Posts: 5,186 Wherever I am. J Junky master
Junky master J Joined: Jan 2003 Posts: 5,186 Wherever I am.	Shorter tire like 26 to 27 inches tall go with 3.23's. Taller tire go with 3.55's. Myself I went from 3.23's to 3.73's with 28" tall tires. I like it. 3,200 RPM down I-5 staying up with most of the traffic. Easy, peesy. 2010 Black Challenger SE <> 3.5 V6 Custom Shift Knobs www.flameball.com Check It Out

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Junky] #1633548 06/15/14 04:26 PM 06/15/14 04:26 PM
Joined: Sep 2013 Posts: 464 KY Telvis OP mopar
Telvis OP mopar Joined: Sep 2013 Posts: 464 KY	Quote: Shorter tire like 26 to 27 inches tall go with 3.23's. Taller tire go with 3.55's. Myself I went from 3.23's to 3.73's with 28" tall tires. I like it. 3,200 RPM down I-5 staying up with most of the traffic. Easy, peesy. I'm running 255 60 15 on the rear. I think I am going to either get an A500 and swap or do the lower gears in the 904. If I do the 904 I will keep the 3.23 gears and get a better torque converter. If I do the A500 I will go with a lower gear set, maybe the 3.90 gears. I'm going to see if I can find me an a500 locally. Anyone know how to easily tell the RH from the RE? That's King Weenie to you!

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633549 06/15/14 08:07 PM 06/15/14 08:07 PM
Joined: Jan 2008 Posts: 795 Glendale Az D Darryls-Demon super stock
Darryls-Demon super stock D Joined: Jan 2008 Posts: 795 Glendale Az	I drove my Challenger round trip this year to the MATS from PHX with a 3.55 gear and a 8 inch convertor and after putting over 600 miles on the car that weekend I see no reason in the would to put an OD tranny in the car, it sounds fantastic at 3100 RPMS and 70 MPHs. 8177229-IMG_1273.JPG (385 downloads)

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: BigBlockMopar] #1633550 06/16/14 03:25 AM 06/16/14 03:25 AM
Joined: Jan 2003 Posts: 5,791 Hamilton, Ontario Canada Magnum master
Magnum master Joined: Jan 2003 Posts: 5,791 Hamilton, Ontario Canada	Quote: Ever considered going with an overdrive transmission and have best of both worlds? ANY gear choice will be a compromise in either direction. Another problem with low gear sets in a 3 speed trans. Too much rpm drop at the gear change. Modern cars have twice as many gears to cover every situation. Launch, high speed cruise and mileage. 69 Super Bee, 93 Mustang LX, 04 Allure Super

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Magnum] #1633551 06/16/14 06:18 PM 06/16/14 06:18 PM
Joined: Jan 2003 Posts: 2,931 P Paul_Fancsali master
Paul_Fancsali master P Joined: Jan 2003 Posts: 2,931	I currently 4.10s in a Duster 340 that engine wants the gear. In my 360 car I run 3.91s now soon to go back to 4.30s or 4.56 gears all you need is a LT tire of about 29-31 tall cuts into gear real fast. The 4.30s were the best all around street gear tall tires cut the revs and the car had a ton of response as far as people passing you wait until you hit a hill. Lesson learned use a quieter muffler As far as gas mileage I get the same with 3.91s as I did with 4.30s. Also my Duster should be getting lousy mileage with 4.10s and 25 tall tires I get 14 around town with a stick

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Paul_Fancsali] #1633552 06/16/14 09:22 PM 06/16/14 09:22 PM
Joined: Mar 2005 Posts: 3,142 Central NC gch master
gch master Joined: Mar 2005 Posts: 3,142 Central NC	Several years ago I switched from 3.55's to 3.73's in my Polara and I hate it.Too many rpm's at anything above 60 and it just fries the tires at will.I wish I had kept the 3.55's.I have a 3.23 pumpkin that I may swap out.I don't drive mine often or on the highway but I can't even look at the loud pedal without going sideways.Granted mine is torque heavy and if were lacking low end I would probably be more tolerant of lower gears.

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Darryls-Demon] #1633553 06/17/14 05:23 PM 06/17/14 05:23 PM
Joined: Jan 2003 Posts: 28,067 Irving, TX feets Senior Management
feets Senior Management Joined: Jan 2003 Posts: 28,067 Irving, TX	Quote: it sounds fantastic at 3100 RPMS and 70 MPHs. I would pull my hair out having to listen to an engine at 3100 rpm at 70 mph. The Imperial runs 3.23 gears and a 29" tire. I plan on slamming an OD in it because I don't like the RPM it pulls on the highway. Telvis, look in truck and vans for the OD transmission. They're pretty easy to find around here. Cab, I did the 4.30 gears and 833 OD transmission. That 3.09 first gear was good for a couple car lengths then I had the long drop to the 1.69 second gear. We're talking cruising here, not racing. We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon

Re: Swap 3.23 to 3.55 rear end... Is it worth it? [Re: Telvis] #1633554 06/17/14 06:19 PM 06/17/14 06:19 PM
Joined: Jan 2003 Posts: 1,120 MassHole Central rtman super stock
rtman super stock Joined: Jan 2003 Posts: 1,120 MassHole Central	Had 3.55s in my '70 Charger R/T. My conclusion was that the 3.55s weren't particularly good at anything. Didn't give the blistering low-end torque you really crave (like with 3.91s or 4.10s) and weren't as smooth on the highway as 3.23s or 2.76s. I went back to factory 3.23s. The car liked them better (heavy car with AT with stock converter). For my , optimal is a low gear and an OD, but that's pricey. I'd swap out the converter before changing the gearing. Good luck.

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