Hello All, just seeking some opinions here.. I took my RR out for a drive the other day and wasn't entirely happy with the high RPM over 60/70mph (3.55 gearing). Many years ago I drove a friends '69 RR with 383 4spd with 3.23 gearing and remember how good it felt on the highway. My car is a springtime/autumn driver (no A/C). I'm now leaning to 3.23. Thoughts?
3.55 vs 3.23 - 1972 440/4spd RR
- Thread starter 4404ME
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Guess you've got to decide if you like roasting tires or cruising the highways more. I can't see bothering with the hassle of swapping the pumpkin or gears to drop a couple hundred rpm. I have 2:94's in the back of my Bee and love it (cops hated it!), but it ain't no tire roaster that way. HP2 has 3:54's in it and highway seems just fine with the hemi hummin away. 3:55's in the automatics run fine as well.
r4sedan
Well-Known Member
You won't notice much difference. You would have to go 2.94 or 2.76's to notice a difference for cruising.
Runcharger
Well-Known Member
10% difference, it's the difference between 3.55 that doesn't do anything well or a 3.23 which can be used on the highway and is still sprightly around town. Personally I think 3.23 is tailormade for a stockish 440.
I had 3.23 in my 4-speed '70 Road Runner many years ago. With 235x60x14 tyres, that car flew down the highway. It was a little hard on the clutch, but I didn't tend to hang on that pedal much. Around town it was a bit harder....used 3rd more than anything.
On my '70 GTX with a 4-speed, I started with 4.10 gears.......lots of fun around town for roasting the tyres, and easy to drive/harder to stall. Made teaching my wife to drive it a lot easier. But down on the open road, it got quite noisy inside - extra engine revs made more interior noise. Swapped out for 3.55 gears afte a few years, and it was much nicer to drive all round.
With my A100, I started with the 4.10 gears (automatic trans) - that was horrible, but I had no choice at the time - had to wait for the other head to be re-built with different gears. Very noisy inside - especially since at the time we had no carpets. Nearly had to use ear-muffs to drive any distance. Burnouts were insane of course....but how often can you get away with doing that on the open road?
Changed the truck out to 2.76 gears, and it became quiet, but sluggish....burnout were laboured. Now I have swapped everything around again, and have an aggressive sure-grip unit and 3.23 gears in the A100. Does great burnouts, and skips along quite nicely on the open road. No slouch around town either.
Here's the new sure-grip and 3.23 gears in action....
I ran 3.55's for years 70 mph 3000 rpm. When to NeHOA meets (from CT.) in western Pa. and Rochester with a side trip to Niagara Falls. That CT. to Rochester to Niagara Falls back to Rochester was 400+ miles in one day.
66 Sat
Well-Known Member
I think it's worthwhile, just to take that "edge" off the rpm e.g. if you're currently at 3,100 rpm at 65 mph then the drop to 2,800 rpm might make all the difference. It's finding the sweet spot where everything comes together, where the engine is as its happiest.
Like posted, tire size plays a part in all this also.
My 67 has 3.23 sure grip and a 26.5 tire . That is 2,700 - 2,800 at 65mph. 28 rear tire would drop the rpms some more. If possible mabey barrow a taller set from a friend for a test drive.
You may find a happy medium without swapping gears.
My 67 has 3.23 sure grip and a 26.5 tire . That is 2,700 - 2,800 at 65mph. 28 rear tire would drop the rpms some more. If possible mabey barrow a taller set from a friend for a test drive.
You may find a happy medium without swapping gears.
gtxrt
Well-Known Member
you didn't say if your RR is a 4-speed. the 4-speed in your friends car will be turning about 200 RPMS less than automatic with the same gears because of the torque converter slip. a 3.54 in a 4-speed would feel like about 3.31 in an automatic.
I have 3.23 in an auto 440 and 3.54 in a 4-speed 450 and I definitely notice the difference. Similar size tires.
Depends on tire height and usage. Do you drive the freeway often? My wifes 360 Challenger has 3.55 with a 4 speed. 275/60 15 BFG T/A's 60 mph it's no big deal. If it had a shorter tire or more freeway time I'd rethink it. We did take it on a 500 mile trip with 2.76. Got 18mpg and drove great. However with the 2.47 close ratio 833 the take off was little tough on the clutch. If it has a 2.66 1st gear 833 it would've been better. Obviously it doesnt have 440 torque. But at 9.0 -1 on 87 octane it's been 12.70's@108 in street trim. So it does have fairlly decent power.
Doug
Doug
Thanks to everyone who replied..food for thought..my tire-burning days are about 50 years out..now just basically wanna do some cruising without rattling my teeth! Thanks Again!
68RoadrunnerJKH
Active Member
You need a 5 speed. None of the aforementioned transmissions were below 1:1 final drive ratio. My 61 Chrysler 440 4 speed 833 had 3.23 posi 8.75 and 255x60x17 rear tires. I don't care about 60 MPH here in Texas. If you don't run 75 on the freeways you'll get run over. That is about 3300 RPM. Way to high even for a forged crank 440 comfortably for hours at a time. I'm going to replace it with a 2.94 so I can actually go somewhere without sucking 8 MPG while in route. BTW - Putting a 6.4 and TR6060 with 4.10 posi in the rear. Should be about 2300 RPM at 80 in 6th gear. Planning on driving to more distant shows.
Portagee
Well-Known Member
I struggled with gear set choices/transmission ratios/tire sizes for a while when trying to decide on what RPM I was comfortable cruising at. To help, I made an excel spreadsheet that auto-calculates RPM vs speed for a given car (after inputting some known or hypothetical values). Was very helpful to visualize RPM drop after gear changes, as well as highway cruising RPM. Happy to share the doc with anyone who wants it. Screenshot examples below:
#41
Well-Known Member
The bar has really changed from the old days now that everybody's daily driver has overdrive. 3.23 is only a very small change from 3.55. If you really don't care about maximum stoplight to stoplight acceleration, you may also want to consider 2.94's. Not quite the acceleration killer of 2.76 but long enough legs for cruising and keeping up with traffic on the highways.
My cars: 3.91, 3.55, 3.23, 3.23, 2.94, and 3.23 with overdrive = 2.36. It's no fun getting passed by the mini-vans on the highway when I drive the 3.91 and 3.55 cars
My cars: 3.91, 3.55, 3.23, 3.23, 2.94, and 3.23 with overdrive = 2.36. It's no fun getting passed by the mini-vans on the highway when I drive the 3.91 and 3.55 cars
Slap Stick
Well-Known Member
Consider a newer lock up converter if possible.
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