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Rear end gear with 727?

I'm on the opposite side from kerndog (respectfully disagree!). I keep the suspension stock because for me these cars are a time capsule, I really enjoy the torsion bar suspension as designed it's a different feel from anything modern. The thing that people neglect is bushings for the front end which leads to tons of slop and wandering and bump steer at speed and all sorts of issues. Rebuild the front and better alignment yes that is definitely true, power tour at 80mph is good.
 
This depends on several things....The money that you're willing to spend and what kind of daily driver that you're used to driving.

Higher performance engines make their power at a higher rpm, so a "stall converter" slips more at low engine speeds. This allows the engine to more easily rev past the low rpms and get into the power range without the converter fully engaging. Think of it like when you rev up a manual transmission car before releasing the clutch. A low stall converter would be like releasing the clutch at 1500 rpms. A higher stall is like releasing it at 3000 rpms.

Overdrive, whether in an automatic or a manual transmission is THE way to go when you want to have flexibility in a street driven car.

A torquey Big Block will do fine with a 2.76 or 2.94 axle gear once it is moving but it will not feel as snappy from a stoplight as it would with a 3.23 or 3.55. Sadly, this is an area full of compromises.

The TKO series has been replaced by the TKX. Even the TKO requires some floorpan modifications but nothing structural. The TKX is slightly smaller but you're still looking at cutting a hole for the shifter. These Tremec trasnsmissions have shifters that must pass through the floor just like any other manual transmission. Stock 4 speed models had the shifter and linkage on the side. The Tremecs require a hole on the top of the transmission tunnel. It is not difficult to do.

Actually, the TKO had two overdrive ratios available, .64 and .82. I have the .64 ratio. It is excellent. The TKX supposedly only has the .64 ratio.
What you'll find with the 5 speed is that no matter the condition, you always have the right gear to use. Mine has the 2.87 first gear ratio. This is deeper than any regular Mopar 4 speed so it gets the car moving a bit better. The .64 overdrive means that at freeway speeds, the engine will now rev 36% slower than a 727 or a regular 4 speed. Freeway speeds of 3000 rpms will rattle your brain after awhile. Most if not all of us have become accustomed to lower rpm freeway operation with our later model cars. The interior noise is reduced, the engine noise is reduced, the car gets better mileage and the road trips are much more comfortable. The Tremec 5 speed swap was one of the best things that I did to my car. I went from maybe 10-11 mpg to 15 in my 440/493 Charger with a 3.55 axle gear.
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While that may not seem extreme, any increase in mileage means an extension of time and miles between fill-ups at gas stations. If you've ever worried about making it to the next station, longer range really eases your nerves.

This thread is long but it covers a LOT:

Tremec 5 speed conversion in a 1970 Charger

The 6.4 HEMI is a great engine but will cost you about double to swap in compared to a 440 when you factor in the fuel system, electronics, special mounts and exhaust system. The parts to do a 440 swap are easier to find and a lot cheaper. A stock 6.4 will make about the same as a mild 440 but get better mileage. The decision as to which engine to go with is up to you. Both have pros and cons.
Good luck!
Kern thanks for taking the time to type all of that out. I think I’ve talked myself into going 440 after doing more research and definitely leaning hard toward the tkx. I’m in no rush and only want to do this car one time as opposed to my dart that I’ve re done a few times haha. It scared to spend money on this one and want do it right. I think the 5 speed/ 440 is the way to go. I was supposed to have the car at my house today but the old man I’m buying it from forgot and went to NC for the weekend so now it will be Sunday or Monday. Gonna be a long weekend haha. Thanks again for all of the input I really appreciate everyone’s help!
 
I'm on the opposite side from kerndog (respectfully disagree!). I keep the suspension stock because for me these cars are a time capsule, I really enjoy the torsion bar suspension as designed it's a different feel from anything modern. The thing that people neglect is bushings for the front end which leads to tons of slop and wandering and bump steer at speed and all sorts of issues. Rebuild the front and better alignment yes that is definitely true, power tour at 80mph is good.
I’m in between on front suspension. The new stuff is really nice. But the older stuff is okay too, I think depends on what the car is and how it’s used and preference for sure. My dart when I first purchased in high school (2000 or 2001 maybe). I would take a hard right turn at an intersection and the tires would fold up and ride on the outside part of the tread and would eventually drop and ride on the inside portion. When it dropped it would shoot me the oncoming lane. Last time it did it a tractor trailer was coming. I drove home and parked it then saved up to have the whole front end rebuild lol.
 
If cruising comfortably at 80 for long distances is parg of the plan, some sort of OD is the only solution "in my opinion".
Any rear gear capable of that with a 727 will be a turd off the lights, regardless of how much torque you make (you still have to hook that power up).
It all depends on what you want. Some like the 3.23 but for me, that kills the acceleration 'fun factor' way too much.
Something else that gets lost in the conversation is how squirrely these old dogs can be at 80+ on the freeway without some steering/suspension/brake mods, so don't neglect that stuff if your goal is high-speed cruising.
Thanks bean. I agree that part is left out a lot. Honestly I plan on rebuilding the front end, rear end, rebuild a 440, replace all lines, and upgrading the breaks and master cylinder. Want to do this car one time and do it right. Thanks for the post bean, I appreciate it. :)
 
Thanks bean. I agree that part is left out a lot. Honestly I plan on rebuilding the front end, rear end, rebuild a 440, replace all lines, and upgrading the breaks and master cylinder. Want to do this car one time and do it right. Thanks for the post bean, I appreciate it. :)
:thumbsup:
 
I have 3.55s with a 28 inch tire on my 70 coronet. . My 440 hums along at 80 just fine. Also 3.23 with same tire in my 66 coronet is great at 80.
 
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