Hiqhway gear choice 2:94 or 3:23
#177025
12/28/08 02:02 PM
12/28/08 02:02 PM
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Anonymous
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I've got a 69 coronet I initially built as a weekend warrior, but life changes (family) has made it a work commute and cruiser vehicle. I have a moderate built 360 with 727 trans and 8.75 third member with 3:55 sure grip. Cruising at freeway speeds is now annoying and expensive. What RPM would 2:94 or 3:23 gears me at 70mph?
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Re: Hiqhway gear choice 2:94 or 3:23
[Re: BSB67]
#177028
12/28/08 02:25 PM
12/28/08 02:25 PM
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Joined: Jul 2003
Posts: 4,793 Holland MI Ottawa
2boltmain
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What if you can fit a tire that is say 2" taller in the rear?
Keep old mopars alive.
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Re: Hiqhway gear choice 2:94 or 3:23
[Re: BSB67]
#177032
12/28/08 03:33 PM
12/28/08 03:33 PM
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Great advise guys. I'm running 17x9s with 275/40s on the rear. Last time I checked, taller tire options were limited. I can only fit about 1" taller anyway. Using the math formula for the rear gears, I can drop 300rpm using 3:23 or 520rpm using 2:94s. I've got the original a one leg 2:73 741 third member, but I don't want to take all the fun out of it.
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Re: Hiqhway gear choice 2:94 or 3:23
#177035
12/28/08 04:51 PM
12/28/08 04:51 PM
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Joined: Jan 2003
Posts: 1,771 Rustylvania
Mr_fixit
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Rustylvania
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Re: Hiqhway gear choice 2:94 or 3:23
[Re: stumpy]
#177039
12/29/08 09:16 AM
12/29/08 09:16 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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I Live Here
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Grand Haven, MI
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nitto makes some 275/50's IIRC that would be 1-2" taller than your current tires.
I had 3.55's with a low gear 904 and 27" tires (255/50R17's) and hated it on the highway. I swapped out to a A500 and love it (effective gear ratio in OD is ~2.45:1)
I'd personally go with the 2.94 or maybe even a 2.76....
or keep the 3.55's and swap in an OD tranny (either a 518 or 500 automatic, or an A833OD manual)
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Hiqhway gear choice 2:94 or 3:23
#177043
12/29/08 11:39 AM
12/29/08 11:39 AM
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Joined: Feb 2003
Posts: 4,204 Fort Worth, TX
Clair_Davis
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Ditto to what Patrick said. If you've already got, or have easy/cheap access to a low-gearset 904, you could install that with the 2.94's (or even 2.76's) and probably not feel much difference in performance but still benefit from the lower cogs for highway cruising.
Of course if you've got to get a trans anyway, a healthy 500 might be the way to go, although there's no benefit from the smaller trans in the OD department, so clearance might be an issue.
If all that means extra money that you can't put towards gas (or family stuff - I'm there now too), then the 2.94's would be an easy compromise.
Clair
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Re: Hiqhway gear choice 2:94 or 3:23
[Re: Clair_Davis]
#177044
12/29/08 01:18 PM
12/29/08 01:18 PM
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Anonymous
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Thanks for all the replies. Lots of good information. I especially found the visual Speed/RPM calculator helpful at http://vexer.com/68rt/speed.html With my 25.7" rear tires, 2.94s would give me 2730rpm at 70mph and 2.76s would give me 2563rpm at 70mph, not accounting for T coverter slippage. My dual plane 360 has good hp & torque between 2-5000rmp. Since I don't have the funds for a OD trans swap, I think I'll go with the 2.76s. Since my stall is 2200-2400rmp, I'll still have some take off power, I just won't be posting 1/4 mile records. Plus, I found a NOS 2.76 R&P on e-bay for $75. Anybody see any problems with this set up?
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