Re: What gear ratio are you running without an overdrive?
[Re: ProSport]
#1874033
07/20/15 01:06 AM
07/20/15 01:06 AM
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Joined: Jan 2003
Posts: 17,928 Akron, Ohio
ProSport
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 17,928
Akron, Ohio
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You guys have really nice street combos! I have a healthy motor and I think this car would run easy 10's in street trim but I really don't plan on racing it at all and just want to make it more streetable.
MikesDuster, I want to stay with the 275/60/15, any taller on an A-body and it might start rubbing the rear quarters and may sit up too high, I think the 28's look perfect.
1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
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Re: What gear ratio are you running without an overdrive?
[Re: Spaceman Spiff]
#1874046
07/20/15 01:20 AM
07/20/15 01:20 AM
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Joined: Mar 2005
Posts: 1,373 Rancho Cucamonga, CA
D_C
pro stock
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pro stock
Joined: Mar 2005
Posts: 1,373
Rancho Cucamonga, CA
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'71 Charger, 4:10's with 30-inch tall tires, 440, A727 TF Trans.
Yes, I can and do drive on the Freeway, but not often. It does tend to wear you out a bit.
I also have 4:10's in my '74 W200 Power Wagon pickup, with 33-inch tires, manual transmission, 360 engine, also Freeway Driven.
My '79 CJ5 Jeep, AMC 304 V8, manual Trans, 33-inch tires has 3:73 gears and is a very good compromise of acceleration performance and freeway driving.
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Re: What gear ratio are you running without an overdrive?
[Re: ProSport]
#1874376
07/20/15 03:39 PM
07/20/15 03:39 PM
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Joined: Jan 2003
Posts: 17,928 Akron, Ohio
ProSport
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 17,928
Akron, Ohio
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Paul, That would give me a headache lol, I'm not worried about my motor, it could handle a 250 shot of nitrous. I'm just worried about my annoyance level. I got real spoiled to my Mustang going 70 at 1900 rpm's. I think tightening the converter some might be all it needs, if not I'll install some 3.23's.
Last edited by ProSport; 07/20/15 03:40 PM.
1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
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Re: What gear ratio are you running without an overdrive?
[Re: Spaceman Spiff]
#1874397
07/20/15 04:12 PM
07/20/15 04:12 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Back calculate it.What's the max cruiser rpm you are comfortable with? What's your max cruise speed? What's your tire size or how many revolutions of the tire per mile?
With those three numbers you should be able to calculate it. Trick is that 60mph is one mile per minute. So revolutions for a tire to roll one mile become tire rpm at 60mph.
For example, 3000 rpm at 80 with 27" tall tire.
27 x pi /12 = 7.07 feet per revolution
5280 / 7.07 = 747 revolutions per mile
Turn ideal rpm at 80 into rpm at 60
(60 / 80) x 3000 = 2250 rpm at 60
calculate gear ratio 2250 / 747 = 3.01 That's optimum gear ratio assuming the car is either 4-speed or converter slips only a little bit. If converter slips 3% then multiply ideal gear ratio by 0.97, giving you 2.92 as the ideal ratio. . Now pick your closest factory gear ratio.
Done.
R.
Last edited by dogdays; 07/20/15 04:13 PM.
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Re: What gear ratio are you running without an overdrive?
[Re: ProSport]
#1874398
07/20/15 04:12 PM
07/20/15 04:12 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,096
Irving, TX
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I hated the 4.30s in the hot rod. They were fun for the first ten minutes. After that, they had to go. I swapped them for a set of 3.23s at the Nats. Literally. I saw some guys looking at 4.30s in the swap meet. They had 3.23s in their car. I proposed a straight across swap with them doing the work.
I got up to speed on the highway, dropped the 833 into OD and smiled all the way home.
I miss the OD and plan on stuffing my 518 OD into the Imperial.
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
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Re: What gear ratio are you running without an overdrive?
[Re: ProSport]
#1874563
07/20/15 08:46 PM
07/20/15 08:46 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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The highways around here are ~70mph almost constantly if you plan on getting anywhere, tollways push 80. Obviously you can go as slow as you want, but my biggest annoyance with 3.91s was the constant screaming of the engine just to maintain a reasonable speed...hence the double-overdrive 6spd that now resides in my garage. If I kept it with a non-OD, I would have put 3.23s in it and putted along, I was done and over with running low gears on the street. At 3,200rpm instead of 70, i'll be at 110! 70 at 2,000.
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Re: What gear ratio are you running without an overdrive?
[Re: Kern Dog]
#1874759
07/20/15 11:53 PM
07/20/15 11:53 PM
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Joined: Mar 2010
Posts: 984 Tennessee
Hemi ragtop
super stock
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super stock
Joined: Mar 2010
Posts: 984
Tennessee
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I have been around the block on this and have THIS to report:
High stall converters and taller (Lower numerically) gearing do result in excessive slippage, sorta negating the advantage of the taller gearing. I ran a Gear Vendors overdrive with a 3.91 gear, 28" tire and a slippy 9.75 converter. Not fun. The car felt lazy at freeway speeds, like a boat in the water in terms of part throttle feel. The combo was fine for wide open throttle, it just sucked for everything else. I don't care to drag race, I enjoy distance drives, cruises, cornering on twisty roads and such. I eventually sold the GV and went with a 3.55 gear and an 11" converter that made a huge difference in how the car feels. I really like this combination. I really have to reply to this as I am the member that bought the G/V from Frankenduster. Let me say right here that he is a stand up guy, fair and honest and I love his car. I have a 4,175lb convertible 66 Coronet with a 540" HEMI. 4.5" stroke, 246@ .050 I roller cam and 3.54 Dana. Torque is not a problem with this set up! Last fall, I drove the car almost 400 miles round trip to the Mid TN Mopar show in Lebanon TN from Chattanooga. Most of the trip was Interstate at 70+ MPH. 3,300 rpm with semi trucks on your bumper is NOT fun! The car had a 9.5" converter and would still "slip" 300 RPM going up a hill. With the G/V I installed a Hughes "2,800" 11" converter. Now 70 MPH is 2,500 RPM on the flat and level. It still gains 200-300 RPM on a hill. But it is SO much more pleasant to drive on a trip! In an hour drive, the noise, vibration etc. is VERY reduced. With the 640+ ft.lb. of torque, I should have sprung for the TCI "power adder" converter for $900 with a stall of 2,200 RPM but couldn't afford it at the time. The OD ratio ends up at 2.76 and the car is just a joy to drive @ 60-70 MPH. In short, if you have the torque, you just don't NEED deep gearing, I like my "rear end" just fine, don't you?
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Re: What gear ratio are you running without an overdrive?
[Re: stinger]
#1874836
07/21/15 01:06 AM
07/21/15 01:06 AM
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Joined: Dec 2013
Posts: 4,806 Wichita
GY3
master
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master
Joined: Dec 2013
Posts: 4,806
Wichita
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Once you've driven modern muscle with a 5 or 6 speed you realize what your missing out on.
My '63 was built to do lots of street duty with 2800 stall and 3.55 gears and 275/60's. I had ran 3.23's in my '71 'Cuda but wanted to step it up a notch with the '63 build.
I'm going to throw a set of 2.76's that I have lying around just to see what it's like on the highway. If it does okay it might get the suregrip in that 3rd member!
With over 500 cubes I don't think they will be a problem...
'63 Dodge 330
11.19 @ 121 mph Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
9.92 @ 135mph with a 350 shot of nitrous and 93 octane pump. 1.43 60 ft. 3,750 lbs.
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Re: What gear ratio are you running without an overdrive?
[Re: Kern Dog]
#1874894
07/21/15 04:33 AM
07/21/15 04:33 AM
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Joined: Sep 2009
Posts: 1,805 ky hills
thehemikid
top fuel
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top fuel
Joined: Sep 2009
Posts: 1,805
ky hills
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I ran 4.56's in my tube chassis street Cuda with the biggest QTPro Hoosiers at the time. If I remember right it turned about 2700rpm at 55. Also ran 4.30's in my 62 Dart 330 with (I think) 28' Hoosiers. Those 2 cars where for wk end warrior street cruising though. Edit: Now that I think about it, those 28's were more like 383man's 30's. Now that I have my 70RR back on the road, 1st time since 1983. It's a Dana 3.54 4spd with 27" BFG's. Tach says about 2750 at 55. Calculator says it should be about 2400-2450. Car sounds like 2700-2800 to me, lol ...probably cause I'm getting used to these modern OD cars & trucks. On the list for the A855 for longer Cruises/trips. Will make dew till I get the last few miner things fixed on this RR. Then I may do a Passon 4spd OD if he'll do a trade-in on the 5spd. Hey...mickm I got her going!
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Re: What gear ratio are you running without an overdrive?
[Re: ProSport]
#1874912
07/21/15 08:12 AM
07/21/15 08:12 AM
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Joined: Jan 2003
Posts: 10,088 Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,088
Frostbitefalls MN (Rocky&Bullw...
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It might be necessary to go to a bigger converter core to get the characteristics you want. I raced a 535 in a 3400 lb car with a stock 340 converter, which is 10 3/4 inch core. The stocker only lasted six passes but stalled to 3800 behind that motor with 906 heads. You should be able to get somewhere around 3000, to 3200 (maybe even 3400?)with a stock type configuration but modified guts to make it live. Then the 3.23 gears and tall tires won't make the converter slip too much. The bigger core simply has more leverage which helps reduce slip. I can relate to the rpm problem for long cruises. I even have a lockup trans, and 3.55 gears with 28.3 inch tall tires is still buzzing the motor more than I like. Funny, forty years ago it didn't seem so bad. Guys were running more gear on the street all the time, and driving freeways with them.
Last edited by gregsdart; 07/21/15 08:15 AM.
8.582, 160.18 mph best, 2905 lbs 549, indy 572-13, alky
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