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700R4 & 3.73s: too MUCH gear ratio???

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Old 08-07-2003, 02:20 PM   #1
Glensgages
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Default 700R4 & 3.73s: too MUCH gear ratio???

I know some members here have put 700R4s in their C3s. The 1st gear ratio in 700R4s is 3.06:1. My '82 Cross-Fire (no-laughing, pleeze!) has the 700R4, and 2.87:1 rear gears. The Cross-Fire needs ALL the help it can get, so, I'm considering swapping the 2.87s for 3.73s. My question is this: the 'effective' gear ratio in 1st will be 11.4:1 (3.06 x 3.73), deeper than my Z28 with custom gears in the THM400 (2.75:1) and 4.10 cogs (11.27:1). I'll eventually up-grade the Cross-Fire to 300-325 HP (where's CARTEK when you need 'em? :lol:), and run BFG Drag Radials, but, WILL THIS THING HOOK-UP? Is it 'too-much' 1st gear? Other offereings are 3.31:1 and 3.55:1 ratios. Anybody with the 700R4 and 'gears', please respond. THANKS in advance..... :chevy :chevy :chevy
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Old 08-07-2003, 02:28 PM   #2
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

Sounds like a good combo to me.....I run them with my Th-400 :cheers:
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Old 08-07-2003, 02:38 PM   #3
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Alwyn678)

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Sounds like a good combo to me.....I run them with my Th-400
Yeah, but your 1st gear is just 2.48:1 ratio; your 'effective' gear is 9.25:1 (2.48 x 3.73). For your set-up to have the same 'effective' ratio, you'd need 4.56 gears (11.4 divided by your 1st gear ratio of 2.48 = 4.602...); would you 'hook' then? :confused: :eek: Most of my driving'll be on 255/60R15 BFG TAs; when I go track-testing, I'll run Drag Radials...
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Old 08-07-2003, 02:51 PM   #4
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

You are correct. That first gear is gonna be super duper grandmaw. If you still do any cruizing at all I would go with something lower. Do a POLL on 700R4 users, see whats the general consensus.
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Old 08-07-2003, 03:00 PM   #5
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

That's a similar gearing that I have in my '68.. I love my gearing :D :D
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Old 08-07-2003, 03:02 PM   #6
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (LAvetteman)

well i got 3.70 and a 700r4 in mine and i love it,im actually planning on swapping to 3.90 this winter.Its a pleasure to drive on the highway also.
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Old 08-07-2003, 03:02 PM   #7
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

I'm runnin' 3:73's with a 4L60 (700R4) in my 93....these gears are very driveable ...mine is a daily driver, I've been on two road trips over 1500 miles each and I drag race the car twice a month, every month...the track I run at is a 2.5 hour drive each way on the interstate... on the highway I'm running around 2900 - 3000 RPM @ 80 MPH....I think the 73's give you the most bang for the buck for a drag/street car with an auto tranny....my only drawback is the Dana 36 presently in the car...I don't want to chance stickies out back till I swap a 44 in there...I've still turned a lot of 1.9X 60' times with worn Eagle GSC's....oh, I've got a Transgo shift kit also.... good luck

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Old 08-07-2003, 03:09 PM   #8
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (LAvetteman)

Sub 425 hp 355 ci drag vettes with 700R4 go with 4.30 gearing to maximize the 1/4 mile. because your only going through the end in 3 gear.

I have been driving around with 4.11's since the late 80's with my 700R4. It does a good job of closing up the gear spacing. For bigger 383 - 427 ci small blocks that can spin over 6000 rpm I would recomend 3.90's

3.73 is still over geared in OD unless you have the TQ to pull it.

I first had a 3.55 rear gears and you had to be going 80 mph to drive in lockup fourth gear. So I jumped straight to 4.11 even with them I can go @ 85-90 miles an hour in second gear and 125 in third and never hit redline in 4th gear
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Old 08-07-2003, 03:11 PM   #9
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

The combo is explosive off the line if you have the torque,so I tend to ease into the gas.Be carefull not to run too big of a cam though.When the OD kicks in you need to have plenty of low end,or it'll labor the engine too much.This is not the case with the 406,but an overcammed 350 may be a problem
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Old 08-07-2003, 03:22 PM   #10
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (The Money Pit)

I run the 3:73 plus 700r combo and love it . I donot turn the car much over 5k and I find the gearing to suit my needs . I have a torquey motor and really can't comment on your c/f engine . Overtaking performance will make ya smile :D

gman
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Old 08-07-2003, 03:28 PM   #11
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (GrandSportC3)

I just checked.. my exact setup is 3.27 first gear and 3.73 rear gears.. I use a 28 inch tall rear tire for racing.. My best 60' time so far with this combo was 1.591 :D :D
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Old 08-07-2003, 03:30 PM   #12
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (GrandSportC3)

Guess you got your answer :cheers:
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Old 08-07-2003, 06:42 PM   #13
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

I'm running 700R4 with 3:70 gears in the rear.....I also have a Super Yank 3500 stall Converter. A stock converter will be very doggy out of the hole.......You should also consider upgrading to a later year 700R4 and a B&M 3000 Holeshot....They can do wonders with the internals.....
I use first gear to launch me out of the hole....Almost instantly I shift to 2nd since my 5800 RPM light flashes. I do not preload the car....I launch from idle....So that first gear throws me up in the air....the pull is in 2nd and 3rd and I'm through the lights at the end of the quarter. :flag :seeya Cappy
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Old 08-07-2003, 10:52 PM   #14
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (8T1-7T9 BIONIC VETTE)

I currently have 3.73s with my 700R4 and if I was to do it again I would go with 3.90s. Rod
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Old 08-07-2003, 11:56 PM   #15
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Red73)

i said it before and i will say it again a lot of gear is just a crutch for lack of horsepower look at my 3:07 rear gear 700r4 does 1.50 60 ft and it will be in the 1.4s soon as we have better air in the fall :cheers:
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Old 08-08-2003, 12:06 AM   #16
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (CORKVETTE1)

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i said it before and i will say it again a lot of gear is just a crutch for lack of horsepower look at my 3:07 rear gear 700r4 does 1.50 60 ft and it will be in the 1.4s soon as we have better air in the fall...
I agree, Cork, but, have YOU ever tried making horsepower with a 'primitive' computer and a Cross-Fire? :banghead: :lol: :mad :cry I know it's currently stock, but 2.3xx 60' times? Even if I WAS deep-staged; that's bad!!! I had just 'assumed' that it'd 'run-thru' 1st gear, spinning the tires at will. The '82 DEFINITELY needs some gears; on the rolling country-side roads near my home, 40 MPH is just 1000 RPM in OD with lock-up. It 'lugs & chugs', until the ECM 'finally' tells it to un-lock, down-shift, or BOTH! I end-up driving around in 3rd gear, unless on the open road. Even with 3.73s, 40 MPH in OD/lock-up will STILL ony be 1300 RPM, if my figgers are correct. I figger in 3rd, it'll be approx 1850; no more 'lugging & chugging'..... So 1st gear won't be 'too deep'.......?
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Old 08-08-2003, 12:12 AM   #17
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Alwyn678)

I have the 700R4 and 3.73's. It takes a good throttle control to the leave an intersection without smoking the rear tires.

I personally would recommend, and wish I would have, gone to 3.55's or a 3.4x size instead.

I also am running 285 wide tires, but they are only 26" diameter so that even lowers the total drive ratio even more.
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Old 08-08-2003, 12:22 AM   #18
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (BSeery)

BSeery: I thought I'd heard you mention that before. I'm running 27" BFGs; that'll help 'some'. If my '82 wasn't in such immaculate condition, I'd just drop the ZZ502/THM400/3.36:1 combination in it, and be done!!! But, I'm not gonna 'cut-it-up' (swap motor and/or transmission) in any way.....
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Old 08-08-2003, 12:34 AM   #19
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (Glensgages)

I am going to go to 275/50's so that will take me up 27.8 from a 26.0 size.
I only lose 10 MM in width, but that extra size will hopefully fill up the wheel well area. Once I get those on there, then I will see how the launch and car control change.

I am also adding a 900 CFM fuel injection system. It's a throttle body and all four barrels open at the same time. The guy at the Holley tech line said if it hooks up, the combination of the ZZ4, 700R4's low first gear, the 3.73's and 900 CFM of fuel injected mixture ought to be pretty "dramatic" leaving the line.
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Old 08-08-2003, 01:24 AM   #20
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Default Re: 700R4 & 3.73s: too MUCH gear ratio??? (BSeery)

Quote:
I am going to go to 275/50's so that will take me up 27.8 from a 26.0 size.
I only lose 10 MM in width, but that extra size will hopefully fill up the wheel well area. Once I get those on there, then I will see how the launch and car control change.

I am also adding a 900 CFM fuel injection system. It's a throttle body and all four barrels open at the same time. The guy at the Holley tech line said if it hooks up, the combination of the ZZ4, 700R4's low first gear, the 3.73's and 900 CFM of fuel injected mixture ought to be pretty "dramatic" leaving the line.
Looks like a good upgrade...When are you having this upgrade done???.....Please post pictures of the burn outs.....They should be awesome.....Be Bad, Be Different, Be the Proud.....Make your Vette the way GM should have..... :D :flag :seeya Cappy
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