700R4 RPM 2500 @ 70/75MPH Normal?
Thread Starter
Junior Member
Joined: Sep 2018
Posts: 4
Likes: 1
From: Detroit
Car: 1992 Firebird Formula
Engine: 5.7 TPI
Transmission: 700R4 4SPD Auto
Axle/Gears: 3.23
700R4 RPM 2500 @ 70/75MPH Normal?
Hello,
Asking if this is normal, my birds running at 2500 RPM around 70/75 MPH with 700R4. I just had the trans rebuilt it's got a 3.23 rear end. It ran like this before having rebuilt as well.
Asking if this is normal, my birds running at 2500 RPM around 70/75 MPH with 700R4. I just had the trans rebuilt it's got a 3.23 rear end. It ran like this before having rebuilt as well.
Supreme Member
Joined: Sep 1999
Posts: 3,042
Likes: 822
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
Sounds right to me. You'd be at 3000 without overdrive...
Joined: May 2012
Posts: 443
Likes: 117
From: Arcadia, OK
Car: 1990 Pontiac Firebird Formula
Engine: L31 350 TPI
Transmission: Tremec TKX
Axle/Gears: 3.23 Posi
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
FWIW, mine (700R4/3.23) turns about 2050 at 70mph on stock-size tires (245/50-16). I have verified the speed accurate to +/- 1.5 mph. I have not verified my tach, however, the gear ratio speed calculator (http://www.apexgarage.com/tech/gear_ratios.shtml) calculates this to be about right. Are you running different diameter wheels/tires than stock? According the speed calculator, 2,500 rpm with stock (25.6-inch diameter) tires and .70 overdrive/3.23 final drive ratio, you should be going 84 mph.
Supreme Member
Joined: Sep 1999
Posts: 3,042
Likes: 822
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
Your tach is off...
Supreme Member
Joined: Mar 2003
Posts: 4,771
Likes: 15
From: Florida
Car: 1987 Black IROC-Z (SOLD)
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
Easy check for correct RPM.s & speed with the 700R4. In OD the tach @ 1000 RPM.s and the speedo @ 40 MPH....at a steady speed.
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Supreme Member
Joined: Sep 1999
Posts: 3,042
Likes: 822
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Supreme Member
Joined: Sep 1999
Posts: 3,042
Likes: 822
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
With a 3.23 rear gear and overdrive, you should be around 2200 RPM at 75mph with a 26-inch tire. Maybe closer to 2400 if the torque converter is not locking up...
Joined: Mar 2014
Posts: 4,556
Likes: 811
From: South Ms
Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: 700R4 RPM 2500 @ 70/75MPH Normal?
Are you positive it's still got the stock 3.23 gear or maybe it has been swapped for 3.42s?
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