selecting a rear gear for 200r4

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
I am currently changing my wheels and transmission. Currently is has 25.3" tall rear tires and a 2 speed powerglide, with 3.08 gears. I am switching to 27.6" tall rear tires and a 200-4R transmission.

So it will be:

64 Belair Wagon
4000 lbs
290hp GM crate 350
200-4R with .67 final drive
27.6" tall rear tires


I want to be able to cruise down the highway comfortably around 75-80, but I dont want the rpms so low that it is lugging. I think if I leave the 3.08s in there, the gearing will be too tall.

Thank you for any thoughts,

2000r4.png


200-R4.....................2.74.....1.57....1.0.....67
while the steep rear gear ratio, and low transmission first gear seem badly matched the low hp 350 and 4000 lb weight ,
the 4.33:1 rear gear will be appreciated, when you feel the leverage advantage,ideally you'll want to cruise at the lower edge of the really effective torque curve, and thats near 2400 rpm, especially if you tow or have to climb steep inclines!
with the fairly tall tires being matched to the reasonable cruising rpm of 2500 rpm,
at 70 mph, if PERFORMANCE is the goal
a 3.90:1 rear gear would be about the best match if mileage,
and performance were the goal!
obviously the 4.11:1 is the compromise
http://garage.grumpysperformance.co...late-gear-ratios-and-when-to-shift-calcs.555/

http://garage.grumpysperformance.co...hing-the-drive-train-to-the-engine-combo.741/

http://www.blocklayer.com/Rpm-GearEng.aspx

http://www.wallaceracing.com/gearcalc.php

http://www.wallaceracing.com/gear-speed.php

Using Transmission Gear Ratio: .67 gives these RPM with the 27.6 tire diameter you listed



Engine Speed (RPM) MPH 3.73 Gear MPH 3.55 Gear MPH 3.36 Gear
8000 RPM 262.85 MPH 276.17 MPH 291.79 MPH
7500 RPM 246.42 MPH 258.91 MPH 273.55 MPH
7000 RPM 229.99 MPH 241.65 MPH 255.32 MPH
6500 RPM 213.56 MPH 224.39 MPH 237.08 MPH
6000 RPM 197.13 MPH 207.13 MPH 218.84 MPH
5500 RPM 180.71 MPH 189.87 MPH 200.61 MPH
5000 RPM 164.28 MPH 172.61 MPH 182.37 MPH
4500 RPM 147.85 MPH 155.35 MPH 164.13 MPH
4000 RPM 131.42 MPH 138.09 MPH 145.90 MPH
3500 RPM 115.00 MPH 120.83 MPH 127.66 MPH
3000 RPM 98.57 MPH 103.57 MPH 109.42 MPH
2500 RPM 82.14 MPH 86.30 MPH 91.18 MPH
2000 RPM 65.71 MPH 69.04 MPH 72.95 MPH
1500 RPM 49.28 MPH 51.78 MPH 54.71 MPH
1000 RPM 32.86 MPH 34.52 MPH 36.47 MPH

Using Transmission Gear Ratio: .67 gives these RPM data:

Engine Speed (RPM) MPH 3.90 Gear MPH 4.11 Gear MPH 4.33 Gear
8000 RPM 251.39 MPH 238.54 MPH 226.42 MPH
7500 RPM 235.68 MPH 223.64 MPH 212.27 MPH
7000 RPM 219.97 MPH 208.73 MPH 198.12 MPH
6500 RPM 204.25 MPH 193.82 MPH 183.97 MPH
6000 RPM 188.54 MPH 178.91 MPH 169.82 MPH
5500 RPM 172.83 MPH 164.00 MPH 155.67 MPH
5000 RPM 157.12 MPH 149.09 MPH 141.52 MPH
4500 RPM 141.41 MPH 134.18 MPH 127.36 MPH
4000 RPM 125.69 MPH 119.27 MPH 113.21 MPH
3500 RPM 109.98 MPH 104.36 MPH 99.06 MPH
3000 RPM 94.27 MPH 89.45 MPH 84.91 MPH
2500 RPM 78.56 MPH 74.55 MPH 70.76 MPH
2000 RPM 62.85 MPH 59.64 MPH 56.61 MPH
1500 RPM 47.14 MPH 44.73 MPH 42.45 MPH
1000 RPM 31.42 MPH 29.82 MPH 28.30 MPH
 
Last edited:
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