I got curious about the T-5 in my Sedan Delivery project. I haven't driven the car yet but it is getting close to that time. I was wondering what kind of MPH @ what RPM I can expect running 15" tires. I am wondering about cruising speeds on the highway with the 235 engine I built. The transmission is a 1352-145. It came from a GM 1985-86 S-Truck 2.5 L4-2.8 V6 The rear end came from a 1996 S10 4WD pickup, 3.73 gears according to the glove box code. Using the factory sticker on the transmission, I found this information on the gears. Rev gear 3.76 1st gear 3.78 2nd gear 2.18 3rd gear 1.42 4th gear 1.00 5th gear 0.72 I have no idea how to calculate the MPH. Can anyone ***ist?
probably mostly be in the 2000-2500 rpm range at highway speeds of 55-75 mph. Hopefully you'll have enough torque to "pull" that gear. Might expect to have to downshift for grades.
Here you go. Just a bit of Math, and ***uming a 30" OD tire with a 93% deflection ratio. Vehicle Speed (MPH) High Range Engine RPM - 1st Gear - 2nd Gear - 3rd Gear - 4th Gear - 5th Gear 2140 - - - - - - - - 11.5 - - - - 19.9 - - - - 30.5 - - - - - 43.3 - - - - - 60.2 2380 - - - - - - - - 12.7 - - - - 22.1 - - - - 33.9 - - - - - 48.2 - - - - - 66.9 2620 - - - - - - - - 14.0 - - - - 24.3 - - - - 37.4 - - - - - 53.0 - - - - - 73.7 5500 - - - - - - - - 29.5 - - - - 51.1 - - - - 78.4 - - - - 111.3 - - - - 154.6
As said depends on the rear tire. During my 40+ years in the ch***is business I did lots ch***is with a T5 trans and the overwhelmingly most popular rear end ratio was 3.78. Majority of these cars used a 29/31 inch tall tire. Most of the times the rpm's hovered in the low 2's at highway speed. Seemed to work well.
My Rambler SW with the 196 straight six and T5 does about 2200 rpm at 55-60 mph. Yes I need to down shift for grades. 215/70-15 tires
By all means, go to the calc. formulas on various websites, there's a bunch of them. Try several and see if they match up. I had a T5 with 3:73 explorer Ptrac with 25" tires--not a good combo. I tried several of the formulas and found, at least for my use, that a 3:50 gear was the key. Good response all around and great cruising rpm. Sold the car though, didn't install it. Tall tires might make a good difference for you, I wanted the look of the lower tires.
3.73's are a great combo with a 0.72 O/D and 25" diameter tyres. At 65 mph it would be cruising at 2346 rpm [vs 2201 rpm for the 3.5 rear] Especially for @RMONTY with an old 235 Blueflame The formula is: MPH x 336 x [Rear Ratio x Transmission Ratio] ÷ Tyre Diameter = RPM 65 x 336 x [ 3.73 x 0.72] ÷ 25 = 2346 RPM
My 52 with a 235 and 373s in the rear has no trouble making highway speeds. I've had it moving along with traffic many times. I don't know what the rpms are and honestly I don't care. Once it's moving I can still accelerate in 5th with no issues. The inline may take a little longer getting up to speed, once it is cruising it moves along just fine. The one big improvement is not listening to the engine screaming any more like it did with the stock 3 speed.
1st gear will be very low, and with your 235 six you will quickly get into 2nd gear about the time you get through an intersection. But that's not a bad thing with a little six and will make it feel peppy off the line. The .72:1 5th gear will make it a great highway cruiser with a 28"-30" rear tire and be in the 2200 rpm range at 70 mph. The little 235 will really appreciate that lower cruise rpm, and last a long time.
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