The Stovebolt Site Forums The Parking Lot Tons 'o Fun Cruising speed?

After working on it a long time, we have just gotten our 1953 3800 on the road. It has the 17” bias tires, and original gear ratio. I have not verified the speedometer with another car or gps. But if I get going in 4th and just kind of have my foot on the throttle some to where it feels “right” the speedometer shows I’m going 30 mph. I knew these trucks were slow, but that’s slower than I thought. How fast do these trucks cruise in stock form?

My '57 2 ton originally had a 7.20:1 rear end, factory governed RPM is 4000, with 9.00 or 10.00 x 22.5 tires it would do 45 - 50 mph. I now have a 2 speed differential with 6.80:1 and 8.10:1 ratios, 10R-22.5 drive tires at approximately 41 inches tall, it's pretty happy at 55mph and can hit 63 mph at 4000+ rpm. My speedometer is roughly 2 - 3mph slow but the GPS gives me the above-mentioned speed.

First, you need to verify the accuracy of your speedometer. Time yourself between mile markers on a highway, or use the GPS function that most smart phones have. 60 seconds for a mile is 60 MPH, etc. I'd expect your comfortable cruise speed for that setup should be somewhere in the 45-50 MPH range without overspeeding the engine. My 59 3800 flat bed with 18" dual rear wheels, a 235, a SM420 4 speed, and a 4.56 gear could cruise at 50-55 without any problems.
Jerry

Comparing to a Task Force 2-ton is probably not an accurate comparison.

PA Farmer -- my '49 3800 was identical to yours in that I had a 216, the 4-speed SM-420, 17-inch bias plies and the 5.56 ratio HO-72 rear axle. A decent cruising speed was 45 mph. I could barely get to 55 but it was screaming like it was going to come apart.

When I found the 4.11 third member to swap out in the HO72, it gave me a comfortable 50-55 mph cruising speed ... as long as I was on level ground. Any hills or head winds and it would not maintain that. And it was slooooooooooowwwwwwww going up through the gears. And not at all good in heavy traffic.

Switching to a 235 or a 261, coupled with the rear axle gear change made the truck very modern road friendly with those relatively simple upgrades. I still run 17 inch bias plies. But even here in NE Alabama, I have to down shift to make it up the mountain (State Highway 79 in Skyline) or risk blowing a head gasket ... again ...

I didn't want the OP to think he was being ignored, so I just gave him some info about different gears and tire diameter. Certainly a world of difference between his truck and mine but I figured some info is better than no answer.

John, not to nitpick, but didn't Charlie originally have a 4.56 ratio, not 5.56?
Jerry

Roger that!! Thanks!



Jerry --- You're probably right. I may have been thinking the 4400 axle gearing ... Or heck, even the 359 Pete's ... All I know is that in pure stock configuration, my 3804 could get to 55 mph, but it took most of the morning to do so and any kind of a headwind, bump or the slightest uphill grade would slow it on back to 45. Making it tedious in traffic and absolutely not capable of highway or long distance travel.

The simple upgrade of the rear axle 3rd member (4.11 gear set) was still too tall for the 216. Adding the 261 took Charlie a lot of places he'd never been before, mainly off the trailer and into the left lane -- From Trailer Queen to Road Warrior!!

Hmmm- - - - -sounds a lot like my first job pushing a big rig- - - -a 1964 Freightliner cabover with a 8V71 Detroit and a Road Ranger 10 speed. Don't even whisper "hill"- - - - -it would slow down 10 MPH!
Jerry

The mid '70's GMC with the DD 8V71 and 10 speed that I drove could do an ok job, I was loaded at 80,000 every night from Columbus to Ann Arbor, didn't seem to matter if it was Budweiser or Michelob Light, the light beer seemed to be just as heavy as the full strength Bud. Truck only had 500 or 600 thousand miles on it so maybe it was fresh enough to run, prior driver did have the wick turned up a little and it would run 3100 - 3200 rpm.

That's right on the ragged edge of hand grenade territory for an 8V71- - - - -factory spec governed speed was around 2150-2300.
Jerry