dgrinnan Posted February 3, 2023 Report Share Posted February 3, 2023 I have seen different people post different speeds they cruise at in their stock trucks. I have an original 218 (recently bored to .040) with an original 3 speed transmission and the original rear end in my 1947 WC. Based on your experience, what is a comfortable sustainable cruising speed without running at extreme RPMs? Quote Link to comment Share on other sites More sharing options...
kencombs Posted February 4, 2023 Report Share Posted February 4, 2023 (edited) Not knowing the actual rear end ratio but guessing 4.10 or lower, 50-55 would be comfortable for you and it. Edited February 4, 2023 by kencombs Quote Link to comment Share on other sites More sharing options...
1949 Wraith Posted February 4, 2023 Report Share Posted February 4, 2023 Tire diameter also effects rpms. But if you are running close to stock tires 50- 55 is a nice cruise in my '42. Suprisingly there is more there if you need it, but we are driving on 80 year old brake technology. Quote Link to comment Share on other sites More sharing options...
PT81PlymouthPickup Posted February 4, 2023 Report Share Posted February 4, 2023 Tall 16" tires and a 3.90 differential with standard trans I had her up to 70 mph. The flathead six sounded like she was ready to blow up. Stay off the interstates! Lols! Quote Link to comment Share on other sites More sharing options...
moparfun Posted February 4, 2023 Report Share Posted February 4, 2023 Just went through a rear axle re-gear for the same reason (it didn't like highway speeds). The 50 had a 3.91 carrier I found a 3.54 carrier, swapped it out and am very happy with the outcome now able to run with traffic and not taxing the motor at all Quote Link to comment Share on other sites More sharing options...
Young Ed Posted February 4, 2023 Report Share Posted February 4, 2023 Personally I've found I run out of nerve before I run out of engine. At least mine with tall radials starts to feel top heavy around 55-60. I have a 218 stock trans and a 3.90 1 Quote Link to comment Share on other sites More sharing options...
PT81PlymouthPickup Posted February 5, 2023 Report Share Posted February 5, 2023 23 hours ago, 1949 Wraith said: Tire diameter also effects rpms. But if you are running close to stock tires 50- 55 is a nice cruise in my '42. Suprisingly there is more there if you need it, but we are driving on 80 year old brake technology. Yeah! And even with upgrades to brakes, gear ratios, and tires, which I've done, it's still a bit risky driving these old trucks at modern highway speeds. Like Young Ed indicated; how much nerve do you have? Lols! I suspect also that my truck might be easily rolled over in a high speed mishap? My 39 has the earlier design door latches which were noted for flinging open in accidents where the driver is thrown out, usually under the wreck. I try to stay off the major roads as much as possible. On the other hand, at my age, it might be a better way to go than ending up in some nursing home. Lols! 1 1 Quote Link to comment Share on other sites More sharing options...
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