greg g Posted March 16, 2021 Report Share Posted March 16, 2021 (edited) If you listen you can hear the sweet spot is between 45 and 55, but 60 is doable and on the blue roads just about right.l just re read or post and noticed you have OD! That changes a lot. The OD will drop cruising rpm in high gear to about 2400. So if you use it when you get to 45to 65, except for you brake pull you should be golden, you gas mileage will also go up to 19 to 20 over the road. It makes a big difference out on the road.makes it quieter and gives you piece of mind with the rpms reduced. Some folks use theirs in the city splitting second gear instead of all the shifting. BIG NOTE, do not reverse with OD engaged, and he OD will freewheel under 30 mph when on. So under 30 you get no compression braking. Some say they can shift into low gear when the OD is feewheeling as it stops the input shaft from turning so it acts like a 1st gear synchro. Hope we can ride along with you through pictures more posts to this thread as you make your way South. Like a through the windshield daily journal. Give you something to do before hitting the sheets. Edited March 16, 2021 by greg g Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted March 16, 2021 Report Share Posted March 16, 2021 (edited) Yes, the piston speed calculator I posted is mean (average) piston speed. Max piston speed will be higher at mid-stroke. This is a little too technical for our flatties but is probably useful for establishing reasonable guidelines. In other words.......don't push these engines beyond what they were designed for if you want long, reliable service life. Speed limits were customarily 45-50mph in the late-1940's---my '48 P15 (no overdrive, 3.91) is in it's sweet spot at 55mph. That's about all the brakes I have, too. ? Edited March 16, 2021 by Sam Buchanan 4 Quote Link to comment Share on other sites More sharing options...
meezy Posted March 16, 2021 Author Report Share Posted March 16, 2021 1 hour ago, greg g said: If you listen you can hear the sweet spot is between 45 and 55, but 60 is doable and on the blue roads just about right.l just re read or post and noticed you have OD! That changes a lot. The OD will drop cruising rpm in high gear to about 2400. So if you use it when you get to 45to 65, except for you brake pull you should be golden, you gas mileage will also go up to 19 to 20 over the road. It makes a big difference out on the road.makes it quieter and gives you piece of mind with the rpms reduced. Some folks use theirs in the city splitting second gear instead of all the shifting. BIG NOTE, do not reverse with OD engaged, and he OD will freewheel under 30 mph when on. So under 30 you get no compression braking. Some say they can shift into low gear when the OD is feewheeling as it stops the input shaft from turning so it acts like a 1st gear synchro. Hope we can ride along with you through pictures more posts to this thread as you make your way South. Like a through the windshield daily journal. Give you something to do before hitting the sheets. I'd heard the same thing about reverse in O/D... but George Asche said it was fine to do it and I found this image somewhere... what are your thoughts on that? Quote Link to comment Share on other sites More sharing options...
greg g Posted March 16, 2021 Report Share Posted March 16, 2021 Yeah, George took two I got to make one. Apparently my reverse hold out doesn't work correctly as it makes funny noises if I don't remember to pull the cable out when I park in the garage and try to reverse out the next time. I don't trust it. 1 Quote Link to comment Share on other sites More sharing options...
Adam H P15 D30 Posted March 16, 2021 Report Share Posted March 16, 2021 (edited) Just another tidbit of info, When I had my flathead Ferd with an R11 OD, I would stop and pull the OD lockout (OD off) when going over mountain passes. I cooked the brakes once coming down a pass in the Sierras before I learned that valuable lesson. They freewheel as you probably know... Edited March 16, 2021 by Adam H P15 D30 Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 16, 2021 Report Share Posted March 16, 2021 3 hours ago, Sam Buchanan said: That's about all the brakes I have, too. This right here is the key factor. Doesn't matter how fast you can go if you can't choose how you stop. 2 Quote Link to comment Share on other sites More sharing options...
greg g Posted March 16, 2021 Report Share Posted March 16, 2021 My car has semi anti lock brakes. No matter how hard I stomp they can't lock up the tires on dry pavement. In the wet yes and on gravel but not on concrete or tarmac. 1 Quote Link to comment Share on other sites More sharing options...
meezy Posted March 16, 2021 Author Report Share Posted March 16, 2021 5 hours ago, Adam H P15 D30 said: Just another tidbit of info, When I had my flathead Ferd with an R11 OD, I would stop and pull the OD lockout (OD off) when going over mountain passes. I cooked the brakes once coming down a pass in the Sierras before I learned that valuable lesson. They freewheel as you probably know... Not above 23 mph in mine. You can engine-brake downhill for sure! Quote Link to comment Share on other sites More sharing options...
Adam H P15 D30 Posted March 16, 2021 Report Share Posted March 16, 2021 7 minutes ago, meezy said: Not above 23 mph in mine. You can engine-brake downhill for sure! Out of OD but handle pushed in, mine freewheeled. Not sure you would want to be in OD going up and down mountain passes 1 Quote Link to comment Share on other sites More sharing options...
meezy Posted March 17, 2021 Author Report Share Posted March 17, 2021 43 minutes ago, Adam H P15 D30 said: Out of OD but handle pushed in, mine freewheeled. Not sure you would want to be in OD going up and down mountain passes Ah - yeah. Point taken. Quote Link to comment Share on other sites More sharing options...
meezy Posted March 17, 2021 Author Report Share Posted March 17, 2021 22 hours ago, michaelmarks697@yahoo.com said: What about the car train to Sanford Fl? Wow - I'd never heard of that. Interesting option! Thanks. Quote Link to comment Share on other sites More sharing options...
meezy Posted March 17, 2021 Author Report Share Posted March 17, 2021 9 hours ago, greg g said: If you listen you can hear the sweet spot is between 45 and 55, but 60 is doable and on the blue roads just about right.l just re read or post and noticed you have OD! That changes a lot. The OD will drop cruising rpm in high gear to about 2400. So if you use it when you get to 45to 65, except for you brake pull you should be golden, you gas mileage will also go up to 19 to 20 over the road. It makes a big difference out on the road.makes it quieter and gives you piece of mind with the rpms reduced. Some folks use theirs in the city splitting second gear instead of all the shifting. BIG NOTE, do not reverse with OD engaged, and he OD will freewheel under 30 mph when on. So under 30 you get no compression braking. Some say they can shift into low gear when the OD is feewheeling as it stops the input shaft from turning so it acts like a 1st gear synchro. Hope we can ride along with you through pictures more posts to this thread as you make your way South. Like a through the windshield daily journal. Give you something to do before hitting the sheets. I'm not much for "blogging" - but I'll def post some pics and may damn well appeal to this very thread in a breakdown somewhere in Appalachia! Thanks for your response. Good info. Quote Link to comment Share on other sites More sharing options...
Booger Posted March 17, 2021 Report Share Posted March 17, 2021 2 hours ago, meezy said: Wow - I'd never heard of that. Interesting option! Thanks. those trains head north every spring with thousands of snow birds and their cars, so they have to "deadhead" back. Call Amtrak might get a great deal Quote Link to comment Share on other sites More sharing options...
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