Recently picked up a 49 shoebox, V8 with overdrive, my question is . . . is it ok to drive with the overdrive in all the time? Or was it to be used for highway cruising? Just curious. . . thanks! josh
If OD cable is in, no clutch needed for shifting at low speeds. 2nd over is the most flexible gear you could ask for. Just remember to disengage the OD when parking.
Putting it in reverse will disengage it without pulling the cable out. There's a ton of good OD info here. Search.
You lose your engine braking capability on down shifts when OD is engaged. Might as well get an automatic if switching in and out of OD is a hassle.
Back in the day, in town speeds were slower and some people would drive in town with the overdrive cable out-disengaged-so you would have compression braking in stop and go traffic. With modern traffic speeds, this probably is more for residential use, as the larger streets are into the 30mph plus which would let you use the overdrive more than occationally (2nd overdrive and underdrive--like 302GMC said). The stock 4.11 gears are made for less than todays interstate highway (freeway) speeds when you run the stock flathead V8. In Colorado the 4.11's are nice, I bet.
thanks for the info fellas, I did search but did not come up with my answer. it is no hassle at all to disengage it, I just didnt know if I was doing any damage DRIVING it in OD all the time. I put it in reverse when I park it all the time and evidently that disengages it when parked. THANKS FELLAS!! josh
The freewheeling unit is a large one way clutch sprag unit. It will only free wheel going forward. When a person is breaking in a new motor, it's not a bad idea to run with standard drive for the first 500 miles or so. This gets the valves to seat in better but it can be hard on the old fiber cam gears. If your in hilly country where you need the motor to help you brake its a good idea to disengage the OD.
I know this is an old thread but I too have just recently acquired a 51 shoebox with OD and am curious about it. The OD "T" lever has been "In" (pushed in towards the dash) since I bought the car and been driving it like that ever since. Is the "In" position "On"? I was under the impression that pulling it would engage the OD, haven't tried pulling it yet as I've been sketched out that I am going to break something, wasn't sure when I could engage it. Thanks
Cable in is "overdrive engaged". DON'T pull it out unless you are STOPPED or you could damage the overdrive. If you are driving with the cable out, you can push it in to engage the overdrive. If the cable hasn't been used for a long time it might be stuck or very stiff so it's a good idea to get it loose and operating smoothly or get a new one. Check where the cable attatches to the lever on the transmission and make sure it pushes the lever far enough to completely engage the overdrive. When you park the car, shift to reverse and that will disengage the (free wheeling) overdrive, and set the parking brake for good measure. A new separate reproduction overdrive wiring harness is relatively inexpensive and can save some headaches if you have old frayed wiring. Solenoids can be expensive to replace and relays also. I have converted Bosch relays to work and the are cheap and reliable. Here's a wiring diagram for the Bosch relay, and you can put it in an original housing to hide it.
Thanks! I talked to a few people about this and was actually able to test it out on the road and it seems to work. I haven't disengaged it since i bought the car. I've just left it in. I get it up to about 30 mph, let off the gas and then accelerate a bit and I can feel it engage, the RPMS go down and the car feels more comfortable at higher speeds. Anything over 60 mph though does feel like I'm pushing it too hard. I'm contemplating throwing a t5 in it as I've heard it transforms the flatty into something I can really take anywhere. I appreciate the advice!
5th gear in a T5 isn't going to feel any different than third gear in overdrive with your current setup.
Yes, you need taller rear end gears. I had a 57 Chevy rear in my Model A with 3.55 gears which gave me a nice cruising speed and kept the flathead RPMs down. The old Ford overdrive rear gears were 4.11, I believe.
The original rearend would be a 4.11, the OD ratio is .70 approx. So effective ratio in high OD is 2.87. Any higher than that and the flattie won't handle it. I've had several ODs over the past years. All would run faster in second/OD than in third OD. RPM just too low to generate max power. That's why almost all OD equipped cars have 4.10 or 4.11. Repeating what was mentioned above, second OD with the auto up/down shift is a very useful gear in traffic.
The Jalopy Journal
