As a bit of visual reference I drew a graph of 3 different Toploader ratios with my specific wheel/tire combo and axle ratio. This is for the existing close ratio 3 speed, and the two overdrive toploaders. This was just to see how bad the gaps are between gears.
that chart is rather dated, eh? mid 70s-late 80s when 55 mph was a thing. And before overdrive became common
Because I was terrible at math, I use this: https://spicerparts.com/calculators/engine-rpm-calculator
I like to see what the RPM drop will be when shifting. Basically comparing what I have now to what I'm planning on installing (car unit OD). The truck OD has an even worse gap between 2nd and 3rd.
Hotrods and overdrive isn't traditional....My 34 came stock with a 4.10 gear as did street hemi cars of the 60's did to....
Of course it did. My ‘38 Buick is 4.40. Weezer engines and hilly, curvy roads, some dirt, most cars drove around under 40 mph. Low rear gears minimized constant shifting. OD’s gained in popularity as roads improved and so did automobiles. Ray
My avatar 1927 Dodge Brothers had a 4.56 and a lot of road clearance for muddy roads In the 50's if overdrive was more readily available I'm sure it would have been a hot rod item. We had a club member with a 40 Ford with 4.44 gears that was almost useless. OD would have been a blessing.
What about Charlie Ryan's song "hot rod Lincoln" released in 1955? It was a Model A with a Lincoln motor, got 12 cylinders and uses 'em all! And man alive....shoved in down into overdrive. The song was later released in 1960 and 12 cylinders was changed to 8.
that's exactly what I was thinking... but then I realized it's a song, it's not a real hot rod, is it?
The B-W overdrive was available since the '30s, and virtually every manufacturer offered it at one time or another. Ford used the Columbia two-speed rear axle through '48, then switched to the B-W OD in '49 after converting to open driveline. Studebaker, Nash, Hudson and Ford sold literally millions of cars equipped with B-W overdrives. But by the late '50s their popularity had waned as automatics became more popular and by the mid-'60s demand was low and they were dropped from the option lists. The last OEM installs were Ford PU trucks in '72 (and very rarely seen). And they were definitely used in factory 'performance' applications before GM's exclusive use contract on the T10 expired in '61. As to the OP's dilemma, it might be useful to think about the gear spreads in percentages. The OEM OD trans offered in '60 (I'm assuming it's the same or very close to the '59) behind the 352 featured 63% spreads between 1-2 and 2-3, 70% between 3-4. In other words, engine speed dropped to 63% of the previous gear then 70% in OD. The Y-block was similar at 60%, 70%, then 70%. Typical rear axle ratios were 3.89 for a final ratio of 2.72 in OD. The existing three-speed he has is pretty close to OEM; it's got 67% between 1-2 and 62% between 2-3. The OD units are considerably different; the car unit has 56%, 55% , and 81% OD. Fairly even between 1-2 and 2-3. The truck unit has 59% 1-2 (closer to 63) but 52% 2-4 and 78% OD. Now where it gets interesting is comparing 'final' drive ratios in each gear. In other words, a 2.49 first and 3.89 rear equals a 9.49 'final' ratio. When you do the math, you get this.... OEM Ford B-W OD, 3.89 rear. 1st 9.49, 2nd 6.06, 3rd 3.89, OD 2.72. Ford car toploader OD, 2.91 rear. 1st 9.54, 2nd 5.32, 3rd 2.91, OD 2.36. Ford trk toploader OD, 2.91 rear. 1st 9.45, 2nd 5.58, 3rd 2.91, OD 2.26. First gears are all about the same, and the nod IMO goes to the truck trans for second gear. The problem here is the OD ratios will be useless at any road speed below 60 mph and marginal until about 70 unless the OP lives somewhere where it's dead flat. I've been eying a TKO for my '60 Ford and have called a couple of vendors for their advice and the one thing they've all been consistent on you need to be at 2K+ RPM to really make it useful. I've got OD manual trans in both of my DD and below 60 MPH the OD just doesn't work around here as I'm below that threshold. If you swap to a 3.25 rear ratio, the numbers get better. More expense, but more drivable. Ford car toploader OD, 3.25 rear. 1st 10.66, 2nd 5.97, 3rd 3.25, OD 2.63. Ford trk toploader OD, 3.25 rear. 1st 10.56, 2nd 6.24, 3rd 3.25, OD 2.53. About a 260 RPM gain, just enough to tip into the 'useful' range. The car will be very 'lively' in 1st and 2nd.... Anyway, food for thought....
Squirrel : It IS a real Hot-Rod : There's even a thread about it on here, along with a story about the restoration.
The reason I graphed it was to see how the 0.81 OD compares with the 1:1 third and the 2.91 axle with small wheel/tire. I find it quite favorable, 2,000 RPM at 66 MPH is very conservative is think. Heck my NA 4 banger late model car is 2000 at 65. My 225HP 4.6 Ford van is 2000 at 70mph.
Absolutely and the RPM optimal band too. As compared to modern off topic veehickels, those 55 mph RPMs be high. But for my 318 there most likely bang on..
My 87 year old Mother informed me many a teenager drove way faster in the early 50s than we think. She mentioned being in a 50s Oldsmobile with a neighbour kid doing a 100 mph. She was quite scared....lol On the 40 mph stuff she said my Grandfather drove like that...lol
This is super easy to recreate in Excel. You could enter any transmission gear ratios, tire sizes and auto generate the graph for as few or as many mph points as you want.
The Jalopy Journal
