Almost always a person with a T question can find the subject previously discussed on this forum. I tried to find the Ruckstell gear ratios for a TT and found the question asked a few times but no answer other then "really slow". There is information on the standard T ratios but none on a TT. So I made a chart. Comments/corrections are welcome.
Good Lawd no wonder you need an auxiliary tranny in a TT! Max out at 29 mph, sheesh. I would think since no one is really hauling many significant loads with a TT, a set of "cruising" gears for the rear end would be most helpful. Maybe something where high Ford would give you 4 or at most 4.5 to 1. Would make touring in a TT a lot easier. Then Ruckstell would give you 6.4 to 1, plenty easy to make it up any hill in high Ford with that. Of course if you had 4-1 with a Warford or other aux, you could scoot on down the road in OD. When I'm a gozillionaire I will manufacture parts like this on a whim and make them readily available to the T(T) crowd. =)
Would a Muncie overdrive at about 3-1 (I dunno what a Muncie overdrive has?) give me a resulting 4-1 overall with TT high speed gears of 5 1/6-1?
Keep the calculations coming.
do we need to start an excel spreadsheet with all these calculations?
Actually, with standard 7.25:1 gearing, a speed of not more than 15 mph was recommended, and with 5.17:1 gearing, a speed of not more than 22 mph was recommended, according to Ford Dealers Data Book 1923.
It's silly, but in another thread Tom Lovejoy posted pictures of his this TT with its "new" Rocky Mountain Six Speed which made me think. How many combinations and what top speed if you put a Ruckstell behind it and a Muncie (or similar) ahead of it?
We do need a spreadsheet! And of course, we'd need two spreadsheets, one for 5.17:1 and one for 7.25:1 rear end gears.
You would need a 0.77:1 (1:1.29 is the same) overdrive to get a 5 1/6:1 ratio to 4:1.
There is a bunch of good overdrive info at:
Fords recommended speeds of 15 and 22 mph would limiting the engine to less then 1200rpm. Maybe a prudent recommendation but I bet not many were actually held to that speed. At least with todays roads, maybe a little higher speed would be reasonable. If a standard T was limited to that rpm then the top speed would be 28 mph.
Thought it would be a good place to add this one. I've never come across this unit, but looks like a neat one.
So it looks like from that other thread at:
that my Muncie overdrive at 0.717 is lower than the 0.77 you calculated to get my rear end down below 4:1