There's an unrestored Fuller O/D unit nearby still mounted to the rear axle. Is it any good for a TT with Ruckstell? Other than the bolt-on unit at the axle, what other parts were needed (lever, shorter drive tube?). Thanks!
There were many different manufacturers of over and/or under drive units for model T and TT vehicles. Some of those manufacturers made several different models or offered different gear ratios in similar models.
I am not familiar with any units under the Fuller name.
Overdrives can range from a low of about 15 percent over clear up to one I had was more than 60 percent over. One turn in from the engine resulted in nearly 1.7 turns out to the pinion gear. It was used in a boat-tail speedster with a 4 to 1 rear end ratio and worked very well. There are also some units (like the Moore) that were generally intended to be used as an underdrive with a ratio of 2 to 1 that can be assembled backwards resulting in a 1 to 2 overdrive. I have heard of this being done, but have no first-hand experience with one to know how well it worked.
I had a Universal overdrive unit in a TT I used to have. It had an about 5 to 7 ratio and worked very well in that TT (with a 5.2 to 1 rear end ratio). I could cruise at 40 mph pretty much all day.
I love my auxiliary transmissions in my model Ts, both cars and trucks. (I don't use them in brass era Ts) If that Fuller is in good condition, and was made for a T or specifically a TT, it should be a wonderful thing to have on a TT you want to drive. Whether you also have a Ruckstell or not, really doesn't matter. Unless you plan to load your TT up with a couple thousand pounds of something, you really do not need a Ruckstell in a TT. But they are great to have anyway.
A word of advice. Before you invest any significant time or money into such a transmission? Make sure it IS an overdrive if that is what you want. More of these units were built as underdrives than as overdrives because it was under the heavy loads these trucks were often used for that low gearing was needed more than higher speed gearing. I have known several people with TT and AA trucks that paid good money to buy and install a transmission only to then discover they wound up with another super low gear they really didn't need.
Photos would be nice. Thank you.
Drive carefully, and enjoy, W2
One big advantage of mounting a gearbox in a shortened drive shaft and torque tube is that it alleviates or eliminates the shaft whirl vibrations to which TTs are very prone.
The Fuller (aka Fullford) gets a brief mention in VF 26-2, but it doesn't mention ratios.
The ideal overdrive ratio also depends on which axle ratio you have. If you have the lower 7.25:1 worm, then an overdrive of about 0.6:1 would be good. If you have the 5.17, you might find that 0.75:1 is as high as you can use. Either of these combinations will give you gearing, when the OD is engaged, a little lower than the Model T car's.
There's no reason why you shouldn't have a Ruckstell as well; but I doubt you would need it, and it's all adding friction.
Given a choice, an OD Fullford seems much preferable to a Ruckstell on a TT.
I've got a Fuller sitting on the floor of my shop in FL. It was on my TT when I got it. It used the Ruckstel shifter and was a direct and underdrive that was mounted to the front of the rear end. Could be used as a "poor man's Ruckstel". Do you think maybe it could be installed backward and be direct and overdrive?
Many years ago I had a TT with a Langbein. I was able to swap the internals end for end and make it into an overdrive. Made it very driveable. - John
All that said, what's the EASIEST way to get a few more MPH out of an otherwise stock TT?
Put it on a trailer.
Quite some years ago, a local fella put a standard large drum ('26-7) car axle under his Ton Truck by taking the rear cross member from a car frame and fitting it to the truck frame ahead of the truck cross member. He used the car rear springs in this set-up and, while the wheelbase appeared a bit shorter he had the speed he wanted without the hassle of finding a truck O.D. He had no plans to load the vehicle with any more weight than he would a car and the whole arrangement could be swapped back to the truck rear end if the next owner so chose.
Nothing is easy! IMHO, a high speed ring and worm, then an aux trans should do it for you.
Use larger tires on the rear axel.Bud.
I have Hi-Lo TT transmissions, Lincoln Moore set-ups, Rocky Mountain 6 spd set-ups, all attach to the TT rear ends by the rear end. email@example.com