I have a Chicago Mark E tranny mounted in a 27 coupe. Works great in over & under drive( yes, noisy in overdrive). Only problem is it will slip in to neutral when I am driving in Model T direct. anyone know of any adjustment to correct this? Thanks
I bet Clayton Paddison would have an idea. He knows the Chicago transmission well.
Speedster/racer "Hall-of-Fame"r, the late great Vic Sala liked the Chicago transmission over all other similar Warford, Muncie, and Jumbo Giant transmissions. A good Chicago will shift better and easier and run quieter than the others.
Unfortunately, anymore at least, really good Chicago transmissions are hard to come by. They have a weakness in their design that makes adjustment of the upper shaft, gears, and bearings critical. If run too long, with all that not properly adjusted? They will wear crooked, and ruin the gears.
The design flaw is that there is no real pilot shaft or bushing between the input and output shafts. Instead, they have three tapered roller bearings (like later model T front wheel bearings) that press in together from adjustments on both the front and back in the case.
The good thing about this arrangement, is that it gives you the ability to properly "best center" all the gears to run at their best. The bad thing is, that not everyone ever always adjusted it properly. Then trouble follows.
The first step, is to carefully remove the top-cover/shift-tower. Check to see how well lined up the gears are, and how far engaged the direct connects (relative to exactly where the shifting forks hold it). Provided that all the gears look good? And it hasn't been run too much in poor adjustment? A simple adjustment may fix it right up. Also check to make sure that the detents are working properly to hold it in gear. Detents often become gummy, or worn out, or detent springs collapse or break. Any of those problems will allow a transmission to jump out of one or more gear positions.
Unfortunately, the proper adjustment of a Chicago transmission is fairly easy???? However, explaining it is not. And I have never seen any good written instructions.
Basically, once the lower/cluster gear is properly installed, you must assemble the upper shafts and bearings and gears in proper spacing and adjust the entire assembly forward and back lining up all the various upper and lower gears to run and hold at their best. You must also check the direct engagement to work with the shift tower's detents. Some minor shimming may be necessary (or even some grinding and fitting of the middle bearing).
Once the upper shaft is placed and lined up exactly where everything needs to be? The input and output bearings are adjusted by use of a large (almost three inch diameter) threaded ring threaded into the case. There are hole in the ring to drive it looser or tighter. There is also a slit in the threaded portion of the ring with set screws to skew the ring and lock it in place. Some of all that is fairly easy to figure out, but difficult to explain.
The input end must push in from the front enough, and the output must push in from the back enough, to put heavy pressure on the center bearing. Two adjustments that must apply pressure, or pre-load, to three different bearings.
Without the proper pre-load on those bearings? The torque under load pushes the upper gears over to one side a little. That causes rapid wear, and can turn a Chicago into junk quickly.
So check it out. Hopefully, with a little work? You can get a good usable transmission out of it.
And ask more questions here.
Drive carefully, and enjoy, W2
I am curious, my Chicago has a U- joint at the front of transmission. It has never came out of gear. It has never been completely disassembled after being removed from a home built tractor with another transmission behind it. I guessed at the pre load and now wonder if the U joint helped keep the transmission alignment better without the side thrust of not having that design of U joint.
I can post pics just like Clayton can as I have mine torn apart except for the main shaft in the bottom. I'm still trying to figure out how it comes out.
Yes , Jerome would appreciate pics.
Thanks Wayne , good info.