MTFCA Forum

Bought a mark e at Hershey last yr. Finally got around to putting it in this week. Under engagement is good and deep, direct is good and deep, over is not. Only about half way. I noticed that the shift rod for over has two detent notches. Why is this?

Vic Salla, Speedster/Racer Hall of Famer, preferred the Chicago transmission over all the others. Jumbo Giant, Muncie, Warford? Vic wanted the Chicago. And he bought a lot of them. Unfortunately, a lot of the ones he bought turned out to be junk, and he and I discussed that a bit. I had one, a really beat up totally toasted mess, that someone else had given me. So, out of curiosity, I took it apart and played with it a bit.
My understanding is, that there were a couple different series Chicago transmissions. They look alike from the outside, but are assembled differently, and they have different problems. I also understand that some of the internal parts do not interchange between the different units.
But that is what I have been TOLD! I do not know that for a fact?

What I did find out from playing with the one I have, and doing some reverse engineering, is that the version I have MUST be assembled by someone that knows and understands the thing! I found out why so many of them are junk! IF (big IF) they are assembled incorrectly, the transmission WILL eat itself alive in a very short time! There is nothing that automatically positions the input or output gears for proper alignment to the lower cluster gears. Even worse, there is no pilot shaft or bushing or guide of any kind between the input and output shafts! The entire input/output assembly is held together by three tapered roller bearings that MUST be perfectly adjusted and positioned and maybe shimmed to align the gears properly.
The input shaft tapered roller bearing pushes the input shaft into the case from the front. The output shaft tapered roller bearing pushes the output shaft in from the rear. And the third tapered roller bearing pushes the two shafts apart and holds the position between the front and rear!
Part of the flaw in this design is that if the preload on the three bearings is too tight? Like a wheel bearing, it will chew itself to pieces, only much faster due to three times the rpm of the wheel bearings! On the other hand, If the preload on those bearings is too loose? Even by only a couple thousandths of an inch? That tiny amount of looseness under the torque of the drive line will force the gears offsides, resulting in the gear alignment becoming crooked. That, in turn, causes the gears to chew themselves up, as well as the bearings, which in turn quickly loosens things even more and in turn again causes gears and bearings to chew each other up even faster!
In addition to those issues, the front to back placement of the gears can actually be put in the wrong place by as much as a quarter inch either direction. This would result in the gears not lining up properly. And it would also result in your questionable shifting depth.

Vic liked the Chicago, because for his driving, they shifted faster and better than did any of the other common after-market auxiliary overdrive transmissions for model Ts. I think Vic knew how to set them up right. He alluded to that in some of our conversations. The problem was, that way too many of the ones he bought had already been ruined by previous people that thought guessing was good enough. Once he got them apart, he found the parts didn't meet his high standards. In his later years, finding good ones became very difficult.

Check the assembly of yours very closely! Make sure all the bearings and gears line up like they need to! And be very careful with the bearing preload in the upper shafts.
And no, I do not have any magic numbers to advise.

I did a search and found a post from clayton. It looks my my set up. If you look close it is a very short engagement when Gear 2 goes around of gear 1 in high. Its basically half the engagement of the other two gears. The notch in the shift rod would also point to it being correct. If anybody has a chicago ou there, does your high hear engage as deep as low and direct? Thanks.

Thanks for the Information Wayne. I have a chicago Mark E(not installed) I guess I should take the top off and inspect it just too see what I have going on inside.

Tim