833 Synchro Rings

A friend (yes Greg, I have those) just pulled apart his 4-speed that wasn't shifting too well and found these brass synchro rings installed in the 2nd and 3rd position. They have the dog teeth machined off; 1st and 4th position are stock.

I've never seen anything like this, I assume it is some form of "slick shift" mod; anybody here seen this? He bought the trans and installed it without removing the side cover for inspection.

I have seen some many years ago with every other tooth removed but none like that.

Any idea what the thinking is there??

The old way of "slick shifting" a trans was to remove every second (or more) of the teeth on both the slider and the gear. But the syncro ring (minus teeth) was still necessary as a spacer. Maybe this was someone's way of doing it "half assed".

I just rebuilt my 18 spline and I was using a “slick shift” 2nd gear with normal syncros. I’ve never seen syncros with no teeth.

Had several of those trannies thru here for rebuilds. They worked pretty good for foot flat on the floor, pull stick hard, touch the clutch for us poor guys that still wanted decent street manners. As long as the gear teeth were sharp it was a cheap way to do it, one less thing to get the slider by. We had a $50 tool set and $5 in our pocket so DC sliders and gears were out, and try doing a nice grind every other tooth out of a slider or gear in your backyard with basic tools. Even with the teeth missing it will get the next gear up to speed.

That's for the guys that don't use the clutch during drag racing shifts, they just "blip" the throttle and bang the next gear.

That was my thinking, they use the toothless ring as a brake to slow the gears at the shift but no synchronizing.

We use a modified ring like that in the 2nd gear position on the Face plated or pro shifted boxes when keeping the 1st gear syncronized.

For some cars with mechanical secondaries that works but 6bbl setups with vacuum pods like to be shifted with your foot flat on the floor. A block under the clutch pedal to limit clutch plate departure, those rings, and a 10w-30 and atf mix in the box would get you right down the street. Gear oil seemed to make it a little harder to do it, straight atf was best, because it is thin and the rings grab the gear better/faster.

Well kinda, I guess with no teeth it could be called semi synchronized. The teeth just give it the last 1/8"or so of alignment/syncronization. When flat footing and shifting hard it goes right in, and has nice street manners as long as your teeth are sharp, the ring friction surface is fresh, and the oil is not too thick.

I'm sure you know the two end carbs on the six pack are closed by the two little rods attached to the center carb as soon as the center carb is closed. They are opened slowly by vacuum but closed instantly by the return spring when the throttle is released.

Yes I know, that is why they do not respond well to blipping the throttle. The return spring starts the closing, but the air velocity and vacuum thru the carb is what actually closes a carb, that us why the blades should never open a full 90 degrees, bad sheet will happen without a barndoor spring.

I hope you're joking with that statement. The throttle return spring closes the carb, not air velocity and vacuum. Air velocity and vacuum is what draws fuel through the boosters. When you let off the throttle the carb has to close immediately or you'll end up in an accident with the car in front of you.

Godscountry 340 is correct. It is Vacuum opening and manual linkage closing. Any release of the pedal closed all 3 the same amount instantly.
Any other way would be crashing the vehicle.

You can go out to the car with engine off and open and close carbs and see it for yourself.

The vacuum/ air velocity is at play as the blades close, if you do not believe it drive 70 down the highway, stick your hand out the window flat, then turn it 90 degrees. Let me know what happens, same principle. The throttle shaft bore is offset like .030 from the throttle plate bore so there is always a slight pull to close it, and keep it from slamming wide open. A 6bbl with vac pods will never open or close instantly. If I start my 6bbl there is enough play in the linkage that you can slightly open the 2 end carbs, not move the center carb and spring, and magically it returns to idle, all while running, I could care less what It does when the engine is off. It has to be the vacuum acting on the .030 offset of the throttle blades that creates more force to close than open. I could be all wrong here.

Those were sold by Mr.Gasket back in the day and you are correct they were used top slow down the gear for easier shifting when the gears were "slicked-up". I used to have a set for a Muncie in a bubble pack distributed by Speed Industries from Medina Ohio but made by Mr.Gasket.
Don't know why they put them in the transmission you are working on. That thing must have shifted like crap at any speed.

Gus