Hydraulic Shifter Prototype Th400

S3700029So i had this idea,”i wonder if we could get rid of the shifter”. so i proceeded to go through my books and chart the flow through the housing and before long i had the blueprint for the adapter plate that you see here.

Basically, on a 1st/reverse only transmission, you basically have 3 components getting oil in the valve body since we are not worried about shift: the rear servo to hold the reaction carrier in reverse and low 1, the forward clutch pack, and the direct clutch pack which gives you reverse. i reasoned that basically we could use a hydraulic valve to make the clutch packs shift direct from line pressure. this would eliminate the valve body, mid plate, and mechanical shifter entirely so there is no more tail mounted shifters and holes in the floorboard.

so i started my taking a 1/4 inch plate and fabricating it to the valve body. i then tapped and installed 4 1/8″ pipe fittings so they lined up in the passages of the case. these were line pressure(pump supply psi), reverse oil port, forward clutch port, and rear servo port. i then plumbed a hard line from rear servo to the line psi port so whenever the engine is running, line psi is applied to the servo to maintain the gearset in a locked low 1/reverse orientation. this leaves 3 ports: forward, reverse, and pump.

now, what next? i need a hydraulic control valve. my first thought was a valve off a log splitter so you can still get that slam shift effect, but the plumbing is all wrong. you see a common valve is open center and locks psi to the work ports when in neutral. our clutch packs once disengaged must release psi to sump to release the clutch pack. unlike on a cylinder of a log splitter we have springs to return the clutch pack to home position. i considered using multiple valves- but ended up on a control valve used for a hydraulic motor-which allows the work ports to bleed to the tank(or in this case the oil pan is our supply tank). the prince number for the closed center valve is RD2575M4EDA1. in it’s original use like on a conveyer belt or a stump grinder, when you shift it to neutral the hydraulic motor cannot come to a dead stop so it allows it to spin and bleed psi to the sump. in this case i would be using the float position to bleed clutch pack psi and allow for neutral.the line/pump pressure is also is blocked off on this valve due to being closed center, which is necessary so we don’t disable the other circuits within the tranny that feed the converter and oil cooler. pressure relief is a non issue as there is still the psi regulator in the tranny maintaining psi at 150-225psi.

Are you confused yet? here let me simplify it for ya now. basically what we sould be doing is getting rid of the stock tail housing shifter and rod entirely and replacing it with a hydraulic valve for shifting- eliminating the need for a floor shifter of any kind. you would mount the valve on the cage and run the hydraulic lines through the firewall and down to the tranny- and there would be 4 signal lines. i believe i would need a custom oil pan and plumb the lines oil the passenger side of the pan to the valve.

would it work? hell yes it would work. will i be building it…..no. the plate and fittings you see in the photo is about all i am willing to develop for a multitude of reasons. it’s going to take time and money to get a finished product developed and producing several could be a nightmare. if someone could mass produce these…….THEN you have to deal with chicken shit promoters who will make it illegal cause everyone will bitch about it to em at the derby til they do make it illegal. THEN you also have to consider everyone and their brother who build the best shifters on the planet bitching to officials and promoters to make it illegal because it cuts into their profit. And finally, i really thought it was a bit overkill for what you would end up with.

So piss on it, i packaged it up with the blueprint i had drawn up and its in a place gathering dust til hell freezes over. But since i decided to abandon it, i figured i would share the idea with you guys to show you what is possible.

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