Monthly Archives: November 2013

Electric Valve Body Prototype



old design for 1st/reverse only

line pressure constant to the rear band then control psi to the direct and forward clutch assemblies . maintain direct/reverse clutch bleed to apply via a controlled orifice in the set crew in the center support. forward is un-metered. the valve to do the job was tentatively found and available for 150 bucks. system pressure still dictated by front pump modifications and at this point not impede system opressure to cooler or converter/lube circuits.

1/2 inch steel plate with 1/4″ pipe tapping will replace the valve body with 4 lines to a hydraulic control valve. this would be line in-forward-reverse-and bleed to sump. open center valve. this would work to eliminate shifter but leave 4 hydraulic lines….actually 6 hydraulic lines to rupture causing not only a routing issue but a safety hazzard.

it was built never finished. wasn’t right. new design concept:

i need electric over hydraulic.  base design using 4L60 or 4L80 technology is more desireable. accessable parts and solenoids. i think we can keep the constant flow to the rear band for 1st/reverse hold and use the two prong plug off the older th400 kickdown. one would be used for forward and one for reverse triggering. obviously neutral would be no power but fluid would still flow to the rear band via line pressure. free flow of clutches to sump while line is blocked off completely. this would be better as if i went open center with old design i may lose all system pressure bypassing the regulator feeding everything else to converter-cooler-lubricating. so we need  two triggering solenoids to that both deadhead line psi when not engaged and vent the clutch pack.

basically we are looking at a custom valve body out of aluminum with two spool valves- fed by line pressure and allowed to vent to sump off the clutch pack when dissengaged. each valve would have independent constant pressure from the control line off the regulator. when energized the vent port would close and line pressure sent to that clutch pack. when de-energized a spring would return the valve to vent the clutch fluid as well and block off the line psi to maintain system pressure.

so what we are looking at is two spool valves most likely normally closed to line psi while maintaining vent to the clutches. basic two power wires out the transmission and system is grounded through the case/chassis. when energized it engages a clutch. all shift controlling would be done externally this would cut cost and simplify the routing of wiring to trigger the car.

to prevent multiple clutch lock up we could use an industrial controller which automatically dissengages one power while engaging the other, and leave a toggle switch for neutral next to the two place switch. basically and arming switch. possibly have a solenoid to hit and dissengage park next to the arming switch. either way i think a two place switch is the way to go either forward or reverse no neutral. simplfy the shift and leave neutral or park separate. therefore eliminating false shift

looking at if i am thinking 2 inch thick aluminum with a custom 4-6 inch deep pan. i am thinkin either no filter or a custom filter “sock” of some kind. no paper element.

grove on the line psi side  toward the right of the diagram for supply, then cut the port to the left side supplying fluid to a trigger over the direct-reverse passage and following through to the rear servo. the forward clutch valve/trigger oil/spool is a different story. being at the front i can either run it sideways over the old rooster head manual shift area of replumb it to the rear next to the reverse spool.

here again we leave some kind of solenoid to trigger a park or abandon it all together, which is not an option to me. overall the valve body is only concerned with 1 supply line-1 constant supply while running- and two control ports. if we need a second gear it would be three ports and there is a possibility of using two solenoids both energized to create a 2nd gear shift via spool valving, but it is over complex and unnecessary at this point.

so at this point i have the concept but i need to figure out the valving and the solenoids. we are going with an aluminum plate for the control body for sure. re-examine gm electric tranny stuff i think would be the way to go. if we can find an existing valve to use and simply use one part of both. also could we use i long valve on one solenoid to move it forward after armed and energize solenoid for reverse. forward being the stronger end of the car in failure AND stronger circuit for the most part. even in this design we would need a separate arming solenoid to dissengage the tranny but would be a simple circuit such as a TCC circuit in comparison to the rest. this would leave one valve for machining reducing cost.

if we do two inch thick we can tier the passages, however 1″ with one valve also simplifies cost and machining as well. we have a cost factor. so we do a static passage to the rear servo-to supply one valve. no energized we got forward/reverse energized. a second valve would have to vent and deadhead line psi. either we use two control valves of 1 control valve and one arming valve. it would be left up to a cost issue.

the overall goal is a 1 or 2 wire control valve body on the existing design of th400 1st/reverse only. possibly an upgrade for existing trannys.

it appears that the modern solenoids control the oil flow via an internal pintle on the valve on the solenoid to move the main valve to trigger shift. this adds a layer of complexity. we will be looking at an oil tolerant valve from the old design to go into the pan. these exist in an industrial enviroment. engineering two oil circuits to accomplish one goal is ridiculous. i am thinkin two valves-oil tolerant externally to go in the pan, leave the valve body in the air. more research but not abandoned. this is neat!


after a day or research, the older design seems more practical than i thought before for both cost AND perception because it is a visual difference AND mechanical may sell moreso over than an electrical design. i believe i can use a 1/4″/-4an metal braid line with the modified log splitter valve as before. i would use a two piece oil pan with a drop out center plate so i can fab the lines to the steel plate. the original had brass fittings they may be swapped for steel, welded, then faced on a lapping machine for proper seal to the case. omit the oil filter and tap the oil pick up and modify a chevy engine pick-up to weld to the tapped case pump pick-up tube.

the electrical design is not abandoned. i think the proven product and method to do this would be a custom aluminum valve body with milled passages and drilled for two spool valves. a mid plate is a definite in this design to isolate the passages. i would use two solenoids out of a 4L60E. i believe these fire an oil charge at a valve to create shift. i think if i can use an existing valve out of either a 4L60E of 4L80E then mill the aluminum to fit the passages it would be the most cost effective. exhaust each out the top(bottom to sump)/ deadhead pressure when not in use to line. basically two 3-way spool valves. as for an arming switch it would be nice to have a switch to arm the panel and dissengage park. a biondo type solenoid to go in and out of park would be ideal. so when you arm the panel it energizes to dissengage park while arming two switches for forward/reverse. this would require a 3 wire plug though. it would be much simpler to omit the park but it is a liability concern. perhaps a pinion brake with a park pin is a better option or a pin engagement to a nerat yoke.


First/Reverse only Transmissions

First/reverse only is a concept that has been around in demo derby for years and years. i remember walking around in the pits with my dad talking to people back in the 80’s as a kid. they modified their stuff for first/reverse only….or had a transmission shop do it….along with water in the tires……and running all thread instead of wire and chaining the hood. Anyways, when i started out to build a first/reverse only transmission(which started as a wager), i wanted to not only keep it from shifting, but eliminate moving parts. in essence K.I.S.S.(keep it simple…..stuipid).

the actual modification to prevent shift is actually rather simple. you unplug the modulator valve from engine vacuum and disable the governor. modulator valve is low speed shift control. governor drives just like a speedometer off the output shaft.  on both the th350 and th400, line oil pressure from the pump is supplied to the gear drive end of the governor. as road speed increases, weights fly out in a governor action working against supply oil(instead of a spring like an engine governor would work). the faster you go- the more signal oil is let by. this signal oil is then sent to the 1-2 and 2-3 shift valves. the tension of the springs in the valving controls shift point……and the size of the holes in the mid plate control how fast the gear applies.

on a th400, my method for disabling shift is to remove the governor and both supply lines entirely. you then drill and tap the oil supply port at the rear of the valve body which is meant to supply the governor. you leave the signal oil/return port open. this does two things: you line pressure is not lost anywhere in the governor circuit cause it is essentially completely removed. the other is there is no bleeding past of the fluid on any of the valving that may eventually build up and try to trigger a shift. if you are familiar with case drain on a hydraulic system, in essence that’s what it is.

Now, after298116275 the fact i figured out that by simply modifying the governor to stay closed would give you the same effect. contrary to what anyone claims, i had 15-20 transmissions running successfully in events across northern IL before i ran across this modified governor from a builder out west. it does work but it would still have the effect of wanting to shift into 2nd at high speed. here again this was caused by case drain effect. so i discovered people sticking clips into the 2nd gear shift valve. i never did this on anything i built. in fact, i use to modify my pile of old governors and sell em for a few bucks at shows years ago. this still works on th350’s and th400…….just not as effectively as my method. i would say this is about 85% effective whereas the other is 100%.

The other part unique to my 1st/reverse design is locking in the first gear holding member. on any automatic transmission to get gear reduction you have to have one holding member and one driving member to get what is called planetary action. on a th350 it is a piston style holding clutch to the rear of the case. on a th400 it is a rear 3 rib band on the front planetary gearset. a 727 also uses a band if i remember right. anyways,on both the 350/400 transmissions, reverse and 1st gear are the same gear-powerflow. the forward clutch drives first gear, while the forward clutch releases and the direct clutch is engaged to drive in reverse. so i reasoned that by permanently anchoring the holding member you not only eliminate moving parts but ensure the gearset is held. you also reduce friction and strain on your first gear holding sprag.

on th350 transmissions, i tried many different methods of doing this, as well as my friend Jim. it was hit and miss one trans would win derby after derby….the other wouldn’t pull out of the driveway. after a ton of thought i realized what was happening and found the fix, but elected to quit building th350 for demo derby cause i started seeing gearset damage and snapped output shafts. for this reason i quit building th350 for derby specific. i will rebuild one and use the 4L60 center support … can use it for whatever you want after it leaves my shop and it will work!

on a th400, i had much more luck. just find a way to lock the rear servo completely engaged so the the rear band doesn’t dissengage. the picture to the right was my first attempt at figuring this out using a modified rear servo cover and a hommemade adjustment screw. i then removed all the seals and pistons from the bore, plugged the oil ports off, and set the tension on the rear band manually. this didn’t work out at all… sucked royally. so i took a different approach to it entirely.396007827 it happened qute by coincidence i had a GM 8.5 rear end i was setting up in the shop at the same time…..looked at the servo……looked at the shim kit of that rear axle……and that worked. i eventually abandonned the idea of blocking off the oil ports to the rear servo and ended up suing the stock rear servo/accumulator with new seals but both return springs removed. you then use shim washers to shim the piston down in the bore to tension the rear band. HOWEVER, i also discovered this is an adjustable thickness of shim. there are 3 different pins used on the rear servo all different lengths….and you also have wear to the fron planetary and rear low 1 holding band. i have used a specific washer from lawson products, and on average you use 2-3 washers….sometimes one.

the most successful way to set the rear servo/band tension like this is remove the rear servo…….remove both both springs and seals ….set the accumulator on the bench…..then reassemble it back into the bore. you then stick about two washers under the servo cover and press down to the case. you want the servo cover to barely hover above the aluminum case. if there is a giant gap there it is too much. if there is no gap and you don’t feel the tension on the band……you need more washer/shim. when you get it where you want it, you then install your seals, the inner accumulator, shim washers selected washerand torque it in.

Now, it is very important that you do not overload the rear servo tension. you are suppose to prevent movement moreso that set tension. you are still getting oil flow to it in low 1/rev for holding. what we are doing here is preventing it from dissengaging fully causeing friction/heat. it will still move slightly even when shimmed. if you overtension it, it will warp the case and even screw up how the whole planetary gearset rides in the case/center support. i showed several different people how to build my style 1st/reverse only. pictured here to the right is precisely how not to do it. the 3/8″ washers will float around against the rear servo cover and your apply will jump all over the place. you would be better off just running a stock rear servo set up over this. the yellow spring works out quite well for rear servo return/accumulator springs.

There are numerous other small things i do to my derby transmission builds, and they all kinda work together. first/reverse only in my opinion is somewhat overrated in modern demo derby. with these huge geared rear axles and what not, you almost need more than one gear. and for a wire car it is a bit overkill for what your going for. a properly built stock th400 transmission driven wisely and maintained properly can win any derby, and have. the whole object of going 1st/reverse only or 1-2/reverse manual shift is to add longevity and performance to a transmission for a performance edge


360 Modular Brace for TH400/Mid-Plate Pan Bracing

Years ago i came uS3700012p with the idea of putting in a mid plate between the oil pan and the transmission case. On a th400 aluminum transmission case, they can be prone to breaking at either the rear tail shaft housing or just up from it off of the locating lugs for the rear band. When the shifter is mounted off the back of the case, it becomes a weapon next to you if the rear of the case lets loose. i had 2 or 3 friends take one hell of a shot to the legs when it happened. So, by adding a plate off the 13 oil pan bolts to the rear 2 tailhousing bolts/ transmission mount, it prevents the shifter from comming over and nailing you.

of course, this has evolved into a complete underbracing solid steel oil pan. you then add a rear tailhousing plate and build gussets from the steel oil pan to the rear tail plate. in this picture to the right is a finished mauler brace pan. i named it mauler cause it reminded me of wolverine’s claws that shoot out of his hands. on this one,  i did not use a rear plate. i elected to drill and tap the tailhousing  so i could bolt the pan brace from beneath. this allowed a 4X4 crossmember to butt up to it and use a port-o-power to wedge it into the car.

there are some plus’s and minus’s to this. you have to use allen head screws to make everything clear. it ends up about a 4 quart capacity but has a smaller depth profile than the deep sump th400 truck oil pans.  it is damn near bulolet proof, but when you finish welding it up, it can be a complete pain in the ass to get it to seal at the pan gasket. also it can be a pain to remove for simple service. i highly recommend running good old dexron II/III and servicing your trans frequently. i would pull the drain plug after every run and change out the filter every 3-4 events…….or once a year. by circulating in 3-4 fresh quarts every run it keeps your fluid juiced up… to speak.

what a lot of people forget though is that those big nerat bell housings have a tendency to want to pull upward and off the front of the aluminum case as the car noses up. even with top bracing….it can still pull the bolts. simply drilling and installing two bolts to the bottom of the bell is all you need(also pictured). all it is doing it keeping the bottom of the housing from moving forward. think of it as a safety strap.

now with the big push of people either going back to more stock builds or selling out completely, i decided that htere has to be a more simple and easy way of doing this other than the freaky warlord monsters i have built. so i came up with a spider bracing plate. it fits over the stock oil pan with an access hole to pull the drain plug, so there is minimal sealing issues of fit problems from welding. it can be removed without dropping the pan and is able to be removed without battling your rear bracing plate/top bracing. it is bolted to the housing and the rear bracing plate.

you then run 4 tubes cross the top for your top bracing. you can build one of these elaborate spider’s web looking things for a top brace(i have), but i have had successful builds out there wil as little as four 1/2″ I.D steel pipes from rear plate to back of the steel housing. the distributor protector and/or the nerat housing takes most of the abuse of keeping the nose down on the car. your bracing is there to keep the aluminum case in tact. the nice thing is that this set up is easy and straight forward, cost effective, AND can be removed in pieces to comply with different rules. i mean you can remove all of it and swap on a J.W. Performance bell housing for a stockish approach……or drop the bottom spider brace plate if no skid plate is allowed at the track from under the car……or you are 4-6 hrs from home and something grenades in the transmission and you need to swap in a different center unit into all you bracing.