HEMI Technical Info

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Lenco Transmissions Tech

LENCO transmissions are a planetary design.
Planetary transmissions rely on a central sun gear to provide a 1:1 direct drive ratio once shifted from the launch ratio. In order to achieve an underdrive first gear launch ratio the LENCO transmission relies on planet gears which rotate around the sun gear. Each sun and planet gearset provides two speeds. Those two speeds are (1) the lower underdrive ratio and (2) the direct 1:1 final lock-up drive ratio. Each LENCO transmission is thus a two speed and is housed in one dedicated two speed case. You achieve more than two speeds by combining multiple cases For example, a three speed requires two cases, A four speed requires three cases, A five speed requires four cases and a six speed requires five cases. Since each case contains one gearset and provides both underdrive and direct drive, multiple cases (gearsets) provide multiple underdrive ratios. You must multiply each case's underdrive ratio in order to determine the first gear ratio. In the example of a four speed, the case nearest the engine would
contain a 1.37 ratio planet gear set. The middle case would also contain a 1.37 planet gear set. The rear case a 1.31 ratio gearset. By multiplying these three ratios you come up with a 2.46 first gear ratio. Second gear ratio is 1.80 and third gear is a 1.31 ratio. Final drive ratio is 1:1. You will need to add a LENCO reverse unit in order to back up.  RATIO CHART
It is not necessary for the driver to disengage the clutch when shifting from ratio to ratio since all shifting is done with the engines clutch fully engaged

Case - cast from  aluminum (original) and Magnesium, The CS1 is available with up to five speeds and offers your choice of 19 first gear ratios. The CS1 planetary gear size is 1". Magnesium case is standard. Air or manual shift. The CS1 will control up to 3000 HP. Shafts are available in Marage or 300M material.16 or 32 spline

Uses special cut monster 2" gear sets in forward low gear case. Second gear set case, in the event of 3 or 4 speed applications, utilizes standard sized 1" gear. The CS1N case is slightly larger than standard CS1 at a 9" diameter and a 9 1/4" length.
CS2 design is engineered for race cars producing up to 2500 HP. The CS2 is a smaller and lighter version of the CS1, planetary gear size is 3/4".
The very compact CS3 is engineered for cars producing up to 1800HP and weighing up to 2700 pounds. Standard planetary gear size is 1/2".

CS3  ( 5 speed )- left

CS1  ( 3 speed )- right

ST1200 Street Strip
Pro Street and street/strip applications up to 1200 HP and 900 lb ft of torque 8620 steel instead of 9310 material for the ST1200 gears. premium grade bearings instead of the much more expensive aerospace-spec bearings as used in all other transmissions. The ST1200 comes with aluminum cases instead of the magnesium style race units

Lenco Drive


BRT - Lenco


Sprag Clutch
The Sprag clutch is utilized in each shiftable section of the LENCO with the exception of the reverse. Its used to force the gear set to make it's ratio by preventing the sun gear from rotating in one direction. When this same section is shifted the Sprag then allows the sun gear to rotate in the same direction as the crankshaft.

Small sprag width is .803"
Large sprag width is .980"
Strips and Clips sprag Assembly
Double Large sprags"

Clutch Pack
Cannon / Reverser
direct drive - with reverser / Cannon to control clutch arm position
1 3/4 output shaft                  1 7/8 - 1 3/4 input shaft

minimum of .060" to a maximum of .090" of clearance between face of pilot bearing to beginning of clutch spline

Air Shifter
cs1-150 PSI   
Screw the servo into the transmission case until contact is made with the shift fork pin. Now rotate counter clockwise 1/2 to 1 turn and tighten lock nut
To set the shift pressure install checking lever into tower screw jam nut all the way up the tower so it's out of the way. Now rotate tower clockwise until it lightly touches pin on shift fork then rotate tower counter clockwise 2 turns and place hook of scale in top hole of checking lever supplied with transmission (this lever should be about 5 1/2" over all length) and pull scale slowly to shift section, taking note of highest reading this is your shift pressure. If the shift pressure is set to your application lock the jam nut your finished, if not you then need to add shim to raise pressure or subtract shim to reduce pressure. If needed you may vary 1 full turn up or down from your 2 turns out in order to achieve the shift pressure desired.
cs2-250 PSI
There are two different size air servos for the New Generation transmissions. The small air servo (2.5"piston diameter) and the large air servo(3"piston diameter) for the CS-2 large case transmission and Lencodrives. The air servo is attached to a rotary shift plate by an adjustable arm which is pre-set by the factory and should NOT be changed. The arm is held into the servo piston by a set screw. Run the air servo jam nut and o-ring up the threads on the servo. Screw air servo into case until it bottoms out against the jam nut. Rotate air servo into case until you see the set screw in the air servo piston boss inside the case. Apply a small amount of Red (271) Locktite on the set screw. After inserting arm into the air servo piston boss, run set screw in until you can no longer remove the arm from the piston boss. Warning: Do Not over tighten set screw. The arm must be free to move in all directions. Screw air servo counter-clockwise about five or six turns before you reassemble the transmission. Assemble next section on to case and bolt tight.
Once installed, make sure the air servo is loose and can turn freely. Remove fill plug on top the transmission case you are going to adjust. Sight through plug hole, where you will see the outer edge of the rotary shift plate. Screw air servo in (clockwise) until you see the rotary plate start to shift, now screw air servo Out (counter-clockwise) until the rotary shift plate stops moving. Then, continue to screw air servo Out (counter-clockwise) one half turn. This will allow for free play in the shift system. Run air servo jam nut and o-ring down against the case and tighten with a 1 1/2" wrench. Do Not Over Tighten. Add fluids as necessary and install fill plug. Attach air lines and your race ready.
Cs1  2speed / rev  14" not inc output shaft
Cs1  3speed / rev  22.5" not inc output shaft
Cs3  3speed / rev 19.5" not inc output shaft
Cs3  4speed / rev 25.75" not inc output shaft
Cs3  5speed / rev115 Lbs / no oil32" not inc output shaft
Std o/p shaft 3.5" pro shaft 4.5"