The CS1 design is our largest and strongest transmission.  We recommended the CS1 for use in ultra-demand applications such as Supercharged Alcohol Funny Cars and High-HP/High-Torque Pro Mod cars.  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.

CS1 2 speed
1 Magnesium case.
Handles up to 2500 HP.
Designed for use in supercharged boats, pullers, mud boggers and other severe duty applications.  Shown with air shift servo.  Available with lever shift system.

CS1 3 speed
2 Magnesium cases
Handles 2500+ HP.
Recommended for supercharged alcohol and nitromethane fueled cars and boats, Top Sportsman and Pro Mod applications as well as very high torque pullers.  Air or lever shift.

CS1 4 speed
3 Magnesium cases
Handles up to 3000HP.
Ideal for heavier cars where the advantage of a wide gear ratio selection is desired.  Commonly used in supercharged or nitrous oxide assisted Pro Mod and Super class types of cars.  Air or lever shift.

Reverse unit
Magnesium case.
Mates to CS1, CS2 or CS3 transmission.
5 1/2 long, manual shift only.

2 Low Gear
Ultra-Severe Duty
Brute Torque CS1N

The biggest and baddest of all LENCO transmissions. Specifically engineered for the rigors and demands of hyper-torque applications . 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 our standard sized 1 gear. The CS1N case is slightly larger than standard CS1 at a 9 diameter
and a 9 1/4 length.
As with all LENCO transmissions the CS1 is based on individual 2 speed planetary units with additional speeds being achieved through utilization of multiple 2 speed units.  CLICK HERE for diagram and description.

We also offer a 2" low gear Mega-HP, Monster Torque
2 speed for the most demanding of applications. 
See description at right


A1    Air servo snap ring
A2    Air servo top
A3    Air servo o-ring
A4    Air servo piston bolt
A5    Air servo piston top
A6    Air servo piston shaft
A7    Air servo spring
A8    Air servo housing
A9    Air servo base o-ring
A10  Air servo jam nut
A11  Air servo jam nut o-ring

M1    Shifter lever
M2    Shoulder bolt
M3    Shoulder nut
M4    Max tower
M5    Fine adjust nut
M6    Max tower body
M7    Course adjust nut
M8    Adjust nut o-ring
M9    Max plunger
M10  Plunger o-ring

1    Complete 2 speed assy.
2    Front seal
3    3/8x24 set screw
4    2 speed only case
5    1/2"-13 pipe plug
6    Low drag case bearing
7    Ring gear
8    Planetary thrust bearing
9    Planetary assembly
10  Planetary thrust bearing
11  PLanetary thrust race
12  Thick clutch housing snap ring
13  Clutch housing
14  Sun gear
15  Sun gear support bearing
16  Sun gear snap ring
17  Clutch hub
18  Pressure plate spring
19  Clutch pack
20  Pressure plate
21  Pressure plate snap ring
22  Pressure plate bearing
23  Thick clutch housing snap ring
24  .180 shim
25  Shift fork
26  Lite weight roller plate assembly
27  .030 shim
28  Sprag cover bolts
29  Lite weight sprag cover
30  3 eared thrust washer
31  Large sprag washer
32  Large inner sprag race
33  Large sprag
34  Large Lite weight outer race
35  1 3/8"shaft space
36  Two speed(only)output shaft
37  Thick shaft snap ring
38  Sealed rear bearing
39  Case o-ring
40  Rear lid for 2 speed only
41  5/16 an washers
42  Case bolts

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.

Different Sizes
We utilize several different styles and sizes of sprags depending on which application the transmission is used for.

Small Sprag Assembly
This is a our small Sprag, note the snap ring in the outer race and single brass thrust washer. Unfortunately, we no longer sale small Sprags do to the ever increasing horse power produced with today's motors. We found the small Sprags service life growing shorter and shorter, so we have discontinued it and highly recommend upgrading to our large Sprag assembly.

Large Sprag Assembly
This is our large sprag and unlike the small sprag doesn't have a snap ring in the outer race and has two brass thrust washers. This is what comes standard in most new LENCO transmissions. It's capacity is much stronger than the small sprag.

Large Strips and Clips Sprag Assembly
This is a specialized sprag and is used in applications where tire shake is a constant problem. It has special attachments to help it react quicker between the locked and the overrun position thus extending its service life.

Double Large Sprag Assembly
This is our double large sprag assembly and is used primarily in the boat applications, but has found its way into some car applications. This is a very extreme duty sprag assembly

Clutch Pack Information
Lenco Transmissions utilize several different styles of clutch discs depending of which style LENCO you have. You will also find different clutch disc numerical counts in each case. Our most common style clutch disc is
GREEN and comes in two sizes depending on which style transmission you have. There is also a BLUE disc and a TAN disc. Both of these styles come in one size only.

Our blue, green and tan disc are supplied new at approximately .058"- .061" thickness. When discs wear to .052" or less they must be replaced. Glazed, burned and chipped discs must also be replaced immediately.
Your clutch packs need to have the proper air gap or clutch pack clearance in order to operate correctly.
First you need to determine which style clutch packs you are working on - see chart. You always sequence assembly with one floater and then a clutch disc. Repeat the procedure and end up with one floater. It is sometimes necessary to have an extra floater disc to reach the desired clutch pack clearance. Normally the extra floater would go next to the planet case. Leaving the pressure plate spring (wave spring) out, place the pressure plate on top of the clutch pack. Now take all the lash out by lifting up on the clutch housing (outer housing) and press down on the pressure plate. Next measure the distance between the top of the pressure and the bottom of the snap ring groove of the clutch housing. This is your clutch pack clearance and should be between .080"-.120". Clearance can be adjusted by adding or subtracting floaters . We offer different thickness floaters for correcting the clutch pack clearance. Once you have achieved the proper clearance reinstall the pressure plate spring and clutch housing snap ring. The clutch pack is now complete and ready for installation

(Only on CS-1 style or center shift transmissions)
Air shifted LENCOS come pre-adjusted from the factory. If it is necessary to remove the servos you need to reinstall them with their lock nut spun completely to the top of its travel (next to top housing). 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. No further adjustments are necessary as there is ample reserve travel in the servo.

Once the servo is installed make sure it is loose and can turn freely. Remove fill plug on top the transmission case you are going to adjust. Sight through plug hole and 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. 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 you are race ready.

All shift levers when in the forward position result in the transmission being in first gear. The tallest lever to the right is used to shift the transmission from first to second gear. The second lever, and second tallest, is used for third gear. The next lever is used for fourth gear and final lever for fifth.

Roll up to the water box and stop. Shift all sections except the front section - you are now in first gear. Next start the tires spinning, now shift the front section so that you are in high gear. Proceed with burnout.  You always need to come out of the water box in high gear to prolong the life of the transmission.

To measure the shift pressure install checking lever into the tower and screw jam nut all the way up so it is out of the way. Now rotate tower clockwise until it lightly touches pin on shift fork. Next rotate the tower counter clockwise 2 turns and place hook of testing scale in top hole of checking lever supplied with transmission (this lever should be about 5 1/2" over all length). Pull scale slowly in order to shift the transmission. The highest scale reading is your shift pressure. If the shift pressure is set to your desired number lock the jam nut. If the pressure is not what you wish you then need to add shim to raise pressure or subtract shim to reduce pressure. If necessary you may vary 1 full turn up or down from your 2 turns out in order to achieve the shift pressure desired.

If you have any questions about servicing your transmission please call our tech line at
(800) 854-2944 or (619) 287-2500 in California).


1.  Check dimension A with steel rule or calipers.  This dimension, A, represents the distance from the rear outside face of the bellhousing to the outside face of the pilot bearing once the pilot bearing has been inserted into the crankshaft.

2.  Install input shaft into transmission.  Measure dimension B - which is the distance from the face of the transmission to the end of the clutch disc spline (do not include input shaft pilot material).  Dimension B must be from .060" to .090" shorter than the A dimension.  If input shaft is too short you may add up to .100" shim between pilot bearing and crankshaft receiver hole.  If input shaft is too long, however, you must machine it so proper required dimension range is achieved.

LENCO transmissions are shipped with the shift levers removed in order to prevent damage during shipping. To install lever remove bolt, insert lever in shift tower so that it faces forward and install bolt. When the installed lever is loose that section is in low and when the lever is tight the sections in high.
CS1 Technical information
1   Sprag cover bolts
2   lite weight cover
3   3 eared thrust race
4   Large sprag washer
5   Large inner sprag race
6   Large sprag
7   Large L/W outer sprag race
8   Reverse intermediate shaft
9   Shaft bushing
10  Thick shaft snap ring
11  Reverse front bearing
12  Reverse case o-ring
13  Reverse case
14  Pipe plug
15  Reverse cross shaft plug
16  Reverse cross shaft plug o-ring
17  Reverse lever bolt
18  Reverse lever
19  Detent plunger nut
20  Reverse cross shaft retainer
21  Detent plunger o-ring
22  Detent plunger
23  Cross shaft o-ring
24  Reverse cross shaft
25  Thick shaft snap ring
26  Reverse planetary
27  3/8" washers
28  Reverse planetary bolts
29  Reverse sun gear
30  Reverse ring gear
31  Reverse half of ring gear
32  Reverse ring gear snap ring
33  Reverse thrust race
34  Reverse thrust bearing
35  Forward drive gear
36  Reverse slider
37  Reverse shift fork
38  Reverse output shaft
39  Reverse lid bearing retainer bolts
40  Rear lid bearing retainer
41  Rear lid bearing
42  Rear lid o-ring
43  Rear lid
44  Rear lid seal
45  Rear lid seal retainer
46  Rear lid seal retainer bolts
47  Rear lid washers
48  Rear lid bolts
49  Drive shaft cover rear lid
50  Drive shaft cover clamp
51  Drive shaft cover tube



Small sprag width is .803"
Large sprag width is .980"