Transmission User Guide

Clutches-Line Loc

Clutches – Line Loc

With the JEFFco Planetary Transmission we recommend the Mcleod Street Twin, Borg & Beck style for street strip applications. For drag race only a single sinter iron disc on a B&B counterweight finger is a good choice.

The Street Twin unit fits inside the STD Lakewood scatter shield @ 6 3/8 depth. Its holding power is good to 1000 Hp. It also has counterweight features for more clamping. We do not use the diaphragm style.

We also stay away from hydraulic throw out bearings because some don’t give the feel when letting out the clutch. We do recommend a line loc for drag starts. The clutch should be loaded, this protects the sprags!

Transmission Installation and Operating Procedure

The JEFFco Saturday Nite Special The JEFFco Performance transmission is a planetary type of unit built to satisfy the needs of the Pro street machines that want an advantage on the street or strip. Mash the throttle down and start pulling the levers, it’s that easy. Missed shifts are eliminated.

With four forward speeds, reverse and neutral and a 3:00 low gear to get things moving, the clutchless designed transmission is truly streetable. Quiet running gear sets deliver superior strength, while also giving some cars as much as 7/10th quicker E.T.’s.

Other User Friendly Features are: Unique shifter with neutral lock out

Will fit in the stock cross members of Chevrolet i.e.: ’67-’81 Cameros, Novas, and others.

Bolts up to a stock Chevrolet Bell Housing or scatter shield


When installing the transmission to the engine, be sure the front unit is shifted, as to lock the front clutch pack. This keeps the ring gear from being pushed back if the transmission does not slide in easily or mis-measurement occurred.

NOTE: It is very important that you check the input shaft clearance to the pilot bearing in the crankshaft. There should be .060 – .090? Because of different motor plate thickness and scatter shield lengths, you may have to make a spacer for the pilot, or turn the input shaft back a little on a lathe. An O-Ring can be used to take up clearance on the end of the pilot to make clearance to spec.

JEFFco Operating Instructions

The transmission is shipped dry, with no oil. If it is not going into service immediately, put 3 quarts or so in the unit and rotate so rust will not occur in the unit. The capacity is 4 to 4 ½ quarts. I highly recommend motorcycle 2 stroke transmission fluids, such as Torco, Bel Ray Gear Saver, Golden Spectro (75-85 wts). These oils pour like 20-50 Motor Oil. DO NOT SUE SYNTHETICS, they tend to slip the clutches. Oil should be changed weekly on new units, for 2-3 times.

While speaking on oil, it would be recommended that a pump and filter system be used to clean and cool the fluid as to extend the life of the unit. The JEFFco test unit has seen 10,000 miles with no problems. The fluid was changed regularly and the shift pressure kept at correct levels.

The vent line is located on the left side of the transmission, and should have a hose run to an elevated 12 oz. plus catch can, or similar, mounted on the firewall. When the transmission fluid is cold, fluid will run up the line and when warm, decrease.

Transmission Mount: The transmission mount was designed to make installations easier. On some cross members, the transmission mount will need more clearance. Heating the cross member with a rosebud or torch, and then dimpling it with a 1” piece of pipe has been done with good success. This seems to be better than grinding on the cross members.

Adjustment Procedures

Disconnect the Heim Ends and Clevis from the lock over levers; place the checking tube over the locking lever. Put the hook of a Fish Scale (0-50 lbs.) in the tube and pull slowly to shift. Check the highest reading, just before the lever drops into the detent. Do this at operating temperatures, warm if street driven, cooler if drag racing only. 20-28# is a goof for most applications. Repeat this procedure on the 2nd and 3rd cases of the transmission.

If adjustment is needed, loosen the lock nut on the shift tower and turn clockwise to raise the pressure. Half a turn can equal as much as 7-8 lbs. Or as little as 2-3 lbs. One turn can equal as much as 10-15 lbs. or as little as 5-6 lbs., so check them and keep track.

Shift Pressures



22#-28# Carbureted gas engines

#26-#35 Blown Engines




Notes: – The heavier the car, more pressure is required to lock up the clutch pack – The transmission is shimmed by the length of the cases, so when the unit is hot, the cases grow in length My experience has show that a loss of 5-6 lbs. from cold to hot can occur, so if street driving is going to be done a lot, set the pressures when the unit is at temperature.Shift Pattern All levers forward in first gear. The tallest lever to the right is First to Second gear, the next lever to the left is Third gear, and the next lever to the left; the shortest, is Fourth gear. The short far right lever is the reverse, forward, neutral When shifting in and out of reverse, make sure the clutch is disengaging, grinding will otherwise occur. Engine R.P.M. also plays a factor in putting the transmission in gear because there is no syncro. The lower the R.P.M., the better it is to shift in and out of reverse. If engine shut-off is required – do so.Burn OutsShift the rear unit before spinning the tires. While the tires are spinning, shift 2nd gear handle. If more tire speed is desired, shift 3rd gear. Come out of the water and push in the clutch when desired. Dry hops in the wrong manner do not help the sprags, it just tears them up. Sprags are a mechanical devise that require load to lock them.Do’s and Don’ts of operating a JEFFco Performance Transmission1. DOchange the oil often during the break-in period and on a regular basis after that.2. DO check shift pressures at operating temperature and keep them at proper levels.

3. When driven on the street, the transmission is shifted more times on a cruise than most race card do at the track in 3-4 weekends. So when shifting on the street, DO NOT slowly shift the unit. This just wear the clutches in the transmission out faster. To shift when cruising, DO accelerate, let off the gas, and let the R. P.M. drop, then give a quick pull to shift. Ease back in to the gas, easing back into the gas while cruising, DO accelerate, let off the gas, and let the R.P.M. drop, then give a quick pull to shift. Ease back in to the gas, easing back into the gas while cruising will help prolong sprag life. You can also use the clutch like a syncro transmission, clutch in, pull lever. Down shifting is done by pushing a lever back and matching your speed with what R.P.M. you want to be at.

The JEFFco Saturday Nite Special has more than proven itself on the streets and drag strips. When automatics have been broken, broken, and broken again, the JEFFco in the same applications is still going strong. Simply stated, “If you’re not pulling levers, you car may not be wroth driving.”

Have fun and best of luck,

Shawn 619.441.7344 JEFFco Performance

Common Transmission Problems and Solutions

EFFco is very proud that you have chosen our product. We will do everything we can to make the use of our product easy for you. The transmission has long been known as a complicated mechanism that needs special tools to overhaul, but that is not always so. With preventative maintenance, the transmission life can be greatly increased. Here are some of the answers to possible problems or questions associated with the transmission.

Shift Pressures;

When should I set the pressures?

The shift pressure should be checked regularly. The handles should need a slight tug to pull them. If the handles are easily pulled, then the shift pressure is probably too low and the clutch packs inside the transmission will be excessively worn or damaged. For adjusting pressures, remember to make the holes in the floor pan or tin large enough so a socket, (11/2”), can tighten the tower nut. Read install information for pressure checking procedure.

When should the transmission oil be changed?

Oil cleanliness will determine how long the transmission will last! Period. There is no filtration inside the transmission, so oil should be changed often (often is weekly for the first few weeks). The oil should be changed when the oil is warm, this allows the “trash” in the oil to flow out. If the oil is not warm, the sediments settle on the bottom of the transmission and get stirred up upon the next startup. A filter is recommended, but not necessary.

Oil flows between all the cases. Pulling one drain plug will drain 80-90% of all the oil. Draining from both plugs is recommended. Four speeds require 4-4 ½ quarts. Check install information for type of fluid.

Problem I can’t pull the handle and make the transmission shift.

Solution The ring gear was pushed back while installing the transmission.

1. Lock the front unit before installing and it won’t happen (read installing information). 2. Is there enough input shaft clearance? 3. If this has happened, don’t be upset. You are not the first person, nor the last it will happen to. 4. Call factory about how to fix it.

Problem Car will not move in low gear, but will move If one of the handles is pulled.

Solution Almost always a result of sprag damage. Sprag damage can be prevented though driver education: 1. Don’t burp engine in low gear. 2. Don’t shift high to low under power. 3. Don’t do low gear water burnout’s. 4. While at the starting line, the clutch needs to be loaded, the “drive line” slack being taken up. NOTE: If on a pass; the car or truck gets out of shape and the driver lifts, this unlocks the sprags. The pass should be aborted, if the driver gets back on the throttle sprag damage could easily occur because the engine is getting a run at the sprag. NOTE: Check sprags if a broken rear axle, rear end of driveline problem has occurred.

Noise The transmission is a relatively quiet unit. It does not have the gear drive sound like other units. With mufflers on the cars, more noise can be heard than of cars which are uncapped with open exhaust. Rear end noise happens often, and is transferred up the driveshaft and makes finding or isolating a noise hard. The two most common noises are: 1. When the handle of a unit is pulled, you can hear a whine noise. a. Can be caused by a pitted front bearing, which can happen because of “trash” in the oil. Front bearings can be replaced easily during transmission service. 2. A more grumble sound is heard after the handle is pulled. a. The inner race of the sprag assembly could be the cause of this noise. It could be indented. This is usually caused by bad driver technique. A four speed has three sprag assemblies in it. Inner races and sprags can be replaced easily during transmission service.

Problem Unit leaks oil between bell housing and transmission case.


1. Throw-out bearing collar bolts need sealant because they are exposed to oil (early models). 2. Check front seal. Don’t push the seal all the way in. It will stick out about 0.075 inches, but still clears the collar for proper location on input shaft sealing ring.

Problem:Transmission grinds going into gear.


1. Lower R.P.M. 2. Start car with transmission in gear.

Question: Is it necessary to carry spare parts?

Answer: It is always possible that a failure could occur due to experimentation or driver error. In any event, it would be wise to carry the following:

1. Clutch Pack: 9 Disc.-10 Steel

1 Sprag

3. Inner Race

4. 4 Quarts Fluid

5. Shim Assortment

6. O-Rings, Assortment

7. Shim Disc .090

8. Pressure Plate Spring

TOOLS: 1. Alignment tool, sprag cover. 2. Pressure checking tube 3. Fish scale 0-50 lb. 4. Allen wrenches This should handle any problem that could be repaired in the field.

Shawn 619.441.7344 JEFFco Performance



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