Adler clutch, mechanics notes

Note that this is a English translation of a German document and some detail may be lost in the translation.

Chapter 1

Clutch disassembly with motor in frame

If this is the first time you are disassembling the clutch as an Adler twin owner you will be shocked to hear that to renew the simple clutch parts you are required to strip half the motor. The utmost care and attention should be applied during this work.

Step 1

Remove the left hand footrest and the gear lever, including the cover plate (make sure that the clamp screw on the gear lever is completely removed).

Step 2

To get to the crankshaft lock nut it is necessary to remove the “Adler” name-plate which is secured by 2 pan head counter sunk screws. The name-plate has no jointing compound on it but might be a tight fit in its recess. Behind the plate is a thick soft seal held in place by a washer.

Step 3

The nut should be in view now with its locking mechanism. On old motors a tab washer is used and on new motors a split pin. Remove these to loosen the crankshaft nut. Before attempting to remove the nut put the gear lever back on the shaft and select 4 th

gear. Using a 22mm box spanner or socket on the nut, apply the foot brake and loosen the nut. Remove the gear lever.

*NOTE* This thread on the crankshaft can be left hand or right hand thread – both exist due to design changes at some time, though most are right-handed.

If the motor is out of the frame and on the bench there are other possibilities for locking the crankshaft:

a) Insert a suitable piece of soft wood in through the left exhaust port so that it sits under the piston as a stop.

b) If the cylinders and pistons are removed use a piece of hardwood in the left hand crank port to rest against the conrod and stop the rotation of the crankshaft assembly.

c) Obtain a piece of silver steel 100mm long and 15mm Ф (precision ground steel). Fit the steel through the gudgeon pin hole in the left hand conrod. This will stop the rotation of this crankshaft assembly.

Step 4

Drain the gearbox oil. Loosen the 5 cover screws, which may have been damaged by the previous use of screwdriver blades. An impact driver with a good fitting blade can be used. Before removing the screws place a container under the unit to catch the remnants of the gearbox oil (make sure the container is large enough). Using a soft headed mallet, tap the clutch adjustment screw which should loosen the cover.

Step 5

Hold the kick-starter lever and pull it while softly tapping the cover on alternate ends. It should slide off the location points. If the gear lever shaft comes out with the cover, make sure that note is taken where the spacer fits and place the assembly to one side.

NB: if the motor or the machine is leaned to the left the remains of the gear oil will flow from the engine. Store the removed items and assemblies in a clean, safe area with any notes. The clutch assembly is now accessible.

Chapter 2

Correct removal of the clutch assembly

It is now obvious that the clutch assembly is attached to the crankshaft and that it is also connected to the gearbox. Study the layout and understand the function before starting the removal of the clutch.

How is the clutch assembly attached to the crankshaft?. The ”M” engines up to the middle of 1953 used a splined shaft with a woodruff key. After this the “MB” engines used a tapered shaft without a key.

“M” engine design:With this design invariably there will be play in the springs and it should slide off easily. With a low km engine, or one with a small amount of corrosion, the use of a two arm bearing puller may be necessary.

NB: it is important that a protection cap for the end of the crankshaft be made on the lathe. Pressure from the extractor spindle can destroy the end of the crank shaft .

Do not attempt to remove the clutch assembly on “MB” motors with a bearing puller. This tool, if used will distort the clutch plate cage and destroy the clutch assembly.

The Correct Removal Procedure for MB motor

Assemble the protective cap on end of crankshaft.Unwind the bolt of the clutch removal tool .

Screw the removal tool onto the threaded part of the clutch until it butts up against the #16006 bearing. Use a spanner to stop the tool turning and carefully tighten the extractor bolt.

Apply a hammer to the end of the shaft after applying reasonable tension, repeat until clutch is released.

Behind the clutch assembly are a number of parts as per sketch. Ensure that the parts are labelled and a sketch of the assembly order noted. It has been recorded that 80% of the motors on re build are assembled incorrectly.

Chapter 3

Disassembly of the clutch assembly

If we want to get to the parts on the inside of the clutch assembly we must simulate the de-clutch operation, ie release the spring pressure on the clutch pads.

Using a 22mm socket piece assembled on the crankshaft side and a 30mm socket piece assembled on the clutch pressure bearing side, compress the assembly in the vice until it compresses no further.

This should allow you to :-a) rotate the plates with the friction pads inserted, and

b) this should make it easy to remove the screws, nuts and toothed discs.

Carefully release the pressure of the springs and place all of the parts in a bowl to be cleaned with an appropriate cleaner.

The assembly of this clutch will be done in the reverse order.

Chapter 4

Causes of clutch failure

In my experience only 2 or 3 times have I replaced clutches due to worn out parts. The most clutches I have repaired have been due to wrong assembly and bad workmanship. So take your time, do it right the first time, and the parts will last a long time.

Ensure when cleaning the clutch cage that the groove behind the toothed section (see sketch ) that all of the debris from normal use that can’t get out is removed.

2 different types of drive plate exist

a) One with red layer and glittering metal particles. This is the correct type to use.b) The other is a dark black layer attached that will probably be disintegrating. Keep the plates and refurbish them, preferable replace with new plates. Old plates must show no distortion to achieve perfect clutch operation. Damage due to wrong use of extraction tool ( bearing puller ) can be seen with teeth on plates being bent .

b) Checking clutch cage for wear and damage. Using 2 screwdrivers (flat blade) to remove the bearing (16006). Place

the blades in the gap between bearing face and clutch cage and lever the bearing off. Behind the bearing there is a large washer that is not shown in the spare parts list.

Label the washer and it’s location.

Check the cage flatness with a straight edge.

The outside rim of the cage is up to 1mm higher than the middle. Permissible distortion of the middle is 1mm. To check the roundness of the cage offer the “Driver” and “Driven” plates in to the cage. They should move in and out freely in an axial direction. Test the “Drive Hub” in the same way. Any points catching should be flattened with a hammer and dressed with a file until totally free in operation.

Chapter 5

Parts to measure and check and correct before assembly

Drive Hub

This is the most critical part of the clutch assembly and must run true to the tapered boss and the fit on the crankshaft.

Check that the surface is flat within 0.5mm – 1.0mm

Clamp the Hub in a 3 Jaw chuck on a lathe and clock the run out with a dial gauge.

We need to establish the dimension of the datum face of the drive hub to the shoulder on the crankshaft spigot.

Step 1

Using fine grinding paste on the two tapers, rotate the drive hub on the crankshaft spigot until the two surfaces are lapped in. (a uniform grey matt surface). This will ensure that the two parts fit perfectly (clean off the grinding paste).

Step 2

Fit the thick washer on the crankshaft spigot. Fit the two dished spring washers as per sketch. Now fit the drive hub onto the crankshaft spigot with hand pressure until it seats on the taper. We are now ready to measure

The measurement

A 0.1mm gap is required between the datum face on drive hub and edge of spring washer. See drawing aboveThe recess shown in the sketch with >2mm is a guide as to what to do. If it is less than 1.5mm the hub must be replaced. When the recess is more than 1.5mm the washer must be adjusted on a surface grinder.Assemble the thick washer and the hub onto the crankshaft spigot. Push the washer against the datum face of the hub and measure the gap between washer and spigot face ---dimension A.

Measure the width of the two spring washers ---dimension B. NB: adjust washer until dimension A becomes 0.1mm larger than dimension B.

Chapter 6

Assembly of the clutch basket

A new bearing should be fitted to the basket ( part No 16006). Heat the bearing in the oven to 100-150°C. This should then easily fit onto the cold basket hub. Make sure the large washer is fitted to the hub before the bearing. If the bearing is not an interference fit when cold use a drop of Loctite.

Assembly of clutch parts into the clutch basket

Step 1

Hold the clutch basket horizontal with the teeth facing up. Assemble the “8” dished spring washers and the “8” clutch springs.

Step 2

Assemble the drive hub so that

a) the thread must be pointing down, andb) in the correct position in the milled relief to accept the fixing screw at the time

of assembly of the washer.

Step 3

Fit the clutch plates starting with a friction plate, alternate the assembly of the plain and friction plates. Ensure the assembly is relative to the milled relief for the fixing screw. Now fit the clutch cover plate.

Step 4

Fitting the screws

Before we can fit the 8 screws we must clamp the assembly together in a vice or with a large “G” clamp. Use a 22mm socket in the centre. From the under side use a 30mm socket to press on the inner ring of the bearing. Now transfer the assembly and sockets into the jaws of the vice and compress the springs. This is easier with a 2nd pair of hands. The plain and friction clutch plates should move freely. Now fit the 8 screws. Remove the completed assembly from the vice.

Step 5

Centre align the clutch plates in the cage before fitting to the crank shaft.

Use the clutch extractor (see MB drawing ) to compress the clutch springs by screwing it onto the thread until the clutch plates are free. Align the plates so that the inner splines are in line. Now insert the primary gear carefully until it is fully home. Fit the needle bearing on to the crankshaft and now fit the complete clutch and extractor onto the crankshaft ensuring :-

a) the primary gear fits over the bearing smoothly, andb) the taper of the crankshaft and drive hub come together in a good

fit.

Support the clutch in this position and remove the extractor. The clutch plates should be aligned now and the clutch, primary gear and needle beading can be removed from the crankshaft and stored ready for motor assembly.

Assembly and alignment of cage and clutch plates - Motor M.

The clutch assembly is the same procedure as described before except instead of the 22mm socket, a piece of tube or bar can be used that is a good fit in the primary gear bore. With this method patience is required to get a good easy fit onto the crank shaft.

Chapter 7

Motor assemblyStep 1

Oil the needle roller bearing and fit it onto the crankshaft. Then the primary gear on top of it. Ensure they fit up against the spacer.

Step 2

Take this bronze washer and coat on side with grease and slide it over the crankshaft and into the recess on the primary gear. The grease will ensure it stays in place on assembly of the clutch module (see sketch).

Step 3

Now fit the thick spacer and the pair of dished washers as per sketch.

Step 4

With an approved degreaser, clean the conical part of the crankshaft and the mating part of the clutch so that there is no grease on the surfaces.

Ensure that these surfaces are roughened before mating together.

Step 5

Now offer the clutch assembly to the end of the shaft ensuring that teeth in the clutch fit onto the primary gear teeth. Push and turn the clutch assembly until the tapers mate and bite. The clutch assembly will not turn at this point.

In assembling always push forwards even if it snags a little, do not pull it towards you. It is possible that the bronze washer will be dislodged.

Step 6

It is important at this stage that the drive hub of the clutch assembly fits tight on the taper of the crankshaft. Using a piece of tube or a socket against the face of the hub, drive it home with a tap of a hammer.

Step 7

Assuming the clutch operating cam and cable on the left hand side of the motor are still in place we must now check and set the adjustment screw. NB: these instruction are for the motor out of the frame situation.

To adjust the clutch operating adjustment screw, fit the clutch lever assembly onto the free end of the cable. The adjustment screw on the crankcase must be screwed in as far as it goes. Now locate the cover including the gasket but without the clutch push rod

assembled. Fit the two centre cover screws, DO NO TIGHTEN. Now screw out the adjustment screw until there is no play and remove the cover. The view should be as per the sketch.

It is important that the 80° angle is achieved. The adjustment is achieved with the 3 screws and the elongated holes in the lever.

Step 8

Now fit the clutch push rod and spacer. Take the cover and coat the gasket with liquid gasket material and locate it on the crankcase. Fit the 5 screws with uniform torque on opposed screws. Clean excess gasket material from crankcase.

Step 9

Fit the locking nut onto the crankshaft. Lock the engine as previously discussed. Using a torque wrench tighten the nut to 40-45 Nm

Now check if the split-pin hole in the shaft aligns with the slot in the nut. Adjust by tightening if necessary. Fit a new split-pin and fold down the ends correctly. Now fit the thick soft gasket and the cover plate. Finally fit the Adler cover.

NB. Ensure that the thick soft gasket material is at least 3mm thick or the cover plate will rub on the locking nut.

Chapter 8

Removal of old clutch cable and fitting of new

1 Remove foot peg and gear lever2 Remove cover with “Adler” printed on it and then the small cover, not3 forgetting the thick gasket.3 Take out the split pin or bend back the tag on locking washers.4 Use the rear brake to lock the engine and remove the crankshaft nut.5 Take out the 5 screws securing the clutch cover. Put drip pan under the motor and remove the cover.

6 Ensure the cover is removed without damage.7 Remove the clutch cable nipple from the clutch operation lever cam without losing the spring.

8 Remove the adjusting screw from the case. 9 Assemble new clutch cable with spring and adjusting screw.

10 Fit the adjustment screw into the crank case and fit the cable nipple into the clutch operating lever.

11 Clean sealing faces of crankcase and cover of gasket material.12 Make a new gasket and coat the gasket with a liquid gasket material.13 Fit the clutch push rod and washer. Fit the cover with gasket with care onto

the crankcase. Ensure that the clutch-operating cam is in the correct position so that it does not restrict the seating of the cover onto the

crankcase.14 Fit the cover screws.15 Engage 4th gear, fit the retaining nut onto the crankshaft and tighten to

40Nm torque. Ensure foot brake is operated.16 Fit split pin, thick soft washer, small cover and “Adler” printed plate.17 Assemble foot peg and clutch lever.18 Adjust clutch cable and lever for correct play.19 Run the motorcycle and make final adjustments if necessary.