OEM Clutch Pedal Assembly Components: 1g DSM

1g DSMs had a poorly designed clutch pedal mechanism.  Instead of using a simple, direct mechanical connection between the clutch pedal and the clutch master cylinder (as Mitsu did on 2g DSMs and all later models), Mitsu chose a rather funky design. The main offending component is a lever arm (which Mitsu calls a clutch pedal lever arm: part no. MB599879).  For reasons explained below, play develops between this lever and the shaft it attaches to. When no play is present, when the clutch pedal is pressed, it translates into movement of the hydraulic piston in the clutch master cylinder, which in turn actuates the clutch slave, which in turn pushes on the clutch fork and ultimately separates the clutch assembly from the engine. This is how the clutch pedal mechanism was designed to work and this is how it actually does work as long as there is no play in the clutch pedal lever arm.

Once play is present in the clutch pedal lever arm, when the clutch pedal is initially pressed there will be NO movement in the clutch master piston. Instead, the pedal will travel a certain distance without actuating anything.  Once the amount of play has been overcome, the pedal will begin to actuate the necessary components as intended.  As long as the amount of play is very small, the clutch would operate satisfactorily and most people would be unaware of any issues with the clutch pedal.  However, once the play becomes big enough (and given enough time it will) the pedal will move a good distance BEFORE any movement in the clutch master piston occurs.  At that point, the pedal can travel only as far as the physical limits of its travel (basically, the floor of the vehicle) and if the clutch master piston has not moved a sufficient amount, your clutch won't disengange.

The above explains WHAT is happening, but not WHY.  A explanation of the why follows:

The clutch pedal assembly is comprised of a clutch pedal rod (with a pedal pad at one end and a steel shaft welded (at a 90-degree angle) to the other end--we'll refer to this steel shaft as the clutch pedal shaft). When the clutch pedal is pressed, the clutch pedal shaft rotates.  At the other end of this rotating clutch pedal shaft is the clutch pedal lever arm (part no. MB599879). This clutch lever arm has a "D" shaped hole punched into it.  This hole roughly matches the shape of the end of the clutch pedal shaft.  The clutch lever arm slides over the end of the clutch pedal shaft and is held in place by a nut threaded onto the end of the shaft.  The source of all the problems is the D-shaped hole punched into the clutch pedal lever arm.  A punched hole is simply not a precision hole (which is why we used the expression "roughly matches" above).  It can never really match the D-shaped shaft it was intended to fit into. In fact, we'd wager that there were probably a good number of 1g's that rolled off the factory floor with a small amount of play present at that location.  But even without any play initially present, over time, play will inevitably develop. The design virtually guarantees it.

So if this is your situation, what are you to do about it?  There are a couple of options.  One is to replace the clutch lever arm with a new one and start the process all over again.  The idea is that the new one will eventually develop play just like the one it's replacing. However, it may take many years to do so and, in the meantime, you could enjoy several years of satisfactory performance. 

The other option is to replace the clutch lever arm with a new one and WELD it into position so that no play can ever develop.  As you can imagine, this is the preferred method. 

On a 1g DSM, because of the way the clutch pedal mounts to the vehicle, it is necessary to completely assemble all the various components together and then weld the clutch lever arm in place.  This means all the various plastic bushings must be in place while the welding operation is taking place. As you can imagine, welding heat and plastic bushings don't make good companions.  This is one of the reasons we offer a brass bushing (RTM-9179) to replace one of the plastic bushings (MB058634).  As it happens, this is the bushing located very close to the clutch lever arm (and thus the welding heat).  As long as one is careful welding, a brass bushing at this location is able to survive the welding operation without problems. If the OEM plastic bushing were at this location during the welding operation, it would be virtually impossible to NOT melt the bushing to at least some degree.

The parts associated with the clutch pedal asembly include:

MB599879: clutch pedal lever arm
MB534210: pedal assembly bushing
MB534211: pedal assembly bushing
MB058634: pedal assembly bushing
RTM-9179: brass bushing to replace MB058634
MF473492: clevis pin
MB555171: clevis pin bushing
MB151106: clevis pin washer
MF472042: clevis pin cotter pin

NOTE: MB599879, MB534210, MB534211, MB555171 are out of stock.

NOTE: The main pedal/rod assembly (MB599233) has been discontinued by Mitsu and is no longer available.

NOTE: Photo is for display purposes and depicts various components (many of which are out of stock).  Be assured that your order will correspond to your selections in the drop-downs.

Application: DSM (1990-94).

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