Throwback: Head Porting By David Godfrey

David Godfrey's Article About Head Porting David Godfrey is somewhat of a legend in the XR4Ti circles, being a prolific problem solver a...

Wednesday, December 2, 2020

Throwback: David Godfrey's Manual Clutch Adjuster

DAVID GODFREY'S MANUAL CLUTCH ADJUSTER

David Godfrey is somewhat of a legend in the XR4Ti circles. He was one of the first to figure out a bigger front disc brake option using off the shelf discs, as well as a rear disc brake conversion. The clutch adjuster is one of his creations that is still highly desired. This helps preserve the plastic quadrant the clutch cable rides which is prone to break, given the repeated tension the piece is under while being actuated dozens of times every time the car is driven.

David no longer makes this and his site is no longer maintained, or even available. I pulled this out of the Internet archives to give it a new place to live, so people can see it, and hopefully start making them again some day. Last time I saw them being sold they were $120-150/ea.

Chris



 
Thanks for your interest in the Merkur XR4Ti manual clutch adjuster. I have been working on this project for some time and have developed a product that will allow for the clutch release point to be manually adjusted. Benefits of this are cleaner engagement of gears, quicker shifting, and elimination of the failure prone ratchet adjustment mechanism.
 
Important to the design is to come up with an adjuster that would work for both T-5 and T-9 transmissions and either the XR4Ti or Mustang clutch cable. I can easily come up with a one off solution to fit my car, but when a design has to fit multiple configurations and be installed by a typical XR owner (whatever that is!) the constraints get a lot tougher.
 
The manual clutch adjuster works by rotating the cable cam through it range of motion. Slight modification is required to the cam and an existing hole in the clutch pedal needs to be enlarged for the adjustment screw. These are simple mods that can be done by that "average" Merkur XR4Ti owner.
 

A few years ago I conducted a survey on the IMON list of clutch quadrant failures. Of the 30 something reply's I got only one person had a failure of the cable cam. All other failures were either the ratchet teeth or the spring. The pedal mounted adjuster can use the cable cam even if it is stripped.

Contents of the clutch adjuster kit are:

CNC machined aluminum Clutch Pivot assembly

Pivot trunion assembly with set screw
Pedal trunion
Adjustment Rod
Spacer
Lock Nut
 
 




 
Installation instructions
The clutch pedal needs to be removed to install the clutch adjuster. The best way to do this is to remove the whole pedal assembly from the car. This task sounds a lot worse than it is.

Begin by removing the sound deadener panel, lower steering column cover, and lower dash from the drivers side. Release the clutch cable by pulling up on the pedal to disengage the ratchet. The end of the cable can then be pulled from the cable cam. From under the hood pull the cable from the guide tube. The hardest part is now over! 

Remove the spring clip from the end of the brake booster rod where it comes through the brake pedal. Remove the connector from the brake light switch or the entire switch by twisting it 90 degrees and pulling it from the bracket. If you XR has cruise control disconnect the hose to the vacuum switches.

With the above done the pedal assembly is ready to unbolt and remove. There are two 17mm nuts where the pedal bracket meets the firewall. You will have to pull the carpet back to see them. Remove the nuts and flat washers. There is a 12mm-headed bolt going up from the pedal bracket to the dash support structure. Remove this bolt and the pedal assembly can be removed. With the clutch pedal assembly out make sure the nylon bushing on the end of the brake rod does not fall off and get lost.
 
 



STOCK PEDAL ASSEMBLY
 
With the pedal bracket out you can see a big hair pin type clip that holds the clutch pedal on the shaft. Remove this clip and the two nuts that hold the guide tube to the pedal bracket. You can now remove the pedal from the shaft.

Remove the clip from the end of the rod that holds the ratchet in place. Remove the rod, ratchet, and ratchet mousetrap spring. Disconnect the large spring to the cable cam and discard. Remove the cable cam from the pedal.

 
 


CLUTCH PEDAL, GUIDE TUBE, CLIP

PARTS REMOVED FROM CLUTCH PEDAL

Using a hacksaw, sharp knife, or side cutters, remove the tab from the end on the cam as shown in the picture. Make sure the tab is completely removed and flush with the flat surface.
 
 



 STOCK CABLE CAM 


MODIFIED CABLE CAM

Place the clutch pivot on the cam and press the pre-installed roll pin in place. The cam is now ready for installation. The roll pin can easily be pressed into place using a bench vise or channel lock type pliers.
 
 


CAM WITH CLUTCH PIVOT INSTALLED

The pedal needs to be modified so the adjustment rod can be installed. There is a small slot on the front of the pedal near the pivot. Drill the slot out with a 1/2" drill. It was easier to drill the hole if the slot is made somewhat round by using a rat-tail file. When the drill is through the pedal rotate it slightly up to elongate the hole. Remove any burrs with a round file. The spacer needs to fit in the hole and be able to rock up slightly.
 
 



SLOT IN CLUTCH PEDAL


DRILL OUT SLOT TO 1/2"

 


ROTATE DRILL UP AS SHOWN

Place the adjustment rod through the spacer and then through the hole in the pedal. Thread the pedal trunion on the adjustment rod with the flat side of the trunion facing away from the pedal. 
 
 



ADJUSTMENT ROD, LOCK NUT, SPACER, & PEDAL TRUNION INSTALLED

Place the pivot trunion in the clutch pivot. Place the cam in place on the pedal and turn the adjustment screw in until the end engages the pivot trunion. Snug up the set screw using a 1/16" Allen wrench to engage the groove in the end of the adjuster. The set screw does not need to be tightened down on the adjuster, but just engage the slot to keep the adjustment rod captive to pivot trunion.
 
 



MODIFIED CAM & ADJUSTER INSTALLED


PEDAL RE-INSTALLED ON BRACKET

Place the pedal assy on the shaft and install the guide tube and the big hairpin clip making sure the clip is fully seated in the groove on the shaft. The shaft is spring loaded so it can be pressed out to make putting the clip in place easier. Install the clip before tightening the nuts on the cable guide tube. Turn the adjustment screw rotating the cam to the forward position.

And now, the most famous instruction, "installation is the reversal of removal."

With the cam rotated all the way forward (adjuster rod fully extended from the pedal) place the clutch cable through the guide tube and hook the end over the cable cam. Turn the adjuster screw to tighten the cable and set the release point. When satisfied with the adjustment tighten down the lock nut making sure the spacer is properly engaged in the pedal trunion. Install the lower dash and other parts. Once installed the clutch adjuster can easily be reached from the foot well area.

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