Tech article by Cory Walden ( Desert Thrasher )

This article is about how to convert your stock mechanical linkage clutch to a much improved hydraulic set-up using readily available aftermarket parts. It is a very simple conversion all you will need is a slave cylinder, master cylinder, rod end, a coupler nut or female threaded rod, a brake line, and a weekend. The reason behind this conversion for me was the installation of fenderwell headers that hit the stock clutch linkage, but it is a great advantage over the stock clutch no matter the reason you need/choose to do it.

These parts I used for this conversion came from Wilwood Engineering:
  • Master Cylinder- Here you have a few options, Wilwood offers several master cylinders, the most common one for a clutch setup is the small aluminum master cylinder with either a 3/4" or 5/8" bore. Either bore size will be adequate, I have used the 3/4" bore before in another project and it works great. The part numbers are; 260-1304 for the 3/4" and 260-2636 for the 5/8". Or you can choose the large aluminum master cylinder. I personally prefer this one just for the looks. It comes in 3 different bore sizes, but 3/4" is the smallest and I recommend this as the biggest bore size you buy. I first attempted to use a 1" bore and the pedal was so stiff that I could hardly press in the clutch. The part number is 260-6764 for the 3/4" aluminum master cylinder.
  • Slave Cylinder- P/N 260-1333 This is a very nice unit, it works by pulling your clutch fork.Other parts you will need:
  • Male 5/16-24 Rod End- I ordered mine from Summit Racing, but you can find them at many other bolts and fasteners store.
  • Coupler Nut or Female threaded rod- I used a coupler nut (a hex nut about 2-3inches long), but I could only find them in coarse thread so I had to tap it for the 24tpi fine thread. Both the rod end and the master cylinder plunger rod are 5/16-24 thread. I bought mine from a local bolt store.
  • A 3/16" brake line about 3 1/2 feet long- I went to my local parts store. How else are you supposed to connect the slave and master cylinders?
  • A brake fitting- Again from the local parts store. This is needed because the Wilwood Master Cylinder does not come with any fitting to put the brake line into.
  • Brake Fluid- From a local parts store. Duh! How else is your new clutch gonna work?
  • 5/16" threaded rod- From local parts store. For the slave cylinder bracket.
To get started you need to remove the old linkage:Remove the 2 bolts on the frame rail that hold the clutch arm mechanism. Also remove the clutch rod. Next remove the bolts for the pivot arm bracket that bolts to the bellhousing/engine block.This will leave your clutch fork hanging by the throw-out bearing, which is fine just leave it there for now.Now you are going to need to mock up the new master cylinder. As in the Zf 5spd tranny swap the new master cylinder is going to go in the speedometer cable hole, it will need to be enlarged a little, I used a die grinder and a metal cutting bit. Once the master cylinder fits flush against the firewall, attach the coupler nut and rod end to the master cylinder plunger rod. Have a friend hold the master cylinder in place while you go under your dash.

Tech Tip: It is easiest to remove the fresh air vent box so you have access to the pedal assembly.

With the plunger, coupler nut, and rod end as one piece; line it up so that it is as straight a shot as it can be when held against the clutch pedal. For myself it lined up just above where the clutch pedal bent upwards, see pictures.

Place a mark on the pedal where you will drill the hole to bolt the rod end to.

Next you have a choice, you can either crawl under your dash and remove the clutch rod from the pedal, and drill the clutch pedal under your dash. OR you can remove the whole pedal assembly ( I recommend this because it will be easier to drill the clutch pedal while its out). But of course the steering column must come out for this to happen. I am not sure if the pedal assembly will maneuver around the steering column, so I just removed mine.

To remove the steering column you will need to remove your steering wheel, use a steering wheel puller do to this(if you have the stock wheel). Remove the column cover and the mount located on the firewall. If you have the stock column shift linkage, manual or auto, it will need to be removed too. As well as any of the wiring connected to the column.

Next remove the steering box ujoint if you have the one piece shaft or the upper steering ujoint for those who have the two piece shafts. Now you can unbolt the column from under the dash, remove the two bolts that hold the column in place. These will probably be rusty and or hard to get out. With this all done the column should just pull out from the dash, or with some slight maneuvering at least.

Now to remove the pedal assembly you will have to remove your brake master cylinder (and power booster for those who have power brakes) as well as unhook your plunger rod from the brake pedal. Leave all your lines connected and place the master cylinder out of the way (this saves time by not having to bleed it again.) Then all you need to do is unbolt the 6 bolts that hold the pedal assembly on the firewall and the 2 under the dash. The whole assembly will basically fall down to the floor board, some persuasion may be necessary. Remove the clutch rod from the pedal, they are held in by a cotter pin. Now it is time to drill a hole in the clutch pedal. I used a 5/16" drill bit, drill through the pedal where you made your mark from earlier. And that's it for the pedal assembly. I bet you are glad that you went through all that extra work to remove the assembly, instead of acting as a contortionist and bending your body in all odd shapes to unhook that clutch rod and drill that hole.

OK it is now time to start the actual installation: Remount the pedal assembly and brake master cylinder. Place the new clutch master cylinder in place and mark where you will need to drill the holes to mount it, I used a sharpie marker. Drill the holes with a 5/16" drill bit. You will also have to grind part of the pedal assembly bracket to fit the upper bolt through to the master cylinder. For the upper hole the bolt will need to come from the inside out. Use some short 5/16" bolts with flat washers to mount the master cylinder.

With the master cylinder mounted you can now adjust where the clutch pedal will sit. I placed my clutch pedal even with the brake pedal and adjusted the coupler nut and rod end to accommodate it. Use a long 5/16" bolt to bolt the rod end to the pedal. Place the bolt through the hole you drilled in the pedal and tighten a nut down on it, the rod end will fit on the rest of the boltshaft. You can adjust the length of the plunger now by threading in or out the coupler nut and the rod end, then use the lock nuts to lock it all together.

After you get the coupler nut and rod end properly adjusted, place the rod end through the bolt from your pedal. Then use a nut to secure it in place. Now your master cylinder is all mounted!

The next step is to mount the slave cylinder:

You will need to drill a 5/16" hole in your clutch fork, where the rounded dimple part of the fork is located. I had a hell of a time drilling my fork, I eventually gave up and pulled it out completely, then used a torch to blow a hole through it. It is a pain in the butt to put the fork back in, but that might be the only way you can do it.

With the hole in the fork (and the fork back in place) place the threaded rod of the slave cylinder through and use the supplied spacer and nuts to support it (don't bother tightening it now because you will need to make adjustments later).

The rod end of the slave cylinder should be somewhat close to the transfer case crossmember. You will need to fabricate a bracket to mount the rear of the slave cylinder to the transfer-case crossmember lip. I used a 5/16" threaded rod about 6 inches long, but you can make your own bracket if you wish.

Line up the slave cylinder with the clutch fork, it will approximately be about where the crossmember mounts to the frame, I went a little farther over to the passenger-side and drilled my mounting hole because I didn't want to drill through the double plate area of the crossmember, see pictures.

Tech Tip: I have re-drilled my mounting hole through the double plated crossmember on account of some minor binding with the bracket at an angle.

I bent the 5/16" threaded rod in a 90degree angle at one end, leaving enough room to thread two nuts and the crossmember. Then I bent another 90 degree angle on the other side of the rod but in the opposite direction with enough room to thread two nuts and the rod end of the slave cylinder.

Next I mounted the 5/16" threaded rod to the crossmember by using two nuts with the crossmember between them to lock it together. Then I mounted the slave cylinder to the threaded rod by placing the slave cylinder rod end between two nuts and locking them together. You have lots of adjustment from both the front and rear of the slave cylinder.

Tech Tip: I had to use a coupler nut to lengthen the bracket for the slave cylinder. I cut my threaded rod bracket in half and placed the coupler nut between them to get more adjustment for the clutch. Depending on the length of the bracket you make you may or may not have to do this.

You may think that the threaded rod is not strong enough to hold the slave cylinder, but I have been using the same type of mounting for the hydraulic clutch in my 1956 F100, for several years now. I have had no problems with it.

OK we are almost done now!

Now you can run your brake line from the master cylinder down to the slave cylinder, remember to use the brake fitting for the master cylinder. It is a good idea to use a slightly longer brake line than you need so that when your body flexes it doesn't stretch out the brake line, just like the factory spiraled brake lines. You can run your new line anyway you wish, I chose to keep mine close to my firewall because of the fenderwell headers, leaving some attempted spirals for the slack.

Time for that brake fluid!

Fill your master cylinder and have a friend help you bleed the slave and master cylinders.

Make any and all adjustments to get your new clutch to work properly, there is a lot of adjustments you can make so be patient. The front of the slave cylinder is adjustable as with the rear of the slave cylinder, and if you use a coupler nut like I had to then you have even more adjustment.

Now you can enjoy your new hydraulic clutch!

Price List:
Small Aluminum Master Cylinder
260-1304 3/4" bore*$45.95
260-2636 5/8" bore*$45.95
Large Aluminum Master Cylinder
260-1101 3/4" bore*$49.99
Slave Cylinder
Summit Male Rod End 5/16-24
*You will need to choose one of the 3 master cylinders.

The above prices are from Summit Racing.

The remaining parts can be acquired from local parts stores.
  • Brakeline 3/16" SAE
  • Brake fitting
  • Brake fluid
  • 5/16" coupler nuts; possibly 2 total
  • 5/16" bolts; 2 short and 1 long
  • 5/16" nuts; 8 total
  • 5/16" flat washers; 2 total
  • 5/16" threaded rod
by Cory Walden