Replace The Clutch Master Cylinder on a Lotus Elise and Exige
Fixing a failing clutch master cylinder on the Toyota powered Lotus Elise and Exige is pretty simple but tedious. Of course, the engine and transmission are Toyota units, so they are pretty easy to locate parts. However the clutch master cylinder and pedals are all Lotus specific parts.
Mine started failing and I had to spend a ton of time researching online to find anything about the procedure, let alone finding the parts or photos of the parts.
There are some differences in the years, all of my research focused on the US Federal cars so I don't have any information for pre 2005 cars or post 2012 cars. If you gain any experience with those cars, please comment below.
Anyway, the job is pretty simple mechanically. Honestly it'd be a 1 hour job if the car wasn't so damn small and I had this guide. Researching parts, getting under the dash and just finding enough space to remove bolts and parts quadrupled that for me.
Note that the clutch master cylinder and pedals are different on the 2005 cars. I have a 2005, so I'll be covering those in this article with notes about the 2006+ differences.
Again if you have any info to add, please comment below.
When the clutch master cylinder is failing there are several signs that can help you identify the problem:
- The pedal is soft or seems to be engaging at a different point
- It may be difficult to shift into gear
- The brake fluid reservoir is low.
- The brake warning light is on (indicating low reservoir fluid levels)
- There is brake fluid below or around the clutch master cylinder under the access panel or footwell.
- Holding the clutch pedal down for longer periods causes the clutch to engage lower then when you quickly press the pedal down and release.
Remove Access Panel
Remove the access panel on the driver's side of the car. You'll need to use a 3mm allen key to remove the hold down screw.
The panel then slides outward, away from the center of the car. It has a lip that slides under the black plastic grill, and 2 small nubs that slide into the rubber grommets at the center rib on on the clam.
Remove Brake fluid resevoir
Remove the brake reservoir cap and remove brake fluid using a turkey baster. Remove enough to get the fluid level below the clutch fill tube positioned on the side of the tank.
The two tubes on the bottom are for the brakes, which we won't be concerned with today.
Disconnect clutch master cylinder fill tube. You'll have to twist it off the master cylinder later, so I found it easier to press it out of the reservoir now.
To access it from inside the reservoir, remove the filter cup that's inside the reservoir and press it out using your fingers.
Cut the zip tie holding the brake/clutch fluid reservoir in place.
Remove the radiator grill. Use a allen key to remove the 2 screws at the rear edge. Then pull the grill out similarly to how the access panel was removed.
The grill has 2 tabs that stick into the clam along it's leading edge and it also interlocks with the grill on the opposite side.
To gain enough space to move my reservoir off the bracket, I needed to loosen up several of the clam mounting points to gain enough flex in the clam to pull over the bolts.
If you need to do this, remove the large hold down at the base of the windshield, and the 2 impossible to see nuts under the clam's ridge as shown.
The area under the clutch master cylinder and brake master cylinder is cavernous, sharp, and will devour any nut or tool you drop on this job.
To prevent losing hours trying to find nuts or wrenches from the depths of the front clam. Jam the area under master cylinders full of wadded up paper towels. It'll absorb brake fluid and keep your dropped fasteners from going too far.
Remove Fluid Reservoir Bracket
The bracket will be in the way when removing the clutch cylinder, remove the 2 13mm nuts holding it in place. You'll need a stubby wrench to get this off, there just isn't much room to move.
Notice how damn long the new screws are that keep the reservoir in place. I cut these in half to prevent me from having to loosen the clam next time I'm here.
Disconnect clutch hydraulic line
Remove the retaining pin from the hydraulic clutch line using a small or medium sized pair of needle nose pliers.
With the pin out, the o-ring sealed metal portion of the line will pull back from the plastic housing on the clutch master cylinder.
You probably won't be able to completely disengage the line until the clutch master cylinder is completely disconnected from the car, it's a very tight space with little to no room to move.
Disconnect Clutch Master Cylinder from the Clutch Pedal
Consider removing the driver's seat.
You need to be upside down, back to the floor, with your head and arms under the dash to reach the clutch pedal. This position can be pretty demanding depending on your size and how claustrophobic you are. It's much easier with the seat out.
Pre-2006 cars use these gorgeous extruded aluminum pedals, which also means that the clutch master cylinder attaches to the pedal differently.
2005 and before use a rod that screws into a large round pin or trunnion captured in the pedal. It has an 8mm hexagonal section on the rod that you can use an open-ended wrench to remove it from the trunnion.
2006 and up use a clevis and pin that attach to the pedal. Disconnect the clevis from the pedal. If you have a photo of this or know the fastener sizes, please leave those in the comments.
Here you can see the 2005 and before clutch master cylinder, hexagonal shaft, and trunnion out of the car
Before you get out from under the dash make sure the rod is fully pressed into the master cylinder like it would be with the clutch pedal pressed down.
Note this may spray fluid out, so your wad of paper towels or assistant will be useful here.
Unbolt Clutch Master Cylinder
Use a 13mm hex socket and wrench to remove the outer most bolt holding the master cylinder to the firewall/pedal box. For me, these we're very tight, requiring a good amount of torque to break loose. When removed it was obvious they had thread locker applied to them.
The bolt closest to the brake booster was impossible to use a socket on, I used a stubby 13mm closed end wrench (12 point) and cheater wrench to get enough torque.
Note: The Lotus service manual says that you must remove them from inside the car. This was not the case for my 2005 Elise. The nuts inside the car are part of the pedal box and not removable. So please inspect these 2 bolts before you start trying to remove them. I suspect the instructions applied to older versions of the car.
Remove Clutch Master Cylinder
Now for one of the most annoying parts. There is no good way to describe exactly how to maneuver the master cylinder out of the car given the cramped space. It will require calm persistence and patience. I promise, you're nearly there.
There are 3 things in the way.
- The master cylinder's clutch rod forces you to pull the part pretty far out to free it.
- The brake booster is so close and large, various parts of the flange, fluid feed tube, or body of the master cylinder will jam into it.
- The clutch hydraulic line is metal, in the way, and itself very confined and difficult to move.
Begin by making sure the clutch rod is fully pressed into the master cylinder. (I mentioned this before when you were under the dash.)
Disengage the hydraulic line from the master cylinder. To do so, I cautiously rotated the master cylinder coupling upward along with the hydraulic line. This rotation separated the two far enough that I was able to free the hydraulic line from the plastic housing.
Now, calmly wiggle, rotate, and move the master cylinder out into the space forward of it. I say calmly because you'll want to find the least stressful way to install the new one without breaking it.
For me, the winning combination involved gently flexing (not bending) the hydraulic line upwards, making room for the master cylinder to go down, under it into the small space in deeper toward the front of the car.
This is the only way I could get it out far enough to free the clutch rod that protruds into the car. But once I did that, I was able to pull the rod end back up and out of the car.
Of course, the whole time, various parts of the housing are going to jam into the brake booster. Through careful methodical persistence, I found a way to rotate the entire housing as it was coming out to give me enough room. By the time it was pulled forward far enough to free the clutch rod, I'd guess I had rotated the whole thing about 360 degrees.
Install Clutch Master Cylinder
Press the clutch rod completely in, and try to recreate the voodoo/kung-fu maneuver you just completed to remove the old one.
Take periodic breaks for your back/knees/sanity if needed.
Re-connect the hard hydraulic clutch line to the clutch master cylinder housing.
Remember how you removed it by sort of rotating the master cylinder up and flexing the line up at the same time? Do that, but put them together this time. Be cautious about not damaging the o-ring on the fitting.
Re-install the clutch master cylinder hydraulic line's retaining pin. It just slides in from the top.
Get back under the dash and screw the clutch rod back into the trunnion on the pedal. Go slow to make sure you don't cross-thread the trunnion.
On my car I screwed the rod all the way into the trunnion. This is how it was when I removed it.
Re-install the 2 large bolts holding the clutch master cylinder to the car.
Mine had blue thread locker on them, so I chased the threads with a tap and die set, and re-applied new thread locker.
Thread the zip tie for the reservoir through the bracket before installing it. It's much harder to do when it's in place.
Re-install the aluminum reservoir bracket using the 2 nuts that came off.
Slide the reservoir in place on the bracket.
I trimmed the long, thin, threaded bolts that slide into the bottom of the reservoir to reduce difficulty of removing again. (maybe I won't have to remove any of the clam bolts)
Connect the fluid fill line to clutch master cylinder. Be as gentle as possible, the structure and angle of the plastic nipple seems pretty susceptible to damage.
Zip tie the reservoir to the bracket.
Refill brake fluid and bleed
Refill the reservoir with fresh brake fluid. Remember, brake fluid naturally absorbs water from the air which is bad, so don't use old stuff.
Fill it up nearly to the top as you'll need a bunch of fluid to bleed the clutch.
Bleed The Cluch
We used a vacuum fluid evacuator, but you can use a pressure bleeder or just the traditional 2 person method if needed.
The master cylinder was completely dry, so this will require a little work to completely bleed the system. Because of this I really liked the idea of a vacuum or pressure method.
The clutch slave cylinder is located on the front bottom side of the transmission near the firewall.
Jack up the rear of the car and remove the belly pan to gain access to it.
Bleed the system completely till you're sure all air trapped in the master cylinder is removed.
Test the clutch pedal feel with the engine off. It should be fairly stiff and you should be able to feel the clutch spring's resistance.
If you're not confident it's completely bled, continue bleeding until you are satisfied.
Check the clutch master cylinder for leakage. Look around the fill tube, hydraulic line, and inside the car to make sure there are no leaks with the new parts or loose connections.
Tighten the bleed screw.
Replace the belly pan.
Lower the car back onto the ground and clear the area around it.
Now test the pedal with the car running. I quickly tested clutch engagement by driving back and forward just a few feet. It should be obvious if it's not right yet.
Final check on the brake fluid level - make sure it's at max.
Re install all the screws and panels you needed to remove before. Be sure to re-install all the clam bolts if you took any off.
The two under the center ridge are the worst, probability of loosing them in the nose of the car is about 99%. Seriously, you should celebrate if you manage to install them without any trouble.