When the aftermarket for the Focus ST just started the first and only manufacturer of after market clutches was Spec. Putting a big turbo on the car I didn’t want to deal with the stock clutch not holding up due to the increased torque. I jumped on the Spec clutch (mainly because it was the only option). Since then Clutch Masters has thrown their hat into the ring. About a week ago I had the Clutch Masters FX250 put on.
This is going to be a very bad comparison of the two manufacturers. The comparison is bad because the products from each aren’t really the same (aside from there being a clutch and a flywheel). The parts aren’t directly comparable.
This is also an unfair comparison because I had the Spec clutch for 10K miles and I’ve only had the Clutch Masters one for about 300 miles.
The whole reason for changing clutches is the Spec one was giving me issues. I had been driving it hard and abusing it pretty regularly. The real trouble started when I accidentally downshifted on the highway from third into second instead of into fourth with the revs really high. Burning clutch ensued. As someone who has been driving a manual regularly for over a decade this was very embarrassing. After this the travel decreased significantly making it hard to be smooth. The car was still drivable but I think it broke the slave cylinder. A few months after the incident the engagement point dropped to the floor. Having some issues I drove on it like this for about two months. None of this is something you should do.
The clutch was toast. I wasn’t too happy that the Spec clutch only lasted 10K miles. It should have been able to hold up to what I threw at it. This is a performance clutch and the whole point of getting it was because it’s supposed to be able to take abuse. I decided to get a Clutch Masters as a replacement. It’s not really that I’m upset with Spec per say, I mainly wanted to try something else. I haven’t seem anything out there comparing Spec with Clutch Masters so I figured I’d find out myself. I needed a new clutch anyway so why don’t I found out which is better for when I need to get the next one.
Choosing a Clutch
I realize that not everyone knows how to choose the right clutch. You really need to choose the appropriate clutch for your car’s torque numbers and your driving conditions. There are different clutch materials with different performance characteristics. Daily driving is different than occasional track days. Let alone thinking about professional racing. I’m not going to go into a detailed comparison of clutch materials, how they differ, or how they relate to different diving conditions. Just realize that of this combined can impact the feel of a clutch and what it can handle.
I’m only going to cover torque numbers. For reference the Focus ST (at least the 2013 model I have) has 270 lb-ft of torque. My car as tested on a dyno is putting out 343 lb-ft. This is why I wanted a clutch that can handle a bit more power.
Realize that a dyno measures torque at the wheels. Clutches hold at the flywheel (it touches the flywheel). Clutch manufacturers provide their torque number at the flywheel. Meaning, if you have numbers from a dyno you need to figure out the drive train loss and then calculate the actual torque at the flywheel.
Every engine is different and the only way to find the real drive train loss is to dyno a car then dyno it again after adding power. You also want to do so under the same conditions. Preferably on the same day. I didn’t do this so I had to figure it out using numbers from the internet and typically numbers for a manual transmission FWD car.
Typically a manual transmission FWD car will have around 12% loss. That said, 15% is a safe number. At 15% my car is putting out 395 lb-ft. If you want to be paranoid use 25%. This puts my car at 429 lb-ft of torque at the flywheel. I kept these number in mind when choosing a clutch.
These are the parts I’ve actually had on my car and have driven with. I’m going to list specs for what I had/have and their equivalents. Just keep in mind for the subjective section I’m comparing the parts in this section. Both clutches are non self adjusting single disk clutches. Other than being a clutch that’s all they have in common.
- Light weight aluminum flywheel
- Stage 2 clutch
- Steel flywheel (not light weight)
- FX250 clutch
One thing to keep in mind is Spec does not offer a steel flywheel. Clutch Masters offers both aluminum and steel.
So there is an aluminum flywheel and a steel one. The Spec stage 2 (I had) is the equivalent of the Clutch Masters FX100 (never had) and the Spec stage 2+ (never had) is the equivalent of the FX250 (I have). So the two sets of products I had/have can’t really be compared fairly, but I’m going to compare them anyway.
Specs (not the company)
I only had/have the stage 2 and the FX250 but I’m going to include the other two I mentioned in the specs. I’m only going to compare the clutches and flywheel combos in the subjective sections.
Spec and Clutch Masters list their torque specs differently. Spec lists the actual torque number the clutch can handle. Clutch Masters lists their’s as a percentage over stock. I’m going to list both the percentage and what it works out to.
Spec Stage 2
- 485 lb-ft
- Segmented Kevlar
Spec Stage 2+
- 545 lb-ft
- Full faced, carbon semi-metallic on one side and Kevlar on the other
Spec Aluminum Flywheel
Clutch Masters FX100
- 70% over stock and 459 lb-ft
- Steel back organic
Clutch Masters FX250
- 110% over stock and 567 lb-ft
- Clutch Masters formula button on one side and a heavy-duty steel back organic on the other
Clutch Masters Steel Flywheel
Note: These prices are subject to change as dictated by the manufacturer. These are the prices I pulled at the time of this post and is roughly what I paid.
Light Weight Aluminum
I went with an aluminum at first then steel second. Aluminum revs faster than steel but can wear a clutch faster. Each one feels different and since Clutch Masters makes both types I figured why not try the steel one.
I absolutely loved the feel of the aluminum flywheel but it did have a few drawbacks.
The biggest drawback was it reved faster than I could shift. This is probably a big part of how I accidentally suicide shifted. I guess some people would see this as a positive (fast reving not suicide shifting). I see it as, if you can’t go all out without bouncing off the redline you’re not getting the most out of your car.
Another drawback is the flywheel being so light and the engine reving quickly means it was super easy to spin the tires when stopped. So easy that it was really difficult not to. My tires didn’t fair well and I’m getting very close to needing to replace them.
The last drawback is increased vibration. It was noticeable but not unreasonable. In traffic it wasn’t an issue but it did wear me down on multi-hour trips (this is a big deal for me).
It just doesn’t feel as nice as the light weight flywheel. I can’t really explain how but I don’t like it as much. This is personal preference because I really liked how the light weight one felt after switching from stock. The steel one feels more like stock so I can’t really say this is a negative in general. That said, it just doesn’t feel as nice to me.
The steel flywheel feels heavy. Really heavy but not nearly as heavy as the stock dual mass one. I almost never spin the tires. Reving is slower but in a good way. I can actually manage to shift.
There is less vibration than the aluminum flywheel. I don’t feel tired after a long trip like I did with the light weight one. You might not think it matters but I really do feel a difference. Again if you don’t don’t drive for hours you’re not going to care. As someone who drives 2+ hours at least once a week this matters to me.
One thing I haven’t mentioned is how the car behaves when letting off the gas. I can’t really compare because of the car’s rev hang. I want to say the light weight aluminum flywheel revs up faster and revs down slower than the steel one. But it’s really hard to tell with the ECU compensating when reving down. The tune I have does not disable this.
Spec Stage 2
The Spec stage 2 felt nearly identical to stock. I’d say 95% identical. It was a little heavier but not enough that it really matters. It felt great. The engagement point was in the middle of the pedal and had nice, linear, and fairly long engagement length. I’d say exactly the same as stock except for the little bit increase in weight.
It took me about 15 miles before I was comfortable with it. This is probably due to it being so close to stock. There wasn’t any learning curve.
The issue I have with this clutch is it just didn’t seem to hold up. I know there are a few people with Spec clutches on their ST’s but I don’t think any have a Stage 2. If I had a Stage 2+ I might have had a different experience. There is some hate on the internet about Spec clutches being hit or miss. There are people reporting their Spec clutch failing between 4 and 10K miles. I don’t know anyone (I’ve met in person) with a Spec clutch. Also, you can’t believe everything you read on the internet.
Clutch Masters FX250
This is the worst feeling clutch I have ever had. The engagement point is high (could be something to do with installation but probably not) and the engagement length is short. I really don’t like the feel. I’ve been driving with it for over a week and I’m still not used to it. It feels really different.
I almost wish I hadn’t have bought it. That doesn’t mean I don’t wish I had bought from Clutch Masters. I probably should have gotten the FX100? I assume that has a more similar feel to the Spec stage 2 and the stock clutch. I can’t do much about this now.
This clutch kit came with a new slave cylinder. Clutch Masters says you must use it. My guess is that it’s stronger and is necessary to prevent it from failing like the stock slave cylinder did with the Spec clutch.
Pretty must all opinions I’ve seen have been positive. I know a few people with Clutch Masters clutches and they’ve all had good experiences with them.
The biggest unknown is how long will the Clutch Masters last. I’m hoping a long time. Driving on a bad clutch isn’t fun and clutches are expensive. Especially the installation.
I haven’t been driving with the Clutch Masters clutch very long and it hasn’t been fully broke in yet. I also don’t think clutches really hit their stride until about 1K miles. So I don’t know how it will end up feeling and if it will get better. I’m hoping a lot better.
I don’t know how the Spec stage 2+ and the Clutch Masters FX100 actually feel. This comes back to this being an unfair comparison because the two clutches I had/have aren’t really equivalent. I can only assume that the equivalent clutches will feel more similar.
Spec stage 2 is higher than the Clutch Masters FX100 and the Spec stage 2+ is lower than the Clutch Masters FX250.
All of the clutches should be enough to hold for my worst (25% increase) scenario. That said, I like a bit of head room for situations where it’s necessary. Like a really bad shift. I think if I had more headroom (if I had a Spec stage 2+) I wouldn’t have had a problem.
Similar to the torque numbers Spec stage 2 is less expensive than the Clutch Masters FX100. The Spec stage 2+ is more expensive than the Clutch Masters FX250. So you get more with the Spec stage 2 for less money but you get less with the Stage 2+ for more money. Once again, not really that great of a comparison. What this really comes down to is if you want Stage 2 / FX100 or Stage 2+ / FX250 “class”.
Clutch Masters flywheels are more expensive than Spec. Even the Clutch Masters light weight aluminum flywheel (that I did not list) is more expensive than Spec’s flywheel. Thankfully you only need to buy a flywheel (per manufacturer’s clutches) once. So if you stick with the same company (and the same wight/material) you don’t need to buy a new flywheel every time you need a new clutch.
Same. Good. No complaints. Responsive.
Even though I really liked the feel of the aluminum flywheel with the Spec stage 2 clutch, I don’t think I would get it again. The biggest drawback for me is the increased vibration with the light weight flywheel. I really felt it on long 2+ hour trips. Like I said I do this about once a week.
My other concern is the longevity of the Spec stage 2 (same goes for the Clutch Masters FX100). I think it would be fine in normal operation. I didn’t think they would hold up to abnormal abuse because they don’t have enough headroom. The Clutch Masters FX250 (and probably the Spec stage 2+) should be able to handle more (accidental) abuse.
Today I’d stick with my choice of the steel flywheel and the stronger clutch. After having the Clutch Masters FX250 for 10K miles I’ll have to reevaluate my decision. Both flywheels have an advantage and a disadvantage and the same goes for the clutches. Neither is perfect so it’s a which is worse (for me) decision.
After a few more days of driving the FX250 is slowly feeling better. I’ll update again when I hit 1K miles.
I’ve hit a little over 1K miles on the new clutch and I couldn’t be happier. Now that it’s broken in it is very easy to use. I’d say about 85% the feel of stock. It is a bit high but not too high. It has dropped a bit more toward the center. The engagement length is much better and longer than before.
The clutch is smooth for the most part. Normal conditions it feels good. Spirited it’s fine as long as you don’t drop the clutch. It’s easy (not as easy as stock but not much harder) to be smooth. If you want to be a bit more aggressive and drop the clutch you’re in for a surprise. HUGE bang! You don’t just hear it but you feel it throughout the entire car. If you’ve dropped the stock clutch this is 10x that.
Now that the clutch feels like it should I can really talk about the flywheel. Simply put it makes driving much easier compared to the lightweight one. The engine revs slower. Noticeably slower. While this makes acceleration slower it means you can shift before hitting redline. The lightweight one reved a little too fast for my taste.
Starting from a stop is also quite a bit nicer. I constantly spun my wheels unless I was super careful and barely pressing the accelerator with the lightweight flywheel. The heavier flywheel (when the clutch is broken in) I spin the wheels less often and not nearly as much. City driving it’s quite a bit nicer.
Overall this clutch and flywheel is a great combo. It doesn’t sacrifice drivability or comfort. Using that un-quantifiable measure of “feel” that’s really personal preference, I like this setup better than Spec. I still like the feel of the lightweight flywheel and Spec clutch. But after having some time with the Clutch Masters setup the way it’s meant to be, I don’t think I’d go back to Spec.