Hydraulic clutch systems aren’t designed to be adjustable in the same way you would adjust a mechanical cable clutch.
While there’s a popular belief that all hydraulic actuated clutch systems are non-adjustable or self-adjusting, there are some designs that let you make adjustments to compensate for the typical wear and tear of your clutch disc’s friction material.
Stick around as we answer the question: “Can I adjust a hydraulic clutch?”
What Self-adjusting means
But first, before we continue, we need to be clear on what a self-adjusting clutch refers to. Normally,you want about an inch of free play in your clutch pedal. That is the distance your pedal covers where you don’t feel any resistance or rather, the distance your clutch pedal moves before anything happens.
If you feel that, then you’ve got yourself a properly adjusted clutch pedal and it won’t be riding itself. However, over time, as your clutch pedal slowly loses adjustment, the point of engagement also rises higher and higher. This is because of the wear and tear of the friction padding on the clutch disc.
Sooner or later, the clutch pedal’s free play is lost, and your clutch starts riding itself. The worst part is you may not realize it if you’re not too keen. A hydraulically operated clutch system is designed to automatically make adjustments to compensate for the normal wear and tear.
In some older vehicles, you regularly had to make clutch adjustments. Eventually, customers grew tired of regularly making adjustments and replacing worn-out clutches. In some of these cars, you only had room to make slight alterations in the length of your slave cylinder’s pushrod.
However, these changes were limited and were not meant to compensate for the normal deterioration of your hydraulic clutch due to aging. To satisfy their customers, manufacturers began implementing self-adjusting cable and hydraulic clutch systems. They automatically adjust your pedal’s free play over time.
Optimum free play
For your clutch to work correctly, there’s an optimum amount of free play needed in the linkage between the clutch lever and pedal. On the one hand, if you have too much free play, the clutch may start dragging, which is quite problematic, especially in heavy traffic.
A clutch drag refers to the tendency of your vehicle to creep forward while in gear when the clutch is depressed fully because of too much clutch linkage clearance.
Conversely, if there’s isn’t enough free play then you might have yourself a slipping clutch. Like stated, as the friction material on the clutch disc wears down over time, it will require adjustment.
It’s recommended to regularly check and adjust your clutch pedal’s free play after every 6,000 miles or as per the manufacturer’s handbook . While older vehicles require you to make adjustments after a certain interval of time, newer ones typically come with a self-adjusting hydraulic clutch system.
When there’s no more room for adjustments
Now, at some point, there’s no more room for making adjustments, in which case, it’s time to get a replacement. And because of normal clutch wear, it will eventually lose its free play.
Unfortunately, unlike the mechanical linkage clutch system where the driver can easily feel the loss of free play that would tell them it’s time to hit the garage, you’ll not be able to detect it in your hydraulic actuated clutch system.
Failing to detect the loss of free pedal play early enough could prematurely wear down your clutch or cause failure. So it’s important that you are spot on about your periodic service checks. Always remember to check your clutch for wear regularly, which is something most people forget to do.
What usually happens is having too much clutch pedal free play. This is typically caused by burnt-out or loose linkages. It can be easily fixed by either replacing or tightening the fitting.
You typically get replacements when it’s completely burnt-out. It doesn’t have any more room for adjustment, and the point of engagement has become too high. On the other hand, if the engagement point is too low, then there are two possible reasons for it.
It could be that there’s a leak in your master or slave cylinders allowing air and other contaminants to seep through to the hydraulic system; a classic clutch bleeding symptom. If the pedal play improves after bleeding the clutch, then there’s a leak that needs to be found and fixed.
The other reason is that your floor mats are very thick making it impossible for you to depress the clutch pedal all the way down. You’d be surprised how much car travel you can lose with some of these thick floor mats.
Now back to the main issue.
Can I adjust a hydraulic clutch?
Most car and garage owners assume that hydraulically actuated clutch systems are generally non-adjustable and don’t refer to the manufacturer’s manual. Fortunately, some hydraulically operated clutch systems allow adjustments to be made on the free play and height of the pedal.
That being said, any adjustments made should follow what the vehicles’ manufacturer’s handbook for a properly adjusted and working clutch. We can’t stress this enough because of the variety of problems that arise with an improperly adjusted clutch.
Anything less or more than the optimum free play will cause a clutch slip. Since the pressure plate will not be able to exert the required pressure on the clutch disc or place the fork in contact with the clutch it may cause some serious damage.
Moreover, the heat generated from clutch slipping could damage the clutch. It’s release mechanism as well as the flywheel if it gets hot enough, and they may need to be replaced.
If you have an adjustable hydraulic clutch, then your slave cylinder’s pushrod should be fitted with a locknut and threaded. For those of you who are uncomfortable with the engagement point of your clutch, there are plenty of guides on how to adjust a hydraulic clutch.
Steven Reilly is a qualified mechanic and his passion for cars goes beyond just the technical aspects. He is also an amateur racer and all round car enthusiast. When he is not driving them, he can often be found in his garage under the hood of a rare model. Steven Reilly has lost track of the number of hours he has spent setting up his fine collection of rebuilt models. He believes that cars can provide a constructive and fun opportunity to teach the youth important life skills. In line with this, he is developing a community outreach program, potentially dubbed ‘Cars for change’.