Ridiculously hard clutch pedal after pedal box change
Discussion
Hello all,
I'm rebuilding my Ariel Atom 3 on a new chassis.
Originally it used a Tilton 600 series overhung pedal assembly. I've now switched to a Tilton 800 series which has identical mounting points etc, it's a straight swap. The original clutch master cylinder was a Tilton 74 series in 7/10" bore size. I've upgraded to a Tilton 76 series in the same 7/10" bore size.
Other relative things of note, I've changed the clutch assembly to a brand new identical assembly from the same manufacturer (these are built to order and I've triple checked with them that all the measurements/specifications are 100% identical). I've also replaced the standard Honda K20 flywheel with a lightweight 3.5kg RPC flywheel which "works with all clutches" etc.
I've also made and run all new clutch/brake lines using the same type of Goodridge hose.
Since carrying this out, the clutch pedal is ridiculously hard. Initially, I didn't even think it was moving the clutch arm on the gearbox, that's how stiff the pedal is. However, eyeballing the clutch arm at the same time as pressing the pedal shows it's moving.
I stuck the driveshafts in temporarily and put it in gear, as expected manually trying to rotate a driveshaft is very difficult. Pressing the clutch pedal allows the driveshaft to easily turn by hand. So to me that proves the clutch is engaging/disengaging.
I cannot see anywhere to adjust the clutch pedal, other than the physical position of the pedal on the Tilton pedal assembly. There does not appear anywhere to adjust the pivot point or pressure ratio etc.
In theory nothing has physically changed to affect clutch feel, but something must have. Today I swapped out the clutch master cylinder for a Tilton 76 series in 5/8" bore, so one size smaller. The pedal feel has improved, but it's still too hard for my liking and nowhere near how it used to feel. It's not a paddle clutch, it's an uprated organic clutch and prior to this it didn't feel much stiffer than any "normal" road car.
Does anyone have any ideas? I'd be grateful for any help or suggestions, I am at my wits end.
Thank you
I'm rebuilding my Ariel Atom 3 on a new chassis.
Originally it used a Tilton 600 series overhung pedal assembly. I've now switched to a Tilton 800 series which has identical mounting points etc, it's a straight swap. The original clutch master cylinder was a Tilton 74 series in 7/10" bore size. I've upgraded to a Tilton 76 series in the same 7/10" bore size.
Other relative things of note, I've changed the clutch assembly to a brand new identical assembly from the same manufacturer (these are built to order and I've triple checked with them that all the measurements/specifications are 100% identical). I've also replaced the standard Honda K20 flywheel with a lightweight 3.5kg RPC flywheel which "works with all clutches" etc.
I've also made and run all new clutch/brake lines using the same type of Goodridge hose.
Since carrying this out, the clutch pedal is ridiculously hard. Initially, I didn't even think it was moving the clutch arm on the gearbox, that's how stiff the pedal is. However, eyeballing the clutch arm at the same time as pressing the pedal shows it's moving.
I stuck the driveshafts in temporarily and put it in gear, as expected manually trying to rotate a driveshaft is very difficult. Pressing the clutch pedal allows the driveshaft to easily turn by hand. So to me that proves the clutch is engaging/disengaging.
I cannot see anywhere to adjust the clutch pedal, other than the physical position of the pedal on the Tilton pedal assembly. There does not appear anywhere to adjust the pivot point or pressure ratio etc.
In theory nothing has physically changed to affect clutch feel, but something must have. Today I swapped out the clutch master cylinder for a Tilton 76 series in 5/8" bore, so one size smaller. The pedal feel has improved, but it's still too hard for my liking and nowhere near how it used to feel. It's not a paddle clutch, it's an uprated organic clutch and prior to this it didn't feel much stiffer than any "normal" road car.
Does anyone have any ideas? I'd be grateful for any help or suggestions, I am at my wits end.
Thank you
If the master cylinders are of the same diameter then it can only be the pedal ratio that's affecting the effort needed to operate the clutch.
Have you checked that both the 600 and 800 series are the same ratio? Are there any adjustments that can be made to the pivot points or the pedal pad?
Put both aside by side and see if they differ. Worst case, refit the original and see if the clutch is the same.
Have you checked that both the 600 and 800 series are the same ratio? Are there any adjustments that can be made to the pivot points or the pedal pad?
Put both aside by side and see if they differ. Worst case, refit the original and see if the clutch is the same.
Where is the biting point ? has it moved ? Is the slave/bearing on the fingers moving a sensible amount ? Usually around 1/2" or so. Doubtful more.
When you are bleeding it at the slave, does the pedal move freely then ?
As above, is the pedal to slave ratio the same ? Why are you changing the pedal box in the first place ?
When you are bleeding it at the slave, does the pedal move freely then ?
As above, is the pedal to slave ratio the same ? Why are you changing the pedal box in the first place ?
Thanks for the replies.
I initially set the distance from the pivot point for the clutch pedal arm to the bottom of the foot pad to be the same on the 800 series as the 600 series. However, the 600 series doesn't have any real adjustment, the 800 does. In the manual for the 800 series, it appears that by moving the foot pad higher/lower actually alters the ratio grom 5:1 to 6.2:1.
I can't start the engine yet so checking the biting point isn't yet possible.
I bled the system on my own under vacuum, unfortunately I wasn't able to check the pedal feel during this process.
The reason I'm switching to an 800 series pedal box is because that is ABS compatible. I'm fitting an adjustable ABS system so need to use ABS compatible cylinders etc, the 600 series won't allow this.
Thank you
I initially set the distance from the pivot point for the clutch pedal arm to the bottom of the foot pad to be the same on the 800 series as the 600 series. However, the 600 series doesn't have any real adjustment, the 800 does. In the manual for the 800 series, it appears that by moving the foot pad higher/lower actually alters the ratio grom 5:1 to 6.2:1.
I can't start the engine yet so checking the biting point isn't yet possible.
I bled the system on my own under vacuum, unfortunately I wasn't able to check the pedal feel during this process.
The reason I'm switching to an 800 series pedal box is because that is ABS compatible. I'm fitting an adjustable ABS system so need to use ABS compatible cylinders etc, the 600 series won't allow this.
Thank you
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