Monte S2 clutch push rod repair.

[Rupunzell]

Got asked by a Xweb member to fix a S2 clutch pedal push rod. Never seen one of these before, out of curiosity and want to know, took this on.

The clutch master cylinder push rod is longer than what is used on the S1, this one is really wore-out.

Set up the pedal assembly in the BP, cut off the riveted end of the push rod pivot with a roughing end mill.

Done, then press out the old wore out pivot.

Pivot off.

Make a sleeve to convert the 10mm_ish hole to fit a 5/16/M8 dia NAS bolt. The IKO, M8 rod end
thickness is 12mm, OEM push rod is 8mm thick. The bushing is 2mm thinner to compensate for this difference.
Sleeve has a very slight press fit and held in with RC609 Loctite. Easily removable if needed.

Made the replacement push rod in the same way as previously posted, except the push rod is longer on the S2 pedal assembly.

End view.

Bernice

 

[lanciahf]

Thanks Bernice for fixing the clutch pedal. Last spring I picked up a S2 pedal assembly. Differences between the S1 & S2 assemblies are pretty neat. The brake pedal is set further away, so one has more leverage and they use a sort of "fulcrom" push instead of a simple pin. See below. Foot pedals are smaller and they use X1/9 pads.

 

[Rupunzell]

Interesting, appears the folks involved deleted the vacuum brake booster, then tried to make up for the pedal effort different by larger front rotors and a lever at the brake pedal. This design trades off pedal travel for pedal effort.

Gap between the engagement of the push rod to brake master cylinder's piston results in extra pedal travel, magnified by the mechanical advantage from the lever design.

Different mixed bag of results.


Bernice

 

[lanciahf]

Bernice, Are you saying I will have a brake pedal with a higher effort and less travel?

 

[Rupunzell]

Brake pedal with less effort, but more pedal travel. The lever action trades of pedal travel to gain more force at the brake master cylinder.
It can work due to the theory of fluids being not compressible being applied to a brake system. In practice, there are LOTs of places where expansion of the hydraulic (brake system) can happen, hoses, seals and ... with all that brake fluid remains vastly not compressible.

Teflon-metal braid brake hoses would be a good thing with this brake pedal design as those brake hoses have lower expansion under pressure helping to reduce expansion in the system.

The other helper for a system like this would be to modify the brake master cylinder push rod to an adjustable on just like what was done on the cutch master push rod. The adjustable push rod will take up the free play between push rod engagement to the brake master cylinder piston -vs- pedal. This would help reduce free play in the brake pedal giving the system better pedal feel.


Bernice

Bernice, Are you saying I will have a brake pedal with a higher effort and less travel?