QUESTION
I need to replace the master cylinder on my '87 HC Turbo It is a 5/8" (with 7/16 UNF thread)
I have seen some forum threads with people using the 0.7" master cylinders to reduce the pedal travel - any comments?
A.P. - Blacktown, New South Wales
ANSWER
Does your existing master cylinder have a 3/8"UNF male to 7/16" UNF female adaptor?
The master cylinders that Lotus Marques carries in stock all have 3/8" UNF outlets, so it maybe necessary to supply an adaptor.
It is understood installing a 0.700" bore clutch master cylinder will reduce pedal travel but this has the potential to damage the clutch diaphragm.
If you calculate the difference in swept volume moving from 0.625" (5/8") bore to 0.700", this is approximately a 25% increase in swept volume.
This increase in swept volume will be translated into excessive movement at the slave cylinder and then over-centre the clutch diaphragm (which will eventually cause the clutch to fail).
The only way to restrict the excessive diaphragm movement is to adjust the clutch master cylinder push-rod to reduce the effective cylinder stroke.
A better way to reduce the clutch pedal travel (and promote earlier clutch operation) is to install a stainless braided Teflon hose with a slightly smaller bore (compared to the OEM red plastic hose).
Reducing the hose bore diameter, reduces the total volume to be moved and in turn promotes a slight increase in mechanical movement at the clutch slave cylinder.
NOTE - Changing a clutch hose to a slightly smaller bore requires the clutch diaphragm movement to be checked so that it is not over-centred.
FOOT-NOTE
The standard red plastic hose supplied by the Lotus Factory has nominal bore diameter of 0.175" but grows significantly when subjected to temperatures above 25 Degrees Centrigrade.
The Teflon -03 stainless braided clutch slave cylinder hose supplied by Lotus Marques has a nominal bore diameter of 0.1875" and is stable across a broad temperature range.
Copyright © 2014 Lotus Marques
I need to replace the master cylinder on my '87 HC Turbo It is a 5/8" (with 7/16 UNF thread)
I have seen some forum threads with people using the 0.7" master cylinders to reduce the pedal travel - any comments?
A.P. - Blacktown, New South Wales
ANSWER
Does your existing master cylinder have a 3/8"UNF male to 7/16" UNF female adaptor?
The master cylinders that Lotus Marques carries in stock all have 3/8" UNF outlets, so it maybe necessary to supply an adaptor.
It is understood installing a 0.700" bore clutch master cylinder will reduce pedal travel but this has the potential to damage the clutch diaphragm.
If you calculate the difference in swept volume moving from 0.625" (5/8") bore to 0.700", this is approximately a 25% increase in swept volume.
This increase in swept volume will be translated into excessive movement at the slave cylinder and then over-centre the clutch diaphragm (which will eventually cause the clutch to fail).
The only way to restrict the excessive diaphragm movement is to adjust the clutch master cylinder push-rod to reduce the effective cylinder stroke.
A better way to reduce the clutch pedal travel (and promote earlier clutch operation) is to install a stainless braided Teflon hose with a slightly smaller bore (compared to the OEM red plastic hose).
Reducing the hose bore diameter, reduces the total volume to be moved and in turn promotes a slight increase in mechanical movement at the clutch slave cylinder.
NOTE - Changing a clutch hose to a slightly smaller bore requires the clutch diaphragm movement to be checked so that it is not over-centred.
FOOT-NOTE
The standard red plastic hose supplied by the Lotus Factory has nominal bore diameter of 0.175" but grows significantly when subjected to temperatures above 25 Degrees Centrigrade.
The Teflon -03 stainless braided clutch slave cylinder hose supplied by Lotus Marques has a nominal bore diameter of 0.1875" and is stable across a broad temperature range.
Copyright © 2014 Lotus Marques