Hanns Per Posted October 24, 2020 Share Posted October 24, 2020 in the Caterham CSR 260 I have the original AP Racing clutch cover with the red dot and the AP racing master cylinder with Dia 15mm and the SBD standard slave cylinder. The pressure needed to press the pedal is very very high. Has anyone a solution to reduce the pedal pressure? Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 24, 2020 Share Posted October 24, 2020 you can swop the clutch master cylinder for a smaller one, .7 or .625 are readily available and a striaght swop, you will need to reset your clutch stop too though. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 24, 2020 Share Posted October 24, 2020 https://www.ebay.co.uk/itm/Brake-Clutch-0-625-quot-5-8-quot-Bore-Master-Cylinder-Integral-/371599191865?hash=item568509af39https://www.ebay.co.uk/itm/APS-Brake-Clutch-Master-Cylinder-Integral-Reservoir-Bore-Size-700-quot-/301111802593?hash=item461ba97ae1 Link to comment Share on other sites More sharing options...
OldAndrewE Posted October 24, 2020 Share Posted October 24, 2020 .7 and .625 are both larger than the original 15 mm (17.8 and 15.9 respectively) so will increase pedal pressure Link to comment Share on other sites More sharing options...
Leadership Team Shortshift Posted October 24, 2020 Leadership Team Share Posted October 24, 2020 CSR fitment is different configuration/orientation. Not easy to find alternative m/c's.James Link to comment Share on other sites More sharing options...
revilla Posted October 24, 2020 Share Posted October 24, 2020 Also remember that by simple conservation of energy, whatever you do, to get the same action at the clutch plate, force * distance at the pedal will remain constant. So reducing the force will require a longer travel. Unless of course you go power assisted, which I think is unlikely. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 24, 2020 Share Posted October 24, 2020 are forgot is was a CSR..... If its the same as the race version on the CC site then AP list a 14mm option here:https://apracing.com/race-car/master-cylinders/flange-mounted-types/offset-flange-type/cp4623-type Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 24, 2020 Share Posted October 24, 2020 or does the LHD use remote reservoirs...? in which case you should be able to buy a bare one and take the connecter to your reservoir form your current one. Link to comment Share on other sites More sharing options...
Hanns Per Posted October 26, 2020 Author Share Posted October 26, 2020 I have the 14mm master cylinder and tried it but as mentioned by revilla I am stuck within the law of physics it does help a little but results in longer pedal travel. For the clutch if I am not wrong I need 6-7mm travel minimum. One thing I have not checked yet would is the possibility to increase the diameter and to change the proportionof pedal length to master cylinder pushrod connection or would this accoridng to the law of physics have no impact on pedal pressure? Link to comment Share on other sites More sharing options...
SM25T Posted October 26, 2020 Share Posted October 26, 2020 The lever ratio of the pedal arm would make a difference to the effort needed. Link to comment Share on other sites More sharing options...
revilla Posted October 26, 2020 Share Posted October 26, 2020 Yes I'm afraid it doesn't matter how you do it with combinations of the hydraulic diameters at either end, the leverage at the pedal etc. it will work out the same. 10% less pressure, approximately 10% more travel! Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 26, 2020 Share Posted October 26, 2020 Then altering the mechanical advantage on the pedal may be your only option....unless you pull the engine and see if you can get a slave cylinder with and increase CSA therefore moving the hydraulic ratio back in your favour.Guessing your slave is hidden in the bell tank in which case providing you can identify it and check this option before pulling the engine sure CC will know which model was fitted originally. Link to comment Share on other sites More sharing options...
Hanns Per Posted October 26, 2020 Author Share Posted October 26, 2020 I use the clutch slave cylinder from SBD :Hydraulic Clutch Slave Cylinder 40mm, I think its the one from Titan, they all look the same. I calculated with the surfaces and the stroke of the 0riginal 15mm dia master cylinder I get the required stroke with the this slave cylinder for the clutch. The pedal pressure is OK for the yellow dot clutch cover which I use now with a high tuned 2.1 duratec engine. But its very hard with the red dot clutch cover which is necessary for the torque of the well tuned 2.4 engine I will put in for 2021 season. Anyone ever thought of some sort of hydraulic supporting device? Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 26, 2020 Share Posted October 26, 2020 you could add an indirect servo........or keep the yellow dot cover and use a cerametallic centre plate which will increase the torque capacity of the clutch, naturally there's a trade off in 'feel' though, Guessing you will be looking at circa 220lb/ft for the 2.4AP gave me the following figures based on the stock 5352 organic centre plateYellow dot (-1) cover 215 lb/ftRed dot (-500) cover 280 lb/ftCerametallic v organic increases the torque capacity in the region of 80 lb/ft Link to comment Share on other sites More sharing options...
Hanns Per Posted October 27, 2020 Author Share Posted October 27, 2020 Yes this could be a solution, I did have for a while cerametallic unsprung 184mm clutch, the feel was ok but the fact that it was unsprung was not OK because of the noise generated in the gearbox and clutch. Thks for your hint will look at it. Link to comment Share on other sites More sharing options...
elie boone Posted October 28, 2020 Share Posted October 28, 2020 On a Manual gearbox you should use the spring version clutch, the solid plate suits better a sequential gearbox. Link to comment Share on other sites More sharing options...
Hanns Per Posted November 1, 2020 Author Share Posted November 1, 2020 just read about Hunday electric clutch actuator i.e. clutch by wire Link to comment Share on other sites More sharing options...
Hanns Per Posted November 17, 2020 Author Share Posted November 17, 2020 can someone report of a practial driving experience with cerametallic sprung center plate manual gearbox and road (not race) use only. Woiuld this be OK or a great difference and cumbersome compared to an organic plate? Link to comment Share on other sites More sharing options...
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