Jh roadsport Posted April 9, 2018 Share Posted April 9, 2018 Hi guys, I have a newish 420R. On my way down to Silverstone tonight for tomorrows club trackday I go to push the clutch pedal and it’s halfway down before I touch it. A few pumps it comes back but not for long. I’ve had this issue last year then a mechanic at bookatrack bled the clutch fluid and it seemed better now it’s happened again. I’m at Silverstone tomorrow so it’s short notice to get it sorted. I’ll check the fluid level in the morning though last time it happened the level was full. Anyone else have this issue?thanks in advance Jason Link to comment Share on other sites More sharing options...
ChrisC Posted April 9, 2018 Share Posted April 9, 2018 Hope it’s just a bleed, the CRB or braided hose replacement are engine out jobs :-(. Bleeding is a bit of a pain with access, I have a cut down offset ring spanner for that job (8mm I think), not something I would have in my track day tool box. Link to comment Share on other sites More sharing options...
John Vine Posted April 10, 2018 Share Posted April 10, 2018 Sounds to me like the master cylinder seals are leaking. The initial symptoms are as you describe, but you can end up without any clutch action at all. Note that you won't see much of a fluid level change anyway. If I'm right, the simpler (but more expensive) cure will be to replace the m/c as a unit. The cheaper solution will be to renew the seals using a refurb kit.JV Link to comment Share on other sites More sharing options...
Jh roadsport Posted April 10, 2018 Author Share Posted April 10, 2018 Thanks for the replies. On checking under the bonnet this morning there was some leaked fluid from the cap. So checked the level virtually full. Just a small amount leaked. Cleaned it up and on tightening the cap it didn’t really tighten just went loose again so put a couple of layers of tape around it then refitted the cap and it created a better seal. Was fine for the trackday but on the journey home it went limp again so I’m going to have another go at getting a tight seal on the cap. Hoping that’s all it is. What is it with Caterham using crappy fluid caps that don’t work?? Link to comment Share on other sites More sharing options...
ChrisC Posted April 10, 2018 Share Posted April 10, 2018 Is your 420R under warranty? I agree the cap should be replaced and will cure the leak, but not sure it could cause the problems you describe? It’s unusual to leak from the clutch mc cap, the brake mc, that’s a different story. Link to comment Share on other sites More sharing options...
SM25T Posted April 11, 2018 Share Posted April 11, 2018 The cap is only a dust seal ... It does not form part of the hydraulic operation of the clutch. Link to comment Share on other sites More sharing options...
John Vine Posted April 11, 2018 Share Posted April 11, 2018 Agree with posts #5 and #6. I can't see how a leaking cap will cause the loss of clutch action you describe.JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 11, 2018 Member Share Posted April 11, 2018 The cap is only a dust seal ... It does not form part of the hydraulic operation of the clutch.http://www.rrsilvershadow.com/Techn/Hydr/BestH/Master.gifThat might not be quite the same as a 7's but it shows the general idea.Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted April 11, 2018 Share Posted April 11, 2018 Good animation! The two solid black shapes are the seals. The RH one closes almost immediately when the pedal is pressed and the piston moves. The LH one is the crucial one and is, I suspect, the one that's leaking (albeit slightly) in your case.JV Link to comment Share on other sites More sharing options...
DJ. Posted April 11, 2018 Share Posted April 11, 2018 Change the master cylinder, one from CBS is only £25. It's unlikely to be the slave, I hope. Link to comment Share on other sites More sharing options...
John Vine Posted April 11, 2018 Share Posted April 11, 2018 Alternatively, go for a seal refurb kit from Merlin or Demon Tweeks.(Your m/c bore is likely to be 5/8" -- certainly my R400D is.)JV Link to comment Share on other sites More sharing options...
Jh roadsport Posted April 11, 2018 Author Share Posted April 11, 2018 Hi thanks guys for the info/advice. Yes the car is within warranty so I will get it booked in hopefully they can get it done ASAP. Link to comment Share on other sites More sharing options...
John Vine Posted April 12, 2018 Share Posted April 12, 2018 Glad to hear that you're covered by warranty. Do keep us updated on the repair.JV Link to comment Share on other sites More sharing options...
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