Llessur Posted October 1, 2009 Share Posted October 1, 2009 Small but significant problem with the Spit 6 - brakes seems to work fine under normal use but if you hold the pedal down for long enough it will slowly and gradually sink to the floor. The system's fully bled, there's no sign of any leaks or fluid loss. Am I right in thinking this points to the master cylinder seals?If so, has anyone had any luck with resealing kits? I've heard good and bad stories - mostly bad.If I don't go down the resealing route what are my other options? New GT6 Girling cylinder? Wilwood? Single circuit or tandem? I'm not really too fussed with a servo.I'm on quite a strict budget but I don't like to mess around when it comes to brakes. Any suggestions? Link to comment Share on other sites More sharing options...
Nick Jones Posted October 1, 2009 Share Posted October 1, 2009 Yes, sounds like master cylinder (small internal seal rather than the main seal if no fluid loss). Try a seal kit for about £ 5 or a new (single circuit) cylinder for about £ 40.Seal kit stands a good chance of success and pretty easy to do....Nick Link to comment Share on other sites More sharing options...
Clive Posted October 1, 2009 Share Posted October 1, 2009 Was it not a new MC?Anyways, well worth trying the seal kit as Nick points out.If not, I have a good mc sitting in the garage, but worth resealing before re-use. May even have a kit lying about......I suspect most of the horror stories are when the cylinders are scored or whatever. Link to comment Share on other sites More sharing options...
Llessur Posted October 1, 2009 Author Share Posted October 1, 2009 cliftyhanger wrote:Was it not a new MC?Anyways, well worth trying the seal kit as Nick points out.If not, I have a good mc sitting in the garage, but worth resealing before re-use. May even have a kit lying about......I suspect most of the horror stories are when the cylinders are scored or whatever.Cheers Clive - it was a second-hand GT6 master cylinder that I got hold of around the same time as the engine - in other words it's been sitting without fluid for a year! I suspect this may be the cause of the problem...I'll give the resealing kit a try before doing anything else! Link to comment Share on other sites More sharing options...
GT6Craig Posted October 1, 2009 Share Posted October 1, 2009 I wouldnt even bother with a reasealing kit. I bought a new MC off ebay for £26. Its a modern reproduction but works very well, apparently it provides even more stopping power as the cylinder is marginally larger. Link to comment Share on other sites More sharing options...
Clive Posted October 1, 2009 Share Posted October 1, 2009 184 wrote:I wouldnt even bother with a reasealing kit. I bought a new MC off ebay for £26. Its a modern reproduction but works very well, apparently it provides even more stopping power as the cylinder is marginally larger.Is that one of the 0.75 ones? that will just make the pedal harder and less travel, won't affect the actual braking (but maybe your leg muscles ;D ) actually, soem of the very late GT6's had 0.75, got one on my crashed spit, which had 4 pot brakes.Does it have the large resevoir? most seem to be supplied with the smaller clutch-sized one. But anyway, I have never had a resealed MC leak (thrown a few away as damaged bores though) Link to comment Share on other sites More sharing options...
Llessur Posted October 1, 2009 Author Share Posted October 1, 2009 cliftyhanger wrote:Is that one of the 0.75 ones? that will just make the pedal harder and less travel, won't affect the actual braking (but maybe your leg muscles ;D ) actually, soem of the very late GT6's had 0.75, got one on my crashed spit, which had 4 pot brakes.Does it have the large resevoir? most seem to be supplied with the smaller clutch-sized one. But anyway, I have never had a resealed MC leak (thrown a few away as damaged bores though)Mine's one of the late 0.75 cylinders. I reckon I'll try a re-sealing kit for a few quid and then go on from there. I guess any cylinder damage would be easy to spot/feel?I'll give it a go and let you know how it goes. Just want to be able to drive the thing! Link to comment Share on other sites More sharing options...
Nick Jones Posted October 1, 2009 Share Posted October 1, 2009 When they sink slowly without loosing any fluid it is not the main seal that is the problem but the little one on the end of the piston assembly which is supposed to prevent the fluid escaping back into the reservoir and failing..... If the cylinder has been sitting around empty for a while this is probably causes by crusty deposits of dried fluid. A good clean and a seal seal kit should sort it. Clean with warm water and reassemble using the special red brake grease - excellent chance of success with this type of failure. Do not use anything with mineral oil base as the EPDM rubber seals don't like it.Bigger bore cylinder decreases travel but increases pedal pressure needed. I have gone the other way on my Vitesse and have 5/8" instead of 0.7. Travel is a bit longer but pedal pressures are reduced and 'feel' is better. If I didn't have Goodridge flexihoses the pedal travel would probably be too much.Nick Link to comment Share on other sites More sharing options...
THe Maestro Posted October 2, 2009 Share Posted October 2, 2009 I just had the same problem and have bought a new MC on ebay for 34 quid. It had an ajustable pushrod so I need to swap that for the original one but the washer that holds the old pushrod in place behind the circlip doesn't quite fit inside the new MC. Going to have to file around the outside or something. Link to comment Share on other sites More sharing options...
THe Maestro Posted October 2, 2009 Share Posted October 2, 2009 I just had the same problem and have bought a new MC on ebay for 34 quid. It had an ajustable pushrod so I need to swap that for the original one but the washer that holds the old pushrod in place behind the circlip doesn't quite fit inside the new MC. Going to have to file around the outside or something.I would get it done because it is an MOT fail, I would have got away with it on mine because I was sat in the car doing the brakes but they failed anyway because they were so poor.. Link to comment Share on other sites More sharing options...
GT6Craig Posted October 2, 2009 Share Posted October 2, 2009 Thats interesting, i had the same issue with the washer on mine, but a quick session with an angle grinder sorted it. Link to comment Share on other sites More sharing options...
Llessur Posted April 6, 2010 Author Share Posted April 6, 2010 Cheers all - the reseal kit worked a treat. Only cost about a fiver and took a couple of hours work in total. Brakes are now as good as new. One step closer in being able to make Leatherhead in May! :) Link to comment Share on other sites More sharing options...
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