Swapping from drums to front discs ?

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fozworth

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I’m thinking of fitting Dave Slacks front disc kit to my bus using the stock master cylinder. I’ve heard that if using the std MS you need to remove the non return valves . The person who owned my bus before me had Porsche 944 discs all round and was using the same master cylinder. I asked him if he had removed the valves but he didn’t know as he didn’t fit them himself,but said he never had an issue with brake binding . Would that indicate they have probably been removed?
 

Moseley

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Personally, I’d only be comfortable checking it in person, rather than relying on a previous owners’ comment, but I guess that’s your choice. I believe you would need to take the outlet pipe work off the master cylinder to confirm, I don’t think there are any external indicators to show whether they’re present or not, but someone more knowledgeable than myself could confirm!
 

fallingoffalot

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I checked mine recently, well a year ago, as it's had a disc conversation at some point. I got my info from the Samba, I seem to remember that if you haven't had it done the pads can bind as the residual pressure valve keeps a bit of pressure in the pipe. This is so the drum shoes are partially held in place between brake use to avoid excessive pedal travel when they're hot. I think as the disk calipers only rely on the deformation of the rubber seal in the piston to return the pad any additional pressure would mean the brakes would bind. I didn't actually dismantle mine to check as I assumed that as they weren't binding then the valves had been removed from the front circuit.
 

fozworth

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Cheers ,I spoke with Paul from Harry Harpic & sons and he said it’s more for the single circuit split systems rather than the duel circuit systems . I’ll get the disc kit and look into wether they are there or not . Cheers
 

Graham L

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We’ve removed them recently when fitting a disc conversion (one of David’s kits) but they will only still be there if it’s running it’s original master cylinder. The residual valve is in the additional fitting that is screwed into the master cylinder that your brake lines then go into, if there’s no additional fitting it’s very unlikely you have them fitted. If it had 944 brakes on it before I’d be surprised if the valves are still there,
There’s a good thread on the samba that shows how to check if they are there and how to remove them, it’s a simple process.
 

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