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Forge Twin Piston Dump Valve ServiceOn this page… (hide) This is an article still in draft - work in progress Introduction… Whats in the box…Forge Twin Piston Dump Valve Service The Parts - what you get in the service kit….. This package turned up in the post… So this is what you get in the kit…. Parts are new big piston, 2 piston rings, small piston spring and red grease The Forge Twin Piston Dump Valve http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=0006&product=FMDV004 So after removing the dump valve from the car, this was the offending article to be taken apart… Viewed from vacuum nipple end… Viewed side on…… Viewed from the fmic pipe end… Dirt and stuff inside the piston housing yikes… Dump Valve Disassembly Around the centre of the DV, with the vacuum nipple facing you, you will see 6 allen bolts, remove these using a 3mm allen key, remembering to take them off from opposing sides as this will stop the internal spring causing any unnecessary stresses on the bolts. Keep a good hold of the DVas you remove the final two opposing two bolts as the spring (on mine anyway) is strong and can force the two halves apart with some force and you will be picking up pieces of DV from the floor…like I did once before and leaves with the parts blown to the four winds…. So with the 6 bolts removed you have a dirty DV to take apart. On the left is the ‘bottom’ half of the unit, the hole in the middle is where the vacuum line is connected to. On the right is the top half containing the large spring, spacers, large piston, small spring and small piston. This is the ‘top’ half with the large piston embedded and large spring inserted (atop some spacers), hidden below this large piston is the smaller piston and small spring…. This is the DV laid on its side from left to right: the bottom half (nipple end), large spring, large piston and the top half (Intake end) showing the smaller piston and spring… The top half showing the smaller piston and spring…. The top half apart ready for cleaning, from left to right – small spring, small piston and bottom half DV assembly Dump Valve cleanup Remove the two rubber rings in the bottom half and throw away. They may be worn and if so can cause leaks as the seal they form with the big piston will be compromised. Clean out the inside of this half of any debris using a dry cloth rag not forgetting to do the 2 recesses from where the rings came from. Using a rag or paper towel clean all the gunk / oil / debris from the top half of the DV, also clean the small plastic, throw away the original small spring. Dump Valve Reassembly Now all sparkly and clean, refit the piston and the new spring (that comes in the pack) so that the spring fits snugly onto the piston. Chuck away the old bigger piston and replace with newly supplied piston…. Ensure that the new bigger piston faces with this end downwards towards the small spring. The small indentation in the centre of the bigger piston matches the small piston spring, this side of the piston is not as deep as the second side…. New large piston fitted with deeper end facing upwards. This end will have no indentations and will be totally flat. My DV had 4 spacers inside with the big spring, give them a clean to get rid of any grit and fit back inside this (deeper) end of the piston…. Refit original big spring ensuring the spacers are directly beneath the spring. With the bottom half cleaned out, using the supplied red grease, insert the grease only to the slots where the rings are to sit. Insert two new rubber rings…. And then reapply a little more red grease only over the tops of the new rings… Now that it is all clean, replace the bottom half over and onto the top half all the while keeping compression on the spring and then replace the allen bolts. Ensure you use opposing holes so that the sprung load is distributed evenly around the edges of the DV. You will notice that, like mine, when fitting the two halves together, make sure that they go together smoothly and the rings are not pinched by the big piston as it is pushed in. It’s not as tight a fit as compared to brake pistons but the grease does a good job of lubricating the piston as it slides in. When together you should be able to use your thumb to push down on the small piston (on the left on this photo) and feel no rough resistance to your pushing, just a smooth and even flow as the big piston is pushed against the spacers and big spring…. Clean
Information Source - SIDC forum thread by vimmy, Got me some lights… |
