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April 12, 2011

DNX408 Shock Build Guide

Filed under: News,Tricks and Tips — Tags: , , , — Stuart @ 11:19 am
ttt-dnx408-shockbuildtitle

Shock absorbers are what keep your DNX408 glued to the track so getting them built ‘right’ is important to get the best handling car.  We polled some of our experienced team drivers for information on how they build their shocks so we could write a little guide to cover some of the areas where doing things the correct way can make a difference.

ttt-dnx408-trimpiston Trim any excess from the piston – carefully ttt-dnx408-threadlock Use mininal red threadlock

The first step to get your shock absorbers built correctly is to attach the piston to the shaft.  Make sure there is no excess flashing on the piston to ensure smooth movement. If there is any excess flashing, carefully trim it off.  The piston attaches to the shaft with a screw that will need to be threadlocked.  Here you can either use the red Team Durango threadlock provided in your DNX408 kit VERY sparingly, or use some less aggressive blue threadlock from a third party.  If you use too much red threadlock you might find it very hard to remove the small screw when you want to change pistons in the future. If this happens, you might have to soak the parts in acetone to break-down the threadlock.

TTT-DNX408-partsbling

Insert the shaft and piston into the shock body as we will use this to help build the seals and guides into the bottom of the shock body.  Pull the shock shaft all the way out of the bottom to expose the threads, and give these a plentiful dousing of shock oil.  The oil will allow you to push the o-rings over the threads without damaging them and ensure the shock seal assembly is fully pre-lubed and ready for use.   If needed, you can put another drop of oil on before the second o-ring.

ttt-dnx408-oilshaft Lube your shaft well ttt-dnx408-orings Place the o-rings and spacers on, using more oil as you go

The lower shaft guide should sit flush with the face of the red anodised lower cap.  The part looks similar on both sides and could easily confuse you into thinking you can assemble them either way around.  One side has a slightly smaller diameter and will sit down properly in the lower cap. You can test this easily by pushing it from the outside of the cap and testing which side ‘clicks’ into place. You can then push the shaft through the guide whist keeping hold of the red cap.

ttt-dnx408-rodguide The lower shaft guide is sided – small side down. ttt-dnx408-guideinstall2 Test the fit on the outside of the bottom cap to get the correct orientation, then push the shaft through.

With all the seals and guides in place, liberally oil the parts and carefully push them into the shock body.  The red bottom cap is the final part to be assembled.  You can put a dab of threadlock on the lower threads where the cap rests to ensure it won’t work loose.

ttt-dnx408-oilshaft2 Cover the assembled o-rings and guides – as well as shaft with more oil ttt-dnx408-insertorings After covering in oil – push the guides and o-rings in carefully

Slide the rubber shock boot over the shock shaft and attach the lower shock rod end to the shaft.  You can use the piston screw to slowly screw the shaft into the rod end and avoid scratching the shaft.  Of course to un-fasten this you’ll need to use something to clamp the shaft itself.

ttt-dnx408-screwoncap With the bottom cap o-ring in place around the threads, screw on the bottom cap. ttt-dnx408-screwrodend2 You can use the piston screw to attach the rod end.

Filling the shocks properly with oil is an important step and one you shouldn’t overlook the importance of this stage.  With the shaft extended all the way out, fill the shock body with oil until it’s a few milimeteres from the top.  Slowly push the shock shaft in and out a few times to work-out any air bubbles and then put the shock absorber assembly aside for the remaining air to bubble out.  A good tip here is to use a couple of wheels stacked up and simply pop the shock through and allow it to sit. After sitting for a few minutes, top-up the oil in the damper until it’s at the top.

ttt-dnx408-airout2 ttt-dnx408-airout

There are a couple of different ways of attaching the shock cap and diaphragm. Our team drivers use both of these methods.  The first, and simplest, way is to push the diaphragm into the top cap – taking care to ensure it is fully seated and the shape is intact. Push in the shock shaft to set rebound and place the cap over the now filled damper body and slowly start to screw it down.  Once you’ve got a few threads down, angle the shock slightly and hold the cap steady with the bleed-hole facing upwards.  Rotate the shock whilst keeping the cap steady as this will let the excess air out.  Tighten the top cap with finger pressure.

ttt-dnx408-diaphram ttt-dnx408-diaphram2
ttt-dnx408-shockcap1-2 ttt-dnx408-shockcap1-1
TTT-DNX408-shockcap

Another method that some of our drivers use is to push the shock shaft in to set the rebound and then place the diaphragm into the top of the shock body.  Using your index finger, push the diaphragm in and gently shuffle the diaphragm until it’s properly seated.  Pull down the shock shaft to put some negative pressure on the diaphragm and keep it in place while you attach the top cap and tighten it with finger pressure.

ttt-dnx408-diaphram1st-1 This can get messy ttt-dnx408-diaphram1st-2 Gently press down the diaphragm and wiggle it round to seat it fully
ttt-dnx408-diaphram1st-3 After pulling down the shaft, carefully attach the top cap making sure not to displace the diaphragm ttt-dnx408-diaphram1st-4

TTT-DNX408-reboundlogo2Setting the rebound the same on each side is important but actual settings are down to personal preference and track conditions. Rebound can be thought of like an air-spring which works in combination with the coil spring.  More rebound will stiffen the suspension as the damper is compressed.  Less rebound can allow the suspension to move freely and soak up the bumps. More rebound will handle big landings better and give more ‘pop’ off the lip of a jump as the suspension compresses and releases when the car takes off.

Finish off the shocks by cleaning all the excess oil off that might have spilt / been ejected during the build.  You can use motor spray / brake cleaner to clean up the dampers but be sure not to get any on the seals as this can cause them to swell up.

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