Front fork service …… better late than never!

Aprilia Caponord ETV1000 Rally-Raid fork cap ....... and yes, I've used this picture before!The dodgy wrist and Dog awful weather here in Italy at the moment have both contrived to keep the Capo tucked up in the barn, a hairs breadth from the magic 100,000Km. So while the rain poured its heart out, I decided to have a look through the Excel spreadsheet of service/repairs/upgrades for the Capo ……… and realised that the front Motul fork oilforks hadn’t had an oil change for over two years!

Well I must admit to being pleasantly surprised. The oil that came out was pretty clear and a flush with a dash of 5w oil soon removed the small amount of sludgy dregs from the bottom of the legs. A refill with blended Motul 8.5w oil and a reduced air-gap of 115mm (Std 130mm) works well, so I see no reason to fiddle with settings that suit my riding style. Overall the job took about an hour a leg taking it slowly, sipping tea and watching the clouds drift down the valley!

At this point, a gentle reminder for RR owners. Please remember that the Rally-Raid supplement is WRONG regarding oil volume! The forks take approx. 580cc each for the standard 130mm±2mm air-gap – NOT 680cc as specified ….. Unless you want a mess on the garage floor when it pours over the top of the tube!

Aprilia Caponord ETV1000 Rally-Raid Marzocchi front fork spacersAnd another point that it may well be worth mentioning ….. the fork recall that Aprilia issued in 2004 – has yours been done and what exactly IS done? As far as I can gather, it was simply a new spacer below the spring as the original was the wrong size and could, under harsh riding conditions, collapse and lock the forks solid. Not my idea of a bucket load of giggles that’s for sure. Aprilia say that mine was done in 2006 (thanks Tom at Moto Forza Italia – Silverstone, UK for helping) and Marzocchi say that the current Aprilia part number AP8163475 IS the upgraded part.

The spacer in mine looks fine although definitely showing signs of compression where it sits on top of the cartridge. This time I’ve flipped them over to even out the wear, maybe next time I’ll look into adding aluminium caps to the spacers to spread the load more evenly.

Anyway, that’s all done and dusted for now …… next stop, some new brake pads I think. The fronts look like the remaining material has about the same thickness of a well sucked After Eight mint! 😳

Oils well that ends well

A last item remained on the Capo service ‘To-Do’ list … fork oil replacement, a job I hadn’t tackled before. It turned out to be a nice simple job, the only fly in the proverbial being the Aprilia document itself ….. or to be more exact, the amount of oil specified in the document.

Firstly lets clarify terminology – the shiny 50mm shaft clamped to the bike is the ‘fork tube’, the painted part that holds the wheel/mudguard is the ‘fork slider’. The complete thing is the ‘fork leg’.

Removing the wheel, mudguard, crash bars and lower fairings only takes a few minutes and with the bike snugly supported below the sump guard, it was time to remove a fork leg. Tip1 – break the seal of the fork cap first (19mm socket) before dropping the leg out, Tip2 – only remove one leg at a time, it makes both the job and re-alignment much easier. Releasing the clamp bolts with the bodywork removed as you can see from the pictures, also makes for less hassle, swearing and knuckle grazing as well!

Once out, secure the leg vertically and remove the cap completely. I found it easier to hold the cap still and rotate the fork tube anti-clockwise to do this … don’t worry, nothing pings out under spring pressure on this type of fork. Once undone, you can let the tube drop down, oil won’t pour over the brim. Next, you have to remove the cap itself from the damper rod … use a 19mm spanner to break the seal between the locking nut and the cap. Once done, you can remove the cap by hand – again, don’t worry about spring pressure. The spring releases all it’s tension before the cap comes off.

Put the cap to one side and slide the spring out – make sure you have plastic inserts still attached at each end. Do it slowly to allow the oil to drain back down the coils and back into the slider … much less messy! No doubt the damper rod dropped into the slider, it’s not a problem. Now you’ve got to drain the oil out. I place a finger across the end of the tube to catch the damper rod and spring spacer while draining the oil. Once drained, tip the whole thing upside down and catch the spring spacer – careful the damper rod doesn’t shoot out and damage itself by hitting the bench. After pumping the slider/tube and damper rod, several times leave the leg upside down to drain for at least a few hours.

Clean everything and when you’re ready, start the refill. Now the book says to refill with 680cc of oil – 130mm below the lip of the compressed leg. The problem is that if you do this, oil will pour over the rim of the tube – clearly wrong! The book is also very woolly regarding oil grade and never mentions the grade that was used by the factory. Comparing the old oil to 5/10/15/20w fork oil, I’m pretty confident they used 10w, however I chose to use 8.5w based on load and riding style. After some experimentation and riding, this is the refill that works for me (updated 03/09/2014).

  1. Insert the fork spring spacer and compress the leg completely.
  2. Fill the leg to a depth of 115mm ±2mm (130mm ±2mm in the book) – blended 8.5w fork oil works for me. This is approx. 600cc of oil (580cc for 130mm air gap).

Remember to extend and compress the leg / damper rod while filling to expel as much air as possible. When done, rebuild and refit the leg. Repeat the exercise with the other leg. One fork leg controls rebound, the other compression damping – stripping is identical though. Don’t forget to torque the clamp bolts – 25Nm (18ftlb). Reassemble the mudguard, wheel, brakes and bodywork and sit back and relax, celebrating a job well done with a nice cool beer!

UPDATE 21/07/2011

In hindsight, the original oil may well have been closer to 15w …. the only thing touched outside the factory on this bike was the fork recall at 600 miles. The oil the dealer used and the oil used by the manufacturer may well be different!

Since then, I’ve replaced it for a blend that works out at 8-8.5w …… and it’s bloody fantastic! The bike tracks well off-road and both front/rear suspension work in unison on-road. The blend used is Motul  5w (78%) and Motul 20w(22%) with a combined range of approx. cSt@40c = 29 and cSt@100c = 7.5