New Fork Spring Noise

[aj_mariner]

Bought new springs for forks and shock from local Beta Dealer. New fork springs are Eibach EMS for 48mm Sachs (2017 300RR RE). Installed the first one and refilled with oil, now the fork makes a sound like an old mattress. The new springs feel like they were sandblasted and not polished afterwards. Will polishing the outside of the springs with fine emery cloth fix the noise? Anyone try this or is it a waste of time? Cheers.

[KB112]

I can't imagine that it is necessary to polish your fork springs. Can you describe the sound a little better? Seems like it would be hard to here the spring scraping the fork was with it sitting in a bath of oil.

Also, just curious, did you measure the length of the stock spring vs the Eibach?

[katoom400]

if you don't like the noise you could polish the springs, otherwise they will polish themselves after some miles...when you hear the noise stop, change the oil!

[bryanaverill]

My genuine Beta lighter springs did that at first. The noise wen away after a couple rides.

[aj_mariner]

So polishing them did the trick. No more old mattress sound. At first I was a little pissed that it was something you had to do after buying a brand new part but it only took an hour or so. Nabbed some 4"x6" sheets of 240 grit, wrapped it around the spring, and ran it up and down like a porn star. I also lapped the flat ends to smooth them out and get rid of the cut marks. Last, sprayed them down with brake cleaner to remove the crud. Can't upload pics from my phone so I'll have to do that later.

This seems like something that should be done whenever changing fork springs. It will reduce wear on the inner tube and keep the junk out of your oil.

[aj_mariner]

The Eibach spring was a couple mm longer than the stock spring

[bikesparky]

This seems like something that should be done whenever changing fork springs. It will reduce wear on the inner tube and keep the junk out of your oil.

I agree!
In my opinion that's part of the reason the CC forks wear out prematurely as the "rough" springs hit the inside of the inner tube and create wear and oil contamination.

[aj_mariner]

I don't want a repeat of the dirty oil syndrome madness. Polishing new springs seems like it would be a service carried out by suspension shops who want to go the extra mile. My fork oil looked pretty good. Some metal fines but nothing to jump up and down with a 22 page post about. It's a dirt bike, and some dust will always make its way past the seal and into the oil.
After disassembling the forks, I noticed that there was some dirt that had settled into the bottom of the inner tube. With the compression assembly out and fork extended, I hosed down the internals with contact cleaner several times, dumped out the remaining liquid and blew out with air. Then installed the bottom rebound adjustment cap, filled with oil and exercised the fork several times to recoat all internals and washout any leftover residuals. Dumped the oil into a separate container to be used for the same purpose on the next fork. Reassembled the fork completely and refilled with 350cc of Motul 5W Expert Fork Oil.

From here on out, I plan to change the fork oil every time I change engine oil just to simply get them on the same schedule. Being new to dirt bikes, I just wish that more maintenance guidance would have been provided in the owners manual regarding fork and shock oil change frequency.

On a side note when I did my first fork oil change, 350cc came out. The fork "Supplimentary Shhet" in the owners manual lists fork oil quantity as 388cc. Not sure if this is the quantity used when the forks are completely dry or what, but I am going to try this quantity at my next oil change and see if it makes much of a difference. If anyone else is going to be doing a fork oil change in the near future, you might want to try this...if not, I'll post about it later.

Rant complete. Time to ride the gnar.

[aj_mariner]

Here's a pic of the polished spring

IMG_0192.JPG (57.63 KiB) Viewed 11782 times

[McKay]

I tried Eibach stiffer springs at first, found the same thing.
Went to Race Tech springs, way better quality on finish and the rear spring is about 3/4 longer than Eibach. That is a good thing for me.