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Front spring replacement...

Posted: Mon Jul 25, 2016 12:59 pm
by MyTriggaz
Picked up an fzr600 about a month ago and the po had gotten progressive springs part # 11-1129 that he didn't install yet. I'm kind if new to motorcycles but have decades working on cars so I'm going to do this myself. After doing lots of searching, I didn't find anything that was exactly what i was looking at doing. I just want to replace the springs only. the seals seem to be fine since I do not see the signs of a bad seal or leaking. All I found were instructions for removing the fork and doing a complete service on them.

So I'm looking at installing them soon and have a couple questions...

Can I just drain the tube oil, lift the front of the bike, take off the top caps, and just pull out the springs, drop in the new springs and put it all back together with new oil (compressed fork , 4" from the top)?

Anyone know the exact amount of fork oil is needed for each side to bring it the the 4" below the top?

The sheet that came with the spring said for the fzr600 I would need a 3.75" spacer. I assume the stock spacer is not that size and i would replace it with a new PVC spacer that is 3.75"?

Do the tighter coils go at the top or bottom in the tube?


Thanks for any help.

Re: Front spring replacement...

Posted: Mon Jul 25, 2016 2:31 pm
by willandrip
If doing it without a full strip your assumptions have it pretty much covered.

Best to remove one leg at a time completely and wash out the oil residue with petrol or other solvent..be careful some solvents destroy seals.
Pump them with the drain removed...you will get loads of metal particles and sludge out that otherwise immediately contaminates the (probably original ) oil.
Repeat until rinse is clean...pump it a good few times.

The correct oil capacity should be in the works manual.....
This figure is now useless as the replacement springs will take up more volume when fitted and the levels or amounts will be useless.
You will need to check the level of EXISTING oil with the spring inserted after checking its correct without the spring installed.
Use this as your datum .
Then fit the new spring and see if you can get the level the same.
Then if necessary drain out that oil carefully and measure the capacity .
Note the capacity for future reference.

This is often hard to achieve as the springs/spacers may be massively different ..thus the levels will be.
Best to underfill rather than overfill and burst a seal or lock the fork travel with too much oil.

Manufacture complete new spacer or add to existing with washer between new and existing to prevent distortion/override..

In my experience when fitting springs the tighter wound springs go to the lower of the fork..this is the reverse of
what would seam logical.

I am adding a pic. so you can see how different two springs can be ...FZR 400.
Exactly as fitted to machine..see coil orientation and spring mass difference that WILL alter oil volume and hence compression ability.
Single spring original Yamaha..Pair replacements...Wurth progressive
Image