How much sag is too much sag?

[Zwartie]

In preparation for an upcoming suspension upgrade (later this summer), I decided to remove existing rear shock to measure it up - my '92 FJ has an FZR rear swing-arm and shock so I want to make sure that whatever I get to replace it (RPM or Penske) that it will be the right one. So anyway, after I removed and measured the shock, cleaned and re-greased the linkage and then reinstall the shock I thought it would be a good idea to measure how much sag there is. See below:

View of the rear shock linkage assembly:


Rear Shock Removed:


Suspension Uncompressed - Rear wheel is off the ground - measured 15" from top of axle nut to rear panel mounting screw:


Suspension Compressed - Rear wheel back on ground - measured 13" from top of axle nut to rear panel mounting screw:


So the difference between uncompressed and compressed (no rider or passenger) is 2". I would like to know if that seems normal or if as I suspect; the suspension has simply run out of Kookaloo. A few things to note: The bike has approximately 92,000 km on it. The FZR suspension was installed by the original owner at 30,000 km but that being said, I have no idea how many kms were on the FZR shock when it was installed so I'm going to assume that it has at least as many kms on it as the bike. The preload is also cranked up all the way.

My question to the group: how much sag is considered "normal"?

Thanks,

Zwartie

[racerman_27410]

what you are measuring is free sag..... what i feel is more important is rider sag (you and your gear on board) as these are the numbers that are most important.

For rider sag numbers you should be looking for approximately 30% of available travel both front and rear.

no wonder the spring has a lot of preload on it as the FZR is quite a bit lighter than the FJ.

KOokaloo!

[RichBaker]

Free sag, under the weight of the bike alone, should be between 10mm and 20mm. With just the rider aboard, you want ~30% of total travel. If you have less than 10mm with the correct sag with rider, the spring is too soft, and has too much preload. More than 20mm w/rider sag correct, the spring is too hard....

[A11an0n]

Sag should be measured with the bike unloaded and then with you sitting on it.  I'm not sure of the parameters though.  I know on my dirt bike it is 100mm, I'm sure its different  on the FJ though.

[markmartin]

http://www.fjowners.com/index.php?topic=764.0

I used this thread in the suspension files by andyb.  Check out the post by Pat C. quoting Bill P., for specific FJ sag measurements.

[Mike 86 in San Dimas]

My mother in law has way too much sag

[FJmonkey]

My mother in law has way too much sag

Way too much information Mike... And why are you paying attention to it??? 
The drinking or the pregnancy?

[Mike 86 in San Dimas]

My mother in law has way too much sag

Way too much information Mike... And why are you paying attention to it??? 
The drinking or the pregnancy?

Well you know what they say about mothers and daughters