front springs compression, and they are spent

[FastCletus]

took some advice and went about ordering front springs for my bike   through alot of deductive process i am pretty sure I have a cb 900c front end on my bike cb 750.  heres is where it gets funny as to why my front end sinks so low
my current springs are 503mm long  seems the replacment ones are 533mm from progressive .  i guess after 25K miles springs tend to shrink 30mm  

cant wait to get new ones and see how they feel

[sgtslag]

They are amazing.  However, if you do not replace the rear shocks, as well, you will notice their shortcomings...  Just an FYI.  Front and rear suspensions work hand-in-hand.  Even if your shocks appear to be in good working order, they are 30+ years old -- the springs are likely sagging just from age.  Sorry, not trying to be a salesman for Progressive, just want to see you have the best, safest ride possible.

Did you compare the lengths of the fork springs for both models before you ordered?  Hope they are correct for those tubes.    Cheers!

[FastCletus]

no don't think your being a sales person at all.  i am on this site for advice and experience .  absolutely going to get rear shocks as well.  originally wasn't going to spend that much, just finally decided if your going to do it right then do it right the first time.  have to wait for next pay day for shocks though.  or sell some more stuff on ebay.
cb900 f and C were way off from each other.  900c was the most close to what i have.  I have a email out to progressive now just to confirm which ones I need.  

engine - done
suspension - almost done
seat - at shop now getting recovered

this bike is coming along nicely

[Beekeeper]

I was having a real problem with the front end on my 79F.  I put the progressive springs in, added a longer spacer for preload since I'm a toad, and it cured all the problems.  What was misleading to me, was the original springs met specs when I measured them.  They were just tired I guess, and the front end felt like it was floating, or sliding on ice.  Now, rock solid.  You'll enjoy them.

[sgtslag]

The Progressive's are an advancement in technology, remember.  The OEM springs were state-of-the-art in their day (maybe?), but we've progressed tremendously since then.  Back in the 80's, the newest oil standard was around "SF", today, we are up to "SL", or "SN", and the differences between "SF" oils (will void a warranty on a new car...), and "SL" oils, are considerable!  Cheers!

[FastCletus]

so get this.  just got off the phone with progressive, and with the difference of 30mm between the new spings and my old ones, he said that would be very odd.  now I wonder if the springs that were in there were even the right size to begin with.  mine has about a 2-3inch spacer in it now.  he also said to have 1/2 -3/4 inch pre load.  (which I assume means 1/2 -3/4 inch out side the fork tube prior to putting fork cap one) damn why cant shit be easy???

[sgtslag]

If I remember correctly, mine, on two different bikes (CB750K, and the Voyager XII), stuck out a bit, prior to putting the caps on.  I had the tubes fully extended, with a jack under the engine, holding the front wheel off of the floor.

Relax.  See what you have when you install them; fill them with the proper amount of oil/ATF Fluid (this can be a challenge, read the instructions carefully, then read them again, and...  guess), cap them off, then take it for a short, careful, test ride.

Cheers!

[FastCletus]

beekeeper - thats exactly what my front end feels like.  

I measured and it looks like i have about 8mm of preload.  ie pvc cap sits outside fork tube 8mm.  

[Beekeeper]

I think the spacer that the 79F called for in the instructions was 1 inch.  I think I finally settled on 1.5 or 1.75 inches, and changed to a 20wt fork oil.  I'm a pretty heavy rider, but that cleared everything up. Remember, the more you compress the spring with preload, the more oil will be displaced, so pay attention to the instructions.

[FastCletus]

Here is where we are.  New front springs are amazing  Totally correct and a more normal bike feel.  Here's what else I learned about my bike.  The springs that were in it were for a 250cc of some kind I dont recall.  and to stiffen them up they put a spacer in it. A cb 900 front end with the wrong springs in it didnt last long,and to be honest seemed quite dangerous.  New springs dont require a spacer.  

Rear shocks should be here today or tomorrow.  Cant wait