Suspension concerns on my '89

[milehighFJ]

I recently purchased an 89 with 15K one owner miles. The suspension feels so soft, that when I hit a deep man hole cover or bump, it's obvious something is not right. On medium to hard front braking, the front fork will dive several inches. I suspect it needs new fork springs, as the originals are probably tired. What is the best route to take on a fork overhaul? Progressive springs and new fork seals? Any other suggestions? I think the rear shock is questionable as well. When my 120 lb. wife is on the back, I believe there is too much travel back there during the same conditions. Any particular parts house or vendor suggestions?

Thanks in advance Gents.

Enjoy the Summer.

[Arnie]

Doug,

Your best option may be to find an FZ1 that's had the engine removed and the frame buckled.  Then you can steal both the front and rear suspension :-) Good luck finding it.

"Progressive" brand springs are still way too soft.

Almost as good would be to service the forks (new seals, metals, oil ) and install Race-Tech Emulators and heavier springs.  Which springs you use will depend on your weight, and riding style.
Note: If you do install Race Tech Emulators you'll lose the external adjustment of damping.

Still a huge improvement would be to service the fork, and install stiffer springs.  Again, spring rate will be determined by your weight and riding style.  Springs of between 0.8 - 1.05 kg/mm rate have been used by many on this list successfully.  Springs are available from Sonicsprings.com  or RaceTech.com

As a start, you can use the chart on RaceTech's website.  I think they are skewed towards track use and are 1 or 2 steps stiffer than desired. 
As a point of reference, I weigh 105Kg (230lbs) without riding gear and am happy with the 0.95kg/mm springs I installed along with RTEmulators.

In the rear, you can increase the preload and damping, but you'll get the most improvement from replacing the whole shock assembly.
See the files section for more info.

Cheers,
Arnie

[Pat Conlon]

Hello Doug, yea +1 what Arnie said, stay away from progressive springs and go with .95 or 1.0kg/mm straight rate springs.
Also +1 on Race Tech, who makes some nice cartridge emulators you can install while you're at it.
FYI, Here's a great wirte up about it located in our Files section:
http://www.fjowners.com/index.php?topic=1911.0

Welcome amigo!

[andyb]

Start by making sure there is fork oil in it.  The springs won't stop diving unless they're vastly too stiff, that's the damping's job... and odds are, you have little to no damping.

The standard that many folks swear by is a Penske shock and straight rate .95/1.0/1.05 springs with emulators, if not a full front end swap.  Rather pricy, that route, but depending on what you use the bike for and what the roads are like may be worth it for you.

For seals, use OEM, and only OEM.  The "leakproof" ones... aren't.

Adjusted the preload and damping yet?  It's also possible that the prior owner or their mechanic has been in there and buggered things up a bit.

Start by measuring your sag, checking oil levels (betcha the seals are leaky and the forks are about a quarter full of nasty sludge rather than oil....), and going from there.  You can increase the oil height in the fork (more oil than stock spec) to help resist bottoming somewhat, as well as moving up a grade of oil (they're a little underdamped even when working well).  

Start here, then go to here and consider your budget, the riding you do, your weight, the roads you're on, how much work you're willing to do, and how many compromises you're willing to make (i.e., some fork swaps lose the speedo drive).

In a perfect world, I'd say just throw $5k worth of WSB fanciness on both ends, and adjust to your heart's content...

[milehighFJ]

Arnie, Pat & Andy-

Thanks for the advise. Looking forward to getting this concern sorted out ASAP.

Enjoy.

[Pat Conlon]

Good deal Doug.

Hey Andy, oh hell yea, of course, great advise you gave Doug. 
I  PM'ed Marsh with the idea that we create a "suspension" catagory in the Files section, whatcha think?
We could answer all these recurring questions as well as combine all the wheel mods in one area.

[Firehawk068]

Doug,
You are on the right track with the advice the others gave............
I just Overhauled my forks on my '90.
I went with a great OEM-quality seal/bushing kit that Randy @ RPM sent me (thanks again Randy)
I ordered 1.05kg springs, and Racetech cartridge emulators from Traxxion Dynamics, and used 10wt fork oil set to factory oil level.
I followed the writeup that is in the files section, and the job went really well. the article is very easy to follow.
Unless you mess up and miss one of the steps, you really can't go wrong!
I am fairly heavy (250 lbs) and I just rode 2000 miles from Phoenix to Willits for the rally and back, and the front suspension felt great!
It was not too harsh for long distance touring. Soaks up the hard bumps really well, but the huge difference was felt in the corners.......         I rode Hwy20 from Willits to Ft. Bragg and back a few times, and it felt really planted. Corners like a sportbike should. No more mushy front end!
I also installed a pair of fork protectors that I got from Traxxion, and I'd say they did their job already in protecting the seals. After I got back home from the rally, there was a good amount of bugs/grime plastered on them.
If you are staying with the stock forks, I highly reccomend this setup.

[milehighFJ]

Alan-

Thank you.

[andyb]

Sorry, long day at work and it's a pet peeve of mine, so it's rant time:

If your motor ran on 3 cylinders and spat and blubbered, you'd troubleshoot it instead of immediately working out how to transplant something else in it.  Probably clean the carbs, replace the plugs, and such.  But suspension?  Immediately everyone seems to want to throw parts and money at it!  Make sure what you have works the way it's supposed to first!  It's really not terrible, honest.

-You can adjust the oil weight to alter the compression and rebound (together) speed.
-You can adjust the preload via the adjusters.
-You can further add preload if you like the plushness but have too much static sag by adding spacers internally.
-You can adjust the compression/rebound (together) via the adjusters.  Admittedly it's not by a whole lot 
-You can adjust the resistance to bottoming (the spring rate at the end of travel, or the non-linear portion of spring rate if you prefer to think of it that way) by varying the amount of oil in the forks.
-You can adjust the rake/trail figures by sliding the forks up/down in the clamps (to a degree, they foul the masters after a 20mm raise)

If you've tweaked a bit with these and it's still not right, you now have a good set of stock forks to start with.  They're worth more on ebay if you want to go to a front end swap, and they also are a known quantity... so if you replace the springs, you know that the differences you're feeling are from that, rather than a problem within the system someplace.  You can't stick a stiffer spring in the stock fork and expect it to be anything other than a pogo stick if the seals are trashed and there's a half cup of glop in one side with the other bone dry.  You can't expect emulators to really be that useful if there's a binding problem because everything's bent.  Etc, etc.  If you start with the forks working as decently as they can, it gives you a hugely better starting point for working out what needs to change to fit your riding style and roads the best.  It's also a bunch cheaper, and you're probably going to want to have it right eventually if you're considering anything less than a major swap (and like I said, they're worth more if they're not all buggered up).  Hell, while you've got them apart you could even clean them.

[Arnie]

AndyB,

You're right.  He (milehighfj) asked what to do in overhaul, but I should have replied that his first course of action should be to properly service the forks then set and adjust them for his weight before making any $eriou$ changes.
I helped a friend clean, change oil, and set up his forks a couple of weeks ago and he's over the moon with the difference.  His forks only had oil on one side before.  No visible leaks evident but still watching.

KISS principle, at least to start.

Cheers,
Arnie

[milehighFJ]

Andy & Arnie-

Thanks for the update. I believe I found the right local shop to handle the basics first. Will follow up later.