[Ducati] 748 suspension problem?

Wed Aug 2 08:45:07 EDT 2006

John,

Have you changed the fork oil?

This is one of the most overlooked maintenance items in cycledom, and it is very important to the function of your suspension.  As the oil is forced through tiny orifices in your forks and is sheared between moving parts it loses viscosity.  This loss of viscosity results in loss of damping.  I generally try to change fork oil every year or at least every two years.  If you've never changed it....let's see....2006 minus 1998....that's 8 years.  It's probably time!!!

You'll want new O-rings for the fork caps, new fork oil of the correct weight and some sort of device to assure even oil level in both fork legs.  You might want to make sure you have the correct fork springs in there, too, since you'll have to remove them to measure fork oil level, anyway.  Race Tech makes a cool tool that looks like an oversized horse syringe with an adjustable "needle" length to set fork oil level.  You have to measure it with the springs removed and the forks fully collapsed in order to get the correct measurements.  They sell fork oil and springs, too, though their oil is a bit pricey IMHO. (I think they wanted $15 or $20 per quart).

If you want to revalve your forks, you can do that, too, whilst you have them off the bike, though I don't recommend it unless you're VERY comfortable turning wrenches.  Race Tech, Thermosman, Traxxion Dynamics, Lindeman, and a number of others would be happy to treat your forks to the "royal treatment" for about $1000.  That sounds like a pretty good chunk of change to some folks, but consider you're basically getting a new bike!!

While you're at it, it's probably time to have some attention paid to the stock shock, too.  The stock Showa and Boge units are generally underdamped and only get worse with time.  Ian Falloon has spoken so poorly of some of them that you get the impression he'd as soon have you change them before leaving the dealership!  In my case I'd have to agree, the original Showa units fitted to 91-98 Supersports are complete crap.  The Ohlins replacements are much better and I'm told that the Penske units are as good or better by those who've tried both.  Some of the stockers are rebuildable and the aforementioned suspension shops should be able to take care of the rear of you bike, too.  I don't recommend digging into the shock as it is gas charged and unless you have the equipment to disassemble, reassemble and recharge it you're wasting your time.  Often an aftermarket solution is as economical as rebuilding.  The Ohlins for my bike was about $600 with adjustable ride height.

Good luck with your problem, hope this helps.

Cloner (a.k.a. Scott Cloninger)
Chattanooga, TN.....worshiper at the temple of Smooth Suspension  

-----Original Message-----
From: John Sheerin [mailto:jsheerin at hughes.net]
Sent: Tuesday, August 01, 2006 8:32 PM
To: Ducati Owners Group
Subject: [Ducati] 748 suspension problem?

Hi guys and gals,
I have a '98 748 with around 17k miles, and it's recently started bouncing a
bit while I'm riding.  It basically bounces up and down, not a huge amount,
just enough to make it feel a little nervous, including in corners.    One
ride it was fine, the next (and subsequent test rides), it bounced.  The
frequency doesn't seem to vary much with speed - I'd put it around twice a
second on the bouncing, but that's just a rough estimate.  Road condition
doesn't seem to make a difference.  Pulling the clutch and coasting doesn't
seem to make any difference, and the brakes don't pulse when I use them, so
I'm assuming from that, it's not a drive train or brake problem, but rather
tires or suspension.  It also seems to be better when accelerating, so maybe
a front wheel / suspension problem?  I haven't hit anything that I know of
(potholes, curbs, etc.), and I don't see any flat spots on the tires or
rims, but I'm planning on checking more closely.  The front and rear
suspension doesn't seem to stick when I bounce on the bike in the garage,
but I suppose that doesn't mean anything given my level of experience with
these things...  I looked at all the nuts and bolts - everything's tight.  I
don't see any spots where wheel weights have obviously been lost, and I
still have a decent amount of tread on both tires.

Some of the guys I work with suggested checking the fork oil (I haven't
noticed it leaking...) and making sure the swing arm is greased.  Could
anyone recommend other things I might look at?  Where would you start?

Thanks,
John
http://ldsg.snippets.org/HORNS/

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