Hi all,
I've posted a couple of times seeking answers to my dissatisfaction with the rear suspension action on my 07 S4Rs. >:( Most recently here:
http://ducatimonsterforum.org/index.php?topic=28338.msg492769#msg492769 (http://ducatimonsterforum.org/index.php?topic=28338.msg492769#msg492769)
And previously here:
http://ducatimonsterforum.org/index.php?topic=7996.msg130987#msg130987 (http://ducatimonsterforum.org/index.php?topic=7996.msg130987#msg130987)
So here's the report on the latest mods.
In short, the std 10.5 (not sure of the units - kg-mm?) spring on the stock Ohlins rear shock has been replaced with a 12.3, nearly 20pc stiffer, and the compression valving has been re-specced a bit softer to match exactly that on the aftermarket DU 333 unit Ohlins offered for the previous model, 05 Monster S4R.
Was going to go for a hydraulic preload adjuster but nothing in stock at the time that would fit. So still doing this manually.
The stiffer spring was intended partly to give better support when two-up, which is more than half this bike's useage (we have a custom seat). I weigh about 75kg without gear, my passenger 55kg.
Surprisingly tho, I'm finding the spring not too stiff for solo work. In fact, for fast-ish solo riding on moderately bumpy roads I think it is just about perfect. [thumbsup]
The softened compression damping too is much better, tho still a bit firmer than ideal. :-\ I find I run the compression adjuster about four clicks off full soft, solo, when pressing on; two clicks when cruising.
On the rebound side, there is still plenty of damping to cope with the stiffer spring.
The overall effect solo is to make the bike feel a lot tauter and better integrated when ridden hard-ish. She just soaks up everything, tracking beautifullly over dips and rises. ;D Gone is the somewhat sacked-out feeling of the stock set-up, where it feels as though it is mainly harsh compression damping keeping the shock off the bump-stop.
When cruising, the firmer spring doesn't seem to affect the ride much, and the revalve smooths things out a great deal. 8)
However, when cruising there is still a nasty jolt coming through sometimes from some particular kinds of bump, [roll] and the rear doesn't cope very well with a certain kind of corrugated surface we get over here, which I imagine arises from heavy truck traffic on bitumen that has essentially been laid over sand. And in general, you still feel the road surface a bit too intimately for best touring feel. :(
The only difference between the stock compression valving and the DU 333 valving was the four shims closest to the main piston, which were a bit softer on the DU 333. So one day I will likely get yet another revalve done, softening the next few shims a bit as well. :P (We've already tried affecting the whole stack by going down one mm on the fulcrum shim at the top, but that left not enough to catch the really big hits.)
BTW, as I may have said in a previous post, I've been given access to spec sheets for the stock shock and aftermarket cousin, and they are identical in terms of how many elements in the valves, etc. [coffee] Only difference is in the shim spec itself. In other words, it appears the OEM Ohlins shock (DU 5034) is not mechanically or design-wise inferior to the aftermarket DU 333 version, just differently set up - and the specialist who is doing the revalving for me says the same.
When two-up, the occasional nasty compression jolts are lessened; and when two up with heavily loaded soft panniers and a tail-bag they disappear. It is in this last configuration that you can really feel the rear-end using all its travel when cruising over bumpy going, with the compression damping kicking in nicely to make sure the shock just kisses the bump-stop on big hits - and the compression adjuster set nearer the middle of the range. :-* But the bike isn't built for heavy touring. Hence Ohlins has overdone the damping on the compression side, even on the aftermarket shock. Which fits with comments from Speeddog, who has a DU 333 on his bike and has been very helpful with info. [beer]
The experience heavily loaded does, however, assure me that the shock linkage is fine - indeed, the way it progressed felt very good. So the jolting issues are arising from the compression valving, and not some design issue with the link.
Finally, how is the front end coping with the stiffened rear? Surprisingly well, but given the speeds the rear end can now handle on rough-ish roads, the front does bottom occasionally under brakes into turns when a bump is hit. And you can tell the front-rear action is a little bit unbalanced. So I will at some stage go up about 10 per cent in front spring stiffness, which I reckon will sort it.
Overall though, the changes at the rear have transformed the bike for me. In my last post I said I would take back aspersions I had cast at Ducati's suspension people if I could get the action at the rear end to work as subtly as that at the front. Well, I take back the aspersions: :-[ the back is now good enough that I am noticing a little bit of harshness in compression damping at the front, which I never had noticed before.
To qualify all the above, I should reveal I rode the bike solo last weekend in company with an 05 GSX-R1000 with revalved stock suspenders, and an Aprilia RSV-R I think a year or so older with a Sachs shock and I think a Showa front fork. On the, as I say, moderately bumpy roads we were riding on, each of these non-Ohlins bikes isolated the rider from the road surface much more effectively than my S4Rs did. The owner of those bikes, who unfortunately rode mine early in the piece when I had the rear compression adjuster too firm, thought the suspension on both was far superior to the Ohlins. But he was also recovering from a nasty crash and taking things pretty easy, so didn't get to feel the way the Ohlins give back when pushed. From my perspective, both his bikes did give nice smooth rides, but at the expense of surface feedback - and as set up, I imagine would bottom out a bit when run hard, tho I didn't try.
Apologies if I've been a bit long-winded. Suspension is a tricky thing to write about but for me is a key area of bike performance - perhaps the key area, after the steering geometry. I've felt the stock shock set-up lets down the S4Rs badly. The latest mods make a big improvement. So finally I'm happy enough with the bike to stop looking at the Streetfighter and start looking at doing the ECU and exhaust. [evil]