suspension question

Hey all,
Bought an 848 for a steal -- going to make it into a trackbike and occassional race bike. I plan to invest funds into suspension and tires, and leave the engine alone. In reviewing the race tech website, it' recommends a softer spring for the rear, and harder springs for the front... but the differences in what they list as stock rates and recommended rates seem (to me) to be miniscule. Is the average advanced trackday rider really going to notice the difference between a .96 kg/mm and 1.0kg/mm front spring, and a 8.3kg/mm to 8.0kg/mm rear spring? I do plan on servicing the forks and shock over the winter (I assume the oil in each is as added in 2008!), but am unsure if the spring changes suggested are really that necessary at my pace.

Also, what tires and oil should I use? JUST KIDDING!

 

You didn't give any specs for you or what your 'pace' is.
Spring rate is determined by total weight on them, and speed.

If you're a normal sized person at a normal mid-A pace and just track-biking it, meh... no trophies for that so IMO save your money and have fun.

 

if I was going to spend any money get the motool slacker. Then you can work with actual sag #s to start.
Also see how much ride height adjustment you will need before swapping springs

 

Save your money, for now.

Most advanced trackday riders would notice a diff in feel between 0.95 and 1.0 springs. But I bet their laptime would not be affected much. Your avg advanced trackday rider can barely do 3 laps in a row within 1sec. So when you fit new springs and they go 0.5s faster, was it really the springs that caused it? It'd probably take a great novice racer or faster to have a real affect on their pace.

0.95 to 1.0 is actually two steps as you can mix springs to produce 0.975. My usable range for fork springs was 0.925-0.975. I would change between those 3 rates at diff tracks and with diff conditions. There is no one perfect answer for springrate. The springs you have now and RaceTech's recommendations could both be within an acceptable range.

RaceTech's online calculator is not a good source for setup information. They dont know your riding style, your pace, your track, etc. They may not even "know" your bike in race conditions. You will want to find a suspension tuner that has previous race experience with your bike, can watch you ride for a bit, and will recommend changes for you specifically. Seek one out once you find that your bike isn't doing something that you need to go faster.

 

Going on my dimming memories (which continue to dim, day by day), didn't the 848 have something iffy about the front end geometry? Like new triples being almost mandatory for track use? Or rear rocker? Or both???

 

Thanks for the replies so far -- I've posted the same question on a Canadian Roadracing facebook page, and am getting a range of responses from "leave it alone for now" to "change the springs" to "change the springs, rear rocker, and triple clamps". All on a bike I bought 2 weeks ago and will be preparing over the LONG Canadian winter. My local track is an old, bumpy goat path, that Jake Zemke (yes, he came once) said was the second-bumpiest track he'd ever been on (apparently Blackhawk Farms was worse?). I guess my original question can get missed -- not "should I do it or not", to "would I even notice a difference"? A local fella has an 848, weighs about the same as me, and swears by RT's recommendations (which got me started on this in the first place). Unfortunately there is no suspension tuner local to me. I do know about sag/setup to a fair degree (and have a motool slacker) -- just curious if an amateur such as myself could tell a setup change like that. I've been going to the track since 1997, but off and on, and have been riding LW bikes until quite recently; most of which had very basic suspension unless I swapped out the forks or shocks myself (think EX650 with zx10r forks). I think for now I'll refresh the forks with stock components, and get the shock rebuilt/recharged for now. Thanks for the advice!

 

The more you learn about sag & setups, the less you measure sag.

 

I did ride an 848 back in the day.. Just track days. The thing actually handled very well and quick. Brakes were pretty good too out the box. My biggest complaint was trying to get used to a twin after riding nothing but inline 4's for years. Also the thing was a dog (Came off an R1 to the 848). Changing front sprocket helped a bit but It was even slow compared to a 600. The front springs were a little light for me. Otherwise didnt have complaints about it. I would ride it first, if you like it then eventually start making changes. But, I had ridden mine on the street and in twisties it was hella fun. But after my first trackday I put it up for sale the next Monday. No shit.. Just wasnt for me.

 

@stangmx13 gave you excellent advice.

There may not be one local to where you live, but do suspension guys come to your track days? If so, IMO the best money in racing you can spend, is to work with one a little bit. Im my experience, if you pay for them to service your suspension they will help you with adjustments when they are at the track or remotely if you call them and can give feedback.

 

This right here. Sag starts to become a starting point rather than a destination.

 

There's actually one step after that. Sag can become something you never think about, not even a starting point... so long as you stay off forums

Sag is useful when you don't know all of your parameters, your actual settings. Say you are a trackside tuner working with a random rider. You probably don't know what springs are in their forks, nor how much preload their carts put on them, nor how much everything weighs. Sag is likely the only way to guess at the setup and put the suspension in an ok range of travel. And it's probably not even a good guess because you arbitrarily chose 35mm of sag.

Once you do know all those values sag is useless, especially if your major settings are within range. Sag is a result of other settings, not a setting itself. My setting is "9.0 springs with 10 turns preload" for example. I know what that feels like. When I change springs, I'm now testing "9.25 with 10 turns", or "9.25 with 8 turns". I decide which setting feels best and run it. I do not need to waste time measuring or thinking about sag.

 

When I was working with Lenny Albin (RIP) from Ohlins , he never had us measure sag. When we worked with Tige Dane and James Morse with Cycle Mall, who both went on to work Tech for MA, they never had us measure SAG either.

 

As long as you have some...

 

I have raced this chassis a ton- right now I'm at .95 front and 1.05 rear, but that is also with the Nichols triples and Kyle rear link. I'm 205 in gear and running a mid pack expert pace.

If I were you, I'd just ride the bike as it is and see how you like it. It's very sensitive to rear ride height- and this changes anytime you change gearing because of the eccentric in the swingarm. So the first investment I would make is the ride height measurement tool which pops into the holes in the frame near the rearsets and you can measure to the rear axle. I don't know if the stock ride height bar is adjustable but that IMO will make more difference than anything until you get moving a bit.

Like all bikes, the setup is a compromise between the bike not wanting to finish the corner or not turning in. Even with all of the good parts. I also recall that the fastest setup we've ever had was when the wheelbase was as short as possible. We also relieved the swingarm so it wouldn't hit the tire with the shortest possible wheelbase.

I'm really not sure how much of a difference the linkage makes- It probably helps a lot with weight transfer when getting on the brakes or acceleration.

I'm alot more sensitive to setup changes now than I used to be- nowadays if I put in a new set of brake pads I go backwards for a whole session until I get used to the new feel!

Bottom line, go out and ride it and have fun. Maybe take the long winter and make your own ride height tool! It's just flat aluminum.

As a bonus, parts for these have become alot cheaper since not many people are racing them anymore.

 

Thanks for all the responses -- I have scored some nicely affordable parts for this machine, as it's now considered "old". I have tracked down Foresaken motorsports here in the GWN* who make the offset triples and rear rocker and tie rod. Considering the pathetic state of the Canadian Ruble, I might as well buy Canadian when the time comes.
Next question -- do I paint the bike to APE the Gresini Ducatis ("Why is your bike purple?), or try a home-grown tricolor scheme with spray bombs from Home Depot?

*Great White North, eh?

 

If you're going to rattle can it- why not try something unique like matte red? Decal it up like a factory MotoGP bike?

My new Aprilia has matte black bodywork, looks good with a decal kit.

 

You jump to the dark side?

 

WWWW WWWHHHHH WWWHHHAAAAATTTTTT

Congratulations!!! I think.
There goes the retirement savings for another year.

 

Everyone (OP included) has way more experience than me but I track an 848 and just got into the advanced group at NJMP. Expert is the top so I'm not going real fast. My pace is "three days out of a DOT SC3 rear if I flip it after two". So that's my perspective. FWIW, I used to be a decent amateur racer but that was, um, 30 years ago.

I started with my 848 last year because that's what I had. Starting over, I'd get a set up 676R or R6 and just go. Cheaper to get into, cheaper parts, deeper knowledge base, etc. Now that I have it, I kind of like the uniqueness of it and am going to keep tracking it because why not but it's definitely not a rational decision. @Gino230 is right that cheaper parts are available but it's still going to cost compared to a more common bike.

My bike has an Ohlins shock from a 1098s, 30mm Ohlins cartridges with a 1.0 spring (I'm 170, so 190 in gear?), and a Kyle 30mm offset triple. I threw the shock on just for the hell of it (it was cheap). It felt so nice just riding around, I put the cartridges in chasing that same feeling and the triple 'cause it was for sale and everyone said I should. I love how stable it is but don't like how much effort is required in rapid transitions. I have not changed a single setting on the fork (Mark Rozema installed the carts and we did a quick sag check) or shock, which was previously set up for a guy about 15lbs heavier than me.

Ohlins cartridges were not available this past winter. The Ohlins guy in FL has (well, had) some in stock though, so get them now or keep an eye out for used forks. Check the ducati.ms classifieds. I bought my shock from a guy in Canada. He was selling a set of forks at the time too.

The Ohlins shock made everything else I owned feel like crap. I put a Penske on my RS250 and I'm vaguely annoyed every time I ride my 701 Vitpilen. It was an expensive cheap purchase.

that probably wasn't very helpful but I like to type.

 

Very helpful, Mike -- I too just nabbed a 1098S ohlins for cheap from Japan of all places. In excellent shape. Unless I get offset triples used for a steal, I'll save my pennies up for the long term. I realize the 848 is not the typical option, but at roughly $2000USD (considering the value of the Canadian Dollar) it was too cheap to pass on. I think I'll do the forks as well this winter, as I am sure the oil was the same that was installed back in 2008.