Falco Sachs Blue spring question

[mangocrazy]

Today I spent most of the morning and early afternoon swapping over the Sachs shock for my modified Ohlins (except for an hour at lunchtime watching Rossi post his 100th win... )

Here are some comparison pics of the two. First of all a general comparison:

Shock_2.JPG (100.67 KiB) Viewed 2467 times

And then a closer view comparing the suspension travel available on both. You'll notice the Ohlins has nearly twice as much:

Shock_3.JPG (72.4 KiB) Viewed 2467 times

There are a couple of points that I'd make here - I measured the between centres lengths of both shocks, and with the amount of ride height I'd got dialled in on the Ohlins (about 4mm of the 6mm available) the Ohlins was 9mm longer (326mm vs. 317mm). I also measured ride height with the Sachs and Ohlins fully extended from a point on the bodywork to the top of a steel rod poking out of the hollow rear axle. On the Sachs it was 463mm, on the Ohlins it was 498mm. That's 35mm difference!

So basically on the Falco linkage, 9mm of ride height on the shock equates to 35mm of ride height on the bike - that's a ratio of nearly 4:1...! Bear in mind that all measurements are approximate, but I took as much care as I could. I'd be very interested in knowing what the linkage ratio is for the RSV/RSV-R items. By the time I'd found out how much effective ride height I'd added, the bike was completely reassembled and I was running out of time. When I have time I'm going to back it off by about 10mm of bike ride height, as it's a trifle excessive as it is. It certainly leans quite a long way over when it's on the side stand...

I also got a bit carried away adding rebound to compensate for the heavier rate spring. I put about 10 clicks on, which was definitely too much, as when I took it for a test ride I could feel the bike 'packing down' over successive bumps. Basically the rebound damping wasn't allowing the suspension to return to full extension before hitting the next bump and getting a kind of ratcheting down effect. I'll return it to how it was and add rebound a click or two at a time, I think. The only problem is that to get to the rebound adjuster you have to get up close and personal with the exhaust, so it's an adjustment only to be performed when the exhaust is cool.

But even with those caveats, the bike still felt pretty much as good as when I had the stock Ohlins and RSV linkages. I think once the rebound damping and ride height is optimised, then it'll be a winner. I deliberately took it out over some roads which were 'C' roads - not quite cart tracks, but definitely a long way from smooth. I only did about a 20 mile circuit, but didn't get kicked out of the saddle, which was definitely happening on the unmodified Ohlins.

So all in all I'm well pleased. If anyone else is thinking of doing the same (i.e. using the Falco linkages and spring and the RSV Ohlins or Sachs), I'd suggest preloading the free length of the spring about 11 - 12mm as a starting point (I weigh about 11 stones), only adding about 2 mm of extra ride height on the shock to start with (the Ohlins is already longer than the Sachs) and adding rebound and compression damping as required.

This is still a work in progress, but I think it definitely has a lot of potential.

[paganman]

Does the Ohlins you've just bought have a hydraulic preload adjuster or the normal knurled rings? If it has the knurled rings (most do), then it's probably better, as you can replace the spring yourself without needing to find someone with a shock press (assuming you have a C-spanner, of course). Do you have the RSV linkages, by the way?

Hi Mangocrazy,
My Ohlins has the Knurled rings so should be OK with my selection of C spanners. I haven't got the linkages sourced yet, my shocks from a 2003 RSV R so I've been keeping an eye on e-bay for some cheap ones, no joy as yet. Just got back from Donington WSB, and 2 up with luggage the standard Sachs shock is rubbish, damping faded after 45mins, so need to fit the Ohlins ASAP and enjoy the good weather, hope it lasts?

[mangocrazy]

Hi Paganman, If you've got the RSV-R shock and no RSV linkages, I'd swap the blue spring from the Sachs over and see how it feels. You've got nothing to lose (apart from a couple of hours of spanner twirling) and potentially quite a lot to gain. If you're going to ride two-up a lot, I'd suggest about 14-15mm of preload as a starting point. And before swapping them over, I'd make a note of the amount of preload there is on the Ohlins and rebound and compression settings. It's always good to have a baseline setting to work from.

I agree about the Sachs. Mine is only about 500 miles old, but is still crap. It feels totally agricultural compared to the Ohlins.

[Firestarter]

Today I spent most of the morning and early afternoon swapping over the Sachs shock for my modified Ohlins (except for an hour at lunchtime watching Rossi post his 100th win... )

B*stard! I haven't watched it yet!

[D-Rider]

Today I spent most of the morning and early afternoon swapping over the Sachs shock for my modified Ohlins (except for an hour at lunchtime watching Rossi post his 100th win... )

B*stard! I haven't watched it yet!

He might not have given it away ..... maybe this was coverage of Rossi's 100th lotto win or something.

You'll just have to watch the race to find out for sure ...........

[Chabby]

Thought I'd bump this having recently acquired a yellow spring Sachs shock from an '03 Mille.

Anyone (other than Mango) put the original (blue) spring on this or a similar shock - if so, whats the verdict?

Would I be better off going the normal route and sourcing the '03 linkages instead?

[Froggy]

Hello all. I’m new to your excellent forum.
A short intro : I’d been out of biking for 17 years and after much thought i settled on a 2003 red & black falco for my return! Got it about 3 weeks ago and have already done 1500 miles !!!
As for my username, well that cos i’m originally a geordie but have now been in France for 15 years!
Anyways, I’d read that the rear shock was one of the falco’s few weak points, and confirmed that after the first few rides out. Hence, I picked up a yellow spring sachs mille version for a reasonable price on ebay. Actually, it’s the “sachs competition” version.
However, after putting it on last night, I discovered that to keep a reasonable ride height once on the bike, the static height had to be so high the bike was nearly falling over on the stand. Also, when I got on it, it would sag like 120mm at the back. Oh dear.
Hence, I spent several hours reading through information on the web then came across your forum and it was like a ray of sunshine and explained everything!
So, to cut a long story short, I realised the spring was too soft, and decided to follow mango’s lead and work out a way to reuse the original blue one, since it’s got the right spring rate (especially as I’m about 100kg on a good day!) and since i’m too impatient to order a new spring or to find RSV linkages.
Only problem was that the original blue spring is 145mm long at rest, whereas the yellow one is closer to 160mm. Hence, the length of the preload threads weren’t long enough to get any decent preload into the spring.
I decided to do a few calculations
The two important figures are the "maximum preload spring compressed length" and the result of "rear ride height change / shock sag value when I get on the bike"


First conclusion :
if you can’t change the linkages, then it is better to put on the blue spring instead of the yellow one. If you can't compress it more than 135mm then things still won’t be rosy, but they’ll be less bad!
Second conclusion :
with 120-125mm length, the blue spring would be perfect, since i’d basically have replaced the yellow “weak” spring with a “blue 800lb/in” one. But actually i don’t want quite as much preload force in the spring as i had with the falco one maxxed out (it was too much). So 125mm is my target and since my preload thread is too short I will need 10mm spacers.

Only thing was, I don’t have any spacers. And mannnnnn! today was sunny, 25°C, the twisties were waiting! Ok, hence my idea : remove the preload locker rings from the OLD shock, put them on the new one, then wind them all the way off the end of the threads. After testing, I can confirm, they work great as 10-12mm (ish) spacers. It just looks like you've got 4 preload rings at the top of your shock, but that doesn't bother me!
Here you go:


I didn’t have the shock revalved (ok, it’s the competition one so i don’t know how it compares to the standard version) but i wound compression and rebound damping up to the max and took her out for 3 hours of winding mountain roads. Conclusion? ….. DA DAH!! FABULOUS . I am absolutely totally stunned how much of a difference it makes. I wound off both compression and rebound damping slightly to make it comfortable while still tracking spot on - which shows that the shock has enough choice of settings to compensate for having the standard falco linkages. It now feels glued to the road, tracks great in the bends – soooo much better than before – and is comfortable! I did everything from low speed hairpins to 120mph bumpy bends and she just tracks true. No squirming and no punishing my kidneys. When i’d go over potholes, I’d feel it in the forks, but nothing from the rear! Just unbelievable. It has changed the entire bike.

Conclusion :
assuming the normal RSV shock is similar to the competition version I’ve put on, you can get away without the RSV linkages or a new spring by re-using the blue spring from the old shock. If, as in my case, the preload thread doesn't allow sufficient tightening, then you need to add spacers (either real ones, or my “magic” fix). However, if the preload thread allows you to compress the blue spring down to 125-120mm, then it's a straight swap!
I am soooooo happy now my new bike is perfect :o)
Thanks mango! (and everyone else who made this forum exist)
Pic of my baby

[Samray]

Welcome aboard Froggy. (and welcome back to 2 wheels)
Glad you're finding the forum helpful and it sounds as though you have some interesting thoughts too.

[Kwackerz]

Aye, Welcome back to biking and welcome to aprilia ridersite / ridersite Froggy!

to post images, get them hosted somewhere, get the url of the jpeg or bimap ( ending in .jpg or .bmp) and insert them on your post. highlight the link and then click the 'img' button and it will drop the required code around your link, when you press submit, you should get the image showing..

Welcome anyways and what a brill first post!

[Nooj]

The only problem is that to get to the rebound adjuster you have to get up close and personal with the exhaust, so it's an adjustment only to be performed when the exhaust is cool.

I take a tap wrench out with me when I'm tinkering with the rebound damping, makes things much easier.

[Froggy]

Updated post!
have now changed spring for a custom made one + powder coated red
I love it, hope, you do too :o)
+ higher springrate for higher preload and no need for those home made spacers anymore :o)

Ben

[blinkey501]

I prefer the work of art on the side stand to the ones on the wall

[mangocrazy]

Hi Froggy, I can't believe I missed your post first time around. Excellent work, and a fine piece of lateral thinking in pressing the preload collars into use as spring spacers. I liked that very much - a chap after my own heart...

In fact your bike and mine are the same colour scheme, the Flamingo Red and anthracite. It was that colour scheme that made me say 'I want a Falco', and I'm still delighted with it.

I'm very interested to hear you say you've been living in France for the last 15 years - whereabouts in France are you? The reason I ask is that I have a place in France I bought in 2003 that we get down to as often as we can. We're in the Languedoc, in a little village called Pouzolles (34). We also know another Falco rider who leaves reasonably close, although he and his wife live between Beziers and Carcassonne. His name's Peter, and his forum name is FalcoMille.

I posted up some pics of our hols in July 2010, when we rode the Falco down to the house and back. A good excuse to show some pics of the bike...:

https://www.ridersite.com/viewtopic.php?t=6818

Like the colour-coded replacement red spring on your shock. Just finishes the plot off nicely, I think...

[flatlander]

Welcome skipper sounds like between you and mango all our holidays are sorted