Pelican Parts Technical BBS

Pelican Parts Technical BBS (http://forums.pelicanparts.com/)
-   BMW R1100S / R1200S Tech Forum (http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/)
-   -   ohlins shocks how long till rebuild time (http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/153322-ohlins-shocks-how-long-till-rebuild-time.html)

bradzdotcom 05-11-2004 07:11 AM

umm....yea, sort of:

depends on the units you have.
the front is probably an 842 (there might be a zero or 1 after that number).
that's a 46 clicker. go all the way IN (clockwise). turn out until it clicks ONCE. That's the "zero" point. From there, go out 14 of the possible 46 clicks. If you're really bored, check to see that there's 11 bars of nitrogen (yea, right).

The stock setting is horrible. Change it to 6 to 9 out on the magic gold knob and you'll be a little happier.
it's probably a 180 spring up front. should work fine.

I assume the rear is probably the ever popular 46prc11, otherwise known as a 205. (12 bars of nitrogen, if yer counting).

The compression knob should be at 12 out....from a possible 23-ish.
the rebound should be at 18 out of a possible 55.
I think the stock spring on the rear is a 1093-59 with 16mm of preload. I'd suggest going up one notch beefier for spirited riding.

The fat click knob (FCK) should come out of the box set at 8 revs out, from a possible 20.

As always, keep in mind that the best suspension is the one that wins the mediocrity award: it doesn't do "stunning" at any single particular type of road or corner, but rather works rather nicely in a wide range of conditions.
On the track...it's different. You find yourself cursing about the fact that there should be half or quarter clicks available!

Best part of suspension: it's opinion, all based on what you like and how you ride. That way, everybody is right and everybody is wrong.

...brad



is adjustable rear length 46prc11
should have compression at 12 of 23 possible,
rebound is 18 out of 55
12 bar of nitrogen

stck spring is 1093-59 with 16mm of preload.

fck 8 turns out. about 20 total.

roger albert 05-11-2004 08:10 AM

Hi,
Brad's damping advice all sounds good.

To verify your spring value, you can just read it after the part number.
The front will probably have a 057 in there, meaning about 5.7kg/mm.
Íhlins of course doesn't rate their springs in pounds, but if that's what you're calibrated for, its about 320lb/in. Similarly, the heavier one will have an 062 at the end of the part number.

As has been noted before, the stock spring is a 15kg/mm unit, which for people below 170, is easily enough, even for spirited riding.

Anyway, Brad sounds like he's giving good damping setup advice.
It's also not far from where my Íhlins documentation started out.

Kam 05-11-2004 08:18 AM

Guys you lost me a little on the front shock. I read earlier "go out 12 out of a possible 50 clicks" on the rebound knob.

What adjustments are you referring to in the first 2 paragraphs of your last post Brad?

bradzdotcom 05-11-2004 08:32 AM

kam~

it's the little round knob up by the steering head, in front of the plastic fairing panels. it's the one you can see when you're sitting on the bike.
...brad

Rapid Dog 05-11-2004 12:39 PM

From the "mouth" of Ohlins...
 
Ohlins jerry wohlgemuth [jwohlgemuth@ohlinsusa.com] sez:

Hello Randy.
Front rebound: 16 clicks out from zero
Rear rebound: 18 clicks out
Rear compression: 12 clicks out
:cool:

roger albert 05-15-2004 08:15 AM

I'm working with a spring vendor to i.d. a good aftermarket spring that will fit Íhlins front bodies and offer a rate higher than 5.7kg. Should have that worked out within a week or two.

markjenn 05-25-2004 09:37 AM

My new 6.2 front spring finally came into PPS. Thanks for the part nos and everybody's help.

I was talking to Stig and he thinks I can install the spring simply by backing off the preload rings - no compressor required. Anybody confirm this?

- Mark

roger albert 05-25-2004 10:35 AM

Wish I could say Mark. MANY shocks allow this, but I'm not sure on this one. Rather than a long threaded body, this shock has a short threaded collar than can be located any number of positions up and down that body. Cool design, but may be a limiter on thread travel. Front spring likely has on the order of 12mm preload on it. Plus you'll need enough clearance to disengage the clip. Does it look like you have room to back off at least 15mm or so? Let us know what you find.

markjenn 05-25-2004 12:36 PM

Thanks Roger. I'm going to have it shipped to me and will give it a go. Worst case, I can find someone local who can do it.

- Mark

roger albert 05-25-2004 02:10 PM

Welcome.
I'll have to look at mine tonight and gauge room.
A big 2x6, a hole saw, and a couple friends can work in a pinch, but it's pretty dicey.

markjenn 05-29-2004 02:41 PM

I installed the 62 front spring today. It was easy. There was plenty of room on the shock body to back off the preload rings enough to get the top spring retainer out. Of course, as Roger has pointed out, the position of the threaded collar will affect this quite a bit - mine had been positioned with the circlip so that I had quite a bit of back off room. YMMV.

One thing that has me slightly worried is that the free length of the new spring (180-65/62 L323) is 11mm shorter than the standard front Ohlins spring I took off (180-44/57 L322). There is plenty of adjustment to take up this slack, so I wouldn't think it would have a major effect, but I wonder why the new spring is shorter.

I decided to go ahead and preload the new spring to the same degree of compression as the old (about 13mm) which meant I had run the rings up another 11mm to get the same amount of preload. I haven't had time to do a sag measurement which is probably the right way to do it, but having to take the shock on/off every time to change preload is a real PITA. Maybe later.

The difference in ride is fairly pronounced. The front always felt very soft with my 220-lb weight, especially after I went to the 18 on the rear. Now they seem very balanced. So far so good, although I have such a worn front tire, I'll have to reserve final judgment on handling until I get new rubber.

One other odd thing - the feel under max (ABS engaged) braking is definitely changed - much rougher feeling. Some of that I can attribute to the stiffer spring, but I'm a little worried that perhaps with the shorter free length, maybe I'm coil-binding rather than hitting the rubber bumper. That would really surprise me though - the distance between the coils is the same on the old and new springs and a 5% reduction in free spring length (200mm to 189mm) couldn't possibly change the compressed length that much. I'm probably over-worrying this.

- Mark

roger albert 05-30-2004 07:45 AM

Hi Mark,

In short, yes, I think you're overworrying it a bit (good gedanken experiments though) and your'e feeling just what you should. Since it's raining outside and I'm waiting for the hardware/bolt store to open, I'll elaborate.

Assuming you can get the preload right (which from what I've read, you did quite correctly) the spring freelength means nothing.

Realize, that manufacturing realities cause the length to vary. The ID. and to an extent, OD, are fixed, in order to fit the shock body. There are also a large, but still finite/limiting number of wire diameters available. Since those are respectively cubed and quad'd functions, they're very sensitive and can only allow so much rate granularity. Number of turns is used for finetuning. The winding mandrels are also only available in so many pitches (though companies like hyperpro use variable cnc ones that dispense with that limitation and allow smooth progressions in rate) and so even the most careful juggling of all those variables still sees some differences in free length.

With only an 11mm reduction in free length, there is almost no chance you're going into coil bind. You can verify my comparing shockshaft remaining (sagged) compression travel to the total gap between all sagged coils. I bet you're ok.

Now, all things being equal, a stiffer spring will require slightly less preload (once the collar hits the spring) so you my may want to back off 1-2mm. (5.7 to 6.2 is a 'full' 10%-ish) You're so close now I'd be loath to take it off.

Here's the crux of the matter. I think there are two salient points. The big advantage of the telelever is that the road-holding/spring-compliance rate doesn't have to be artificially compromised radically upwards to control dive under braking. It thus allows a much softer, more compliant ride, in general, but especially over braking. Since the brake dive forces (which are partially rider weight based) are fed largely into the frame, the required front spring rate is a much weaker function of rider weight than in conventional telescopics. This is why I only recommend, at most, even for the heaviest guys, a bump to 6.2. You just don't need much of a spring or range of spring rates to accommodate a large number of riders. The theories by some to need to go to 6.8 are absurd, and would kill the advantage of the telelever to a very great degree.

The 2nd difference to the telelever is compliance under braking, which is not just a function of spring rate on the telescopics many of us are still calibrated for. For telescopics, there are truly enormous binding/sticking/friction forces that affect compliance under braking. They and the tires contribute greatly to chatter. More germane to this discussion, they affect the compliance under a braking, a LOT, so much so that the spring plays only a large, instead of the whole role. Thus, we don't notice even a much heavier spring under braking on a telescopic.

On the telelever, there is just a slightly increased sideload in the shock shaft (which has a much smaller frictional area) and so, we feel only the spring.

So, in short, I think you're feeling just what you should expect to feel. That's the cool part on the telelever. You feel exactly the spring you put on. This experiment you've done should really drive home the advantages of the telelever (and maybe the coming duo-lever, if it doesn't prove to be too compromised in travel) Good learning exercize anyway, eh Mark?

I bet you'll get used to it. I'd look forward to your further comments on it. At 160lb, I have to do high spring rate tuning vicariously/by\-proxy of theory and
feedback of larger riders.

Keep us posted Mark. I'm curious as to how you adjust, and what you find on coil binding.

roger albert 05-30-2004 07:49 AM

Wait a minute, my 6.2 is on the desk beside, me. Free length (190mm) minus the coils, minus 11mm preload) gives about 95mm of travel before full bind. I believe the shock stroke is about 70mm. Youve got tons of margin.

hth
take care
roger

markjenn 05-30-2004 04:19 PM

Thanks for all the help Roger. I'm going to back off the preload about 2mm and call it a day. I was out today and the bike feels good. Damn good. Time to mount new tires and see how this things responds in anger.

- Mark


All times are GMT -8. The time now is 11:16 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.