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Ohins Rear Spring Numbers Mean What?


Mike Stewart

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Guest captain nemo

I wish you could all ride my Guzz and see that it can be quite excellent in stock form. I think I am very fortunate to have stumbled upon the combination of settings that allows the V11 to be both plush and stable. 'Pure Guzziness' has been attained. You have to figure that Guzzi set the bike up for a theoretical rider of about 170 lbs. who most likely rides alone. Also, they probably assume that speeds and corners are averaged for 'real world' velocities. This does not work for the track and its astronomical and dangerous rates of speed (over 100 mph.). If that is what you are doing, then, of course, you should be looking at after market.

 

But I find the spring rates, controls and oils to be perfect. With good engine breaking, smooth throttle control and some body english, I feel every small bump - and can shift weight fore and aft at will. I can 'sit down' the front end or the back end at any time, and feel perfect control over bumps - never rattled - never committed to a particular line....

 

If anyone is curious, I could give you the exact settings as I have them per 'click.' :rasta:

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If anyone is curious, I could give you the exact settings as I have them per 'click.' :rasta:

Why sure!

And if you ever got around to measuring sag, I'd be curious as to those numbers, too.

To use the settings, I'll need to lose about 30# and weigh what I did when I first got my license at age 16.

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Mike,

 

You wouldn't be the first person to find an aftermarket Ohlins shock set-up with too much compression damping, I've been there myself. My first impression of Ohlins shocks (back in the eighties when they were new to the US market) was very poor, sort of a Swedish Marzocchi. I put one on my bike and it rode like an empty truck and the tire was off the ground half the time in the bumps. Remember we are talking about a big guy, I can't imagine what it would have been like for a rider 100 pounds lighter. A quick re-valve and it was the equal of any shock I've ever used. Don't worry, help should near by. It does kinda' piss you off to pay premium prices for some so badly set-up and then pay more (or at least wait even longer) to have it fixed.

 

Cheers,

 

Lex

Lex,

 

That is exactly what the bike feels like, a empty one ton truck! I have installed the LE modified shock with the stock spring and will be going for a ride this morning. This will tell me if the spring rate was causing the problem or if it is an internal dampening problem.

 

Time to ride! :thumbsup:

Mike

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I put 130 miles on today and the LE modified Sach shock was liveable, still has some harshness from the high speed dampening. It is less harsh and more rideable than the Penske shock. :o I talked to a 02 Lemans owner that had installed the Ohlins rear shock and he is really happy with the results. No harshness at all. Give me a break! :homer:

 

Mike

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I guess when they shortened it 10mm you also got 10mm extra pre-load.

Not saying that is the problem, but it could be related.

Perhaps you need a shorter spring for the Penske.

(Which might be unavailable)

For the third time...got any sag numbers?

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For the third time...got any sag numbers?

David, sorry for the delay, gosh, you sound like my 3rd grade teacher, :D

 

The sag numbers for the Rosso for the rear are 8mm. static, 35mm. with rider.

The sag for the V11Sport with the LE Sach are 5mm. static, 30mm. with rider.

On the Penske I have tried their recommended sag which is between 7/8 of an inch. to 1 1/16 sag with rider. I have also tried up to 1 1/2 inch. sag with rider and all settings are too stiff.

 

The Ohlins shock works the best, I can feel the shock working over bumps and humps in the road. With the other shocks I get the kick from the seat and harsh ride. I have read that Ohlins sets up the shocks for the bike and then do track and road time to get it dialed in for dampening and spring weight. I do not think Penske does the same thing and may just go off suspension design to get thier figures. What they may not see is it being a shaft drive with a heavy rear wheel/final drive unit attached.

 

Mike

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For the third time...got any sag numbers?

David, sorry for the delay, gosh, you sound like my 3rd grade teacher, :D

 

From Charlie Brown and the Peanuts, "Waah whanh wanh wa" --the teacher

 

Thanks for the post.

Your numbers seem to imply that your Ohlins spring is very close to the same spring rate as the spring on the Sachs.

If the sag is fine, I would blame it on the damping...and the sag is fine, so it must be the damping. :P

Of course the lack of travel does not help... :angry:

Sorry you have had bad luck with the rear shocks. You are really taking one for the team. I think we will all benefit from your experience and buy Ohlins!

Thank You. :bier:

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I've run out of beer reading suspension threads. :drink:

 

A couple observations:

 

1 Kg is 1 Newton. (there's more to it than that)

 

The spring rates must specify a weight and distance (Kg/mm, N/mm, Lb/in)

 

The rear spring rate of 85 must be Kg/cm. (475 Lb/in)

 

a 550 Lb/in spring is 98 Kg/cm

 

It does seem awfully stiff for a 500-550 lb bike and , say 200 lb rider. Some percentage of the weight is on the front ( anyone know how much??) and some of the weight is unsprung (wheel, tire, brakes, bevel box, and part of the swingarm and shaft).

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The sag numbers for the Rosso for the rear are 8mm. static, 35mm. with rider.

The sag for the V11Sport with the LE Sach are 5mm. static, 30mm. with rider.

which means Mike's weight makes the bike drop

27mm with Ohlins

25mm with Sachs

So just to make the math simple,

if we took a 100 Kg/cm spring, assumed a 2:1 ratio on the axle:shock travel, and the sag had those drop numbers, it would mean that in addition to the bike weight he he would be putting ~135 KG over the rear axle on the Ohlins sag and ~125Kg over the rear axle of the Sachs.

And if we took an 85 Kg/cm spring, he would be putting ~115 KG over the rear axle on the Ohlins sag and ~106Kg over the rear axle of the Sachs.

So, he has to put about 10Kg over the rear axle to get it to sag like the Ohlins. Not a huge difference, but noticeable. (125 -115 + 10)

That combined with hard luggage on the Rosso, and more high speed compression on the Sachs, could certainly make the bike harsher.

Mike, to put some weight over the rear axle, do you want to trade your mistrals for my stock mufflers? :P

The results of my calculations appear a little higher than I would have predicted, I guess because the 2:1 ratio is probably closer to 1.8 or 1.9:1.

I hope that make sense.

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500-550 lb bike and , say 200 lb rider

 

 

Docc,

 

That's me...100N/mm spring is great. Sag set w/o excessive preload, small damping adjustments make a meaningfull difference throughout the range. Thanks for confirming Kg/Newton is same... I thought they had to be as the numbers are always the same.

 

Captain Nemo,

 

Thing is...I'm really happy w/resprung Ohlins...but things can always be better! It's great to get things working the way you want them, & there's so much adjustment available w/the Ohlins you feel you can get them perfect...We all ride different, even day to day...errmm...minute to minute...I know that sweeper coming up I'll just dial in a couple clix compression... :rolleyes:

 

Cheers, KB, Wales :sun:

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The sag numbers for the Rosso for the rear are 8mm. static, 35mm. with rider.

The sag for the V11Sport with the LE Sach are 5mm. static, 30mm. with rider.

which means Mike's weight makes the bike drop

27mm with Ohlins

25mm with Sachs

So just to make the math simple,

if we took a 100 Kg/cm spring, assumed a 2:1 ratio on the axle:shock travel, and the sag had those drop numbers, it would mean that in addition to the bike weight he he would be putting ~135 KG over the rear axle on the Ohlins sag and ~125Kg over the rear axle of the Sachs.

And if we took an 85 Kg/cm spring, he would be putting ~115 KG over the rear axle on the Ohlins sag and ~106Kg over the rear axle of the Sachs.

So, he has to put about 10Kg over the rear axle to get it to sag like the Ohlins. Not a huge difference, but noticeable. (125 -115 + 10)

That combined with hard luggage on the Rosso, and more high speed compression on the Sachs, could certainly make the bike harsher.

Mike, to put some weight over the rear axle, do you want to trade your mistrals for my stock mufflers? :P

The results of my calculations appear a little higher than I would have predicted, I guess because the 2:1 ratio is probably closer to 1.8 or 1.9:1.

I hope that make sense.

David

 

:blink: Now my head really hurts, wheres the Advil . :drink:

 

I think it will be easiest if I went with the Ohlins shock. Do you want to buy the Penske cheap?

 

Mike

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Do you want to buy the Penske cheap?

 

Mike

I'll trade you my Quat-D Muffler with cracked welding for it.

Or give you about half of what you paid.

Put it up for sale, and if you don't get what you want I'll give you $400.

It can't be too terrible as you were excited and liked it at first.

My Corbin saddle moves my weight pretty far aft, so it may be fine for me.

The advantage of shorter travel is less drive shaft wear!!! But more wear on the old bones.

And maybe if I hang the battery where the license plate is it will put more weight over the spring.:blink:

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Because of the two to one ratio, it will take half of 550lbs, which is 275lbs per inch of axle travel.

412.5lbs over the rear axle would make the spring sag 1.5 inches, but the bike does not sag too much, because of pre-load.

(I got 412.5 pounds from taking half of 275 and adding i t to 275)

275/8 is 34.375 so with a 550lb spring, every 34 lbs over the axle will move the spring an eighth of an inch.

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Yah, where the pipes meet the body of the muffler.

It started out as a small crack with no apparent leaking but after I put the bike in gear while it was idling on the sidestand, the sidestand hit the pipe and pushed it over the edge so now it leaks and the engine pops a little.

I will have to get it welded AND reinforced. :wacko:

Atleast I still have my stock mufflers.

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