Good shock for my GRiSO??

Cheers

Sidrat - I didn't measure the change in ride height but as I am tall (183 cm) it doesn't matter. I can still put my feet down flat very comfortably. Of course it might be an issue for a shorter person. I haven't changed front end settings - it's on the 5th preload mark and seems to like it there. No problems with stability over several thousand km of backroad riding and one track day.

Baross, in round figures that increase in shock length would have increased rear ride height by 45mm.
Or enough to reduce your rake by 1.5 degrees, 23 degree rake ............ it should turn in sweetly now.

Thanks Ghezzi - that sounds about right. Ah it now turns sweetly indeed! Very sharp but still very stable at any speed.

Ok. I'll have a go at putting some pics of my Ohlins install here.

Top attachment, original bolt, but required is 2 spacer washers as the top eye is narrower than the one on the Sachs shock.

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The next 3 pics , Lower Clevis attachment. The Clevis is obviously wider than the Dog-bone it mates with. I measured and made 2 steel spacer washers to take up the excess clearance here too. The reason for using washers of such large outside diameter is to prevent the bolt/ clevis/ bearing bushing journal moving sideways. If you don't do this , it can and probably will move sideways and the bolt head or Nut will catch on the Fork. Resulting in damage to parts or if it locks it up, an accident.
Also on the inside of the 2 steel washers are Orings just big enough to fit around the bearing journal. This further helps centralize the fork on the dog- bone
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The bolt selected was long enough so the threaded end protrudes completely through the Clevis. This is so the loads imposed are on a solid section of the bolt and not on the threads. It also prevents the threads of the bolt getting hammered into the clevis and damaging it. Use a Thin nut or machine the back side of a standard Nyloc Nut down to achieve required clearance. Note here that this bolt is only in shear. There is minimal sideways or Tension loads on this bolt, so a Half Nut installed with light tension is more than sufficient. ( Use a dab of locktite for peace of mind if you prefer)
Just Recapping : The Bolt is a 10.8 grade, the parallel section goes through both sides of the Clevis. The thread end is then cut off so it is just Level with the outside of the Half Nut. Use THIN Washers. The inside of the Fork casting flashing was also dressed smooth with a smooth file and Wet or Dry sand paper. 600 grade. This achieved another 1 or 2 mm clearance. Dress length-ways only as cross-ways will leave Stress-Raisers.

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Last 2 pics are the springs I've tried.  My Riding Weight is around 92 Kg dressed to go.
Standard Tuono spring was 95 Nm. A Huge problem I've found pushing this GRiSO hard is that under hard braking the bike would Pogo bounce or skip from front to back until I let go of the brakes. Poo comes out when this happens.    I thought it was all to do with damping settings, but I finally worked out it was having too soft a spring.
I next went to a 105nm. Still too soft. A 115 Nm felt ok but still No Bike Sag and too much rider sag and still skipping under brakes when upset by a few bumps. I've settled on a 130Nm spring, and to date no sign of the pogo skipping.
It could also have been caused by having Zero Bike Sag. IE : nothing for the bike to work against when the the nose dives under brakes and the rear shock was Topping out. My present Sag Readings are Bike Sag = 7mm. Bike Plus Rider = 33mm.

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Waterbottle,

Thanks for the details.

Questions; what do you mean by 'dress lengthwise ' & 'stress-raisers'

Did you use a 25mm clevis mount ? Do you know the part number ? Ohlins usa can only find it if it's referenced to a particular bike.

If you are going to remove any casting marks by filing, File longways down the beam of the fork , not across the beam. Imagine it as filing a nick in a piece of Hi-Tensile fence wire. If you then bend it back and forth it will always break at the nick you filed.
Sorry I can't remember the Clevis Part Number, Ghezzi might remember or be able to find it for us ?
I will be removing the shock for other work i'm doing, so I could get measurements then, But this won't be happening for a couple of weeks yet.

Jesus Waterbottle. That's a whole lot of fucking around to get a shock to fit. You have greater patience than I. And a whole lot more mechanical aptitude I might add.

Interested in your impressions on the spring rate. You're not a heavy bloke by any means, and I'm wondering that if you need a 130nm spring, what does a bloke who weighs 110kgs stark naked use? Matters not to me, as I'm 75kgs dripping wet, but interested in different views.

Thanks for the clear explanation Ron!
I got a 25mm clevis from the Dutch Ohlins importer, so no problem with that. Nobleswood also contacted them.

Strange you need a 130N/mm spring @ 92kg

The 130Nm spring probably would be too much on the standard shock. But as the Eye to Eye length has increased the "Initial" rocker ratio has also increased due to the geometry of this suspension, IE makes a heavier spring Feel soft.
Another issue I had was when exiting a corner and getting back on the throttle, the rear was Squating down, unloading the front end, and the bike wouldn't hold a line. I mean it would go wide exiting the corner. The heavier spring helped this amazingly well.
This shock is on my track only bike, But as set up now it still feels very compliant.

I had the same pogoing front end problem on my race bike, but it was due to white knuckle fever and dinner plate eyes. Everytime I "blipped" the throttle to down change I wasn't fully closing it again.
Other novices with the same problem would pump the brake as they "blipped" the throttle, same result.

Well dispite the swirling chaos around me I recently got to work on the swinging arm bearings, shock & dogbone bearings.

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The PO had lived in Philadelphia, a city known for it's potholes, & I understand the bike lived much of it's life outside.

Looking at the swinging arm shaft, I wasn't optimistic about the bearings

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You can see how much rust was there & on the shock.

Turns out the seals had done there job & the guy on the assembly line had too. The factory paint marks still aligned, the castellated nut was torqued and there was enough green grease ( it hadn't all turned brown ) to work

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.so far so good  

It's a miracle!

I would like to remove this post as it breaks up the flow of Noblewood's post
I don't see how to do that.

Roy

Next step was greasing the dogbone needle rollers, remembering other posts I laid out a white sheet expecting the rollers to fall on the floor & otherwise vanish !

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Again my luck held out. Then a dim memory, or a memory appeared on a dim screen came back. There had been a recall & the work had been done by Fast by Ferraci.


The original shock came out, which after riding 2 other GRiSO's I had concluded was f**ked. This was confirmed by the top bolt being bent as there was nothing to soften the road bumps.

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Driving to a few stores I've found the correct sized 10.9 bolts M10 x 1.5 pitch which will need a bit of machining to fit in place with spacers as Ron has been using.

^^^^^^^

Apropos bent shock bolts, see this from my Norge:


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The shock is now being rebuilt.  I had a visiting gorilla manhandle that bent beast out, and was worried that extracting it might compromise the threads.  

But I got in the replacement bolt and in a dry run it went in and out easily.

Bill

Good, that will give us something to work on in the garage !

GDay Ron

Thanks for the write-up on spring weights. Interesting stuff.
When you fitted the Wilburs to your road bike. Which spring did you fit to that setup ?
Was the spring supplied correct ?

Mick

After much obsessive cleaning of parts & replacing bits the PO had bodged the bike came together Tuesday.

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The eye to eye length of the original Sachs was 319mm, I set the replacement at 328mm. The preload was set by Ohlins when they re-furbished the unit, I gave them my weight. They have more knowledge than I do so thats a resonable place to start. The compression & rebound I adjusted to the middle of the settings.

Had a short ride just now & can say it's a lot better than the broken shock ! I'll be fiddling with the settings for a while yet, learning how the adjustments affect the ride & performance but so far I am very pleased.

Thanks to all who have done this before & shared what they did. It made it all confrontable.

Here's a question; why is the top bolt on the shock a 8.8 grade ? Is the idea that it's better to bend the bolt when the shock fails than have it break if it's a 10.9 grade ? I had to run a tap through to restore the threads.

Fabricating a socket for the castellated nut was easy enough, a 1 1/4" socket & a dremel sorted that out.

The PO had neglected the cleaning part of bike ownership but I was surprised how much road grit had got between the RH swinging arm & the bearing seal, forming a paste with the grease & grinding away at the alloy. What mudguards or other solutions, have other guzzista added to their bikes to reduce a maintenance chore ? The swinging arm & the shock pick up everything thrown from the tyre.

I have a simple sheet of insertion rubber screwed to my inner guard - though I am pretty sure this is different to the GRiSO. The inner guard on the Sport is well placed to easily fix this problem. Been good for years now.

Oz1200Guzzi wrote:

I have a simple sheet of insertion rubber screwed to my inner guard - though I am pretty sure this is different to the GRiSO. The inner guard on the Sport is well placed to easily fix this problem. Been good for years now.

The rubber insertion works well on the GRiSO too, i have been running it for 4 years on mine, keeps the area nice and clean.

sidrat wrote:

Oz1200Guzzi wrote:

I have a simple sheet of insertion rubber screwed to my inner guard - though I am pretty sure this is different to the GRiSO. The inner guard on the Sport is well placed to easily fix this problem. Been good for years now.

The rubber insertion works well on the GRiSO too, i have been running it for 4 years on mine, keeps the area nice and clean.

Hi I'm waiting for Matris suspension components to arrive. I'm having the shock body built longer (based on stelvio discussions). Would love see a photo of the insertion rubber in position.

Cheers,

Moby

Are you ordering a 'Stelvio replacement' Matris or a 'special GRiSO replacement' ? My Matris has enough adjustment to lift the end as long as Stelvio variant (no special requirements just std adjustment); but main issue I had was Matris sent same spring rate for gorilla as for a mouse - which required spring change later on

moby wrote:

sidrat wrote:

Oz1200Guzzi wrote:

I have a simple sheet of insertion rubber screwed to my inner guard - though I am pretty sure this is different to the GRiSO. The inner guard on the Sport is well placed to easily fix this problem. Been good for years now.

The rubber insertion works well on the GRiSO too, i have been running it for 4 years on mine, keeps the area nice and clean.

Hi I'm waiting for Matris suspension components to arrive. I'm having the shock body built longer (based on stelvio discussions). Would love see a photo of the insertion rubber in position.

Cheers,

Moby

Here you go

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It tucks up between the airbox and the rear mudguard, some people drill holes to attach it permanently, some loosen the aribox and when they tighten it up it clamps it in.

Mine was a loose fit so the clamping method did not work and at the time i didnt want to drill any more holes. I simply fed up some very long black cables ties, after making a hole in the rubber (see size below) and then linked them over the frame rails at the top, has worked well for the past four years. Purchased some 5mm thick rubber from ebay for £5, and spent some nice garage time installing it. You cannot see it once its one the bike. Dont go thicker than 5mm as it will just rub against the tyre.

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