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 Reworking Sachs shock ...

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usedtobefast
Grignapoco
Grignapoco
usedtobefast

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Join date : 2018-08-28

PostSubject: Re: Reworking Sachs shock ...    Tue Jan 08, 2019 8:12 pm

Scot p wrote:
Be careful I went down that road lookig for springs for my tuono, CBR1000xx springs should have done it but turns out the stock Honda springs were rising rate and also too long to work with the spacers I had...

Race Tech series 5818 springs are for our bikes.  The compatibility stuff I've posted (big/full list a ways back, & shorter "good target rate springs" just above) all use the same Race Tech 5818 springs.  So a person with a 06 GSXR 750 or 2003 R1 or GRiSO would order the same spring from Racetech.  So the flip side, those 2 example stock GSXR & R1 springs should fit our GRiSO's.  I've already done this with my 9.5 06 GSXR 750 spring, fits perfectly.  

But I guess your point is a bike from this list might have a progressive spring, whereas the Racetech 5818 series is a straight rate.  Guess that could happen.  But the length and inner diameter should all be fine.  And as I pointed out, at some higher spring rates, the springs get too thick (overall outer diameter) to fit our GRiSO's.  Since I'm 155lbs I haven't looked into that upper limit, I think it is up there like for a 250lb rider or so.  

For the GSXR spring, it was a straight rate.  For the R1, looking at the pics on eBay, it looks like a straight rate spring.  

For people that don't look at springs much Smile  , here is how to tell the difference:

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Whoa, those are big pics!  For the older eyesight challenged GRiSO riders.  Smile
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Pisano
Grignapoco
Grignapoco
Pisano

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 11, 2019 9:58 am

inspiring write up! ...thanks usedtobefast.

Did you ever figure out the function of the fastener ( circled in red below) ?  

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usedtobefast
Grignapoco
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usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 11, 2019 10:32 am

I'm assuming it is an oil bleed screw. So you can drain all the oil from the shock from there. And when I filled the shock, I had that screw out, and once only oil (no air) was coming out I screwed the screw back in.

But ... it seems most shocks of similar designs that do not have that screw. Seems like it is just a Sachs thing.

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usedtobefast
Grignapoco
Grignapoco
usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 18, 2019 8:36 pm

Phase II

So my $35 eBay 2003 R1 shock arrived ... looks like this:
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So I get out my ratchet tie down strap, confident with my process of pulling off springs ... but ... not so on the mighty R1!

The R1 has a 8.8 kg spring, the GSXR had a 9.5 that I got off.  BUT, the R1 does not have the "normal" spring preload rings I can unscrew.  It has that ramp preload thing.  So the "softest" setting is still a ride-able spring preload.   With the GRiSO & GSXR, I could unscrew those preload rings and almost release the tension on the spring.  No so with the R1.

So ... the R1 did some damage to my ratchet strap!  It ended up a bit mangled, and with the spring still on the R1 shock.  

Off to google to look into shock spring compressor tools.  

Racetech has a nice one, a bit painful $110, but they say "works for up to 8KG springs", nope.

MotionPro has a nice one, real painful $150.  Ouchie!

Then I run across these for $35:

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They have similar ones on eBay and Amazon for less, but Tusk is the RockyMountainATV&MC brand, they are great to deal with, and support Blake Baggett in super-x and moto-x, so I ordered the Tusk brand.

Then 3 days off while they shipped ...
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usedtobefast
Grignapoco
Grignapoco
usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 18, 2019 8:40 pm

Phase II

So my spring compressor tool shows up, connect it up, looks like this:

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Tighten one side 5 turns, tighten other side 5 turns, etc etc very easy, much more civilized  Very Happy
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usedtobefast
Grignapoco
Grignapoco
usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 18, 2019 8:46 pm

Phase II

After a while, I had enough room to pull the lock ring thing off ...

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And then it is apart ...

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And spring compare ... red is stock, yellow is R1 ... R1 one is 9mm shorter ... I think that will be fine as the GRiSO shock has enough threads to get the preload right (99% sure) ...

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usedtobefast
Grignapoco
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usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Fri Jan 18, 2019 9:00 pm

Phase II

So just to see if the R1 shock had any shims I could use ... I pulled the R1 shock apart ... I'll spare you all the fun and drama of that ... but, major disappointment, no shims the sizes I need in there .. bummer.

So time to order up shims from suspensiondirect.com

On the rebound side, I plan to swap out as follows:

Stock     Change to

30 x .3     30 x .2
28 x .3     28 x .2
26 x .3     26 x .2
24 x .3     24 x .2
22 x .3     22 x .2

Idea is to lighten up the rebound ... I'll leave the first 4 rebound shims as-is, and go .1 thinner for the next 5 shims.

On the compression side

Stock     Change to

30 x .2     30 x .15
26 x .2     26 x .15
22 x .2     22 x .15
18 x .2     18 x .15

Similar idea here, leave the first 5 shims as-is. And since shims are cheap and shipping isn't, I also ordered those 4 in .1 thickness too (Phase III if needed).

In order to keep the stack the same overall thickness, I'll be adding some just below the washer.

For example, the Rebound stack will end up 0.5 mm thinner ... so I'm going to add a 0.2 and 0.3 shim just inside the washer so the stack thickness is the same.  I'll show pics of that later.

So ... shims ordered ... time to mess around with other stuff til they show up ... [insert drink a beer emoji]
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usedtobefast
Grignapoco
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PostSubject: Re: Reworking Sachs shock ...    Sat Feb 02, 2019 9:50 am

Phase II

Shims arrived.

Revalving the shock is way easier and faster than removing and installing the shock on the GRiSO!

So pulled everything apart as in Phase I ... except I now used the nifty spring compressors vs. ratchet tie down straps, which is much easier to do.

Swapped out shims as listed above. Put some blue loctite on the bolt and let that dry for 24 hours.

Put it all back together, same as Phase I steps. Installed the R1 spring (should be 8.8 kg spring).

So for Phase II, compared to stock, I have a stiffer spring (8.2 => 8.8 kg), lighter high speed comp and rebound shims.

Then over to the GRiSO for the shock wrestle mania. Took me 2 hours to remove the Phase I shock and install the Phase II shock. Sad thing is I think this is as good as I'm going to get at this, 2 hours is my remove/install time. (shock revalve time is approx 1 hr, with a 24 hr break in there for the loctite to dry, and I think I can get that to 20 min pull apart and revalve, and 20 min reassemble)

Set spring preload ... 10mm bike sag, 30mm rider sag, spot on target numbers (and a bit surprising that with the 9.5 kg spring I had 10mm & 29mm, would have thought there would have been a bigger difference).

I set comp out at 1.5 turns, rebound out at 12 clicks, went for a test ride.

First off, mentally I'm a pessimistic test rider. Smile Some guys do new thing x and then rant and rave about how awesome it is ... kind of like a test where you start off with a 100 and deduct points for bad things. My testing is you start off with a 0, and add points for things that are right. Smile

I head out, trying to run over as many sharp edged bumps as possible. At first I am disappointed ... it is clear no Ohlins engineers are going to be worried about my valving stacks. Smile It isn't the most amazing plush yet controlled velvet comfy ride ever.

Then some goods things start to be realized. The spring rate feels right, front and rear feel balanced (before with the 9.5 spring shock and stock spring forks the bike seemed off front/rear spring wise).

Phase II shock is better than Phase I shock which is better than stock. Phase II shock is doing nothing worse that PI or stock, either as good as, or better.

Valving front and rear seem balanced, front and rear working and responding similarly.

The rear shock valving is not too soft. It is more active, but does not squat too much on acceleration (stiff spring helping here). It actually is still a bit on the "sport bike firm" side of things vs. the "plush and cushy" side of things ... which is good ... I want to be able to hustle the GRiSO down curvy back roads, it's main purpose in life for me. Smile

Phase I took a bit of the edge off on sharp hits ... Phase II took a bit more of that edge off, but still firm-ish. So this may be good.

It was getting a bit dark, rain sprinkles starting, so GRiSO hustled back to the garage. Now we have ~4 straight rain days in the forecast. Maybe more testing Wed.

Pricing ...

Elko reservoir cap $30
R1 spring via eBay $35
Oil, hum, it is $15 a bottle, and I used < half, so call this $7.50 ? Or 0.00 as I already had the oil?
Shims - $12

Total - $85 revalve

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ghezzi
Fra Cristoforo
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PostSubject: Re: Reworking Sachs shock ...    Sat Feb 02, 2019 2:21 pm

and you haven't played with the external adjusters yet ..............................
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http://www.biketowbrisbane.com.au
usedtobefast
Grignapoco
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usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Sun Feb 10, 2019 9:22 am

Phase II

Further testing, but again limited.  I'm such a sissy ... below 50 F (10 C) and damp roads and the GRiSO stays in the garage.  Smile

Got out for ~20 minutes.  Liking things more.  I am surprised that with the changes I made, the difference is not very dramatic.  I may need to slow down the rebound a bit more (adjuster in a few clicks), but left it alone for this ride.  Tried comp at full closed, 1/2 turn, 1 turn, 1 1/2 turns out.  

I am still in that "low speed comp a bit soft, high speed comp a bit stiff" world.  Meaning, large dips in the road, slow shock shaft speed, comp a bit soft, bike moves a bit more than I like (for a sport bike suspension, moves more like a sport touring bike).  Then sharp jolt (like tree root under pavement, pavement pushed up 2-3"), fast shock shaft speed, oil doesn't flow enough, get a jolt on the rear.  

Phase II is much better at those jolts, but still sport bike firm there.  I guess that is one way to think of it ... it takes sharp jolts like a firm sport bike and then dips and braking are more like a sport touring bike.  I'd actually like the jolts to be worked out more and firm up the slower movements.

I guess I should be happy I didn't end up with some bizzaro un-rideable shock!  It is much better than stock, better than many other stock bikes, at this point.  

Some thoughts on Phase III (if I go there):
- current modified rebound shim stack probably ok
- add 2 shims on the low speed comp (the big shims right next to the piston)
- remove ~2 shims on the high speed comp (the small shims furthest from the piston)
- enlarge holes on the piston?  Not sure about this.  Adds an entire new factor to all this.  All aftermarket valving kits have larger holes in the pistons for more oil flow.  Maybe Phase IV.  

Time to go to Lake Tahoe and ski.  GRiSO on battery tender.  Sad
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ecs
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PostSubject: Re: Reworking Sachs shock ...    Mon Feb 11, 2019 9:10 am

Great detailed writeup Usedtobefast.

Tuner modified the Sachs Shock on my first GRiSO (a 2010 Tenni) and about to do same exercise over here with the new one. Job notes may or may not be of use to you or for others who are larger sized  Very Happy. Difference in both ends was exceptional.

The standard spring tested on the rig at 9.5kg/mm which is 532lb/in.  If yours was 82N/mm (8.3kg/mm), it must be a lottery.

At 225lb --> 11.6kg/mm (650lb/in).
   
Spring alternative is Eibach Coilover (good enough for Formula 1).  A 0700-225-0650 is $70 from Summit Racing.  0700 (is 7 inch), 225 is 2.25in ID and 0650 is 650lb/in.  Also comes in 500, 525, 550, 600, 700, 750 etc

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Compression and rebound pistons were fine to use.  (Note says surface pistons flat both sides if dished.)

The compression stack (12mm ID):
6 x .15 x 38
2 x .20 x 36
1 x .20 x 34
1 x .2 x 30
1 x .2 x 26
1 x .2 x 18
1 x .2 x 18
1 x .2 x 15

The rebound stack (12mm ID):
2 x .25 x 38
1 x .25 x 36
1 x .25 x 34
1 x .25 x 32
1 x .25 x 30
1 x .25 x 28
1 x .3 x 26
1 x .3 x 24
1 x .3 x 22
1 x .3 x 18

Many of those shims are common with the stock so only handful to buy from [You must be registered and logged in to see this link.] or similar for 89 cents each.  

Oil was 3W Maxima.  32oz for $15.95 on Amazon.

200 psi Nitrogen charge.  Schrader valve tapped in although the Elka Reservoir Cap was a great find.

Preload 18mm

Compare to a Matris M46K for $720 delivered.  

Did a similar exercise with forks except 5W oil, RT Gold Valve 2040 for Comp, stock piston for Reb, kept stock springs which tested at 0.98kg/mm, 110mm air gap and 16mm spring preload. Different shim stacks for both.  Compare to $415 for a Matris valve and spring kit delivered.
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usedtobefast
Grignapoco
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usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Mon Feb 11, 2019 5:31 pm

Awesome info. Thanks! I'll think about that shim stack as I ponder Phase III.
I was thinking of adding 1-2 38mm shims to the comp side.

Did the shock jolt when hitting abrupt pavement get greatly reduced? Like a tree root pushing up the pavement or an expansion joint on a bridge.

Interesting that you stayed with stock fork springs and went to a 11.6kg/mm shock spring. Mine felt a bit unbalanced with the 9.5 shock spring and stock fork springs. Maybe I had just gotten used to the low rider 8.2 Smile and the switch to a 9.5 seemed too dramatic.
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DC950
Don Abbondio
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PostSubject: Re: Reworking Sachs shock ...    Mon Feb 11, 2019 6:26 pm

I thoroughly enjoyed reading this. It reinforces a basic fact about suspension that is all too often overlooked: one has to have the correct spring rate and sag for the suspension to work properly.

I've seen many people spend a lot of money having their suspension "done" without even setting the preload!

Now a question: did you ever think of just sticking one of those ebay shocks on the GRiSO ans see what happened?
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ecs
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PostSubject: Re: Reworking Sachs shock ...    Mon Feb 11, 2019 6:37 pm

usedtobefast wrote:
Awesome info.  Thanks!  I'll think about that shim stack as I ponder Phase III.  
I was thinking of adding 1-2 38mm shims to the comp side.

Can't hurt to try.

usedtobefast wrote:
Did the shock jolt when hitting abrupt pavement get greatly reduced?  Like a tree root pushing up the pavement or an expansion joint on a bridge.

I could not fault the performance after it was upgraded - but then I am not Ghezzi.  Speed bumps were no problem but were before.

usedtobefast wrote:
that you stayed with stock fork springs and went to a 11.6kg/mm shock spring.  Mine felt a bit unbalanced with the 9.5 shock spring and stock fork springs.  Maybe I had just gotten used to the low rider 8.2  Smile  and the switch to a 9.5 seemed too dramatic.  

Was pleasantly surprised.  His notes below.  The reason I did it in the first place was because of the fork dive upon braking. I think it all came down to the compression valve and it was not because of the springs.  Even better was that it greatly improved cornering too.
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ecs
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PostSubject: Re: Reworking Sachs shock ...    Mon Feb 11, 2019 7:07 pm

DC950 wrote:
I thoroughly enjoyed reading this.  It reinforces a basic fact about suspension that is all too often overlooked:  one has to have the correct spring rate and sag for the suspension to work properly.  

I've seen many people spend a lot of money having their suspension "done" without even setting the preload!

Now a question:  did you ever think of just sticking one of those ebay shocks on the GRiSO ans see what happened?

No problem with doing that as long as what shows up is correct and you have someone who can set it up properly.  There are just too many combinations of settings that you cannot get out of a box - Ghezzi talks about 12,000.  I equipped the Norge with the Matris drop in forks and the fully adjustable rear shock for megabucks and could not get minimum sag because they gave me a shock with a 13.7kg/mm spring rate.  Then they only gave me one generic setting for rebound and compression. Megabucks and not a lot to show.

For the GRiSO, the tuner gave me a sheet with 4 different sets of settings.  One was Softy, one was Track, one was Daily and the other Passenger I think.  Only reason I sold that bike was because they would not let me import it over here.
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usedtobefast
Grignapoco
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usedtobefast

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PostSubject: Re: Reworking Sachs shock ...    Tue Feb 12, 2019 7:33 am

DC950 wrote:


Now a question:  did you ever think of just sticking one of those ebay shocks on the GRiSO ans see what happened?

What shocks on eBay?  I see a Hagon shock for $500, a Mupo GT1 for $693, a Matris KD for $751, and then some $1000+ options.  That's from US eBay.

I could have paid a local suspension place ~$400 for them to revalve the Sachs and put a stiffer spring on.  Traxxion Dynamics was that same $400, plus shipping both ways ... and they have done GRiSO shocks before and have notes.   So I think that would be better than those 3 shocks on eBay (also since who knows what spring the eBay shocks come with).

Not sure where you are, but I came across one post where Terry Hayes in Wallacia Australia redid a Sachs shock and the owner was super happy.  Terry is a suspension wizard (heard of him from the dirt bike world).

One option that seems "proven" is to buy a used stock Stelvio shock and bolt that on.  From my reading, seems they have a stiffer spring, better valving, and a bit more travel ... all that adds up to a much better ride (again, just reading, haven't tried one).  But when I looked for these I saw nasty abused sad looking used Stelvio shocks for $300+.  But ... looking at pics of the Stelvio shock ... no remote reservoir, does not seem to have a compression setting, and doesn't seem to be rebuildable?  But you can adjust the spring preload by turning a knob.  So not really a great shock.  But if you could find one of these in the $50-$100 range, simple bolt on and go, could be nice.
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