My Re-Spring of the S10 ES Shock

Karl

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#1
This is my write up on replacing the rear shock spring on a 2014 Super Tenere with electronic suspension. I am 6’2” and 250lbs, my Tenere has a tank bag, akro pipe, pannier frames and a Givi Trekker top box so far, apart from that it is stock. I do not ride two up (my Mrs has a Yamaha Tracer). My issue with the bike started the day I picked it up, within 1hr I was scraping the LH peg. Further investigation revealed that with full preload, I had a pitiful 83mm rider sag. 57mm is the magic rider sag figure, 190mm of travel and 30% sag = 57mm. I was far from that even unloaded...

When riding my favourite twisties I had to crank the preload to full hard, damping to hard and remove the peg feeler before I stopped scraping the bloody thing when riding like I am used to (on my old R1150GSA). What would it be like with some decent luggage on?

I can’t afford yet to discard the stock suspension, so time to re-spring. No help on the forums, or google so I went to racetech, who also have no information on the S10 ES but wanted me to up the spring rate by almost 50% (for the standard bike). It was not going to be that easy. The bike specs for the shocks (see attached pic) says the stroke of the ES is longer (+21%) and the spring rate is significantly less (43%). Coupled with the fact that the lower 3 point link and the dog bones are a different Yamaha part number for the ES bike, says to me, that the rate through the linkages is different and a 50% spring rate increase could be too much.
The stock ES spring rate is 75N/mm or 430lb/inch. A 30% spring rate increase would be a 550lb spring. If I keep the same set of the spring (free length 213.5mm minus installed length 197mm = 16.5mm). A quick sanity check says that if I put the new spring in, set the same way, the initial load set will go from 280lb to 357lb. So I figured a 77lb (35kg) static, non preloaded increase, will go some way to offsetting my 250lb (114kg) ass and make me more like a Japanese man.
The next problem was which spring? An 8 inch (203mm) spring with a 10mm spacer should match the current spring length well (at 213.5mm). As can be seen from the shock specs, the ES shock spring is larger diameter than stock and tapers in at each end, 56mm inner diameter at the bottom end, and 59mm at the top end and about 62mm through the guts. 62mm is 2.44 inch ID, so I went for a 2.5 inner diameter spring, Eibach 0800.250.0550. The clearance through the swingarm is tight but it looked like a couple of mm overall increase would not be too much of a drama.
Next step to get the thing out. This is not so hard because the preload motor, compression reservoir and electric connections are outside the rear frame. It looks like it won’t come out though the frame but it does. Disconnect it each end, drop it down as much as you can, twist it out of the top mount and bring it up and out through the subframe beams. I pulled the spring out using my home made spring compressors and removed the bottom seat.

Then I went to the CADD and designed a 10mm spacer that would fit the bottom seat and the spring. I purchased a 101.6mm diameter block of aluminium and turned up the spacer on my lathe at home. Installation is the reverse and thank goodness, there is no clearance areas anywhere. The sag is now:

1up = 70mm
1up plus luggage = 65mm
2up = 56mm
2up plus luggage = 52mm

To be honest, you could go up further in spring rate, particularly if you are 2up. The rate through the linkage looks to reduce the pre loading effect by approximately half. I worry about the pre-load motor struggling and the shock running out of damping with more spring rate. For my conversion, the preload motor seems fine, no real change. Test riding 1up plus luggage with normal damping seemed fine but I was unable to get to my favorite twisties. The damping over the small bumps was good I thought.

In the end of the day, the rear is sitting between 13 and 30mm above what it was (on full preload) depending on the preload selected. As a bonus, it will also sink less on those mid corner bumps. I will let you know my opinion about the handling and damping when I can really hook in, but we know how subjective that is.

Attached Pictures:
1. specs on the difference between the ES and non-ES shocks and springs.
2. ES Shock Just removed.
3. Spring Compressing.
4. Difference between the springs
5. Old bottom seat and new spacer
6. Shock re-assembled.
 

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WJBertrand

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#2
Great post! This is exactly what I want to do. Are you planning to make your spacers available? If not, I would pay a nominal fee for your cad model that I could take to a machinist. Did you buy the spring directly from Eibach or got through Race Tech? Also how did the other (bottom?) of the spring seat/fit with the OEM shock, did you need any modification there? Researching that spring (0800.250.0550) shows it is a 550/lb rate or 96.25 N/mm for a +28% improvement and I've found a number of sources for it. Getting excited to give this a go.
 

Karl

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#3
You guys have much better sources for springs than us, I went to the Australian distributor for mine, In the past, I have used www.eshocks.com to buy from the US.

I will do a drawing for the 3d model of the spacer and upload it tonight.

Here is some info on how the new spring sits.

TOP: The existing pre-load adjuster collar is plenty big enough outer diameter for the new spring. There is now a gap between the outer diameter of the seat and the inner diameter of the spring which could allow the spring to wander around. I wrapped some thick self adhesive rubber sheet I have around the collar in about 8 layers which takes up the slack nicely. You could also glue an aluminium or plastic ring in there, it takes no load.

BOTTOM: You have to re-use the bottom circular seat, it is the one in the photo with a slot in it. The slot means you can pull it out once the spring is compressed. The new spring and spacer slide over the end of the shock and the existing spacer goes back in to lock it all up. You can see from the cross section view in the CADD that the existing seat is grey and the new spacer is red (see pic attached). I did use the lathe to take a couple of mm off the existing spacer so I did not have to compress the spring as much, but this is by no means necessary.

Hope this helps.
 

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Karl

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#4
OH, and Jeff, if you are riding two up with luggage, I would up that spring rate more. However as I said, more spring rate is more load on the preload adjuster and more rebound damping needed out of the shock. Will do the drawing tonight.

K
 

WJBertrand

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#5
Thanks Karl, not going to be doing any 2-up riding and don't want to over tax the adjuster or the damping so your spring seems about right. I've found a good source for the springs state side at Summit Racing Equipment here : http://www.summitracing.com/parts/eib-08002500550 Price seems good too. I'd be interested in the modifications you've made to the retainer as well. I'm visiting a machine shop I could have that done at the same time. I wonder of the upper support can be machined to make a recess to serve as the ring you describe to better stabilize the location at the upper end?
 

Karl

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#6
I did not consider putting a step in the upper collar, I am unsure as to how much meat is there and you would want 5-8mm. Also you would need to make the 10mm thick spacer, correspondingly thicker by 5-8mm to get the same pre-set load. You could also make a top and bottom spacer, but that is just double the work.

As for the mods to the existing lower spring seat (grey part), I just took a couple of mm off the top of the lip that engages my new spacer (red part). This lip is to centre the spring but the engagement to the new spacer is a lot (about 10mm) and is 5-8mm is probably enough. It just means that you can compress the spring a couple of mm less, so it is only for the convenience of installation.

If you buy the spring and dismantle the shock at the same time, the machinist should be able to ensure a snug fit to the existing seat which is pretty rough cast. This is how I did it, but I did it all at home. You could get my spacer made beforehand and it will still work fine.

With removing, doing the CADD, making the spacer and doing other stuff, this job took me about 4-6 hrs so it is not a huge effort.

K
 

WJBertrand

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#7
Yeah, If I can get the spacer made somewhere first before I begin disassembly, I'm thinking maybe an hour? I've got a set of spring compressors designed for changing out McPherson struts and the like that I think I can use for this. I really appreciate your pioneering this!
 

Karl

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#8
It took me about 1/2 hour to get it out and and hour to get it back in. Allow another 1/2 hour if your spring compressor is a good one. I find that my car spring compressors do not fit the shock spring.

Here is the spacer drawing attached.
 

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WJBertrand

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#9
Karl, thanks for this, I'll be getting some quotes on this.


Update: Getting some one-off quotes from local shops is looking like $150 - $200 due to minimum charges. I'm exploring some of the on-line machine shops but some of them won't quote without a solid model.
 

regulator

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#10
Really interested in what you've done Karl.

I'm curious to know if you noticed any issues with the new rear spring and stock springs in the front forks?
 

Karl

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#11
I have not looked into the front forks yet. My rear changes seem to have no detrimental effect on the front, not that I expected any. With a higher rear, the tip in is a bit better and the poor spring rate of the front is not so pronounced from the reading I have done. I will check the sag on the front as soon as I have a mate over to help.

Looking for info on the ES forks and springs if anybody has it?

K
 

WJBertrand

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#14
Karl said:
I have not looked into the front forks yet. My rear changes seem to have no detrimental effect on the front, not that I expected any. With a higher rear, the tip in is a bit better and the poor spring rate of the front is not so pronounced from the reading I have done. I will check the sag on the front as soon as I have a mate over to help.

Looking for info on the ES forks and springs if anybody has it?

K
Karl, any update, impressions on your rear spring replacement? I'm having a spacer made per your specification and will order a spring shortly to dive into this myself.
 

Karl

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#15
So I did get a chance to ride out to some twisty roads on Sunday, it was a little damp at times. I had the pre-load set at 1 plus luggage and I had a tank bag and empty panniers on. I also had a play with the three damping settings, which I had all changed to +3 to account for the stiffer spring rate. Basically the bike was riding as nicely as before, with the added bonus of no scraping and being a little more responsive (with the back sitting higher). I can't see a problem with any harshness in the sharp bumps I went over. I would be tempted to try a slightly thicker spacer (12mm) next time to move the initial sag to something a little less but I think the spring rate is pretty good. I would not bother changing the spacer now tho.

As I said before, If I was 2up, I might consider something stiffer again. Good luck with the mod.

K
 

WJBertrand

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#16
Karl said:
So I did get a chance to ride out to some twisty roads on Sunday, it was a little damp at times. I had the pre-load set at 1 plus luggage and I had a tank bag and empty panniers on. I also had a play with the three damping settings, which I had all changed to +3 to account for the stiffer spring rate. Basically the bike was riding as nicely as before, with the added bonus of no scraping and being a little more responsive (with the back sitting higher). I can't see a problem with any harshness in the sharp bumps I went over. I would be tempted to try a slightly thicker spacer (12mm) next time to move the initial sag to something a little less but I think the spring rate is pretty good. I would not bother changing the spacer now tho.

As I said before, If I was 2up, I might consider something stiffer again. Good luck with the mod.

K
Thanks for the update Karl. I'm thinking of adding some kind of collar at the top to better locate the spring, that could add a mm or so. Have you noticed any issue with the top seating of the narrower spring? I didn't quite follow your description of wrapping it with some rubber. I would worry most about the spring possibly abrading the shock body.
 

Karl

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#17
So the top of the spring already sits on a separate collar to the shock body, that collar is pushed downwards by the pre-load adjuster. The new larger diameter spring is only a loose fit on this top collar. This would possibly allow the top of the spring to wander around, only about 5mm tho. I just took up the space by increasing the diameter of the collar with some packer, in my case it was some thick self adhesive rubber that I wrapped around until it the spring was a snug fit.

K
 

WJBertrand

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#18
Karl said:
So the top of the spring already sits on a separate collar to the shock body, that collar is pushed downwards by the pre-load adjuster. The new larger diameter spring is only a loose fit on this top collar. This would possibly allow the top of the spring to wander around, only about 5mm tho. I just took up the space by increasing the diameter of the collar with some packer, in my case it was some thick self adhesive rubber that I wrapped around until it the spring was a snug fit.

K
Thanks, so it sounds like this collar extends into the ID of the spring far enough to use it to help locate the spring? Got it!
 
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