My average american experience with the T7 rear spring swap - sag numbers.

[mpb1]

I weight 179lb on the bathroom scale.  My bike has the Yamaha Touring Pack with heavy pannier rack and center stand.

 

I was sitting over 70mm sag with the stock spring wound up to max preload.  As soon as I saw Rocky Mountain ATV had Rally Raid shock springs I ordered one in 85Nm per Rocky Mountain's chart.

 

The shock drops out the bottom pretty easy if you remove the dog bone rear link bolts and the bottom shock link bolt.  I did note that the bolts that go through all the linkage bearings were dry, but they are inside the steel inner races of the bearings, they are not part "of the bearing".  Even though the bike is less than 2 months old, the bolts were starting to collect the powdery white corrosion or whatever it is that sometimes builds up down there.  The actual needle bearings were greased fine and the outer surface of the inner race tubes were fine.  I cleaned up the bolts and added grease between the bolts and the inner race tubes, and added some grease to the bearings because they were right there.

 

I don't have a motorcycle shock compressor, so with the stock light weight spring I just compressed it with two small ratchet straps easily enough on a workbench and got the retainer out without trouble.  The new shiny white spring though, I couldn't get to compress with just straps.  I had to use my car spring compressors.  I didn't think the tangs would fit between the tight (compared to my Ford Raptor) spring coils, but I took the threaded tangs off of the rods and they twisted in just fine, then threaded the tool back together and used the back surface of the preload assembly to brace the nut-side tangs.  This worked very well and the spring compressed fine allowing the retainer to slip back in.  I did use the plastic collars that came with the spring.  One fit tight to the bottom spring cup and one fit tight to the retainer.  In free space the new spring by itself was shorter than the stock spring, so with the plastic rings it was the same length.  

 

Back together was easier than taking apart.  I didn't have a chance to grease the front linkage bolt, because the center stand bracket prevents the bolt from sliding out.  If you are installing a center stand this may be a good time to grease that bolt!

 

My sag numbers came right in exactly where I would want them!  I was so happy.  All of the numbers are with no preload in the adjuster, so I have plenty of room if I'm loaded up for a trip or if I ever ride with a passenger (well, it will help with a passenger, I doubt I could get 60mm sag with two adults on the bike). 

 

Using some basic assumptions about linearity, and remember I'm just using a tape-measure, I calculate that I can run 44lbs of payload in the panniers and still see 60mm sag.  My 3-day tent camping setup from my last trip put 31 pounds of gear in the panniers, and after some quick "crossing off" I think my next trip will have about 22 pounds of gear, maybe 25.

 

This gives me 19 pounds of capacity for the bike getting full of mud, extra fuel, extra cold-weather gear, extra water, or whatever I think I could possibly need for a trip.  I find the Yamaha panniers heavy and the rack to be extra heavy.  With a lighter rack and soft-bags, I think I could pick up another 15 or 20lbs of payload.  Probably another 2 pounds if I ever get around to a tail-tidy, that is a lot of plastic and glass light bulbs.

 

I think the 85Nm spring is perfect for my average setup!  With just me, run the preload at zero, with my normal camping setup, run it about half way, and if I'm really really loaded down with 2 extra gallons of fuel, run it all the way up on preload.  That is easy to remember!

 

	inches	mm	percent
travel		200
free spring	26.56	675
static	25.5	648
static sag		27	13.5%
rider (no preload)	24.25	616
rider sag (no preload)		59	29.4%
rider (full preload)	24.91	633
rider sag (full preload)		42	21.0%
rider empty boxes (24.1 lbs)	24	610
rider empty boxes sag		65	32.5%
	lbs	mm	lb/mm
effective sag spring rate	24.1	6	3.80
sag at max preload (empty boxes)		48
desired sag		60
sag available		12
payload available	44.0

[Matth]

Good job. Ive just ridden mine with the 85nm spring and it werks superbly.

so much better and no pre load on either so plenty of adjustments left when my panniers go on

[Tazmool]

Nice writeup, thanks for posting!

I have the exact same 85nm spring waiting to go onto the bike, but with current state of things (work, other projects) it will have to wait till the off season, where a bunch of other things will be done to the bike as well (heated grips, gps etc)

Looking forward to your riding impressions (changes) with the new rear spring setup.

 

Tazmool

[mpb1]

Took my first street ride to "go pick up donuts" just now.  The bike definitely rides taller.  The biggest difference I notice is much less swoopy wallow in bike-length dips in the road.  The bike stays up in its travel much more, but bumps get absorbed more.  Its just like you'd read or watch videos about.  A stiffer spring makes for more compliance by putting you up in a more compliant portion of the travel.  In this case stiffer is not harsher because of that nuance.

 

I'm not sure I felt any difference in steering with the slight difference in rake angle, I was at 70 mm, now I'm 59 mm, so 11 mm over the 1590 mm wheelbase is only .40 degrees.  I'm not sure I could notice that, maybe.

 

I'll "go get donuts" later and give an off-road impression.  I have a feeling there will be a bigger difference there, especially in burmed turns where I'm sure the travel is getting eaten up by centripetal force making the bumps even harsher.

 

I still have my clickers set at  two clicks less than the manual front and rear on compression damping.  I usually run compression damping less and less until I bottom out on a "harshish normal" bump for the type of riding I'm doing, but I haven't felt that yet.

[AZJW]

Your detailed numbers are appreciated and looks like you're right in the ballpark on the 85nm spring. I'm about the same weight and was advised to go with a 90nm which I just received and hope to have installed in a few days. If you continue the " go get donuts" runs, you might be looking at a 90nm also, lol. 

[mpb1]

That's really the best way to tune suspension.  Don't tune the spring or damping rates, tuning the mass only costs you donuts!

[Seventh Son]

10 hours ago, mpb1 said:

I weight 179lb on the bathroom scale.  My bike has the Yamaha Touring Pack with heavy pannier rack and center stand.

 

I was sitting over 70mm sag with the stock spring wound up to max preload.  As soon as I saw Rocky Mountain ATV had Rally Raid shock springs I ordered one in 85Nm per Rocky Mountain's chart.

 

The shock drops out the bottom pretty easy if you remove the dog bone rear link bolts and the bottom shock link bolt.  I did note that the bolts that go through all the linkage bearings were dry, but they are inside the steel inner races of the bearings, they are not part "of the bearing".  Even though the bike is less than 2 months old, the bolts were starting to collect the powdery white corrosion or whatever it is that sometimes builds up down there.  The actual needle bearings were greased fine and the outer surface of the inner race tubes were fine.  I cleaned up the bolts and added grease between the bolts and the inner race tubes, and added some grease to the bearings because they were right there.

 

I don't have a motorcycle shock compressor, so with the stock light weight spring I just compressed it with two small ratchet straps easily enough on a workbench and got the retainer out without trouble.  The new shiny white spring though, I couldn't get to compress with just straps.  I had to use my car spring compressors.  I didn't think the tangs would fit between the tight (compared to my Ford Raptor) spring coils, but I took the threaded tangs off of the rods and they twisted in just fine, then threaded the tool back together and used the back surface of the preload assembly to brace the nut-side tangs.  This worked very well and the spring compressed fine allowing the retainer to slip back in.  I did use the plastic collars that came with the spring.  One fit tight to the bottom spring cup and one fit tight to the retainer.  In free space the new spring by itself was shorter than the stock spring, so with the plastic rings it was the same length.  

 

Back together was easier than taking apart.  I didn't have a chance to grease the front linkage bolt, because the center stand bracket prevents the bolt from sliding out.  If you are installing a center stand this may be a good time to grease that bolt!

 

My sag numbers came right in exactly where I would want them!  I was so happy.  All of the numbers are with no preload in the adjuster, so I have plenty of room if I'm loaded up for a trip or if I ever ride with a passenger (well, it will help with a passenger, I doubt I could get 60mm sag with two adults on the bike). 

 

Using some basic assumptions about linearity, and remember I'm just using a tape-measure, I calculate that I can run 44lbs of payload in the panniers and still see 60mm sag.  My 3-day tent camping setup from my last trip put 31 pounds of gear in the panniers, and after some quick "crossing off" I think my next trip will have about 22 pounds of gear, maybe 25.

 

This gives me 19 pounds of capacity for the bike getting full of mud, extra fuel, extra cold-weather gear, extra water, or whatever I think I could possibly need for a trip.  I find the Yamaha panniers heavy and the rack to be extra heavy.  With a lighter rack and soft-bags, I think I could pick up another 15 or 20lbs of payload.  Probably another 2 pounds if I ever get around to a tail-tidy, that is a lot of plastic and glass light bulbs.

 

I think the 85Nm spring is perfect for my average setup!  With just me, run the preload at zero, with my normal camping setup, run it about half way, and if I'm really really loaded down with 2 extra gallons of fuel, run it all the way up on preload.  That is easy to remember!

 

 

 

	inches	mm	percent
travel		200
free spring	26.56	675
static	25.5	648
static sag		27	13.5%
rider (no preload)	24.25	616
rider sag (no preload)		59	29.4%
rider (full preload)	24.91	633
rider sag (full preload)		42	21.0%
rider empty boxes (24.1 lbs)	24	610
rider empty boxes sag		65	32.5%
	lbs	mm	lb/mm
effective sag spring rate	24.1	6	3.80
sag at max preload (empty boxes)		48
desired sag		60
sag available		12
payload available	44.0

Thanks for the write-up and feedback on the new spring.  I have a 90nm spring from Rally Raid that I want to install soon.  Based on the spring compressor you used, do you think this one will work?  It looks similar to the one you linked above. 

MacPherson Strut Spring Compressor Set

---

MacPherson Strut Spring Compressor Set

 

[AZJW]

@Seventh Son. I'm going to try the floor jack/ ratchet strap method.  ( because I'm cheap!)

 

[Seventh Son]

7 minutes ago, CAJW said:

@Seventh Son. I'm going to try the floor jack/ ratchet strap method.  ( because I'm cheap!)

 

I would too, but I don't have a floor jack. 

[johnnygolucky]

43 minutes ago, Seventh Son said:

Thanks for the write-up and feedback on the new spring.  I have a 90nm spring from Rally Raid that I want to install soon.  Based on the spring compressor you used, do you think this one will work?  It looks similar to the one you linked above. 

MacPherson Strut Spring Compressor Set

---

MacPherson Strut Spring Compressor Set

 

Im very curious to if these would work a well? 

[mpb1]

2 hours ago, Seventh Son said:

Thanks for the write-up and feedback on the new spring.  I have a 90nm spring from Rally Raid that I want to install soon.  Based on the spring compressor you used, do you think this one will work?  It looks similar to the one you linked above. 

MacPherson Strut Spring Compressor Set

---

MacPherson Strut Spring Compressor Set

 

Yes this is the one I have.  It works for the tenere and my Ford raptor, that pretty much covers all the coilover sizes!

[Seventh Son]

On 8/29/2020 at 11:20 AM, mpb1 said:

used the back surface of the preload assembly to brace the nut-side tangs.  This worked very well and the spring compressed fine allowing the retainer to slip back in.

Hi mpb1,

Can you elaborate on this a bit?  I'm trying to picture in my mind what exactly you did here.  I'm probably going to pick up the tool that I linked above and give this a try in the next couple of days.  Thank you.

[mpb1]

The spring is too short to put both tangs from each tool into the spring coil gaps, so i put one tang of the tool in the coil gap closest to the retainer, and the other tang of the tool past the spring, contacting the preload assembly of the shock system.

[Seventh Son]

11 hours ago, mpb1 said:

The spring is too short to put both tangs from each tool into the spring coil gaps, so i put one tang of the tool in the coil gap closest to the retainer, and the other tang of the tool past the spring, contacting the preload assembly of the shock system.

I understand, thanks.

 

Do you think the same needs to be done to remove the OEM spring?  Or will the tangs fit in between the OEM spring coils?   When bracing the nut-side tangs on the preload assembly unit, do the tangs sit evenly flush on the unit?  I'm wondering if there's a risk of the tangs slipping off as you turn the nuts on the unit.   Thanks again.

[Seventh Son]

1 hour ago, CAJW said:

9/1/20 1057 miles. Changed out oem rear spring for a 90nm from RallyRaid.  Kudos to @Gk83 for his post of a DIY spring compressor utilizing a floor jack and ratchet strap. Worked slicker than hog snot.

 

Is that one ratchet strap or two?  I'm going to try to change out my OEM spring tomorrow for my Rally Raid spring.  I'm going to use this spring compressor tool, but not sure if it will work. 

 

MacPherson Strut Spring Compressor Set

---

MacPherson Strut Spring Compressor Set

 

[AZJW]

I used one ratchet strap. It's a bit convoluted,  but start by running the free end of the strap around the far side top coil then under the floor jack, then up to the top coil on the opposite side (inside then out)  then down to the ratchet. I had a long lead on the fixed hook on the ratchet which I had to hook on the opposite side of the floor jack so the ratchet had room to operate.  Set some tension with the ratchet, then finish compressing with the jack.  A piece of horse mat made a good cushion to protect the top of the shock. 

[Seventh Son]

I have neither a ratchet strap nor a floor jack, so I will see if I can do it with the spring compressor tool I posted above. 

 

I'm nervous...

[AZJW]

Actually,  I think your spring compressors are safer. My setup shifted on one attempt and slid off the jack pad. It didn't go anywhere, but got my attention! Just be sure to use a screwdriver and needle nose pliers to remove the lock ring, keeping fingers clear of that area.

[Seventh Son]

1 minute ago, CAJW said:

Actually,  I think your spring compressors are safer. My setup shifted on one attempt and slid off the jack pad. It didn't go anywhere, but got my attention! 

That would have certainly gotten my attention too. 

 

I'm still not 100% sure where @mpb1 on the other thread connected the nut-side tangs of the compressor tool onto the OEM preload assembly.  At first I thought I knew what he meant, but not so sure now. 

 

[mpb1]

Sorry I wish I would have taken a picture.  Maybe this helps!

[mpb1]

16 hours ago, Seventh Son said:

I understand, thanks.

 

Do you think the same needs to be done to remove the OEM spring?  Or will the tangs fit in between the OEM spring coils?   When bracing the nut-side tangs on the preload assembly unit, do the tangs sit evenly flush on the unit?  I'm wondering if there's a risk of the tangs slipping off as you turn the nuts on the unit.   Thanks again.

The tangs do just sit on the top of the preload adjuster.  They do not engage anything.  They could slip off easily.  I was wearing heavy leather gloves and safety glasses.  Im not a religious person but I always say a little prayer when those spring compressors come out of the tool cabinet.  They allow you to store so much energy.

[Seventh Son]

8 minutes ago, mpb1 said:

Sorry I wish I would have taken a picture.  Maybe this helps!

Yes!!!   Thank you!   Now I get it. 

 

Yesterday I tried taking the OEM spring off with a couple of ratchet straps, but the cheap bolt that I used to connect the strap hooks started to bend, so  I ended up cutting the straps off in frustration and destroying them.  I re-installed my shock unit and left it alone.  Today I purchased the spring compressors, but since I haven't yet removed the rear shock again, I couldn't visualize where you placed the nut-side tang of the compressor tool.

 

Again, thanks for taking the time to sketch out what goes where.  Tomorrow is a new day and I'm going to have another go at it. 

[Seventh Son]

1 minute ago, mpb1 said:

The tangs do just sit on the top of the preload adjuster.  They do not engage anything.  They could slip off easily.  I was wearing heavy leather gloves and safety glasses.  Im not a religious person but I always say a little prayer when those spring compressors come out of the tool cabinet.  They allow you to store so much energy.

Got it, thanks.  And I just saw your sketch from the other thread.  I'll have another go at it tomorrow. 

[mpb1]

You will get it.  Just take your time and turn both compressors evenly.  Once the preload is in the compressors not the shock, the spring can bend to one side easily.  You won't be able to get them exactly 180-degrees apart so this will happen to some extent no matter what.  The straighter you can keep the spring the easier it will be to remove the locking retainer.  You will need about 2cm or 3/4" of free space to tip the retainer out.

[AZJW]

Big shout out to @Ktmmitch. His advice on a 90nm spring was spot on. Zero preload = 60mm sag, perfect! 

 

Rider ready to ride 90kg (198.8 lbs.).