'10 Sachs rear shock setup

[Bailey28]

Hey guys, please check this and let me know if the spring rate here is right for my '10 EC300:

The manual says that as delivered the 5.2 spring is preloaded to 258mm.

After a few rides I turned the preload ring in two full turns.

I measured the free sag at 30mm, and the race sag at 110mm. The length of the spring with the two added turns on it is right at 250mm. Bike feels good, handles jumps,, doesn't feel harsh and corners well. I left all of the clickers stock on the shock and fork.

I weigh 185lbs. in street clothing.

I don't think one turn on the preload ring is worth 4mm so maybe the shock was tighter than 258mm as delivered in the crate. I bought it new. Anyone know off the top what one turn of the ring is worth in mm?

 

[mtothef]

good question

got an afternoon of wrenching about to start, and greasing the preload rings was on the list. will do a check. i seem to recall for the kyb stuff on YZ suspensions that one complete turn of the ring netted 3mm of preload, and i was surprised at that since i'd always assumed a turn would be good for about one mm.

if the thread pitch is about the same between that and the sachs (shock bodies look to be about the same diameter), then you are pretty close on the numbers.

 

[mtothef]

birds of a feather...

i've got the 5.2 on my bike, and am also about 185 pounds without moto gear on. i guess my moto gear adds about 10 pounds over regular civvy clothes. when i got the bike i added a little preload to get the sag up there, but hadn't measured it with the spring uncompressed, or taken any measurement of spring set before i adjusted it. currently, i am at:

250mm spring length
30mm static sag
105mm rider sag (in moto gear)

i didn't break out the calipers, but it does look like you'd get about 3mm or so with each complete turn of the preload ring.

 

[Bailey28]

mtothef: Glad to see we got nearly the same numbers. I think the 5.2 is right on for our weight. I am measuring from the center of the rear axle hole to the point at the rear tip of the number plate. I'll call it the white "tip" of the number plate decal directly above the rear axle.

This is the first bike where I didn't have to run out and buy a spring. On my KTM 450 I had to go from a stock 8.0 to an 8.8 or the bike wouldn't ride right.

I think the 110 mm setting makes the bike turn even better than stock and still retains stability for the fast straights. I have my forks set in between the first and second line on the top triple clamps.

If I really had to pick on the suspension, I would say that the forks are a bit harsh on fast hard packed braking bumps as I am entering a corner. The bars tend to shake a bit but it doesn't upset the bike really that much if you are holding onto it.

 

[GMP]

If I remember the thread pitch is 1mm, so 1mm preload change for each turn. Forget about where it is set now. Back it off completely and start at 8-9mm measured preload. Ride it. Increase preload until it steers right and doesn't feel like a chopper. If your over 10 - 12mm or the rear gets harsh you should go to a 5.4 spring. I'm a 190 lb "B" and I run a 5.4 and could actually move to a 5.6 for the faster stuff. Sag #s are not so important, as long as it steers. The rear performs best in the trash with as little preload as needed.