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Old 12-15-2010, 12:44 PM   #19
Beastly Adventurer
ER70S-2's Avatar
Joined: Sep 2009
Location: SE Denver-ish
Oddometer: 6,777
Suspension threads

Thanks to Basketcase:

My stock forks (full extension) are 35 1/4" from the fork cap to the axle centerline. Factory lowered should be 33 3/4".
Metric: stock; 89.5cm: lowered; 85.7cm

Stock fork spring spacer: 37mm diameter (1.465") - 40mm tall (1.58")

The stock DR shock is 455mm long with 128mm travel. (info from another inmate)
Stock rear spring rate is 6.5kg/mm

Stock shock preload:
10.0" (253.5mm) Softest
9.7" (247.5mm) Standard
9.4" (238.5mm) Stiffest

Stock links are 4.5" center to center (115mm)

Shock Spring Seat: stock and lowered

These pics are from the manual:
If you can see the notch at the arrow, your spring seat has been flipped to the lowered position and your shock travel is limited (by intent, when lowering). Also note that the bolt in the clevis changes holes.
Nothing is changed inside the shock.

Stock <-----------------------------------------------------------------> Lowered (yes, it looks raised)

Added 4-4-14:
For fork oil I measure 19.1 oz and pour it in each leg (565ml), per the manual. It's easier than the (compress fork with spring out and measure down 6.5"). When I had the forks apart I drilled and tapped each fork cap, 1/8 NPT. Always use a cutting oil when tapping alum, WD-40 works fine.

Ignore the fork being slipped up in the triple, it's just an experiment.

Then I use one of these with a zip tie loose enough to slide up-n-down. Now I can adjust my oil level without disassembly, which came in handy when I put a 320mm rotor on the front. The brake works so much better that the fork dive with .45 Eibachs, was too much for my liking. Stock oil level is 16-1/8" (forks fully extended, with springs and caps installed), I added 20ml and ended up at 14-7/8". That's 1 1/4" or 5/8" per 10ml. You don't even have to move your handi-bars, way better than removing the springs and collapsing the forks everytime you want to experiment with oil levels.

Motion Pro P/N: 08-0121:

Ignore the oil bubble:

Added 3-11-15:
Things I tried to avoid spending money, that I didn't have, on improving the DR's forks.

Initially, I rode the DR pretty conservatively so the soft springs didn't bother me much, except for excessive brake dive. I started riding in the dirt and the first thing Dirt Bike Magazine taught me was the importance of the front brake, the harder you can brake the faster you can go between corners. So I've always worked on threshold braking, which is 99% front brake. Doing that on the DR was intimidating to me on the pavement, even with the wimpy stock brake. When I upgraded to a 320mm rotor, things got

Easiest (still using stock springs): Increase spring preload. I'm 185 in street clothes, 210 in full ATGATT (which I recommend ). I started with 1/2" additional spacer because I was using 1/4" plexiglass (scrap available), but it was too stiff, so I backed off to 1/4", which was too soft. But both improved brake dive by a bunch. I never tried 3/8" but it would have been my number with stock springs. I found enough change under the couch cushions to finance springs and emulators, so that's where I went. Still thinking I would be riding pretty conservatively, I went with the softest spring rate I could find, which was .45 Eibach's. I don't remember if I got them from PC or Cogent.

Most guys use fender washers, they're more 'adjustable'. 37mm OD

Stock heavy steel spacer on the left, Eibach spacer in the center, Cogent DDC spacer on the right. So the OD isn't critical, but the Eibach is pretty small IMO. ALWAYS put a steel washer between the spring and a plastic spacer.

In the early 70's, one of the fads was air forks, remove springs completely, add schrader valves to the fork caps, air up and ride. I rode an entire summer with no fork springs. There's a very small volume of air in each fork and getting the air pressure balanced between the two was difficult, the solution was a cross over tube. Now instead of two chambers, there was one larger one, so both forks had the same pressure. Back then we used copper as the cross over with flared ends. It was a PITA to get the bend perfect so there wouldn't be any 'loading' on the copper. If you pulled it into position with the flare nuts, the copper would get brittle and crack (and leak ). This happened to me once on the trail and I rode many miles back to the trailer with the forks completely collapsed.

I tried this on the DR too, except I kept the springs and just added a few pounds of air to control brake dive. The cross over is something I found in the plumbing section at Home Depot IIRC. Since the air volume is small, I added a gauge so I wouldn't have to check air pressure (and I wanted to know if the 'system' was leaking). My first choice was a fluid dampened 0-15 pound gauge, I thought it would be good for my 5-6 pound air pressure. It wasn't ... every time the forks compressed a lot, like on a rocky downhill, the needle bounced off of the MAX peg like a machine gun. The 0-30 pounder got the job done. Note: if your bike spends much time on its side, oil will transfer from one fork to the other, some sort of pinhole baffle between the two sides would slow this down and still allow air pressure to equalize.

I got the gauge at Northern Tools, <$20 IIRC

CAUTION: Use a regulated air source, do NOT hit the forks with 100 pounds of tank pressure.

The goop that looks like thread sealant is oil soaked Teflon tape.

Close up of the parts used, with the 0-30 gauge. The parts are loose in the photo, that female fitting points down into the fork cap.

I've always used 1/8" NPT thread fittings. NPT is a tapered fitting and will self seal in the fork cap. If you don't like the air forks, plug the caps, I always use Teflon tape so I don't gall the threads.

1/8" NPT

Pics taken after removal, just positioned.

The cross over doesn't go straight across, it's arced rearward toward the gas tank.

Answers to some earlier questions:
Yep, an 8.x spring in the rear will make the brake dive worse with stock fork springs.

Fork preload thoughts:
Some time ago the subject was fork preload, the reply (from someone I respect) was: use the spring rate necessary for your riding conditions, the preload recommended for your damper of choice (emulator, Intiminator or DDC) and don't sweat the sag. Sometimes it isn't going to be a strict 30% (or whatever) of total travel.

Cogent was pretty clear that the DDCs want 8-10mm preload, I want to raise my spring rate from .45 to .50 because I'm riding much faster with the suspension upgrades. The newest recommended rate is .525 but I never do air time. With this information, sag becomes unimportant for my riding.

Another very experienced DR rider has said that .55 is his upper spring rate for dual sport riding the DR. Although there is a .60 .70 .80 rate available, the DR isn't a MX bike IMO.

Loose on the gravel on turn in:
Are you running a full knobby on the front? It makes the DR a much better dirt bike. I ran a dual sport tire for 40, 000 miles and had to ride like a girl to keep the front tire under me.

Stock fork oil is 10w and is still your best choice. 15w will make the forks harsh (or so I've read). I don't remember what a 7 or 5 weight might do.

I think the first move is adding 3/8" preload, then work with oil level. Disclaimer: I never messed with oil level, it wasn't in my consciousness when making my changes.

Absolutely worth the trouble to drill and tap the fork caps.
2004 DR650: 62,605 miles
2013 WR250R

Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -

ER70S-2 screwed with this post 03-11-2015 at 10:59 PM
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