FORK OIL and DAMPING

[Neil Claydon]

I need to stiffen the damping on my 2000 DRZ400S.

Or more accuratly stop the dive on braking.

I spend 95% of my time on the road, and the off road is hardly challenging stuff. I was going to fit stiffer front springs, but as I am only on 1 tip toe any way it seems a bit silly to make the bike any taller.

The main problem is under braking, it dives to hard and fast for stable cornering. I have recently fitted a 280 mm EBC disc and sintered pads which has only made it worse.

The workshop manual quotes 5 weight oil and an air gap of 165 mm.

Is there any improvement to be had by using a Heavier grade of oil, and a different air gap ???

If any body has any ideas please enlighten me.

Changing the springs is not an option at the moment as I have just ordered

Radiator guards and CFC's from the TT shop, and the wallet is empty, again.

Neil.

[Spud786]

Ten weight oil will stiffen them up quite a bit, you might even use ATF since mainly street (it's cheap), you could start off a 10mm less air gap , and then add by syringe if needed assuming that model has bleed screws..

Back many years ago before the upside downs had rebound adjustment, I used ATF as a test, the compression was great, but the rebound was slow, but for street it probable fine. IMO ATF is alittle heavier than a true 10weight fork oil

[sunnyboy]

I used Mobil 1 ATF, level at 5 inches from top of fork tubes. (approx 7.5 wt synthetic) Huge difference. Cheap. Good Luck.

[Weeeeee]

I was going to fit stiffer front springs, but as I am only on 1 tip toe any way it seems a bit silly to make the bike any taller.

Would stiffer springs make the bike taller? I wouldn't think so, but I could be wrong.

[Ross Buckingham]

I need to stiffen the damping on my 2000 DRZ400S.

Or more accuratly stop the dive on braking.

I spend 95% of my time on the road, and the off road is hardly challenging stuff. I was going to fit stiffer front springs, but as I am only on 1 tip toe any way it seems a bit silly to make the bike any taller.

The main problem is under braking, it dives to hard and fast for stable cornering. I have recently fitted a 280 mm EBC disc and sintered pads which has only made it worse.

The workshop manual quotes 5 weight oil and an air gap of 165 mm.

Is there any improvement to be had by using a Heavier grade of oil, and a different air gap ???

If any body has any ideas please enlighten me.

Changing the springs is not an option at the moment as I have just ordered

Radiator guards and CFC's from the TT shop, and the wallet is empty, again.

Neil.

Neil...when I serviced my 2000 S forks last winter I went with PJ-1 7.5w fork oil. You may even wanna try 10w fork oil. Readjusted the "clickers" to firm things up and it is like a different front-end. No more diving, etc. yet it will take a big hit. Measured my springs while I had them out to find them well with-in spec. Cleaned and inspected all...A pretty cheap "tune-up". As you know the 2000 / 2001 don't have the current suspension fore or aft and I've noticed some internal parts are "not available"...at least OEM. Will rebuild the rear shock this winter although the service manual states it is "not serviceable"...I think seals, etc. are available through Race Tech and some fresh shock fluid could never hurt. I have access to a nitrogen bottle so "top-off" shouldn't be a problem...Try some heavier fork oil in your 2000 and set the "clickers" up fairly hard and I think you will like it ?

[rookie517]

Neil, try 7.5wt with 90mm oil height, that would help.

believe it anot, i'm a certificated race tech guy

[Neil Claydon]

Would stiffer springs make the bike taller? I wouldn't think so, but I could be wrong.

It is my understanding that the stiffer springs will raise the ride hight.

The stiffer springs will have less race sag, which would be enough to ensure that I fall over every time I come to a stop.

(see my other thread,Lowering Links)

Neil.

[Neil Claydon]

Neil, try 7.5wt with 90mm oil height, that would help.

believe it anot, i'm a certificated race tech guy

Rookie, is that air gap for the 2000 forks (not cartridge type)

It sounds a bit radical (75 mm less air gap) will the fork seals take the strain.

It is probably what I need though, I also weigh 220 lb. which is not helping matters.

I think the ATF fluid is the way to go for now, as it is much cheaper than fork oil, and should perform OK as I assume it is the anti-foam property that is important.

Ross, thanks for the input here, I had forgotten that our bike's are the same vintage or I would have asked you directly. Perhaps you should build "My Garage" just to remind me.

Thanks for the advice People, keep it coming.

Neil.

[MilleonAir]

Neil,

I refilled the forks on my 2004 DRZ-S with 5wt oil and left a 110mm airgap. It's hard as nails. I had to back off the compression damping by a few clicks to pass scrutineering at an enduro - the scroot thought it was way too stiff for my weight and potentially dangerous!

I'm about to revert to 165mm but this shows what a difference the airgap makes. The ride height is unaffected by the damping - that's all to do with the spring weight.

Cheers

Ian

[rookie517]

Neil, i do that on my 00 DRZ, with the conventional fork. (same as ya bike)

i use 90mm on the fork as i convert my bike for supermoto.

the oil height only affect the last 1/3 of the compression stroke.

as ya are a big guy, 7.5wt should be just nice for ya.

i use 5wt for myself.

hope this helps.

[Neil Claydon]

Rookie,

I'm going to do it, I can't put up with the dive any longer.

I'll let you all know how I get on.

I suppose I had better do the steering head bearing at the same time.

Neil.

[rookie517]

cool, let us know how it goes

[Neil Claydon]

Ok, will do.

I just went out and bought some oil, and grease for the head races.

Unfortunately it is now Pi$$ing down, well it is summer, and this is England.

As I have to work outside it will have to wait for better weather.

Neil.

[Neil Claydon]

All done, stripped the front end off.

I have re-greased the head races, first time they have been done.

They were all right, not much grease, but no rust and the bearings were both good.

I expected a lot worse, after all the posts on head race problems particularly as it is a 2000 model.

Although not registered until 2003, it has covered 5500 miles and has regularly been pressure washed.

I also changed to 7 1/2 weight oil and set the air gap to 130 mm.

The excessive dive and the under damped feeling have gone, the bike handles much better, and holds a better line through corners at all speeds.

I also fitted the set of seal savers that have been hanging around for the last six weeks. As the bike sees so little dirt I reckon they will be fine, if I keep them clean.

Thanks for the advice every body.

Neil.

[rookie517]

good to hear that!

time to

[depecherider]

So, any suggestions about 2001 Drz400 S fork oil change for a 200 lbs rider and offroad riding? Thanks