Suspension tuning advice

[SS109]

Been trying to get the suspension on the '11 GasGas EC250 dialed in for several months now and can't seem to get it where I want it. It's pretty good but I know it can be better. I'm hoping for a little advice to get me going in the correct direction.

I'm right at 140lbs without gear and a mid to bottom B rider/racer. I ride rocks, hard pack, sand, and silt, from hike-a-bike technical to hare scrambles/GP's, and some very beat up trails.

Forks are Marzocchi PFP 48's, .38kg main springs, 1.4 cartridge spring, Maxima 85/150 5wt oil, 210cc cartridge, 300cc outer, 0mm main spring preload, PFP fully out, compression 19, rebound fully closed, 5mm above clamps. Shock is Ohlins 888, 4.8kg spring, sag 103mm, hsc 3, low compression 26, rebound 8. IIRC, suspension front and rear was re-valved by Motolab for AZRickD who is a 180lb rider of similar skill and when I bought the bike it had .44/5.4kg springs installed

Front is really plush eating up trail junk, does well on square edges, and zero deflection. However, the front wants to wash pretty easily and when riding sand it is really tough getting the bike to go where I want to and to hold a line. Tried slowing the rebound as much as I could without fixing the problem. Next I started dialing out the PFP in hopes of slowing it down. It seems to have helped some but it still feels like I'm maybe 3-4 rebound clicks away from being where I want it.

The rear kicks a lot but not severe as if it's going to eject me but it definitely feels busy.

So, my left fork seal started leaking so I gotta have them out anyway. Should I try to switch to a heavier fork oil, 26.7cst@40 vs my current 16.2cst? Maybe raise the forks some more? Trying to avoid a re-valve right now as my budget is tight being it's the holiday season. I just don't know which way to go as my mind is reeling from all the variables and I think I have lost sight on how to get it where I want it.

 

[Jakobi]

Are you happy/competent to pull the damper shaft out of the cartridge when you're replacing the seal? And do you have the time to consider measuring the current rebound stack, comparing to stock and discussing adding some more rebound to the bike?

 

[SS109]

Yes, I can pull the rebound. Haven't done it before but I haven't ever found anything mechanical I couldn't do. I figured It was going to need to have the rebound stack modified. The next race isn't until January and I have my old KDX to ride until then.

 

[Jakobi]

That's what I would be doing.. and mechanically it's pretty straight forward.

 

[Anders]

Take a look at this thread
http://www.gasgasrider.org/forum/showthread.php?t=11075&page=30
In posts 292 onwards Jacobi and myself discuss the rebound stack modification that I did a couple of years ago

 

[Doc Brown]

Front is really plush eating up trail junk, does well on square edges, and zero deflection. However, the front wants to wash pretty easily and when riding sand it is really tough getting the bike to go where I want to and to hold a line. Tried slowing the rebound as much as I could without fixing the problem.

For riding in sand you probably went in the wrong direction. Let the rebound as it was and start to add more damping, and if possible more pre-load, then make sure your forks are flush with the clamps, if not push them in. What you want is a light front that doesnt dig into the sand.
The deeper the sand the more you need to increase your corner entry speed and steer with the rear keeping the front light.

 

[SS109]

Ok, tore the front end down. Drained both forks and disassembled the leaking leg. Bushings look good. Even the seals look good (inspected using a magnifying glass) but there was a lot of dirt in them. As typical for these forks the oil was filthy with just about 45 hours on it.

Trying to figure out how to get the rebound rod/stack out. Do I have to remove the clicker end? Also, do I just unscrew the nut around the rod going in to the aluminum tube (section w/the preload adjuster)? What about the cartridge section from the tube?

Take a look at this thread
http://www.gasgasrider.org/forum/showthread.php?t=11075&page=30
In posts 292 onwards Jacobi and myself discuss the rebound stack modification that I did a couple of years ago

Yeah, I've read that thread completely through at least three times now and constantly reference it.

For riding in sand you probably went in the wrong direction. Let the rebound as it was and start to add more damping, and if possible more pre-load, then make sure your forks are flush with the clamps, if not push them in. What you want is a light front that doesnt dig into the sand.
The deeper the sand the more you need to increase your corner entry speed and steer with the rear keeping the front light.

My issue is that with our rides/races it is never just sand or hard pack/rocks. It's always a mixture to some degree and the rocks are brutal out here sometimes so I need it to be very compliant to keep from being beat to death. I figure I can use the PFP to help find a good balance once my valving is sorted.

 

[Jakobi]

Trying to figure out how to get the rebound rod/stack out. Do I have to remove the clicker end? Also, do I just unscrew the nut around the rod going in to the aluminum tube (section w/the preload adjuster)? What about the cartridge section from the tube?

Yeah the collar/locknut on the damper rod that locks down onto the base plug while back right off the shaft. You may need to make up a little holder to crack it loose without damaging the shaft.. it won't be really tight though.

Then with the comp adjuster assembly (top of the cartridge) removed the whole piston and shaft will lift out the top.

Take note of the piston band. It's stepped and comes off the mid valve.

On re-assembly an o ring will hold the piston band in place and pop off when you push the piston back into the cart.

BE VERY CAREFUL with the threads on the damper rod passing through the cart seals. Some people tape them, others take the edge off them a little.. they can cut the seal if you're too forceful.

Going back together is opposite, but you will need to index the base plug and locknut to set the number of clicks on the rebound needle. It's not too hard.

 

[Anders]

BE VERY CAREFUL with the threads on the damper rod passing through the cart seals. Some people tape them, others take the edge off them a little.. they can cut the seal if you're too forceful.

Another option is filling the threads with grease as suggested by Paul Thede in the Motorcycle suspension bible. I have done so with good results (no leaks afterwards).

 

[Jakobi]

Yeah I usually make sure they're lubricated as well.. however I don't think packing helps that much.. It's the edge that can be sharp... and the OD on the thread is usually a touch smaller than the OD on the shaft.. It's more of a concern if you reem it through without it being straight.

 

[SS109]

Ok, I'll get it apart when I get home today and post up. Thanks gentlemen!

 

[rvktm]

racetech do a 10 ics spring got them in my 013 mar cc. the problem i had was the fork was good flat out not so at lesser speeds so i softened the ls comp stack and used 16 cts oil think iv got 4.2/5.2 im 180ish. im on one from stiffest on the spring pre lode clip i do think it sits in the midstroke a bit thinking more spring pre lode or one 4.4/one 4.2 spring . has the 888 bean served recently as the gas piston runs out of oil gap over time

 

[SS109]

Yeah, I haven't serviced the shock since I've owned it and suspect it is due.

Ok, my compression stack is...

Bolt
Spring
31.85 x .3
piston
11 x .3
11 x .3
18 x .1
20 x .1
24 x .1
13.8 x .1
31.8 x .15
31.8 x .15
28 x .1
2.5 spacer

My rebound stack is...

Nut
11 x 2.5 spacer
11 x .10
11 x .30
14 x .15
17 x .10
20 x .10 (3)
12 x .10
piston (larger opening facing nut side and there is a small bushing/spacer in it on the same side if it makes a difference)
20 x .10 (2)
11 x .10
11 x .25
18 x .15

 

[SS109]

Any ideas on what I can do with what I have?

 

[Jakobi]

This is your rebound stack..

Nut
11 x 2.5 spacer
11 x .10
11 x .30
14 x .15
17 x .10
20 x .10 (3)
12 x .10
piston

You more damping.. I'd take that 12 x .1 off the piston face.. All it does it let a load of oil bleed on past the stack. I'd slip it in around between or under the 20's.. as I did on mine (see below).

This is what I have in my set..
Piston
20x.10 (2)
12x.10 - bleed moved down to crossover
20x.10
18x.10
16x.10
14x.10
12x.10 - from BV
11x 2.5 - collar

 

[SS109]

Cool! Thank you! I'll get it done and report back as soon as I can test it.

 

[SS109]

Got everything put back together and rode it on Sunday. Rebound was way better. However, now I'm at full soft on the compression. Doh! Only other change was going from 300cc to 320cc on the outer chamber as the forks had almost no bottoming resistance before. Lost some plushness but at least it doesn't beat me up. I'll be fine with them until the next service and then maybe I'll play with the compression side of things. Thanks for all the help!

BTW, I made a video of me servicing the forks. I'll post it in the big Marzocchi 48mm PFP thread. Hopefully it will explain a lot of things for those wanting to service their own 48 PFP forks. Sadly, it is somewhat comical with my little mistakes and my use of words.

 

[Jakobi]

That 12mm face shim holding the rebound stack off the face could have been letting some fluid back through as free bleed in the compression direction too. Depends if the force is enough to flex the whole rebound stack backwards over the ports to close them off.

Pulling a 20x.1 out of the mid comp or even letting a touch more free bleed past the base (maybe a 26 or 27mm bleed shim vs the stock 28mm) might move let you find the happy place. Not hard to drop a few mms of oil out of them in the interim either.

 

[SS109]

Just did a race this past weekend that was mainly MX track and whooped out sand wash. Used all of but 3/16" of my travel so I think the 320cc outer is about perfect. Still have the compression set at full soft and PFP at 0 and the bike actually did really well on this course. However, the next race is a slower, more technical race (lots of rocks) and I'm worried the forks are going to send me off course and that can be quite dangerous in certain sections. So, I don't have any other shims to play with but I think I gotta try something.

Jakobi, you said I could remove the 20x.1. Would I completely remove it or move it to the end of the stack with the collar? As far as the 28, the one furthest from the piston, that is considered a bleed? I thought the ones closest to the piston, being very small in diameter, are bleeds or am I wrong? What would be the effect if I swapped the positions of the 28 and 24 shims? Sorry, I'm really trying to understand the philosophy of how the valving works and want to make sure I understand correctly.

 

[Jakobi]

Jakobi, you said I could remove the 20x.1. Would I completely remove it or move it to the end of the stack with the collar? As far as the 28, the one furthest from the piston, that is considered a bleed? I thought the ones closest to the piston, being very small in diameter, are bleeds or am I wrong? What would be the effect if I swapped the positions of the 28 and 24 shims? Sorry, I'm really trying to understand the philosophy of how the valving works and want to make sure I understand correctly.

Sorry, I have confused you. I read the base valve stack wrong and figured the 28 was against the piston. The stack is very strange that it tapers a lot of bleed and then clamps on the 28.. Are you certain you recorded it correctly?

I also looked at your stacks again and don't think I would change the mid comp stack too much. It only has 2 x 20.1's already..

Did you mention what the float clearance is?