Spring Rate............Confusion!!

[Scramble Champ]

Hello all,

I hope everyone's everyone is well.

I need some help with understanding spring rates/size/weight catagories ect.....

I have a 10 ec 300 with sachs on both ends. I wish I could afford to have the compoets sent to a shop to have valving ect.... reworked but I can only afford springs right now. problem is I do not know where to purchase the springs much-less which ones to get.

Any help would be appreciated.

I'm a 48 yr. old B woods racer at 230lbs.

Thanks

SC

 

[Jakobi]

I'd recommend Dave at STM Suspension. He's on this forum so if you PM or email I have no doubt he'd be able to hook you up with some rates and prices.

 

[gasmonkey]

Dave's da man.He knows.

 

[moto9]

One thing you should know the sachs and marz already have a rebound circuit that is too light for the stock springs.
Heavier springs could have some ill effects and could actually make the fork action worse.
Just FYI.

 

[400_racer]

Having just got round to looking at the suspension on my bike, i have a similar sort of question to Scarmble Champ, if you dont mind me picking your brains guys...

Having made some measurements, i think im right in saying they show i need lighter springs for my lightweight 145lbs fully geared up - yeah i know i need to eat some more pies!

Keeping in mind the stickied thread about keeping preload low and going by feel, i made the following sag measurements to give an indication of whether spring rate is correct or not, pretty sure they show its way too hard...

The shock originally had about 10mm preload which gave:
Rider sag = 100mm
Static sag = 42mm

Tried 8mm preload:
Rider sag = 106mm
Static sag = 46mm

Tried 5mm:
Rider sag = 108mm
Static sag = 50mm

Definitely too hard right? What rate springs would people suggest for my weight? (i will ring a tuner here in UK, but just to get your opinion too)

I have been getting on pretty well with the bike, but have probably just got used to the settings. Slightly embarassed that i havnt looked at this sooner, but am quite excited to see if making changes will make a marked difference to what i already think is a pretty good ride?!

Thanks,
Ad

 

[Jakobi]

Having just got round to looking at the suspension on my bike, i have a similar sort of question to Scarmble Champ, if you dont mind me picking your brains guys...

Having made some measurements, i think im right in saying they show i need lighter springs for my lightweight 145lbs fully geared up - yeah i know i need to eat some more pies!

Keeping in mind the stickied thread about keeping preload low and going by feel, i made the following sag measurements to give an indication of whether spring rate is correct or not, pretty sure they show its way too hard...

The shock originally had about 10mm preload which gave:
Rider sag = 100mm
Static sag = 42mm

Tried 8mm preload:
Rider sag = 106mm
Static sag = 46mm

Tried 5mm:
Rider sag = 108mm
Static sag = 50mm

Definitely too hard right? What rate springs would people suggest for my weight? (i will ring a tuner here in UK, but just to get your opinion too)

I have been getting on pretty well with the bike, but have probably just got used to the settings. Slightly embarassed that i havnt looked at this sooner, but am quite excited to see if making changes will make a marked difference to what i already think is a pretty good ride?!

Thanks,
Ad

Yeah the high static sag numbers are the key here. Ideally you want around 10-12mm preload on the spring giving between 20-40mm of static sag (35mm is the magic number I feel). Adding more preload to get your static sag right then makes your race sag too stiff cause the spring in general is too stiff.

 

[bchatt]

Having just got round to looking at the suspension on my bike, i have a similar sort of question to Scarmble Champ, if you dont mind me picking your brains guys...

Having made some measurements, i think im right in saying they show i need lighter springs for my lightweight 145lbs fully geared up - yeah i know i need to eat some more pies!

Keeping in mind the stickied thread about keeping preload low and going by feel, i made the following sag measurements to give an indication of whether spring rate is correct or not, pretty sure they show its way too hard...

The shock originally had about 10mm preload which gave:
Rider sag = 100mm
Static sag = 42mm

Tried 8mm preload:
Rider sag = 106mm
Static sag = 46mm

Tried 5mm:
Rider sag = 108mm
Static sag = 50mm

Definitely too hard right? What rate springs would people suggest for my weight? (i will ring a tuner here in UK, but just to get your opinion too)

I have been getting on pretty well with the bike, but have probably just got used to the settings. Slightly embarassed that i havnt looked at this sooner, but am quite excited to see if making changes will make a marked difference to what i already think is a pretty good ride?!

Thanks,
Ad

I weigh just a little more than you, at 70 kg. I have found that a .48 spring (thats 2 steps softer) is ideal. It gives me around 105 race sag with around 25-30 free. I'm not sure exactly what preload is required to achieve this, but it seemed normal when i did it, around 10-15mm from memory. I bought this (eibach) spring thru, and after consultation with, one of NZ's top suspension tuners - it was not a random decision. This was after I'd had my bike about 6 months. It made a big difference to how the bike feels - felt lighter, more nimble, easier to wheelie over logs etc., better rear wheel hookup etc., all good. I don't do much in the way of jumps - but fast riding over open ground presents no problems. I still have the original spring and not once have I thought of putting it back.
Also, I find it well balanced to the stock fork springs, which is interesting.
Alot of guys on this site uprate their fork springs, and many also uprate their shock. There seems to be very few of us lighter guys who go the other way.
I believe the 200s stock rear spring is a .50, the 250/300 stock is .52. if your bike was used when you got it, you may even have something stiffer - those figures you quote do tend to indicate something fairly stiff.

 

[Jakobi]

Stock 250/300 is 5.2 rear and .42 forks. Dave at STM feels the balance is out from the factory (IE forks undersprung compared to shock) which may be why you were happy to drop the shock rate and keep the forks the same.

I went up from 5.2 to 5.4 on the rear, and took the forks from .42 to .46 - I weight around the 200lbs mark when fully geared up and this puts both the sag figures for the shock and forks in the range, both with minimal preload.

 

[400_racer]

Interesting stuff guys, thanks for the replies.

Ive just spoken to a tuner near me who wsa very helpfull, although i dont think they generally deal with Sachs/Gas Gas parts but it seems his Showa springs may well fit (they're 260mm long, my Sachs was approx. 258mm measured on the bike - just whether they fit in the cups).

After a quick look at his charts, he suggested either a 4.25 or 4.5 kg/mm spring, which kinda tallies with your 4.8, bchatt, given i am approx. 9 or 10lbs lighter than you.

Having got the shock out yesterday, i cannot find a mark on the spring to show what is in there already Do they even mark them? Short of getting it measured, i'd like to know what i already have.... because..... ...

Having pulled the shock it seems my linkage (havnt yet checked swingarm) bearings dont look too happy and dont wanna turn I think im right in saying if i grease and fit new bearings and refit current shock/spring, my static sag should come down for the same rider sag value, as id need to up my preload. Meaning my spring may well be closer matched than i originally thought. So i may try that first before getting a new spring.

Is my line of thought right here guys?! Probably silly questions but this is the first time ive tried to setup the suspension.

Ad

 

[400_racer]

........or, i could just send him the shock, get him to measure the current spring, and service it at the same time. As i dare say it has never been done. Then fit a new spring if it does come in at a higher rate.

What do you think to fitting a Showa spring in the Sachs shock?

 

[GMP]

If it fits and does not rub the spring guide then you should be fine. I have heard KYB springs fit too.

Preload is the devil. Keeping it to 10mm helps the ride over the trash.

 

[bchatt]

........or, i could just send him the shock, get him to measure the current spring, and service it at the same time. As i dare say it has never been done. Then fit a new spring if it does come in at a higher rate.

What do you think to fitting a Showa spring in the Sachs shock?

That sounds like a good plan.
Minor differences in length and diameter shouldn't matter. The eibach spring I got was about 5mm longer than the stock sachs - no problem, just a little more difficult to compress on installation. It also has a slightly larger diameter, but came with pressed steel adapter plates to fit the caps. A small amount of reaming of the adapter was required to achieve a snug fit to the shock body - you don't want the ends of the spring to be able to move around sideways. I'm sure your suspension guy would get this right for you.
As you mentioned, it would pay to first make sure you haven't got some kind of binding going on, that is distorting your sag measurements.

 

[Scramble Champ]

Thanks Fellas

Hey Guys, sorry I'm just now checking back, (Life's daily grind) Thanks for the SMT Tip and I'll be contacting someone soon for a spring order.

Ride Safe

SC

 

[twowheels]

Look for a 5.8 rear and 0.48 fronts ... and yes I can hook you up with springs now and valving later.

Sachs can be your friend