The Definitive Suspension Tuning Thread

crash n' burn

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Tips and tricks for tuning your manitou fork

There isn't a huge amount of info in those Manitou service guides, so i've found this pretty helpful..


Tips and tricks for tuning your Manitou fork



I’ve always been a fan of Manitou forks because I find them easy to maintain and they have lots of ‘tweakability’. This post looks at some of the routine maintenance that you should perform on your fork and offers some ideas for tuning some of the Manitou forks out there. Most of the information here is applicable to 2004 and 2005 forks with TPC and SPV damping.

Note: Make sure that you read the manual that came with your fork. If you’re unsure about what to do, bring it to someone who can perform the tasks for you. It should go without saying that you should verify with the manufacturer whether or not performing any modifications will void your warranty.

Maintenance

With any fork it is a good idea that you learn how to properly maintain it. It is amazing how many people have never opened up their fork to perform routine maintenance. Forks take a lot of punishment and especially if you live anywhere where it gets wet, gritty, or dusty, you need to maintain them if you want them to last.

Manitou forks have always been really easy to maintain. Early models used Micro Lube ports for grease injection. Newer models utilize a semi-bath lubrication between the outer legs and the stanchions. Working with semi-bath is easy but it is messy so you need to make sure you have plenty of rags and drip pans around before you open up your fork.

But before you bust open you fork, do yourself a big favor and read the manuals. First download the Service Guide for your particular year and model fork from here.

These guides provide the instructions for maintenance. They are pretty good, however the best information online is located at the Enduro Fork Seals web page. These guys have pictorial instructions for many forks which also includes basic maintenance steps. I want to shout out a huge thanks for all the work they have done as it is amazing!

Note: I think you can convert older Micro-lube Manitou forks to semi-bath forks using these Enduro Seals.

Between the service guide and the pictorial instructions at Enduro Fork Seals you have more than enough ammunition to perform some basic maintenance. I’m just going to highlight a couple of points and offer some tips.

There are several fluids used for basic maintenance on Manitou forks:
  • Synthetic Motor Oil is used for the semi-bath lubrication.
  • Regular Motor oil is used for the 3cc that goes over the air piston.
  • 5wt Fork Oil is used for placing inside the right leg.



The 8mm screw located in the bottom of the right leg is actually the bottom of the damper shaft. It is screwing into the bottom of the outer leg, so in order to take the leg off you have to screw the damper shaft IN. Clockwise. This is really counter intuitive.

The bolt on the left side is removed just like a regular screw: counter clockwise.

Other notes on working with your fork:

Go slow. When you put the semi-bath oil into the legs and you go to push the legs all the way back on, put a rag over the open holes in the bottom of the legs. And push the legs back on slowly. I shot synthetic motor oil halfway across the garage onto my wife’s new car one time.

Add some air. When rethreading the damper shaft back into the outer legs, and putting back the bolt on the left side leg, it helps to have some air in both the right and left sides.

Watch out for the air pressure. If the fork is turned upside down, don’t press the air valve. Why? Because there is oil in there and it is under pressure… Flush eyes with cold water if this happens to you. Not that I did this or anything!



Mangling the damper shaft o-ring. There is a rubber o-ring on the bottom of the damper shaft. This o-ring can get mangled when screwing the damper shaft back into the outer legs. A small amount of semi-bath can leak out if this o-ring’s shape is compromised. Some guys on mtbr say that you can find replacement o-rings at the hardware store or use RTV silicone to help seal it.

Many Manitou forks are air/coil springs. The coil is located inside the left leg of your fork. Manitou uses a lot of grease to lube up the coil and compression rod that is inside this leg. They didn’t do a good job of sealing this side so over time the grease will seep down into the insides of the outer leg. When you take off the outer legs instead of having light semi-bath oil drip out, you might find a thick sludge where the grease has congealed with the semi bath. This is usually an issue on a fork that has been sitting on the shelf for a long time. You can clean out the heavy grease, and lube it more lightly. This will minimize the problem however you should check the condition of the grease when you maintain the fork.

Careful when reinstalling the SPV damper shaft. When replacing the SPV damper shaft back into the inside of the right leg, be really careful. Grease the wiper and screw it in as if you were threading a screw. It is easy to mangle the wiper on the interior threads of the inner leg.

Use a proper size socket. You can take off the top caps with a crescent wrench but it is probably a good idea to get the proper size socket. Some Nixons may require a special socket through Manitou. See this thread at mtbr.

Tuning tips for your Manitou fork

Air/coil spring. A lot of the 04/05 forks are Air/Coil springs. The first part of the travel is taken up with the coil spring. These springs are available for your specific body weight — red is medium, blue is soft. You can play around with different combinations of air pressure and coil weights and the trick is to get a good transition between the two. If you have too much air and the spring is too soft, you will create a transition in the overall spring rate, usually around mid stroke.

TPC damping. I had a TPC damped Black 100. It was a super cushy fork, which was fine for downhilling, but I felt for cross country it robbed too much power under pedaling. The TPC lockout damper is mounted in the top of the fork leg offers some compression damping adjustment but not much. The remote lockout on my fork offered no compression damping at all. One way that can add some more compression damping to your fork is to add more oil on top of the air spring in the top of the left leg. As the fork compresses it will have less air volume in this chamber and will stiffen up some.

The forks take 5wt oil. You can try to run a heavier weight oil to affect the compression damping, however be aware that this will also affect your rebound damping.

SPV damping. Stable Platform Valve damping is one of Manitou’s core damping technologies. SPV allows riders to set up a ‘platform’, or firm setting that limits ’spiking’ on the way up and down. Technologies like these are always a tradeoff between small bump compliance and pedaling effeciency. It’s kind of one of those love it or hate it things, but I like it from an XC perspective. I find that there’s a lot of adjustability with the SPV system but it can be hard to zero in on the best setting, so take notes and be patient.

If your fork is an older model, the original SPV damper had some issues with it:

  • The valve used a grease that broke down over time in oil which caused the SPV valve to stick.
  • The wiper for the damper was an O-ring which caused some stiction.
  • There was sort of an on/off type of operation to the check valve which caused a harsh transition between platform and no platform.



Note: Answer changed the damper in 2005 from the SPV damper to the SPV Evolve damper. The one on the left is the ‘05 Evolve the right one is the ‘04.

The Evolve damper has a teflon wiper and uses a newer grease that is doesn’t break down in fork oil. In addition, they drilled a small hole in the check valve. So there is always some oil that flows in the circuit which softens the transition.
 

crash n' burn

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Some tips on tuning your SPV

Minimum PSI. The 04 damper requires a minimum of 40psi in the SPV chamber. The 05 damper requires a minimum of 30psi. If you don’t have at least that much air in the chamber you’ll feel a top out clunk.

Sticky valves can clunk. When the 04 SPV valve got sticky it also produced a top out clunk. The service guides explain how to check for a sticky valve.

Small changes make a big difference. The SPV damper is sensitive to changes as low as 5psi. When making adjustments keep in mind that small changes can make a big difference.

Before you set sag… When setting sag, make sure that you have air inthe SPV valve, but also push down a few times to make sure the platform has broken before measuring the sag.



Elevation changes. The SPV valve is actually influenced by atmospheric pressure. If you have changed a lot of elevation you might need to reset the pressure in it. Do this by taking the blue valve (pictured above) and its insert apart and the put it back together.



Make sure that there is the special grease on the inside. Not much is needed but be careful to not clean it all off unless you have some extra.



SPV volume. The volume of the SPV chamber can be changed by turning in the red nut on the top cap; doing this provides some adjustability for controlling bottom out. This is especially good for heavier riders who feel the fork bottoms out too easily or dives too much in corners.

How to “De-Evolve” the SPV damper

Note: doing this sort of work on your own likely voids your warranty. If you’re concerned about the prospect, check with your local Manitou dealer before you proceed.

There was a post on the mtbr forums by suspension guru Dougal about how to remove the check valve out of the SPV damper completely. He called it ‘devolving’ the damper. The procedure is easy to do and completely reversible. In a nutshell you remove the SPV checkvalve which removes the platform all together. Unlike TPC, there is still some low speed damping that can be tuned by the SPV air valve.

In order to get to the check valve you have to remove the top part of the damper:

http://static.flickr.com/13/15060128_a29069d9ff.jpg

The plastic white piece that is on the spring is the check valve. Take it out and rebuild the damper. Add air to the SPV chamber to add some low speed compression damping. It basically feels like TPC but provides the compression damping adjustability that TPC lacked which made it too cushy for me. Without the platform the small bump compliance is better but it is less efficient in terms of filtering out pedal influenced losses. If you don’t like the feel, just put back the check valve.

Change the feel of your damper. If you have an ‘04 damper and want to make it feel like an ‘05 damper, you can drill a small hole in the check valve which is what Manitou did with in the 2005 version.

Conclusion

Any fork requires regular maintenance if you want solid performance so take care of yours.

Manitou forks can be fun to maintain because they’re so easy to take apart, work on, and put back together. Combine that with some simple things you can perform on your own to customize the performance of your fork for your riding and individual tastes.
 

treggs

Treggs Tuned
Probably a question for the dirtworks reps in here. Is it possible to increase the bottom out resistance of an RP23 rear shock? The standard pressure works nicely and the pro pedal settings are all useful but I am bottoming a bit to often. If I up the air pressure enough to stop bottoming then my sag is incorrect i.e. pretty much none. Basically I just want it to ramp up a bit more in the last 1/3 of the travel.
 

Calvin M

Likes Dirt
06 Boxxer Team

Just got my self a mongoose ecd 06 with 06 teams. Had leaking compression leg and found that wasn't getting full travel so pulled down to do seals and give a service as well. Found that left leg bushes were u.s and had scored stanchion so swooped legs over and re-bushed lowers
Now I still have 20mm of travel left on big hits that bottom the rear and almost snap my ankles.
They are running a yellow spring which is correct for my weight 68kg and I have nice sag as well.
Do I run a lighter oil 2.5wt or mix 2.5 and 5 to give 3.75wt.
Second option run less oil then the 150mm recommended.
I have the compression and flood gate on the lowest setting. Would be nice to be able to have them mid to low settings.
If any one has some solutions would be great.
 
Last edited:

tnankie

Likes Dirt
Probably a question for the dirtworks reps in here. Is it possible to increase the bottom out resistance of an RP23 rear shock? The standard pressure works nicely and the pro pedal settings are all useful but I am bottoming a bit to often. If I up the air pressure enough to stop bottoming then my sag is incorrect i.e. pretty much none. Basically I just want it to ramp up a bit more in the last 1/3 of the travel.

Actually the guys a mojo told me an easy way to do this. Just open it up as though you were going to do a sleve service (you do do those don't you?)

And then smear a good amount of grease on the inside of the sleve, This effectively reduces the volume of air in the unit.

Bingo air volume reduction, instant increased ramp up at the end stroke.
 

captplanet

Cannon Fodder
Fox Float F80RLT- looking for exploded view

anybody out there know where I can get my hands on an exploded view of a Fox Float F80 RLT fork? I've been through the fox website several times looking for an overall exploded view schematic/ cutaway view of the internals, but can only find basic manual and rebuild info. I am rebuilding my2003 version and more knowledge is better than not enough. thanx!

Captplanet
 

wipava_454

Likes Bikes
hey guys

i just bought a new bike, a 2002 norco shore VPS.

its running a Marzocchi Bomber Jnr T up front with 175mm travel using a 7wt oil, and a Fox Vanilla Rc up back with a 600x1.75 spring.

now the guy using it before me was around 60-65kg, and i am 80kg. it seems a little soft all round for me, so im just wondering what to do?

i think i should probably flush the fork oil and add either a 20 or a 30wt and add an extra 10-15mm of oil then recommended.

and with the back im thinking a heavier spring, something around 850ish, but the main thing i want to know, when i buy a new spring do i get a 1.75 or can i go bigger, ie. a 850x2.35 or alike, im new to this sport, and im not 100% sure which way to go.

any comments or suggestions are appreciated

thanks
 

Calvin M

Likes Dirt
hey guys

i just bought a new bike, a 2002 norco shore VPS.

its running a Marzocchi Bomber Jnr T up front with 175mm travel using a 7wt oil, and a Fox Vanilla Rc up back with a 600x1.75 spring.

now the guy using it before me was around 60-65kg, and i am 80kg. it seems a little soft all round for me, so im just wondering what to do?

i think i should probably flush the fork oil and add either a 20 or a 30wt and add an extra 10-15mm of oil then recommended.

and with the back im thinking a heavier spring, something around 850ish, but the main thing i want to know, when i buy a new spring do i get a 1.75 or can i go bigger, ie. a 850x2.35 or alike, im new to this sport, and im not 100% sure which way to go.

any comments or suggestions are appreciated

thanks
Wouldnt jump to a 20 or 30wt that is a massive jump. Try 20ml,s extra of 7.5wt oil. You could go to a 10wt but I think that you should first try extra oil to give more bottom out resistence.
A 850 spring would also be way to hard get your lbs to talk to dirt works to find out the correct spring for the bike with your weight. And you shouldnt change the lenght of the spring so stick to a 1.75 if thats what the bike should have. I would say 650/1.75 or 700/1.75 but best to find out before you go buying one.
 

wipava_454

Likes Bikes
ok there was a couple mistakes in my first post, the forks arent actually junior t's, they are super T pro's. and the spring i am currently running is a 600x2.25

either way i think i will take it out this weekend before i do anyhting to it, and put a zip tie around the fork, and see how much travel i am using/if it is bottoming out and go from there, maybe a 15-20wt oil would be better then something too heavy like a 30wt.

and ill also give the rear a go as it is, and go from there, but im thinking ill have to go to at least a 700x2.25-2.3
 

clockworked

Like an orange
Hi tuners,

I'm about to attempt a spring and oil change on my 07 888 RVs, but before i started i wanted to ask a few questions to you gurus.

Firstly - I weigh 95kgs and i want the fork to be responsive and supple, but firmer than it is stock.

Secondly, the springs i bought are green and as far as i understand these are the 'firm' springs, the problem is after reading endless posts about the topic i am confused as to whether the springs i have a firmer than stock, or the stock ones are in fact the very same firm springs i have gone and bought..

I know that there is a clear listing about the differences between spring weights and poundages, but its does not describe them in terms of colours. So is green the next step up in firmness from stock?

The other question i have is should i step up from 7.5wt oil to 10wt or similar? I don't really want the action to be any slower, i don't think, just firmer

cheers
 

tnankie

Likes Dirt
Secondly, the springs i bought are green and as far as i understand these are the 'firm' springs, the problem is after reading endless posts about the topic i am confused as to whether the springs i have a firmer than stock, or the stock ones are in fact the very same firm springs i have gone and bought..

I know that there is a clear listing about the differences between spring weights and poundages, but its does not describe them in terms of colours. So is green the next step up in firmness from stock?

cheers
ah as my french friend would say, hey guy why you asking that, take them out and look silly.

or as I would say, just pull out the springs you have in at the moment and check what colour they are. if you bought firm ones and the ones in the fork are a different colour (under all the oil of course) then you should be laughing.
 

Mojo

Likes Dirt
not trying to grave dig, just thought i would do a search instead of starting a new thread

one for the mech engineers out there

ive been doing heaps of work lately involving excel calculation tables and spring constants and moments and all that fun stuff

has anyone ever thought about making up a table to relate suspension type to rider weight using calculations and moments about the swingarms within a frame?

is there mathematically perfect suspension set-up? can we create this for riders over and over through the use of calculations? i remeber seeing log computers on some of the orange/mojo suspension parts. how were they working out a more efficient system??

any idea's?
 
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