Manitou Fork FAQ
Tips, tricks and helpful hints.
Tools you'll need to strip most manitous are 4,5 and 8mm allen (hex) keys and a 24mm (15/16 inch) spanner.
To grease the bushings you'll need a microlube gun (if your fork is 1999 or later), a socket and extension (or piece of dowel) with cloth tape or similar wrapped around the end (for premicrolube forks).
Acceptable greases include Englunds Slick Honey, Manitous Prep M, Pedros Syngrease and Finishline Teflon.
I've found that thinner grease is spread more easily and works better, thick grease gums up the fork and slows action noticably. If you've got thick grease then thin it out using finishline chain oil (green cap) in roughly equal parts.
Turn the bike upside down and pull out the damper adjustment knob. Undo the 8mm allen nut behind it and the 4mm on the other side. The lowers will simply pull off.
Clean out all the old grease and polish the stanchion tubes until they shine with a clean dry rag.
To reassemble a microlube manitou simply give the seals a light coating of grease and throw the legs back on (don't overtighten the damper side nut), then give each side a few pumps of grease and work the fork to get the bushes greased.
For a non microlube manitou you'll need the socket or dowel mentioned above. Smear grease around the end of it (on the cloth tape) and roll the grease onto the lower plastic bushings in the outer legs. Use your fingers to smear grease on the upper bushes and underside of the seals.
The 4mm allen key can be useful for locating the damper shaft when reinstalling the lower legs.
Don't grease the stanchion tubes themselves. This gums up the fork as the wipers have to remove sticky grease from the tubes and gives dusta and other crap a good surface to bind to.
The best oil for a through shaft damper manitou is PJ1 motorcycle oil in 2.5wt. If you're heavy or a hard rider 5wt may work better. It gives good results both for damping rates and stopping leaks, Belray motorcycle oil is an untried alternative which also contains seal swellers.
TPC manitous also need a large air space in the damper. This is because they work on displacement (volume change) and the oil level rises in the stanchion as the fork compresses.
Too much oil causes hydraulic lock, too little causes cavitation and both can damage your fork.
The oil is best 5cm above the top compression piston in all forks. To check the oil level unscrew the damper side topcap and draw up the attached compression assembly. When it is clear of the oil let it fall back into the stanchion. The assembly will stop falling when it hits the oil surface. At this point the distance from the cap o-ring to the top of the forks crown gives an approximate height for the oil above the installed piston.
Manitous first dampers arrived in 95 and were through shaft cartridges built into the lower part of one stanchion tube. They use one piston on a shaft which enters the bottom of the damepr and extends through the other side. The result is speed sensitive (through shims on the piston) and rebound adjustable.
In 1998 The TPC (twin piston chamber) damper was introduced in the SX and Xvert forks.
The TPC damper occupies a whole stanchion tube. The lower (rebound) piston is fixed to the damper shaft which moves through the oil. The damper shaft displaces oil which makes the oil surface rise and moves oil through the stationary upper (compression) piston.
The TPC dampers have speed sensitive compression damping, force sensitive rebound damping and have independent low speed adjustment of compression and rebound damping.
In 1999 Manitou introduced TPC Sport on lower level forks. This is a cheaper version of TPC which isn't externally adjustable or speed sensitive. Most TPC Sport forks can have their dampers upgraded to full or part TPC. 2000 bought the introduction of TPC+. TPC+ has force sensitive rebound, speed and position sensitive compression damping.
This modified TPC damper features two compression pistons. One has the majority of the damping shims and has 14mm of float, the other is stationary. The floating piston moves with the rising oil surface allowing the stationary piston to control the compression damping. When the damper shaft has moved 40mm the oil height has risen 14mm, the floating piston hits it's stops and the majority of the compression damping kicks in.
Many TPC and TPC Sport dampers can be upgraded to TPC+, however the 40mm of float means many shorter travel forks may run out of travel before the compression damping has done it's proper job.
If anyone wants to tinker, the TPC+ third floating piston simply threads onto a compression assembly in place of the nut which holds the piston and shims. It should be possible to install TPC+ onto a lockout assembly.
The compression pistons are common size throughout the SX and Xvert ranges, the rebound pistons in the Xvert's are bigger.
Manitou through shaft dampers can be found on the first oil damped manitou, the 1995 EFC through to the 97 manitou Palmer Stroker (FS Ti).
The designs differ in small degrees throughout the models. The 95 EFC and 96 Mach V SX use one way pistons (on rebound all the oil must return through the adjustable freebleed). The 97 Pro C uses a non adjustable damper based on the 96 Mach V SX design.
All the other 96 and 97 through shaft damper manitous use two way pistons which handle the rebound forces of coil springs and preload better than the one way pistons and are more tunable.
Once the lowers are off loosen the 24mm damper endcap and take the left staunchion out of the crown.
Unscrew the endcap, see how much oil you've got left. The through shaft damper needs a small air gap to buffer the pressure changes which occur in use, 10-15mm down from the end is where most seems happy, about the bottom of the threads.
Pour out the old oil and stroke the damper a few times to get the last out.
The lower seal in the endcap is the only critical one and can be replaced with a TPC style endcap and seal with better spring tensioned seals.
Excessive weeping or leaking like the type that'll leave a ring of oil every stroke is too much and must be dealt with.
The top seal isn't critical, any oil which escapes that way is returned by gravity and the forks action.
Push the damper shaft right down before you refill it with oil, sometimes it can come unseated when stroking out the old oil. A symptom of this is a clunk on bottomout before full travel is reached.
Fill the damper with oil to the bottom of the threads and stroke the air out. Repeat until most of the air bubbles are gone.
Refilling the damper totally and bleeding all the air is pointless. The through shaft dampers need a small air gap to buffer heat and pressure changes, leaving no gap will only increase the initial amount of weeping.
Reinstall the endcap, snug it up, not too tight and reassemble the fork.
TPC dampers require very little maintenance, oil changes should be once a year, maintain the oil level at 5cm above the top compression piston and keep on riding.
It is possible to extend the 98 manitou Xvert and SX forks along with the 99 SX manitous to gain a little extra travel.
The modification requires removing any spacer present, trimming the topout bumpers and extending the main spring stack.
The tools you'll need for this job include 4 and 8mm allen keys, a sharp knife and a 24mm spanner (optional).
Start by removing the lower legs as described above, simply undo the bolts and slide them off. The spring side has a black plastic compression rod which extending through the bottom of the staunchion, if your fork has a removable endcap and you have a 24mm spanner then rip in and take the compression rod out. If not you'll have to remove the topcap and spring stack then slide the compression rod out the top of the fork.
Once you've got the compression rod out you must slide off the bottomout bumpers and endcap (if you haven't already). You should see the black or orange elastomer topout bumpers sitting up against the lip on the compression rod. Slide them off and any spacers behind.
To get 100mm of travel from a 98 Xvert you must remove the spacer (10mm) and cut 10mm off the topout bumper then reinstall the bumper without the spacer and add 20mm to the main spring stack.
You can gain a max of about 77mm from a 98 SX fork, trim 7mm off the topout bumper and add 7mm to the spring stack.
Some 99 OEM SX forks contain a spacer to shorten the fork to 70mm of travel. Removing this gives you 80mm of travel and brings the fork back to no preload. You can trim another 7mm off the bumper to gain 87mm of total travel.
It is possible to gain 30mm of travel on a 99 Manitou Spyder, to give 100mm of total travel. Dissassembly is with a long 6mm allen key down each spring chamber to unscrew the compression bolts. Removing the 10mm spacers above the topout bumpers on the compression bolts gives 80mm of travel. Cutting off the lip which the topout bumpers sit against (move bumpers up to underneath spring seats) gives the fork a total of 100mm of travel. You must add 30mm of spacers to the spring stack to use your travel.
The earliest manitous were all MCU sprung. This gave light weight, good performance (for the time) and many tuning options.
Since late 1996 manitou added small coil springs to the MCU spring stack and have gradually been increasing the amount of spring and decreasing the amount of MCU.
The MCU is used now to provide an easily tunable spring element which is cheap to experiment with and provides progression to the spring stack, to absorb bigger hits and bumps better.
Replacing a manitou spring/MCU stack with a single linear spring will not give a good ride. To prevent bottomout the spring rate must be high which gives a harsh small bump ride.
The cheapest and easiest alternative is to tailor the ratio of spring and MCU in your fork to give a supple and active ride while keeping enough progression to prevent hard bottomout.
Spring/MCU ratio For most people on a fully damped manitou (TPC) fork you want around 3/4 of the travel to be controlled by coil spring and the remainder MCU at close to it's compression limit to give a usable spring curve. For an undamped fork you want closer to half controlled by each to give a more controlled ride.
In mid 98 I found that the 5.5 inch Xvert R coil spring will fit inside an SX fork (now it's common knowledge), it also works with standard spring connectors. These springs can compress just under 60mm. MCU can compress about halfway. So for an 80mm travel fork you need to use one Xvert R spring and at least 40mm of MCU.
Using more MCU will make the fork use more of it's midstroke and be less progressive to give a plusher ride overall. Using the minimum 40mm of MCU will give a very progressive ride suitable for a harder or faster rider who still wants the fork working on small bumps at the top of the stroke.
Other springing options are two or three stage spring systems. These are expensive to play with, hard to tune for a particular rider and heavier but do offer the best performance. The spring rates must be different for each coil to get a progressive curve.
Here're some combinations I've found work well:
3.5 inch medium red coil and 5.5 inch firm yellow coil suitable for a 70kg hard rider or 80kg+ average rider.
3.5 inch medium red coil and 5.5 inch soft blue coil suitable for a 40kg hard rider or 50kg average rider.
5.5 inch medium red coil and 5.8 inch firm yellow coil suitable for a 70kg hard rider or 80kg+ average rider.
5 inch soft blue coil and 5.8 inch medium red coil suitable for a 60-70kg average rider.
5.8 inch red medium coil and 5.8 ich yellow firm coil suitable for an 80kg+ average rider.