Revised 10/3/2001
Here's how we do ours. First and most important.. AIR
GAP. This is checked using flat feeler gauges. Make sure the clutch is
not in a bind when checking. Slide the feeler gauge into the "gap"
between the shoes and floater disc. No less than .035" clearance and no
more than .060" I try to keep it around .050"-.055". Anything less than
.035" and the clutch will stay locked up when it gets hot. Anything
more than .060" and you start getting excessive slip in the clutch. You
can get different floater plates to accomplish this(.065" right up to
.105"). Opening up the air gap will work in conjunction with the
weights you have on the cluth as to how hard the clutch will "hit" when
it locks in. You want it to hit hard enough to get a positive
engagement but you don't want it to hit hard enough to bog the motor
when it engages. We are trying to stay away
from the .065" and .075" thick floater disc. The theory here is that
the thinner floater heat up too quickly and warpage is also a concern.
Put in new disc and a .085" floater and you should have around .045"
air gap. A FLAT floater is
also a very important. If your plates are warped you will not be
getting good engagement.
Next.. Lets move on to springs. We change ours out to
the red
springs. (I'll tell you why in a minute) On the springs, go ahead
and spend a little more to buy a "matched" set of springs. Several
companies sell "matched" sets and they are WELL worth the money. Tomar
and Ward clutch springs are what we currently use and are very happy
with both. They should run you around $18-$19 per set, and like I said,
well worth the money.
We start out with a spring height setting of .280" (measured
from the body of the clutch to the bottom of the spring retainer).
.280" should put you around 4,100 RPM engagement and .285" should put
you around 4,000. Next we move on to the weights. (see picture below)
Here's what we do. Take and drill out the factory rivots that hold the
weights on. Pop off the
weights. Then here's how we weight ours. We put in each (12) hole:
#10x3/8" allen head bolt. I re-used the washers from the original
Horstman setup on both sides of the swingarm and then a #10 nylon lock
nut (I used fine thread bolts and nuts). I put the heads facing the
direction the motor turns in. The reason we use the "red" springs is
that once you have added weight to the levers the engagment rpm will
drop down. So you use the red springs to bring the engagement back up.
You can play around with the different lengths and sizes of bolts and
nuts to customize how hard the clutch "hits". This all depends on what
type of track and what racing that you do. The picture of the clutch
below is how we used to weight our clutches. We now use the same
weights on the inner and outer holes.
See Bottom for my shedule of maintenance.
The very FIRST thing you should do before ever running
your clutch (or if you are installing new friction disc) is mark one
tab on each disc front and back. What I do is take a scribe (or a
screwdriver.. what ever you have) and make a line up one side of the
tab and back down the other side. That way both sides of the tab is
marked. Do this on one tab on each disc. That way when ever you take
your clutch apart you will always put it back together the same way it
came apart. If you think you will have problems with which way the disc
are turned when they come out (they look the same) then only mark one
side of the tab. What I'm getting at here is any time you take the
clutch apart for cleaning or maintanence you need to always put it back
together like it came apart. That is VERY important.
Now, lets talk about taking it apart. I always take
mine apart from the spring and weight side. The bolts on the hub side
seem to strip real easy to me and are always stuck in the holes and
generally if you take the plate off of the hub it will "spring" or warp
when it comes off due to the heat it has seen in the past. Taking
it apart from the opposite side will also make sure you re-set your
springs when you get done building. Take and remove the six bolts that
hold down the springs and keepers. Try to keep all the bolts, springs,
and keepers together as they come off. Next there are 6 allen head
bolts on the lever and spring side of the
clutch that holds it all together. Remove these bolts. Now, take the
top plate that hold the levers and set it off. Next you are going to
take the friction discs and pressure plate apart. You want to mark all
of this in a way that you make sure it all goes back together as it
comes off. What I mean it make sure the top pressure plate goes back on
top facing the way it was when it goes back on. Make sure the floater
disc goes back in facing the same way it comes out also. Next, the
bottom friction disc, same thing. The reason for all of this is that
once the clutch is run it is all "seasoned" and worn in together.
Keeping it all in the same order when pulling apart and putting back
together will make sure all of the parts don't need to get matched up
again.
Once you get it all apart we are going to start lookin
at what we have. First lets look at the friction disc. Once they get to
the point where it starts breaking the top edges off the friction part
of the disc they need to be thrown away. They don't cost that much and
it's cheap insurance. Now, if they are not worn to bad here's what
we'll do. I use 150 grit sand paper. What I do is take and sand the
disc on both sides enough to take the "glaze" off and put just a little
rough surface on it. Don't go to much and make grooves in the disc.
This will only wear the disc out prematurely. A good smooth roughened
surface will give the best performance. Next, we will do the same the
pressure plates and floater disc. Same here, just enough to take the
glaze off and roughen the surface. Now, once we have all the surfaces
that will be making contact sanded we will take and clean everything
with brake cleaner and compressed air (or let air dry). Once everything
is dry we can start re-assembling. I don't know if it makes a
difference or not but I always try to keep my finger prints off any of
the friction surfaces. Make sure you get all the disc back together
just the way they came off. Next, put the six allen head bolts in that
hold the plates together and then start putting the springs back on. I
always set the spring height to .285" and then adjust once I get it to
the track, which is genarally .270"-.280" but setting it at .285" and
making
a few "run-in" laps not letting the clutch slip much will work the
plates and disc all together and seat them in.
Once you get this far you are ready to install the
clutch hub. BUT, before you put the hub on we are going to do a little
prevenative maintanence. First if there are any grooves worn into the
valleys of the hub where the tabs have been riding they will have to be
smoothed out. If they are not smoothed the tabs of the disc will
sometimes get caught in the groove and will bog the motor because the
clutch will not release properly. I use a Dremel tool with a barrel
sander to remove the grooves and smooth the surface. Next I add a
little lubrication to the valley. I use neverseize but if you don't
have neverseize you can use a lightweight grease. Take and put just a
small dab on your finger and rub it in the valley in the hub where the
friction disc tab rest. You don't want to over do this, just a VERY
light coat. If you put too much it will sling out when you run the
clutch and if it get's on your friction disc it will ruin the clutch
performance. Just enough to make sure the tabs are lubricated. What
this does is allows the tabs to "float" a little easier and not get
hung (locked) in the hub. If the tabs "lock" in the hub it will chatter
and bog the motor. This also makes the hub last a little longer.
There are a few updates that are available for your MDC clutch that
will make it perform better and last longer. Currently on "update" kits
we do not use the Greased Lightning update kits. They cost more and in
my opinion do not perform as well as other "kits" on the market. Right
now we use a few different kits. One is the aluminum basket with steel
inserts and 3 tab shoes from Tomar which can be bought to interchange
with SMC/Bully/Viper/Stinger gears or the standard Greased Lightning
gears. And
the other kits we use come from Ward karting. From Ward you can get 3
tab, 4 tab, or 8 tab friction disc that will work in the MDC. With the
3 tab shoes
you can only use the 3 tab basket that uses Greased Lightning gears.
With the 4 or 8 tab shoes you use the standard Viper 8 tab basket. Both
the 3 and 8 tab basket are made out of steel and cut out to lighten the
weight. Very good products. With these updated friction disc, basket,
and interchangable drivers your MDC
will be performing at the front of the pack, and most times for less
than what
you would have spent on other clutches.
That's all I can think of right now,if I left anything
out let me know.
Jamie Webb
You can reach me at phinishline@yahoo.com for comments, questions, and suggestions.
This page was last updated on 07/06/2004.