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Clutch Maintenance and Inspection

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Though the DRZ has a very strong clutch straight from the factory, eventually it will need to be inspected and or replaced. Thats where this quick article comes in... This walk though is not a replacement for common sense, a factory service manual, and some amount of general mechanical experience. As always, if your not sure, ask :prof: Here on TT or from another trusted source. :thumbsup: .. Now lets get to it..

 

There are several reasons to inspect the clutch...
-As part of a normal tear down at season end
-As part of an engine rebuild / upgrade
-Upon noticing excessive clutch material or aluminum bits in the oil.
-Experiencing clutch slippage under load
Replacement parts are available from several sources if needed.
A trusted aftermarket vendor for everything needed; clutch springs to billet forged basket is MOOSE RACING (parts reference on the last page). If your just looking for some new clutch drive plates the OEM ones from Mother Suzuki are hard to beat.

 

 

Tear down and inspection

This procedure can be done without draining the motor oil, by laying the bike down on it's side... In a pinch I might do this. But normally I'd recommend just waiting till you needed to change the oil if it's just a clutch service check.
If your digging in to replace parts due to slippage, the oil is contaminated and needs to be replaced in any case. I also find it easier to work on bikes at chest level,, Leaning over a bike on the ground is ok if I have to.. but getting old sucks in more then one way. :cripple:
1: First thing you need to do is get the foot brake lever out of the way. side cover.jpgYou can work around it to some degree, but it's not worth the effort.
You'll need an 8mm hex key or bit to remove the pivot bolt.install brake lever.jpg There is a cotter pin on the back side of the bolt that has to be removed before the bolt can be fully removed.

2: Next remove the 6 hex head screws that retain the cover. Use a 8mm socket to do this. side cover bolts.jpg
You will find two different sizes different bolts.jpg You can stick them in a piece of cardboard to keep them in a known position for the install. But really, it's not that hard to figure out. When you go to install them, before tightening them down, all of the screws should have stick out of the cover the same amount. It will be very clear if you have them in the wrong place.

3: Once the cover is off this is what you will find clutch.jpg
the clutch pressure plate is held to the hub sandwiching the disks by six M5 socket head cap screws (#9). Each will have a special washer (#11)that helps keep the spring (#10) in place. spring_washer_bolt.jpg
Remove all six screws hub springs.jpg and set aside the fasteners and pressure plate in a safe place.

4: The clutch drive plates (aluminum friction disk) and clutch driven plates (the steels) are stacked on the clutch hub alternating each type. install disks.jpg A drive plate will be both first and last in the stack. At the very bottom of the stack you will find the last drive plate is slightly different. the ID is larger to fit around the shudder springs. They must be installed in one specific way, so take a close look. You'll have a pic later on the install section to assist.
clutch disks.jpg

On to the inspection

So its all apart, cleaned up and ready for the inspection.

We are going to look at four areas;
-pressure disk
-clutch hub and basket
-drive and driven plates
-Clutch spring free length
1: Pressure disk... look for any warping of the friction surface, or grooving that runs radially around the friction surface. If it is warped, or grooved,, time to replace. Have a look at the lifter bearing.. does it turn smoothly?

2: Hub and basket... Looking for grooves on the hub where the steel driven plates wear against the hub(the "teeth"). And grooves on the basket where the clutch drive plates wear against the basket fingers.
basket and hub.jpg The wear you see in the attached picture is normal, and not too bad at this point. It becomes an issue when the grooves are deep enough that the disks can catch on them. This will cause a clutch to hang or grab. If they are that bad, it's time for a new basket.

3: Drive plates and steel driven plates...
The drive plates are checked for three basic things..
-General damage, warping, cracks, and such
-Claw width disk check1.jpg
Services limit : Claw Width - minimum 13.2mm. Make sure you measure in several different places. If any of your measurements are below the service limit, the drive plate needs to be replaced (yes you could replace them individually, and thats what the OEM sells them that way,, personally, I always replace them as a set, and normally, if one is bad, the rest are also.)

-Drive plate thickness (at the friction pad) disk check2.jpg
Services limit : Plate Thickness - minimum 2.62mm . Make sure you measure in several different places. If any of your measurements are below the service limit, the drive plate needs to be replaced.

-Driven plate (the steel ones) The are checked for warping driven plate check.jpg
Service Limit: 0.1mm
The plate should not be warped in any direction, curled up from the edge to center, or radially around the circumference. Bottom line, if it does not lay flat on your inspection bench, it's no good, replace it.
A thick piece of glass makes for a good flat test surface. Often you can get a piece cut as a glass shop for next to nothing, ask for tempered glass. When you get it home make a wooden box for it and store in a safe place until next time. I've had the same 18"x18" 3/8 thick piece for more than ten years now.

-Clutch springs... This is a simple check, using a set of calipers measure the free length of the spring. make sure you not compressing is with the calipers when doing this.
Service Limit : 49.9mm
Check all of the springs, if any of them are shorter than the service limit, replace them as a set.

Installing the clutch

1358946477_clutchassembly.jpg.e66490c1f5c2f884ea878719ceb82242.jpg
So everything has checked out or been replaced as needed. Time to re-install the clutch... but it's never that simple.
There are OEM parts, aftermarket parts copied after OEM parts, and aftermarket parts that have to be installed slightly different. I will detail the aftermarket changes in BLUE

NOTE if you're installing NEW drive plates, soak them in motor oil before installing them. Installing dry new plates may cause quick failure.  Material used for the friction pad differs,  Some of this friction material requires pre soaking, others do not...but are not hurt by doing so. This makes it a simple decision, soak um all in oil first,, worst case you had to wait a bit and did not need to.. Vs guessed wrong and not soaking them, and they get damaged the first ride. 

1: Take your pile of drive plates and find the one that has a larger INSIDE diameter.. This is the first plate that you will install. Look at the hub, and insure the anti shudder springs are correctly installed
shudder spring.jpg the shudder spring is really two parts. Part 1 is flat and goes on first, part 2 has a convex curve to it when installed. in other words the outer edge of the spring lifts away from the hub (see picture)
If you are using an aftermarket clutch setup. compare the drive plates,, if all of them have the same size ID, then you DO NOT USE the OEM shudder springs.. IF one of the aftermarket drive plates has a larger ID like the OEM set, then reuse the shudder springs.
Install the first drive plate, then a driven plate (they are all the same), alternate until you get to the last one.

NOTE: There is no reason to off set the last drive plate, it does not affect installed stack height, it does not affect travel of the plates as you actuate the clutch. You can find references to it both ways. It does not make any difference. line um all up, or off set the last one a notch left or right, whatever you prefer, it will work the same.

2: Install the pressure disk, the 6 springs, then the screws with cupped washer.spring_washer_bolt.jpg.
Tighten the springs down in a star pattern install springs.jpg

3: Check the O ring seated in the back side of the clutch cover, make sure it is fully seated all the way around. give it a LIGHT coat of oil.. just enough that will help it slide across the case as you tighten down the screws. Install the 6 screws into the cover, yes there are two different sizes, no you really can not get them mixed up. See the picture for a reference of where they go... install cover.jpg check to ensure they all have the same amount of threads showing, and then tighten um down.


4: Re-install the brake lever,add a new cotter pin if you want (never had this bolt loosen up on me,, but that pin must be there for a reason)

Add oil if you drained it as suggested... Go ride.

Parts reference

Moose Friction plates
Price: $69.74
MFR Part #: F70-5255-8
Product Code: PU_F7052558



Moose Spring Set
Price: $7.70
MFR Part #: MHDS81-6
Product Code: PU_FHDS816



Moose Steel plate set
Price: $32.23
MFR Part #: M80-7210-7
Product Code: PU_M8072107



Moose billet clutch basket
Price: $141.79
MFR Part #: M252
Product Code: PU_11320099

offset last disk.jpg

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