Clutch Hydraulic Rebuild Tutorial

[Patmac6075]

So, as I while away the hours here in sub-zero Wisconsin, I thought I’d put together a tutorial on rebuilding the clutch hydraulics on my 1984 Venture Royale.

My symptoms started last July while stuck in stop & go traffic for more than an hour, at first I noticed my clutch was engaging later and later, it progressively got worse, until it became difficult to drop it into first, and change gears….finding neutral was nearly impossible. Fortunately, the highway eventually cleared up and I was able to get home by pumping up the clutch lever. Once I got home and posted my situation here, it basically came down to two answers…#1 might just need to be bled, or #2 some or all components may need to be replaced/rebuilt. So course I choose the “Quick Fix”…and just bleed out the system…..which worked……. for a while. Near the end of the season I could see in the master sight glass I had lost about half of the fluid….and while I was preparing the bike for storage I could see fluid all over my left exhaust and plenty on the shop floor….Time for a rebuild!

 

This job is not too difficult, and can be done with a very basic tool kit….here’s what I used:

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Tools - #2 Phillips Head, an internal Master Cylinder snap ring pliers (I’ve used two picks for this job, but found I also needed a third hand, I’ve also used a standard snap ring pliers but found they are just a tad too short, These pliers are about $25, and make the job immensely easier!), a 17mm open end wrench, a 10mm open end wrench or preferably a flare wrench, an 8mm combo wrench, a ratchet and various extensions, 10mm & 12mm sockets, and a 5mm long reach Allen key (a 5mm Allen socket and extension works too).

 

Supplies – Clutch Master Cylinder rebuild kit, Slave Cylinder rebuild kit, two new stainless steel hoses, fresh copper crush washers, a quart of clean fresh DOT3 brake fluid, some silicone/dielectric grease, brake cleaner, 2000 grit wet dry sand paper, and plenty of paper towels

 

I first started by removing the middle gear cover using the 5mm Allen key (pay special mind to the bottom most Allen bolt as it has a copper washer/spacer…if this gets misplaced you’ll have an oil leak). Once that’s removed, loosen the slave bleed nipple with the 8mm wrench and crack the banjo bolt on the slave cylinder with the 12mm socket and let it bleed out…..then remove that hose with the 17mm wrench and 10mm flare wrench. Once the hose is completely removed, remove two bolts securing the slave cylinder to the block using the long reach 5mm Allen key. Now remove the slave cylinder from the bike which is easier said than done! Suffice it to say, stick with it, wiggle it around, curse profusely, and eventually it’ll come out….took me about 25-40 minutes.

 

To remove the Clutch Master cylinder first remove the clutch safety switch (located near the end of the clutch lever) by simply inserting a small screw driver or the end of a ¼” extension pushing on the switch tab and pulling the switch free of the Master (it’s a good idea to clean this switch with some contact cleaner). At this point make sure you have plenty of heavy towels covering any exposed plastic or painted surface…brake fluid will ruin those parts in very short order (or you can do as I did and remove all the plastics, it’ll be easier to reach the upper clutch hose union later). Crack the banjo bolt on the Master (if you’re lucky most of the brake fluid will drain out the bottom). Now you can remove the Master from the bike by removing the two 10mm bolts at the handle bars. To remove the upper clutch hose you must first remove the two Phillips screws from the access panel on the handle bar, the follow the hose down to it’s union just below and forward of the battery, again using the 17mm wrench and the 10mm wrench, disconnect the hose and remove it.

Rebuilding Master Cylinder:

I like to work inside an old 10 x 14 cake pan lined with paper towels, it keeps most parts contained and helps keep my work bench clean and disassembly organized.

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Disassembly is pretty straight forward…remove the two screws holding the lid on the Master and drain the residual fluid, remove the lever taking note of the actuators orientation (at this point I like to take pictures or make drawing so I can remember how it all goes together).

 

Now this’ll be where that specialty snap ring pliers comes in handy.

There is a snap ring down the main cylinder bore

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It’s easiest to press down slightly on the plunger while trying to remove the snap ring…be careful, because this is spring loaded…so make sure you’re prepared in case things go flying! Again, I like to lay everything out in the order in which they came out and take detailed pictures so I can put it all back in the way it came out.

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Clean everything up real well with some brake cleaner…inspect the cylinder bore by shining a light down the bore, if it’s not too scored up, you can wrap a pencil with that 2000 grit paper dipped in brake fluid and hone the cylinder, in my case it was pretty clean. Now if you look into the brake fluid reservoir you’ll see two small holes (you may need to get the magnifying glass out to see the smaller of the two!) these both need to be clear of any crud…a squirt of brake cleaner usually clears the larger hole, but for the smaller hole I use a single bristle from a nylon parts cleaning brush…you don’t want to use anything which will enlarge this hole at all, and it is very important that it be cleaned out!

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At this point I like to soak the rubber parts in brake fluid under a high intensity light (to gently warm the parts)….hopefully your rebuild kit comes with a new plunger, just slide the seals over the plunger taking care to make sure you put them on correctly (those pictures really help here). Using plenty of brake fluid as a lubricant just reassemble in the order it came out….this where that snap ring pliers comes in handy again!

I like to smear the plunger/actuator cover with some dielectric grease and the brake pivot with some lithium grease…reassemble everything and Viola….you’re mostly done!

 

Rebuilding Slave cylinder:

For me, I’ve always found it easier to use a grease gun to remove the Slave piston (just open the brake bleed nipple, put a bolt it the banjo hole and pump grease in…make sure the piston isn’t cock-eyed and it should just float out…just make certain you clean every trace of grease out YOU MUST GET EVERY LITTLE BIT OUT OF EVERYWHERE!). My Slave cylinder was in pretty sorry condition

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Also, the bore had a bunch of crud caked in it! I used 2000 grit soaked in brake fluid to polish the crud out and got rid of all the tiny score marks. It really is key to clean up every little bit of crud both inside and outside and all around the lip where the outer seal goes….you cannot clean this area too much!

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Again soak those rubber bits in brake fluid heated under a lamp and they should go back on fairly easily, just make sure you have the orientation correct! Put it all back together the way it came out and you’re done!

Put the Slave back on the bike (it’s even harder putting it back in than it was taking it out, so, good luck with that), put the Master back on, connect the hoses and bleed the system….Total cost about $75 ($100 if you include the special snap ring pliers) and 6 hours labor….

Now in my opinion, I could have just replaced the slave cylinder and been done with it. My problem would have been solved and my cost would have been about $30…..BUT, my bike is nearly 33 years old…if the slave is toast, chances are the master is the next weak link….if I just did those two, then the hoses are the next area to fail….why not get all done at the same time, do it once, and do it right?

Next up…..Brakes

[Freebird]

Excellent tech article. I'll copy it to the Tech Library. Thanks for taking the time to do this.

[Prairiehammer]

Excellent tech article. I'll copy it to the Tech Library. Thanks for taking the time to do this.

 

And all the techniques and procedures are pretty much applicable to the Royal Stars.