Improving a Dominator, part I - Hydraulic clutch

[switch]

After taking my dommie for some serious offroading, I decided it's time to move on to something more dirt-friendly. So the good ol' NX will be kept as a city & gravel bike.

That's how my project starts. Over the next months, depending on available cash, I'll slowly work on my dommie, improving it bit by bit.

The first major improvement was installed this weekend: my very own DIY hydraulic clutch kit. I took a brake pump, reservoir, lever and mounting from an old scooter and bought a used rear brake pump. This, together with a thick piece of metal, some nuts and bolts and about half a bottle of brake fluid got me rid of the clutch cable. There's still a little work to be done, but I'll finish it this weekend (some loose ends with the choke, handguard and the need for a chain roller.

Pictures: Picasa Web Albums - Dorian - Honda Dominat...

The installation is pretty simple, if you've ever worked hand on with braking systems: take the rear brake pump, open it up and remove both the small valve at the rear end the spring within the pump. Polish the screw thread on the rod that normally connects the brake pump to the brake pedal. Exend the rod somehow (either leave 1/3 inches of thread on the end of the rod or use welds), taking special care to keep the rod as straight as possible. The end of the rod needs to be threaded with a 5mm thread (I think), so as to fit the small coupling at the end of the clutch arm on the crankcase. This entire assembly will work as your clutch piston. It needs to be mounted somewhere behind the passenger footpeg, behind the airbox and as high as possible. You wouldn't believe how far up the chain goes...

The mounting is a 4mm thick piece of steel which I chopped & grinded to shape. I welded two 13mm nuts onto the piece and replaced the stock footpeg screws with longer ones, so they could grip the steel plate as well. The clutch piston is fixed with two regular screws onto the plate. That's the whole deal.

The master cylinder for the clutch is pretty simple to install - just remove the clutch perch and replace with the one from the scooter. I'll have to machine a small mount for the choke cable & left mirror, but that will be done fairly soon - just need 2h of work.

If anyone's interested, I'll provide details on the whole operation.

The result is a cable-less, maintenance-free solution that feels pretty much like the stock clutch, except much smoother (almost like a brand new, oiled cable).

[catteeclan]

Good work.

I'll be watching this thread.

[veodoble]

exquisite... good job!

[switch]

Some afterthoughts, after about 1000 miles or so with the new clutch and riding other bikes (including a Husaberg w/ Magura clutch & a 1200gs with built-in hydraulic clutch):
- the clutch is much lighter on my dommie than on those models
- the lever is pretty difficult to cope with (aka: SHORT!); looking to replace it
- overall clutch operation is smooth, no slipping, more than enough de-clutching at max pull
- the position chosen for the pump is not the best: a fully laden bike will have the chain whipping at the pump from time to time
- I'll modify the airbox panel to make room for the pump much closer to the clutch acuator



Next upgrade will be an airbox mod + sport filter, sporket change and carb re-tune. Also looking to buy a small oil radiator.

[Manic Mechanic]

Dont mean to be all negative or anything. You're doing a good job with modding the domi but switching to hydraulic clutch isnt really an improvement.

You've made the system more complicated. Now you have 3 points of possible faliure for the clutch operation. The master cylinder, the clutch line and the slave cylinder.

Making the whole thing less reliable than a simple cable setup. The domis strong point is that its rugged and mechanically (relatively) simple. Why complicate it?

Dont mean to knock the idea. Whatever floats your boat.

[switch]

Thanks for the comment!

It's true that the system has more parts and is slightly more complicated, but we're not talking improvised whatnots here. We're talking brake components. Should either of the cylinders fail, it would be pretty similar to the front or rear brake on the bike giving in. I've heard of tons more broken cables than I've heard of brake failures

[kenny1950]

Well done Ii like the Mod.

I find my cable clutch is OK to use but that if I adjust the cable when the engineis cold as it gets hot it gives quiet a lot of free play and back to tight again as it cools. i think the cases must heat up and expand so altering the clutch clearance.

Ken

[Mervinh]

what do you needf a hydraulic clutch if the dommie clutch is as light as my vigor it could not be lighter, it is lighter than my old 2 strokes an fact the RD400 destroyed a cable in 3 weeks with heavy duty clutch springs in it i ad to strip em out and fit 3 heavy duty and 3 normal
merv

[kenny1950]

One advantage of a hydraulic clutch is that it auto adjusts all the time as the fluid flows back and fourth into the master cylinder as it needs to ..


Ken

[switch]

The dommie clutch is indeed light, but it is tiresome on my hands. The hydraulic clutch is just as light, but 'feels' much better under pressure and it doesn't tire the hand as much as the regular one.

Overall I'm quite pleased with it