Clutch sticking once warmed up

[VAL. H.]

I have a small problem with the R80 sidecar.

Unfortunately I'm nowhere near (200 miles ish) my Haynes manual and most of my tools, so thought the collective might offer a solution/sensible advice.

It hasn't been used much over the winter, just run up and trundled round the yard to keep things turning.

Anyway, we just went for a little bimble and the clutch became sticky in its actuation. I initially thought the cable had given up, but it looks more like the clutch push rod is getting tight once the engine warms up properly. Is this something that can happen, or is it more likely that the clutch is sticking when the engine warms up?

If it's the push rod, can it be easily sorted by pulling off the boot and squirting some oil in? Or is it more like the gear box needs to come out?

I've had a good look at the cable and it is moving freely and in good condition.


Your thoughts gentleman, Val.

 

[Steptoe]

What year is your bike ?


The usual cause of the problem you describe is the one piece clutch thrust piston unit getting stuck in it's tunnel . Fitted to post 1985 bikes, but a lot of the pre 85 also now have them fitted.

gets stuck once the bike is warm, as the bike cools down you'll hear it go bang as it frees off.
This doesn't apply to pre 81 bikes as you can't fit this later unit.

 

[VAL. H.]

What year is your bike ?


The usual cause of the problem you describe is the one piece clutch thrust piston unit getting stuck in it's tunnel . Fitted to post 1985 bikes, but a lot of the pre 85 also now have them fitted.

gets stuck once the bike is warm, as the bike cools down you'll hear it go bang as it frees off.
This doesn't apply to pre 81 bikes as you can't fit this later unit.

Thanks Neil

It's an 89 Mono. Is it located on the back of the box under the rubber boot and easy to get at, or deep inside at the clutch end?


Val.

 

[VAL. H.]

Just had a look on Max BMW looks like it should quite easy to sort out.


Ta Val.

 

[VAL. H.]

Just had a look on Max BMW looks like it should quite easy to sort out.
Ta Val.

Well maybe not. Took the bits out, small amount of water in the boot along with some oil. Gear oil I'm guessing. No signs of corrosion and the thrust piston looked ok. Needle roller in the actuating arm was well seized, though this didn't prevent it working.

Cleaned everything up and reassembled with a little grease on the piston and unsiezed the needle roller. Lovely light leaver action, lighter even than it already was.

Off out for a ride to see if all was now well. Sadly no. much better, but once warm there is still some notchiness in the leaver movement. As I said previously, the leaver and cable are in good order and when the engine is cold the actuation is very light and smooth. I'm also getting some clutch slip which I think is probably a side effect of the original problem.

Looks like I'll be frequenting Motorworks and Motobins websites later.


Val.

 

[Deleted account 220427001]

I have a small problem with the R80 sidecar.

Unfortunately I'm nowhere near (200 miles ish) my Haynes manual and most of my tools, so thought the collective might offer a solution/sensible advice.

It hasn't been used much over the winter, just run up and trundled round the yard to keep things turning.

Anyway, we just went for a little bimble and the clutch became sticky in its actuation. I initially thought the cable had given up, but it looks more like the clutch push rod is getting tight once the engine warms up properly. Is this something that can happen, or is it more likely that the clutch is sticking when the engine warms up?

If it's the push rod, can it be easily sorted by pulling off the boot and squirting some oil in? Or is it more like the gear box needs to come out?

I've had a good look at the cable and it is moving freely and in good condition.


Your thoughts gentleman, Val.

well done val for fixing just abit of work makes a difference with copperslip

 

[Steptoe]

Well maybe not. Took the bits out, small amount of water in the boot along with some oil. Gear oil I'm guessing. No signs of corrosion and the thrust piston looked ok..

They always look ok - The body of the thrust piston wears slightly. Causing the body to tilt in the tunnel and get jammed or cause the clutch to feel sticky.

Just replace the complete thrust piston unit.

 

[Padmei]

They always look ok - The body of the thrust piston wears slightly. Causing the body to tilt in the tunnel and get jammed or cause the clutch to feel sticky.

Just replace the complete thrust piston unit.

Ahhh so it's not that the piston swells then? That's the first time I've heard that.

 

[VAL. H.]

They always look ok - The body of the thrust piston wears slightly. Causing the body to tilt in the tunnel and get jammed or cause the clutch to feel sticky.

Just replace the complete thrust piston unit.

Fitted a new one last weekend. Didn't get to give it a long enough run to get it properly warmed up. Done that today. All as it should be.


Thanks for the assistance. Much appreciated



Val.