Topic: Wrong Oil, Clutch Slipping

[Freebirdbeachbum]

After maybe linking the slipping clutch problem to the synthetic oil I used, I drained it and changed it to a mineral oil.

Does it take a while for the synthetic oil left behind to dissipate because it’s still slipping after about 20 miles?

[DaveBarbier]

I don’t know for sure but I’d bet it would take a little bit to flush out and disperse in the new oil.

But I’m curious, have you tried to adjust the cable? To make sure the clutch is engaging properly you would slacken the cable but screwing in the threaded barrel at the handlebars a little at a time.

Secondly, is the oil specific motorcycle oil? Probably obvious but I wanted to ask anyway.

[Freebirdbeachbum]

I don’t know for sure but I’d bet it would take a little bit to flush out and disperse in the new oil.

But I’m curious, have you tried to adjust the cable? To make sure the clutch is engaging properly you would slacken the cable but screwing in the threaded barrel at the handlebars a little at a time.

Secondly, is the oil specific motorcycle oil? Probably obvious but I wanted to ask anyway.

I'm pretty sure the clutch is engaging properly. It's interesting that initially, that is, on my initial brief test ride after completing the mechanical restoration, I didnt notice any slip but did on the second longer test ride it was slipping like crazy (maybe as the synthetic oil worked its way between the disks?). 

And yes, I did use motorcycle specific oil.

[PeWe]

I have 20W-50 synthetic oil in my CB750. No clutch slip due to the oil that is a motorcycle oil, labeled JASO. 
Modified with bigger bore, 80-100 whp during the years and therefore harder Barnett clutch springs.

I have had slip, when clutch lever on clutch cover had too small lash. Tighten and return 1/2 turn needed. 1/4 not enough.

I got starter gear slip with thicker oil, mixing 20W-60 when weather was hot.

Car oils can have antifriction additives a wet clutch cannot handle.

[Freebirdbeachbum]

Car oils can have antifriction additives a wet clutch cannot handle.

I used my Valvoline VR1 Racing Oil that I use in my vintage Alfa Romeo that specifically says not for wet clutches on the label. I didnt read the label.

[JLeather]

Oops.  I would pull the clutch out and clean the friction plates with brakekleen and then soak in some fresh plain oil and reinstall.  If you keep letting them slip while waiting for the oil to flush out of them you risk permanently glazing them.

[Flyin900]

Oops.  I would pull the clutch out and clean the friction plates with brake kleen and then soak in some fresh plain oil and reinstall.  If you keep letting them slip while waiting for the oil to flush out of them you risk permanently glazing them.

From what I have read on other forums it could be the end of those friction plates, since the oil does soak into the material. Yes the oil is always in between the steel and friction discs plates inside there.
At a minimum you will need to pull the clutch assy and flush the entire motor area through the clutch case opening with the drain plug removed; including a new oil filter too. As noted above try Brake Kleen to really wash both the metal and fiber plates and then a re soak of the fiber plates in normal oil.

It seems that most end up replacing the fiber plates and a minor motor flush.

Personally for the cost of a set of fiber plates vs all the work to clean the old fibers and  reassemble the clutch with the hope their now good and won't slip isn't worth it.

[PeWe]

Flush engine with new motorcycle oil before new clutch.
A test ride will tell if it helped.
All too slippery oil need to be removed before replacement anyway.

[Freebirdbeachbum]

Oops.  I would pull the clutch out and clean the friction plates with brake kleen and then soak in some fresh plain oil and reinstall.  If you keep letting them slip while waiting for the oil to flush out of them you risk permanently glazing them.

From what I have read on other forums it could be the end of those friction plates, since the oil does soak into the material. Yes the oil is always in between the steel and friction discs plates inside there.
At a minimum you will need to pull the clutch assy and flush the entire motor area through the clutch case opening with the drain plug removed; including a new oil filter too. As noted above try Brake Kleen to really wash both the metal and fiber plates and then a re soak of the fiber plates in normal oil.

It seems that most end up replacing the fiber plates and a motor minor motor flush.

Personally for the cost of a set of fiber plates vs all the work to clean the old fibers and  reassemble the clutch with the hope their now good and won't slip isn't worth it.

I'm going to run it around for a period and see what happens before I launch into a clutch replacement. It seems to stop slipping after it gets hot but, if and when I'm in there, I might as well replace the disks.

[DaveBarbier]

Yeah I agree. Run it as is for a bit and change the oil again and see how it goes. Don’t want to replace the friction plates yet if there’s old oil still in there.

Replacing clutch plates is an easy job. Most difficult would be removing the cover and cleaning the gasket surfaces.

[Freebirdbeachbum]

To stick a fork in this thread, I replaced the disks after soaking them in the proper oil and the slipping disappeared.

Thanks all for your guidance.

[Flyin900]

So with the continued riding after you changed to the correct oil, it didn't resolve your issue and you then replaced the friction discs? I think once those friction discs have become impregnated with oil designed with friction modifiers there is no other solution.

[TwoTired]

Synthetic oil will NOT make the clutch slip.  However, the additive package blended with the oil can.  Usually, oils marketed for motorcycles have a proper additive package for wet clutches, as do oils for Diesel engines. But…

[Freebirdbeachbum]

So with the continued riding after you changed to the correct oil, it didn't resolve your issue and you then replaced the friction discs? I think once those friction discs have become impregnated with oil designed with friction modifiers there is no other solution.

It appears so.

[Kevnz]

This is bizarre. I run\have run ordinary, cheap car oil in my 500 and VFR800 for over 10 years with never any sign of trouble. Being cheap means I can change it more frequently. Whether cheap oil changed often is better or worse than expensive oil changed less frequently is probably debateable, but I've seen no evidence to make me change my thinking.

[Deltarider]

Nothing wrong with your practice, Kevnz. Realise that in most markets in the 70s, there wasn't a specific motorcycle oil - whatever that is - around. When I bought my bike in 1980, Castrol GTX2 was everybody's darling in dealers workshops and even that oil wasn't marketed as 'motorcycle specific'.

[PeWe]

There is a risk using cheap car oils to avoid clutch slip.
Like using a bad lubricator to avoid slip.

Better to use a good oil developed for bikes with wet clutch.
Old bikes engine design need an older API class with good amount of correct antifriction additives as the old oils.

Castrol GTX2 worked fine.
But that was before catalytic converters which needed oils with less of the good stuff our old bikes needs.

Car oils can have very slippery additivies to make everything to roll easier, less fuel consumption and no thoughts about a clutch that can be attacked by chemicals disolving the friction plates.

Cars have also separate gearbox with its thicker oil if manual type, our bikes not. Same oil must withstand the gears mangle it.

[Flyin900]

Many modern oils that are car designed today have additive packages to reduce friction and as such will damage the fibre plates with the friction modifiers and clutch slip is the end result.

I have run Castrol GTX automotive oil in all my bikes for the past 20 years, as it is quality oil and specific weights do not have the modifiers, yet other Castrol GTX weights do have those modifiers, which are not good for our clutches. These are shots of the sticker on the back panel for Canada sourced Castrol GTX oils and other countries labels are likely quite different.

The Castrol GTX 20-50 weight and the 10-40 weight from this brand are without the friction modifiers and work well for our wet clutches, yet the 5-20 weight is loaded with the modifiers. Note the panel on the 5-20W has the energy saving notation, while the 20-50W has a blank panel indicating no friction modifiers.

I can buy this Castrol GTX on sale for 5 liters for about $18.00 Canadian and get close to two oil changes out of a bottle. A liter of Castrol motorcycle specific oil would be about $10.00 per bottle, so the 5 liter jug is an easy choice for my needs.

[Deltarider]

I have run Castrol GTX High Mileage 15W-40 for years now and it has proved a good oil. It keeps the rubber parts elastic; even the notorious shifter seal seems to have cured it self. It is not marketed as a specific motorcycle oil - whatever that may be - neither is it labeled JASO MA and it says nothing about zinc either. Should I worry?
No and here is why. When you are in the detective mood, on for instance the UK Castrol site, you can find out a few things about this oil.
First, will it make the clutch slip? Well, certainly not mine. A JASO MA oil may not have more than 1,2 wt % sulphated ash. Guess what my oil has: exactly 1,2 wt %, right on the edge. One could argue: on the edge, that means not JASO MA. OK, but, my clutch has never slipped, so I'm good there. Then the zinc that everybody seems so concerned about. I was not able to find data on that. But I found out something else. I looked up what oil Castrol UK would recommend for the old 70s and 80s VW vans. Guess what: among other modern, fancy (and expensive!) other oils we find the GTX High Mileage 15W-40 listed. Now I picked this van on purpose, as it was powered by an air cooled flat tappet boxer. In those years I have travelled quite some miles in them and I remember in hot wheather it would run pretty hot on long distances. Occasionally we would see temperatures as high as 120-150^o C (248-300^o F) on the VDO.
So, if Castrol sees no problem using this oil in the VW vans of that era, it is also fit for my air cooled engine. I only found this out last year but actually... I already have known for years it is a strong oil. From experience.

[Don R]

 I ran some royal purple 20w50 synthetic race oil in my F1 once. It slipped but I did already need to adjust the clutch lifter, just didn't know how.  It was OK after I adjusted it and better shortly after I did an oil change.