Why does shift feel deteriorate on shared sump/trans engines

[JmanG]

My question is, why does shift feel deteriorate so soon on a shared sump motorcycle where the engine and transmission share the same oil? Ill get a little specific with my example. I've got a Honda 2007 CBR600RR, and ive just passed 48,000 miles on this motorcycle, runs great, no consumption that im aware of. No matter what brand 10w40 JASO2 spec oil i use, gear shifter feel greatly deteriorates after 1500 miles and begins feeling super notchy, with the first gear through neutral upshift into second being the most harsh with 2-6 still a little notchy but not as bad. For that reason, ive made a habit of changing the oil every 2000 miles. And with fresh oil, the gear changes are as smooth as butter again. Now ive used all the name brands in 10w40 weight, Amsoil Metric, Castrol Power 1, Motul 300v, Rotella T6 etc. And no matter what brand, at around that 1500 mile mark, the shifty gets notchy. Now ive read many UOA's on the oils im using and it seems they stay in grade well past 2000 miles. So whats happening with the oil that's causing this notchy feeling?

I should add I use this bike to commute to work yearly, 20-25 minute ride each way to and from work with the coolant temps reading between 165F(thermostat) and 205F when the rad fan kicks on so i certainly feel the oil is getting properly heated up to burn off the moisture.

 

[oldhp]

Maybe go up to Rotella T6 15W40? or a full synthetic V-Twin 20W50?

 

[FastGame]

JMO, it's not the oil, it's the trans and clutch. I'm the opposite of you, I never have shifting problems with the bikes I've owned, OCI's 5000-6000 miles. I've only used Rotella 15W-40, M1 4T 10W-40, M1 15W-50. I don't use my clutch upshifting and all is smooth.

 

[BusyLittleShop]

After 25 years dealing with customers its never the oil it's always clutch drag...
Honda warns that our gears can't shift smoothly if our clutch is part way engaged...

Here are the steps how to check and eliminate unwanted clutch drag...

1 Place your bike on the center stand...

2 Start engine and establish a steady idle at 212ºF (operating temp)...

3 Squeeze in the clutch lever and shift into first gear...

4 Continue holding in the clutch lever and note if the rear wheel coast to stop or not...
if it continues spinning that's unwanted drag... adjust...

To adjust a cable equipped bike turn the small knob clock wise (out)
1/4 turn and test for clutch drag... if your bike is equipped with
hydraulics bleed system for bubbles...

Ultimately you want the rear wheel to coast to a stop when the engine
is idling and first gear selected with the clutch lever is squeezed in...

A tip on TECHNIQUE...
I think we are after the same thing... smooth shift without upsetting
the suspension... the secret is moving the foot quicker than clutch or
throttle... go easy with the clutch and throttle but move your foot
quick... but worry there is no such thing as too quick... its early
form of seem less shifting...

 

[nascarnation]

If it's not a dragging clutch as pointed out above, maybe it's carbon in the oil from combustion?

 

[JmanG]

I do typically use Rotella T6 10w40 since i can get it dirt cheap at Wal Mart and since i do ride in the winter (which can get into the teens) i don't like going thicker than a 10w40 but of course trying 15w40 this time of year wouldnt do any harm, is that weight wet clutch compatible as well? However, ive never liked the feel of clutchless shifting. I know on a sequential motorcycle transmission, it's harmless but ive just always been able to shift smoother and just as quick with the clutch. But clutch cable adjustment is something that actually crossed my mind because i replaced the original clutch cable at 42k miles. It was almost stretched beyond the adjustment points on both ends. But i adjusted it how i always do, with the freeplay in the service manual and making sure it isn't disengaging by the turning the handlebars full stop left and right. I do like your idea by putting it on the rear stand and adusting it that way, which it hasnt been slipping but that's not to say that it's fully disengaging as well. I have always heard these high revving Supersport engines can be hard on oil but i also rarely see used oil analysis on these particular high revving 15k rpm redline 600cc engines so im not sure that's true, especially with modern oils.

 

[benjy]

10-40 is a pretty wide spread using a lot of viscosity improvers + thin 10W oil in the blend! depending on your area temps a 15W or even a 20W may do better in hotter months. been using Spectro 15-50 real synthetic PAO in my 106 inch air oil cooled victory in PA + liking it more than others i used. even though i ride little in cooler temps i like the 15W for quicker circulation + of course the 50W is very protective + thins less in the heat. even thou the vic is not as smooth as my bonneville it shifts better than before.

 

[cven]

Yep, Same thing with most oils I've tried. 1500-2000 miles seems to be when shifting gets notchy. These past 2 changes I ran Belray EXS ester 15/50 and the shifting is smooth as a gravy samich...LOL... almost as good as new oil at 3200 miles, clutch action is very smooth.. Also ran about 2 degrees cooler as soon as I changed over to it. I have 96,000 miles on my bike so I know it well... 1998 TL1000s with a TL1000r engine..

 

[blupupher]

Originally Posted by BusyLittleShop
After 25 years dealing with customers its never the oil it's always clutch drag...
Honda warns that our gears can't shift smoothly if our clutch is part way engaged...
...

That still does not explaiin why fresh oil is smooth, but as miles get on it, it gets notchy, and then changing the oil makes it smooth again.
Nothing to do with clutch adjustment.

 

[cven]

What Blu said above is the bottom line, If the clutch and chain are adjusted correctly and shifting improves with ONLY an oil change it HAS TO BE the new oil that makes shifting smooth again.

Pretty simple if you think about it.

 

[BusyLittleShop]

Originally Posted by blupupher

That still does not explaiin why fresh oil is smooth, but as miles get on it, it gets notchy, and then changing the oil makes it smooth again.
Nothing to do with clutch adjustment.


Has every bike you owned had this notchy problem or just your current bike???

 

[ZeeOSix]

Originally Posted by blupupher
Originally Posted by BusyLittleShop
After 25 years dealing with customers its never the oil it's always clutch drag...
Honda warns that our gears can't shift smoothly if our clutch is part way engaged.
That still does not explaiin why fresh oil is smooth, but as miles get on it, it gets notchy, and then changing the oil makes it smooth again.
Nothing to do with clutch adjustment.


Could be that new oil has less friction. As the oil wears and shears and gets contaminated the friction level goes up and the transmission is sensitive to increased oil friction.

 

[blupupher]

Originally Posted by BusyLittleShop
Originally Posted by blupupher

That still does not explaiin why fresh oil is smooth, but as miles get on it, it gets notchy, and then changing the oil makes it smooth again.
Nothing to do with clutch adjustment.


Has every bike you owned had this notchy problem or just your current bike???

Pretty much all of them, but I have never owned a "modern" bike.
I have had lots of '80s Hondas (CB750, VFR 500, CB125) and Suzuki's (GS250 and GS 500), current '94 VT1100 and a '95 Harley 883.

My current VT1100 starts to get notchy @ 2500-3000 miles (I have only usedSupertech 15w-40 and Peak blend 15w-40), not bad, but can tell a difference (mainly in finding neutral). Has a hydraulic clutch and no bubbles in it for sure. I have no center stand to easily check if there is drag or not, but do have a jack that I will check at some point.
When I bought the bike, I could barely get it into neutral (1-N or 2-N). No idea what oil or how long it was in it for. Drained oil and changed filter and within 10 miles it goes into N very easily with no notchy shifting.

I am not disagreeing that clutch adjustment can play a factor in it, but it just does not explain why an oil change would "fix" the issue. A clutch adjustment issue would always be present.
Unless as said, new oil allows more slippage so you don't notice it, and as it wears and gets use, the clutch starts to grab more, so an adjustment could be a fix (except for hydraulic clutches, if you are bubble free with fresh fluid there is not adjustment that I know of).

 

[bulwnkl]

The described symptoms sound like deterioration of the friction modification system, to me (leaving psychological considerations to one side for a moment). That certainly happens in dedicated manual transmission lubes.

 

[Surestick]

Originally Posted by bulwnkl
The described symptoms sound like deterioration of the friction modification system, to me (leaving psychological considerations to one side for a moment). That certainly happens in dedicated manual transmission lubes.


But, motorcycle transmissions don't have synchros so friction shouldn't have an effect on the dogs engaging.

 

[ZeeOSix]

Originally Posted by Surestick
Originally Posted by bulwnkl
The described symptoms sound like deterioration of the friction modification system, to me (leaving psychological considerations to one side for a moment). That certainly happens in dedicated manual transmission lubes.

But, motorcycle transmissions don't have synchros so friction shouldn't have an effect on the dogs engaging.


Shift forks and gears are still sliding back and forth and a change in friction could make the shifting behave differently. The gear dogs engaging shouldn't be affected bu a change in oil friction because the clearance between the dogs and the corresponding mating dogs (or slots) are large.

 

[ZeeOSix]

Originally Posted by blupupher
I am not disagreeing that clutch adjustment can play a factor in it, but it just does not explain why an oil change would "fix" the issue. A clutch adjustment issue would always be present.
Unless as said, new oil allows more slippage so you don't notice it, and as it wears and gets use, the clutch starts to grab more, so an adjustment could be a fix (except for hydraulic clutches, if you are bubble free with fresh fluid there is not adjustment that I know of).


Yep, there is typically no adjustment on a hydraulic clutch system.

Keep in mind that doing the "rear wheel spin test" while the engine is running in neutral and the clutch lever fully pulled may still spin the rear wheel slightly with a correctly adjusted clutch lever. That's because there is oil between all the wet clutch plates, which will still cause a slight coupling and cause the wheel to spin if there isn't much resistance in the output shaft/chain/bearings and brake drag.

 

[Bonz]

I don't know that Rotella has a 10w40? Unless specific to your area of the country.

I don't see you have tried Mobil 1 10w40 4T, holds up great in my ZRX1200 that makes double the torque and probably 50% again as much horsepower at the wheel. Also Mobil 1 V-Twin 20w50 has held up very well in the ZRX. Look for those analysis threads. I posted one fairly recently of the VTwin 20w50 and the 10w40 4T is right next to it in the next column.

It absolutely could be the clutch is on the thinnest edge of not completely disengaging. New oil hides that but it doesn't last as long as if the clutch was adjusted properly. But if anyone has ever left their bike parked in gear, pulled in the clutch and tried to roll it with it in first gear, the clutch plates don't move freely and you get considerable drag, that happens with the best adjustment on a clutch.

Anyway, sounds like you have done due diligence in exploring fixes and other things to eliminate the issue. I would just go with a conventional 10w40 Valvoline or Castrol motorcycle specific oil and change it every 2,000 miles and call it good, no need for synthetic with that short of an interval.

 

[BusyLittleShop]

Originally Posted by blupupher

so an adjustment could be a fix (except for hydraulic clutches, if you are bubble free with fresh fluid there is not adjustment that I know of).


Brembo radial clutch levers are adjustable...

 

[blupupher]

Originally Posted by BusyLittleShop
Originally Posted by blupupher

so an adjustment could be a fix (except for hydraulic clutches, if you are bubble free with fresh fluid there is not adjustment that I know of).


Brembo radial clutch levers are adjustable...

Don't think they make those for an 1100 Shadow. Maybe there are other ones out there that do fit though.