Topic: 400F whine under load -- countershaft bearing?

[Wil]

Hello, all.  I'm new to the forum.  The exigence for my membership is a problem I'm having with my '76 400F.  Under load, the bike makes a whining noise similar to the one made by a standard shift car in reverse.  If you put the bike on the service stand and run it in gear, no noise.  As soon as pressure is applied to the rear brake, however, the noise is perceptible. 

A friend familiar with bikes suggested it's the countershaft or output shaft bearing.  Any thoughts?  If consensus here is that it is the bearing, can it be replaced without splitting the case?  Any tips on its removal and replacement?  Bearing availability? 

Mucho thanks!

[kpier883]

I had a pretty bad whining when my chain wore out.  Replaced it and the bike was quiet again. 

[sopo400f]

I also have the same problem. Never seen anybody post a solution.

[kajtek]

i have the same, i can see where you would be going with the countershaft/primary shaft bearing. when i had my engine apart i checked the bearings and they looked ok, no play, no wear and were very smooth.

my feeling is that the noise is a gear noise, namely the primary shaft gear to the clutch basket gear. definately not gearbox or output as mine does it when at a standstill holding the brake and feeding in the clutch.

im gonna try a 20w50 oil soon (on 10w40 at the moment), maybe this will make a difference. there is a reference to the noise on this site at the bottom of the page: http://www.cb400f.btinternet.co.uk/trans.htm

not sure if wear on the gears could cause the noise?

i dont know if its inherant to the bike or not, although ive seen some vids on youtube where you definately cant hear the whine.

ashley

[kajtek]

Thinking bout it though, couldn't hurt to replace the bearings? Pretty certain that one of them comes out of the side of the engine, dunno of you could replace both without splitting cases

[Wil]

Ashley -

Thanks for the insight and the link.  It raises some interesting possibilities.  After looking at an exploded view, it doesn't appear the output shaft bearing can be replaced without splitting the case as the oil seal has a tab that holds it in place and the bearing itself is held by a c-ring.  Verification?

I suppose it could be gear lash ...  How about drive chain as suggested by kpier883 above?

Wil

[kajtek]

Hi, output shaft definitely has a tab, cases apart for all the tranny bearings for sure. The primary shaft is got to on the clutch side, remove the cover and the primary gear, there is a circlip that when removed u can pull on the shaft and it comes out along with that bearing. I think the other bearing is accessed from an internal circlip, which could be accessed through the bottom by removing the sump and using 90 degree pliers..

As to the possibilty of gear noise, I tried to research a little on the matter, the reversing sound could be because of the type of cut used on the gears, in some bikes with seperate gearboxes, people using a heavier oil to make them less whiny.  Gonna change oil In a couple of weeks so will report back on that.

In regards to the drive chain, I imagine it could cause a whine but I'm sure that's not the case for me as mine makes the noise standing still when the engine is loaded!

Ashlet

[kpier883]

Was the chain moving when the engine was loaded?  Or, how did you put a load on the engine without the chain participating in the process?

[Wil]

Kpier883 -

Put the bike on the service stand and ran it in gear; no noise.  As soon as pressure was applied to the rear brake, however, the noise was perceptible.  So yes, the chain was engaged, but it wasn't until there was a load on the engine that the noise appeared. 

Interestingly, it will also make the noise if the bike is on the ground and it is under load but not actually moving.  (Held the front brake on and feathered the clutch in first gear.)

Wil

[Wil]

Ashley -

Please do let me know if the 20W-50 quiets it down.  I'm not nearly as close to an oil change as you are!

Are you referring to the countershaft as the primary shaft?  I'm a tad confused.  It's the countershaft that's behind the front sproket, correct?  If we are talking about the same shaft (see attachment, part #143), then are you saying that the bearing can be accessed on that side by removing the oil seal and a circlip, and the entrie shaft pulls out?  I assume, then, that a press would be required to remove/replace the bearing on the shaft?

Thanks again for your help!

Wil

[kajtek]

Hi will apologies, got confused, I'm referring to the primary shaft, part 132, driven by chain from the crank. 143 would be a cases split affair for sure.

And yes I loaded the engine by pulling out clutch while holding the brake, this way I feel it's isolated to either crank chain to primary or primary gear to clutch basket gear. My feelings are its the clutch to primary gear, but unfortunately I cannot prove it!

[Bodi]

Has this sound gotten suddenly louder?
The 400F has a characteristic whine sound from the straight-cut primary gears. Some are louder than others but I have never heard one without it.
Different oils affect the sound but don't eliminate it.
If it has just appeared or gotten a lot louder you may have a primary shaft or mainshaft bearing giving trouble. A misaligned drive chain can make an odd sound as well while the side plates wear down the sprockets.

[Hablo]

My 350f whines sometimes (or at least I only notice it sometimes) in first gear.   

Wil, does your bike do it in every gear or just first?

[kajtek]

Bingo, so it is the straight cut gears. Suppose I should just get used to
It! (kind of an now anyway)..

[Wil]

Bodi -

Believe you are correct about the chain as the culprit.  Adjusted the rear wheel alignment and chain tension, which reduced the whine.  Plan to try a heavier oil (20W-50) to reduce the noise from the gear cut.  Will post a follow-up for those who are interested.  Hope Ashley will do the same. 

Thanks!

Wil

[Wil]

Hablo -

Every gear, although it's louder in the lower gears, say 1-3.

Wil

[kajtek]

As soon as the rain stops I will change my oil! And lube my clutch cable and adjust my drive chain and fix my electro rpm cable..

[kajtek]

Spoo... changed oil to 20w50 mineral moto oil, n it still whines. Can't tell if it's less, I suspect the whine is a little less 'coarse'. Although the whole engine feels a bit smoother and my clutch is a lot less grabby, still grabbing a bit though so I think I will have to pull it, file the notches and replace the friction and steel plates..

I did have a think, and when changing down at speed with serious engine breaking the whine is a lot more friendly, leading me to think that maybe one side of the gears is worn causing more noise?? Who knows...

[Wil]

Noise is getting progressively louder.  Perhaps it's time to buy transmission gears in anticipation of failure.  :-/

[Cb400fnoel]

Hello folks, did you ever fix the noise from your gearboxes? Mines the same!

[robvangulik]

If you can hear your gearbox whining, you exhaust isn't loud enough

[Cb400fnoel]

If you can hear your gearbox whining, you exhaust isn't loud enough

Bril  problem solved!

[Erwin83]

Anyone care to update on their whine and if they were able to fix it? Or is it just something to get used to?

[Oddjob]

If it is noise from the straight cut gears between the primary drive gear and the clutch basket you could try having them coated in a special ceramic coating invented to reduce gearbox noise in cars.

I've had the large gear on the back of my clutch basket done in it, wasn't costly. Only comes in a sort of gunmetal grey but I suppose colour isn't a problem. I wasn't able to have the primary gear done at the same time so I'll need to get that done as well when the opportunity arises. It's supposed to cut down noise and friction evidently, lots of racing engines have the gears done in it from what I'm hearing.

The stuff is called PolyPhen Dry Film Lubricant if it's any use to you, maybe a little chat with a local ceramic coater would answer more questions. Just had a quick chat with the person who did mine and he also says it helps retain the oil between the 2 gears, maybe that alone would dampen the whine.

[Erwin83]

I find it very plausible that it's the straight cut gears, I spent some time reading here and on other fora, and sounds very common to have a whining gearset.
Interesting idea to have them coated. I might try that!

Maybe I'll first try this: I just remembered I swapped the complete clutch basket from my old engine to the new. Would it be worthwhile to also change the small gear out so they complete a set again?

[Oddjob]

Can't hurt, might just be a clipped tooth causing the whine.