Belt Squeal at low speed

[you you]

Time for earplugs.

[iceman]

Time for earplugs.

Doesn't help with my squeal / issue. It's really annoying and taking a lot of enjoyment out of riding. Only started when I replaced the belt and rollers.

Does do it at idle, not sure if it's there at speed but when slowing down it's most of the time until very low speed and clutch not engaged.

[mymitzi]

Since it is only at idle, was wondering if the boss [out side part, that contacts variator] could be causing the problem.
The boss is locked in place on the crankshaft,so the inside part of the boss always turn at the same speed as the crank.
Maybe the movement between the variator and the boss is the culprit?? I generally put just a slight coating of grease
on just the outside of the boss [where it makes contact with the inside of the variator] Some use graphite for this but
I had an experience where the variator center hole wore out and started rattling. Since then, been just putting the smallest
amount of grease.........actually wiping most off. Has solved the "wear" issue for me. Just might be worth a shot??
Was concerned about belt dust making a paste but, its so little grease that its not an issue.

[iceman]

Sorry, that should have said 'does not do it at idle', mostly noticeable when slowing down say 15-30mph with no throttle, stops when clutch dis-engages (or just low revs).
When I put it back together, I did not grease the boss (is that the thing the variator slides back onto, and is hard to fit the belt if it's not sat down inside the clutch plates)? The service manual does not state to lubricate it so I didn't, but I know some do. Basically I thought you were not meant to to stop grease getting into the housing and onto the belt.

[mymitzi]

Yes....The variator with rollers and ramp plate & boss all slide onto the drive shaft together. Understand your concern about the grease but,
there is just a wee bit......hardly noticeable. I put a smaller than pea size dab on my finger and coat the outside of the cleaned boss and
then wipe most of that off. Not sure it will cure the issue you're having, but its free......except for your time. Also was concerned that the
grease might slow down the transition of the variator but that hasn't been the case.... and I run 12 g rollers. Hope you get it sorted.

[mymitzi]

One more thing... [Peter Falk impression] Can you run it on the centerstand with the trans cover off so you can better tell
if the noise is coming from the Front [drive] or the the clutch area [driven] If you can isolate the noise to one or the other,
your that much closer to finding the source.

[Coasting]

SORTED!

Hey folks, learned some valuable lessons.

1. It was caused by worn drive faces. I replaced both faces (ie the two alloy ones at the front - not the steel ones at the rear) and it's gone from "awful and getting worse" to "completely normal".

2. My HUGE mistake was not realising how worn they were - they looked polished with no obvious signs of wear because the surface looked straight apart from a change near the outer periphery - which I'd incorrectly assumed was part of the design (perhaps to stop the belt riding too high on the variator if oversped). Wrong wrong wrong - there's not supposed to be ANY change to the slope of the faces - they're supposed to be completely straight from the inside all the way to the outer edge.

3. In hindsight, the wear appears to have been completely linear - resulting in a bigger gap between the faces - allowing the belt to drop down further - probably to the point where it started riding on the boss thus losing friction with the (worn) drive sides thus causing the squeal.

4. In retrospect I'd recommend changing the drive faces after about 30,000 miles / 50,000 km (or perhaps every 2nd time one changes the drive belt every 15,000 miles / 24,000km).

5. Top speed of the bike has increased by around 6 MPH / 10 km/hr (due to the belt being able to ride higher on the drive faces) - I'd put the drop in top speed down to engine wear (just about to do my 42,500 mile / 68,000km oil change). Now it's back to exactly what it was the day I bought it - I'm a happy guy. Just keep in mind that the speedo still over-reads by 10% as it always have.

6. In the process of changing so many parts (rollers, drive faces, boss, belt, clutch spring, clutch weights/pads) I've discovered a great new supplier - https://bikerzbits.com/ I'd simply look up OEM part numbers - pop them into their search field to identify them - and order them. They appear to be SIGNIFICANTLY cheaper than the likes of Bike Bandit & Partzilla - are still shipping in these COVID-19 times - and don't charge an arm and a leg for shipping. I've ordered from them twice now - they seem to take 2 to 3 days to get the parts on their way - parts take 3 to 4 days to arrive - and parts appear to be genuine OEM. Very impressed. Price in USD to get both drive faces and the boss delivered to my door was USD 43.33.

For comparison, I put one of the new drive faces next to the old one so you can see the wear. The lighting makes it look worse than it does to the naked eye.

https://freeimage.host/i/2I9rlI (URL to photo - site returned a "can't get image dimensions" error when I used the IMG tags).

It's been quite a journey - hope this helps someone.

[you you]

The difference between old and new is really apparent in the picture.

Some good information there. Thanks fo the write up.

[iceman]

Coasting - although both variator faces did show some wear (mostly marks rather than large grooves) it's possible I am seeing what you had due to the difficulty getting the belt back on the variator (boss) seeing how hard it is to press the clutch plates together.

If there is not enough free belt left when putting the variator faces together, then the outer variator face does not press home properly and thus the belt can ride lower (nut tightened against the belt rather than fully home on the boss) - if that makes sense.

Guess I will have to take a look at some point. This time I will try using tywraps to hold the belt together when I pull the clutch plates apart.

[Coasting]

I'm not 100% sure I'm fully understanding what you're meaning - so I'll elaborate on some of the detail in the hope that it helps.

Due to the clearance between the housing that the entire transmission is contained in and the outer periphery of both the drive faces + driven faces, it's necessary to remove both the left hand drive face (at the front) and the clutch + driven assy (at the back) to change the belt.

I'm getting confused by your reference to the "clutch plates" - it doesn't have any "clutch plates" - it has clutch weights+pads in the clutch assy at the back that fly out against their spring tension to make contact with the part called the "clutch outer", but we don't really have a lot to do with that assy unless we're changing/cleaning the pads.

So at the rear we have the clutch assy and driven face assy. It's the driven face assy at the rear that has to move the opposite way to the drive face assy/variator so that the belt tension is constant. So basically the drive face assy at the front is wide apart at idle or when stopped - the belt moves in close to the boss - and the "slack" is taken up by the driven faces being mashed together by the MOAS ("Mother Of All Springs") (not quite the official name for it - it just feels like it when I changed it!).

So when fitting the belt one needs to wrap it around the closed driven face at the rear - and the best you'll be able to do is get it over the shaft (but not the boss) at the front whilst you slide the driven assy + clutch assy back onto the shaft at the rear. At that point you can put the nut on that rear shaft and torque it up to 36 foot pounds.

Because the belt needs to go over the boss and not just the shaft before putting the left hand drive face back on we need to move it - I've found that that's best done by squeezing it together in the middle slightly. It takes a little bit of strength to get it over but it's not too bad. There's certainly no need to try and separate the driven faces to make it happen.

At that point the left hand drive face + washer + nut can be reattached and torqued up to 44 foot pounds. I too worried that I was just pinching the belt so as the tension started to come on the nut I stopped and removed the restraining tool (whatever it's called) that stops the drive face from turning the engine shaft when you're trying to tighten the nut so that the belt had the chance to get out the was if it was being pinched. Everything rotated as expected so I put "the tool" back in place and finished torquing and "job done".

Couple of thoughts/notes:

1. The drive faces are alloy whereas the driven faces are steel - so I think that approx 100% of the wear is going to be to the drive face not the driven face.

2. I suspect that all drive faces wear - and that the rate is probably fairly consistent. Mine got to about 42,000 miles / 67,000km before the squealing started - so I'd say that the chances of worn drive faces being the issue on your bike are probably directly proportional to how close your bike is to having done the mileage of mine.

The whole belt squeal was doing my head in - I couldn't make a lot of sense of it until I understood what was happening. It was simple in the end; it squeals due to slippage - and slippage can only occur due to lack of tension. What could affect tension? ...

1. A change in the distance between the front and rear shafts ... but that's impossible.

2. Too big a gap between the two driven face assys at the rear ... I initially thought that might be the case so I got a new spring but (a) it was exactly the same length as the old one (b) appeared to be the same tension and (c) didn't make the slightest bit of difference after I'd changed it. Could also be due to wear, but (a) the steel looked polished but not worn (mind you I thought the same about the drive faces!) and (b) One of the driven faces had been changed at low mileage because it had a rough bearing (known fault).

3. Belt stretch ... I compared old with new - less than a mm difference.

4. Belt width reduction ... old and new were identical ... and it was squealing with both in the end.

5. Worn drive faces = more gap = less tension (boss length means there's a maximum gap - assuming the rollers aren't ridiculously worn). So that was my "bingo" moment. The more the faces wore the bigger the gap - the lower the belt would have ridden - and I'd almost bet money that at some point it rode so low that it started to make contact with the boss - at which point friction between the side of the belt and the drive face would have been reduced to the point where it eventually started to slip - thus causing the noise.

That's my theory anyway! To put it all another way, I changed belt, rollers, spring (my "other suspects") and it didn't make a damn bit of difference. Changed the drive faces (& boss) and it hasn't make so much as a single squeal on any occasion despite my best efforts to make it do it.

On a side note, it's probably worth mentioning that to get into that area there's no need to take the side panel off, It's a little tricky but perfectly possible to get a small 8mm socket and ratchet onto that front bolt of the fan shroud to loosen it - then use just the socket to undo it. The big alloy housing that eventually comes off also has a bearing at the back to support the clutch + driven face assy shaft so personally I wouldn't run it without that housing on to try to confirm where it's squealing from (plus it probably wouldn't do it with no load anyway) (plus plus I get nervous when the back wheel spins up past low speed when it's on the centre stand because mine isn't particularly well balanced and it starts to jump around a bit - would hate for it to drop off the stand whilst at high RPM).

Hope this helps!

[iceman]

Clutch plates > the two 'faces' the belt rides in - hard to seperate them enough to drop the belt far enough inside them to allow lots of free play variator end (belt) - so using a tywrap to hold the belt in the middle makes it easier.

All I can think of is that there was not enough free play and the variator face was not quite in enough by a fraction of a mm or so. Nothing changed except a new belt, rollers and re-assembly and the noise started.

[Coasting]

Ah - Honda call those the "driven faces". The clutch is on the same shaft, but doesn't have any contact with the belt.

Nothing changed except a new belt for me too when mine started - and the issue went away when I returned to the old belt, but only for a couple of weeks - and then the only difference was that the new belt squealed more.

My thinking was exactly the same as yours about the variator face "not being in enough" (despite being torqued correctly) but it just wasn't the case; despite leading myself down the garden path a number of times the issue was 100% caused by the worn drive faces.

I'm still a bit confused by why you'd want to separate the two driven faces. In theory you could do that, but all that would achieve is that you'd reassemble the transmission in a higher "gear" instead of low "gear". A tywrap around the middle would make it a touch easier to get the belt from the shaft up onto the boss, but other than that it really doesn't make any difference; I just give it a small squeeze by hand and a little push to get it in place.

Once the belt is on the boss then you can put the other drive face back on and torque it up. It does get a little "spongy" towards the end as the belt get squeezed out a little, but I doubt it has to move more than a couple of millimeters. You can interrupt the torquing and turn the drive face to help the belt move if you want, but I don't bother doing that any more.

What distance has your bike done?

[iceman]

>I'm still a bit confused by why you'd want to separate the two driven faces<
Meaning pushing the clutch faces aprt to get the belt back on it and hopefully a little in it.

Bike has done 22,300 miles. rear tyre change at 13,500 and now 1st front tyre change - the original IRC still had near 1.5-2mm all around though. Changed the air filter last year, made no difference to mpg or ride, still original spark plug, no valve check, 141-143mpg on meter, which is actually 137mpg real (litres in / trip) < not bad!

From other post, 2nd time front pads are being changed, the EBC ones did not last long compared to the original Honda ones and I do not usually break hard and use a lot of engine breaking.

[Coasting]

Meaning pushing the clutch faces aprt to get the belt back on it and hopefully a little in it.

Shouldn't be necessary. "Homie" shows how it's done if you scrub to the 7 minute mark in this video if you haven't seen it: https://youtu.be/C6-cCjR8kUY I've got the older bike that takes the older belt without the "teeth" on the outside, but it fits exactly the same.

Bike has done 22,300 miles.

To be honest I thought it would have done more, but at that distance I had already lost about 4 MPH / 6 km/h of top speed due to wear - and without knowing your routine I guess it's entirely possible that you spend more time in the low speed start/stop/crawl zones than I do thus it would probably be reasonable to expect more wear on that portion of the drive faces if that's the case.

Perhaps start by comparing it to the two in my photo? If the surface is flat like the one on the left (or like the one in Homie's video) then that's probably not the issue - but if it looks like mine on the right then that's definitely the problem.

Given your symptoms I'm 99% sure it's due to wear on those faces - too much similarity between our symptoms (looks, walks, and sounds like a duck etc). I'll be changing mine every 31,000 miles / 50,000km from now on.

rear tyre change at 13,500 and now 1st front tyre change - the original IRC still had near 1.5-2mm all around though. Changed the air filter last year, made no difference to mpg or ride, still original spark plug, no valve check, 141-143mpg on meter, which is actually 137mpg real (litres in / trip) < not bad!

Much the same for me. I ran my first rear to 9000 miles/14,000+km (IRC) but it was far too long as I found out when it blew out (luckily I stayed on the bike). I've got a CityGrip on the rear at the moment and it looks like it'll comfortably do more than my usual self-imposed 6000 mils/10,000km limit.

I get great mileage out of fronts too. Brake pads are a funny one - I changed front ones out at 21,000 miles/33,000km and they were getting pretty low. Changed the back ones at the same time and although they weren't quite as low it was still a good time to change them. Plan at the time was to change them both again at 42,000 miles/67,000km but they're both still fine and I don't really know why given that nothing's changed in terms of riding style or location - and I've always used OEM parts.

I usually run the air filter about 50% longer than I should - like you I've not seen any performance hit so I tend to relax a bit more about it now. I finally had the valves checked at 31,000 miles/50,000km - one was slightly off - can't remember if they adjusted it or not. I think the "Honda way" of servicing ensures maximum reliability but is expensive. My way probably goesn't give the same reliability but is one heck of a lot cheaper. I personally think the best compromise is to use an app to remind me to order appropriate parts so that they're on hand when I need them. Parts through the dealer are literally over 3 times the cost - and I'm sure I'm faster ... go figure!

Mine sits around 43km/liter not sure what that is in your units. It drops into the high twenties if I burn the tank at wide open throttle. I've changed my spark plug a couple of times - thought it might need it more as the bike started to burn more oil but it still seems fine. The book recommendation of changing it every 5000miles/8000km is nothing but a rort in my opinion.

[Coasting]

The "gift that keeps on giving" ...

Riding along today when all of a sudden there's a nasty sound coming from the transmission. As I pull over and slow down the engine stops. Bugger.

Called the dealer who came out and gave the bike a ride back home.

Cut a long story short, the nut that secures the left hand variator face to the engine shaft had come undone - best guess is "bozo brain" (ie me) forgot to torque it up.

Luckily no damage apart from a few specs of alloy inside the case where the cooling fins have made contact with the alloy casing.

I had it all cleaned out and reassembled in about an hour. This time I was curious as to how much the belt stopped the face from mating against the boss - felt like about a 1/4 of an inch - so I quickly started/stopped the bike a couple of times as I was tightening it to give the belt a chance to ride out of the way before finally torquing it up to what it's supposed to be (plus a bit for luck). I also marked the nut and shaft and will check that the marks align a few times over the next week until I feel a bit more confident that it's staying in place.

Managed to take a photo of how it looks in that area with everything in place from between the faces if anyone is interested: https://freeimage.host/i/25cxb2

On the plus side, I'm getting REALLY fast at stripping & reassembling PCX 150 transmissions!

[iceman]

I bought a torque wrench and used it on the variator and clutch nuts (would only use it them and wheel nuts, etc) - torqued until 2 clicks at recommended settings. No trouble so far in loose nuts

Tbh - I think marking where the net was or just tightening up to a reasonable tightness will do fine - many changing variator bits on YT never use torque wrenches and those that keep trying different parts for slight %0.x improvements do not seem to bother either.

[Coasting]

Yeah - I think my problem was that I'd just got complacent from having had the thing apart too many times and forgot to do the nut up beyond finger tight. I've never had a problem before - I think I'll probably just be a bit nervous about it for a few days until I can see that it hasn't moved.

Torque wrench generally stops me over-tightening things!

[iceman]

Ordered the two drive faces items, 22102-K35-V00 & 22110-K36-A00 from Bikerbitz, total £9 for the parts and £35 inc tax, shipping (£19 shipping) < still cheaper than ordering here, just hope they fit!

[Coasting]

Ordered the two drive faces items, 22102-K35-V00 & 22110-K36-A00 from Bikerbitz, total £9 for the parts and £35 inc tax, shipping (£19 shipping) < still cheaper than ordering here, just hope they fit!

They're both different part numbers than what I ordered - but it's for a different series of bike - so I'd say that sounds about right.

Keen to hear how you get on with it!

[iceman]

Ordered the two drive faces items, 22102-K35-V00 & 22110-K36-A00 from Bikerbitz, total £9 for the parts and £35 inc tax, shipping (£19 shipping) < still cheaper than ordering here, just hope they fit!

They're both different part numbers than what I ordered - but it's for a different series of bike - so I'd say that sounds about right.
Keen to hear how you get on with it!

22102-K35-V00 is listed against a UK 2014-2017 LED variator kit, but 22110-K36-A00 is a gamble - seems to be about the same so no idea why so many different versions as the boss p/n seems to be identical. Wonder if the slope angle or something varies a bit.