Belt Squeal at low speed

[Coasting]

2014 PCX - 67,000km

I recently fitted a new genuine Honda drive belt and since then have heard a little "belt slippage squeal" for a couple of seconds everytime as the bike starts to move (even with gentle acceleration) - and much the same just before the clutch disengages when slowing down & stopping (but only just before it stops - engine braking is normal up to that point).

At any other time I can make large power changes without any squeal. Previously I've only ever had belt squeal on one occasion (going WOT from around 40 km/hr) - and that was with the old belt that had done around 34,000km (which had a small tear in the outer layer and the usual cracks between the teeth, but wasn't anywhere near failing).

Rollers were changed at 33,000km (had minor flat spots that affected top speed slightly, but apart from that appeared fine). Variator face assemblies look bright & clean with no obvious signs of wear, but I'm not 100% sure what I'd be looking for in terms of wear. I torqued the variator nut to about 45 and the clutch nut to around 35 (as I always have).

It doesn't sound like the sound is going to go away by itself - I'd appreciate any thoughts on what it might take to fix it.

Thank you.

[alx123]

A glazed clutch will make the same sound. Better make sure which one is it. I'll open it, clean the clutch, set the belt again and see if the screeching remains.

[Coasting]

A glazed clutch will make the same sound. Better make sure which one is it. I'll open it, clean the clutch, set the belt again and see if the screeching remains.

Thanks - but it's not that. It's now doing it at speeds up to 40 km/hr - clutch is well and truly engaged.

Would appreciate some input from the gurus here - getting desperate!

[alx123]

You can try removing the variator cover and see what's going on in there while your'e revving the scoot. Just make sure to keep your hands away from moving parts while doing so.

A new "original Honda" belt shouldn't be doing that.

[Gil]

At 67,000km your scoot has quite a bit of miles on it. I would check on the play between the variator and the boss. I recently replace the NCY variator because the play was too much. The symptoms that my scoot had was lag in shifting when trying to accelerate. Also the roller weight had uneven wear.

[Inoplanetyanin]

Measure the specs for drive and driven pulleys, belt width, weight and condition of the rollers, sliders and the diameter of the boss. Clutch springs, rear driver bearings, amount and condition of gear oil.

Report back.

[Coasting]

Thanks all. Will strip it down again this weekend and try to get to the bottom of it.

On the face of it it's only started doing it since the new belt was fitted. The new belt was OEM and was the correct part, and I'm really don't think it's possible for me to stuff up the fitting given that it's such a simple exercise. So all a bit of a mystery.

The only other symptom that I've noticed is that sometimes it sounds like the variator isn't moving after the bike has been off for a while in that the revs go higher than they should and then drop back a bit as the bike picks up speed. No belt slippage and that issue goes away within a few seconds of getting going not to return again until next time it's been off for a while (seems to do it more on rainy days where temps are low and humidity is high).

Should the shaft everything slides on have some kind of lubricant? (and if so what type?).

[Coasting]

OK - so I removed the front and rear assemblies - cleaned and inspected every component - cleaned up the clutch pads and housing - reassembled and ... no change.

The rollers (OEM, stock) are in "9.5 out of 10" condition; a barely perceptable flat spot on a couple and "not even that" on the other 4. The boss looks like it always did - and slides freely. The drive and driven faces are smooth and don't appear to have any uneven wear. The large/powerful spring in the clutch assy didn't seem quite as "fearsome" as I remember it so perhaps a slight tension drop, but that's all pretty subjective.

So still none-the-wiser. I might try putting on the original belt and see what it does just in case it's a faulty new belt - other than that probably the best solution is to just replace everything between the two shafts once I can get my hands on OEM spares at on-the-planet prices again (which rules out local stuff).

It's almost like the new belt is slightly bigger. The CVT is fine when lots of power is applied - it's just emits an annoying audiable squeal whenever making gentle power adjustments anywhere up to 40 km/hr - accelerating or decelerating; not overly loud, but consistent and annoying.

[you you]

I’d pop the old one on and try it...

[Coasting]

OK - so I took the new belt off and confirmed that the part number was the same as the old one. Width is identical to the old one. Circumference is the same as the old one. Construction appears to be the same as the old one. No obvious sign of oil or grease on it. Put the old belt back on and not even so much as a hint of a squeal at any stage. Neither of the previous belts have made any squealing when new either, so there's something different about this one - I just don't know what it is.

The new belt was the equivalent of USD $118 - it's charged to my account, but not paid for yet. I've probably done 100 to 200km on it, and it still looks like new - but I don't have the plastic bag it came with. Dealer is probably going to think I'm nuts, but I really don't want to pay that kind of money for a part that makes the bike squeal something like a 1/2 muted version of a car with alternator / power steering belt issues, and I can't guarantee that another new belt wouldn't do the same thing either (since I don't know what's causing it).

Anyone have any thoughts?

[Old Grinner]

You mentioned the clutch spring didn't seem like it's old self?

One of the riders who used to post here quite often, "homie", made some great videos about PCX maintenance. Perhaps you remember him.

Here's one he did about the PCX clutch and how some grease migrated into areas where it shouldn't be and how to fix it. It caused shuddering/squeeling as he would say. Maybe it will help and maybe it won't in your case but well worth watching.

[Coasting]

You mentioned the clutch spring didn't seem like it's old self?

One of the riders who used to post here quite often, "homie", made some great videos about PCX maintenance. Perhaps you remember him.

Here's one he did about the PCX clutch and how some grease migrated into areas where it shouldn't be and how to fix it. It caused shuddering/squeeling as he would say. Maybe it will help and maybe it won't in your case but well worth watching.

Thanks. By coincidence I came across that video yesterday and viewed it again. Unfortunately there's nothing in it that really applies to my problem. It was very useful initially to get a feel for what I was in for, but I've had everything apart quite a few times now and could probably pretty much strip the entire transmission and reassemble it blindfolded now (literally).

[iceman]

I have a strange noise when slowing down at low speed since installing a new Dealer bought belt (the ebay one I bought went in the bin as it had the white/grey middle part unevenly distributed around it's length). Never noticed the noise on the original belt which came off looking in great condition after approx 19,000 miles.

I did take the cover off and take the variator end out and back in again, but I just live with it as can't be bothered taking it all apart again and the old belt did a lot of miles so not going back on (sealed up keeping as emergency spare).

[Old Scoot]

Does the belt have to mounted in a certain way, is that maybe causing the squealing?
I know that the two drive belts of my wife's Volvo 340 with a CVT drive have arrows on them to be mounted in a certain way.

[Coasting]

Does the belt have to mounted in a certain way, is that maybe causing the squealing?
I know that the two drive belts of my wife's Volvo 340 with a CVT drive have arrows on them to be mounted in a certain way.

I had a good look, but can't see any arrows. The part number is written in white letters along the outer edge of the belt so I made the assumption that if it did have a design direction then they probably wouldn't print the writing in such a way as it had to be read upside down, and so installed it accordingly.

[Coasting]

I have a strange noise when slowing down at low speed since installing a new Dealer bought belt (the ebay one I bought went in the bin as it had the white/grey middle part unevenly distributed around it's length). Never noticed the noise on the original belt which came off looking in great condition after approx 19,000 miles.

I did take the cover off and take the variator end out and back in again, but I just live with it as can't be bothered taking it all apart again and the old belt did a lot of miles so not going back on (sealed up keeping as emergency spare).

Sounds like much the same thing. In my case I could modulate the throttle to keep the bike within a certain speed range that keeps it squealing continuously. In essence I've got 67,000km across 2 belts - reasonably evenly distributed. Both have cracks between the teeth on the inside and one started to show a tear across the outer layer. I'm back on the best of the two but to be honest, neither are looking anywhere near any point of failure.

For what it's worth, I cleaned all parts of my variator under running water - then used a kitchen "liquid micro-abrasive cream" - and then in an ultrasonic cleaner - so not a trace of any dirt anywhere, but it didn't make the slightest bit of difference. When I checked the belt tension it did seem a little on the slack side compared to what I was expecting - and it may be my imagination, but the big spring between the clutch and the driven face didn't seem to put up quite the fight that I remember it doing originally (subjective though). Given that that spring directly influences how hard the driven faces are pressed together (thus setting the belt tension) I might just take a punt and get a new spring and see if it makes any difference.

Yeah - it is a pain to take apart. I've found that if I'm careful with a ratchet I can get the front bolt attached to the black cooling fan inlet off without having to take the side panel off which speeds things up a lot. An 8mm socket attached to an extension shaft in the chuck of a battery powered drill should get the side cover off in under 2 minutes if it helps.

How many miles have you done on the new belt? (I'm just wondering if it's enough to rule out it just needing a bit of time to bed in).

[iceman]

I've done several 1000 miles now on the new belt (new air filter at that time too - old one was dirty but probably would have been fine as mpg and performance have not changed). Really annoying rotary wheeze when slowing down but not going to investigate any more this side of 2020.

[Old Grinner]

FWIW I used to notice kind of a "whirring" noise while decelerating on my 2017 (with stock IRC tires) when the PSI would drop a bit. If I remember correctly hot pavement enhanced it as well. Checking the tire pressures regularly and keeping the recommended PSI up to specs seemed to reduce it.

[Coasting]

Thanks folks,

Plot twist: The old belt is starting to make a bit of a squeal sometimes when I slow down now too. I discussed the issue with the dealer, but he'd never heard of it before. He phoned the experts at Honda and they hadn't heard of it either, but the only thing they could think of was to "check the big spring in the variator" ... considering the variator doesn't have any "big springs" (or any spring for that matter) I'm not left with a feeling of high confidence - however - I was thinking through all the physics of how these things work (before I had the chat with the dealer) and came to the conclusion that the belt tension is pretty much a function of the spring tension of the big spring at the back - which I thought may have dropped - so I've ordered a new spring (and variator rollers - and clutch pads) (the latter were down to about their last third anyway).

The dealer also thought that it's possible the drive faces may have got a bit too polished - I was thinking that there's always the option to give them a light sand blast - but I can see that having the potential for either a whole lot of good or a whole lot of bad; get it wrong and I could easily see the faces being ruined - so I'll leave that as a last resort.

Seems it's the gift that just keeps giving!

PS: I've got the "whirring noise" too. My tyre pressures are always spot on, but I have switched from IRC to Michilin City Grips in more recent times. I plan to coast down a hill with the clutch disengaged to try to figure out if it's something south of the CVT causing it - not too worried about it. I did notice that when I turn the rear wheel by hand that it has a little tight spot in one area - not sure what that's about as the rear brake has a healthy amount of play in the handle.

[Coasting]

Update,

Today I stripped the transmission down again. Replaced the variator rollers (even though the old ones were "9.5 out of 10" - gave all drive faces a bit of "de-polishing) with some medium-light grit sand paper (then chemically cleaned them). Changed the clutch shoes (were due anyway) - cleaned all other clutch components in the ultrasonic cleaner - replaced the spring between the driven face & clutch (old one was only about 1/4 shorter - and tension felt about the same) - put the new belt on and ... the belt noise is just as bad (if not a little worse).

About the only thing I can think of left is to change the drive & driven faces. The old ones looked fine to me, but I guess it's possible that they've worn so evenly that I can't tell without comparing them to new ones.

At least the bike still goes OK.