Clutch-covers' ability to quickly, and *properly*, deflect chips (MS660 "XL"'s, etc)

[Cerberus]

So I was drawn to the XL Stihl 660 clutch-cover, figured "Better chip-dispersal is good because sometimes I do palms, they clog so fast!" (clutch-pack of palm fibres led to the only fail of my chinese 660, a popped clutch-spring)

TL;DR-- if you can choose clutch-covers, wouldn't you want size or volume in the "rear" especially "rear-lower" portion of the clutch-cover? For instance, XL 660 covers simply flare-outwards (whereas an OEM cover, at that spot, has a flared-bottom that tapers inwards & outwards, actually just removing the inward-flare gives you ~10% more lateral area for chips to escape), am I wrong in thinking "more space" = better, here? Or is there a spot you want a choke/tight spot, maybe to prevent chips going up&over the clutch's top?

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Sadly, after seeing a video on the XL's, and inspecting the regular OEM, it seems neither is optimized for chip dispersal, I mean the "rubber chute" on the left side/bottom of the XL is so wide it literally restricts space worse than OEM:
https://cdn.shopify.com/s/files/1/0312/7533/products/066WESTCOASTCOVER-4_480x480.jpg?v=1642186470

The WCS's (sexy) billet cover is the same form/mold...

Is there some kind of reasoning behind the XL "boot", maybe it is good to restrict space in some areas of the clutch-cover? Kinda like preventing the chips from going up&over the sprocket, having a "choke-point" that catches them around the 9pm-->11pm point from the clutch's centerpoint, to cause "spitback" of chips, out&down, from there?

Cannot help thinking the best is to simply use an OEM, remove the rubber chute thing entirely for the extra space, and even take an angle grinder (w/ flap-disk) to that inward-tapered bottom of the cover, expanding the total "width" by over 10% (width of powerhead to clutch-cover's inside facing)

Can't think of any reason that more space "beneath 9pm", at least, would be optimal -- but wanted to ask here before fiberglassing my own or otherwise altering in a way that turns-out to be improper! Thanks

 

[Cerberus]

Actually just looking at that pic I linked of an XL 660 cover's inside-face, just looking at that my thought is "Why include the rubber boot it takes up so much space!", have seen youtubers bemoan this as well with this model's clutch covers, anyway just wanted to ask if anyone knows if Stihl was wanting to choke/create tight-points in their design or if it's just oversight/less than optimal!

 

[Locust Cutter]

Pure speculation for the pinch is to avoid inertial wrapping up/back around the sprocket, especially with noodles, but I could be wrong.

 

[av8or3]

I’m thinking the smaller the cover, the more room for chips to escape. The regular OEM cover should get the best results. The larger West Coast covers just dump the chips at your feet. The littler ones spray them all over, mostly behind.

 

[rogue60]

Over thinking it?
The WestCoast cover is larger so ya don't accidentally cut ya fingers off running the full wrap handle thingy. Also helps control sawdust chips keeping em away from the operator with the angles they get the saw into thanks to the full wrap.
If you want max chip clearing especially when noodling stick with the original small cover.

 

[Cerberus]

Pure speculation for the pinch is to avoid inertial wrapping up/back around the sprocket, especially with noodles, but I could be wrong.

Nah I think you're onto something, examination of the deflector plates (rubber 'chutes' on rear-left wall of cover) seems to come in arching at the clutch more, couldn't be an oversight when designing something as straightforward as "XL version"! Am guessing the same myself, so there's reduced "frontal spray" or whatever you call the top-of-bar stream..

I’m thinking the smaller the cover, the more room for chips to escape. The regular OEM cover should get the best results. The larger West Coast covers just dump the chips at your feet. The littler ones spray them all over, mostly behind.

Smaller, for more room for escape...unsure my brain follows that logic (the extremes would be super tight, which'd be clogging all the time, or no covering at all which couldn't clog)

I dislike dumping at my feet wish I could get more 'rightwards&down' aim but that'd require powerhead-side chutes, am sure longer, steeper verticals will be fine!

Over thinking it?
The WestCoast cover is larger so ya don't accidentally cut ya fingers off running the full wrap handle thingy. Also helps control sawdust chips keeping em away from the operator with the angles they get the saw into thanks to the full wrap.
If you want max chip clearing especially when noodling stick with the original small cover.

lol had never conceived that big flare was a safety feature...honestly thought it was their aesthetic decision, because all that really matters is the fitment of the XL chute (and I guess the elimination of the inward-flared edging at the bottom, can't fathom any case it's desirable to restrict outward flow at the bottom-lip of the case yet they put an inward lip, thankfully 30sec w/ a flap disk can remove that and net you 10%+ lateral space from powerhead to cover ;D )

And yeah am certainly over-thinking it, I guess, all relative right? Not for a second do I think it's of substantial importance or anything, just kinda mussing about with my favorite saw & trying stuff, plus once I heard it contextualized as avoidance of irritant pulps&fibers, which I do encounter here in semi-tropical 9b FL, I loved the idea of having some control on "the stream" of chips but yes this is an over-do and am not advocating others go fiberglass their own, have had little to no trouble w/ the OEM's myself have packed one 1 time and since then I'm cautious and it never happened again...they just cut so fast they can clog quick, when I blew a clutch spring w/ a packed cover it wasn't like I was sitting there bucking-up palms it was a handful of cuts :/

 

[rogue60]

Nah I think you're onto something, examination of the deflector plates (rubber 'chutes' on rear-left wall of cover) seems to come in arching at the clutch more, couldn't be an oversight when designing something as straightforward as "XL version"! Am guessing the same myself, so there's reduced "frontal spray" or whatever you call the top-of-bar stream..

Smaller, for more room for escape...unsure my brain follows that logic (the extremes would be super tight, which'd be clogging all the time, or no covering at all which couldn't clog)

I dislike dumping at my feet wish I could get more 'rightwards&down' aim but that'd require powerhead-side chutes, am sure longer, steeper verticals will be fine!


lol had never conceived that big flare was a safety feature...honestly thought it was their aesthetic decision, because all that really matters is the fitment of the XL chute (and I guess the elimination of the inward-flared edging at the bottom, can't fathom any case it's desirable to restrict outward flow at the bottom-lip of the case yet they put an inward lip, thankfully 30sec w/ a flap disk can remove that and net you 10%+ lateral space from powerhead to cover ;D )

And yeah am certainly over-thinking it, I guess, all relative right? Not for a second do I think it's of substantial importance or anything, just kinda mussing about with my favorite saw & trying stuff, plus once I heard it contextualized as avoidance of irritant pulps&fibers, which I do encounter here in semi-tropical 9b FL, I loved the idea of having some control on "the stream" of chips but yes this is an over-do and am not advocating others go fiberglass their own, have had little to no trouble w/ the OEM's myself have packed one 1 time and since then I'm cautious and it never happened again...they just cut so fast they can clog quick, when I blew a clutch spring w/ a packed cover it wasn't like I was sitting there bucking-up palms it was a handful of cuts :/

Never had a problem with chip clearance cross cutting the grain but yeah noodling yes but that can be over come with technique cutting nose down as to not be pulling the chain parallel to the grain = smaller chips.

Never cut palms myself sounds nasty clogging up the clutch cover could try cutting some of the back off the clutch cover off like some the chainsaw racing guy's do??

 

[Thumper88]

Here are two wide covers. One is the WCS aluminum cover on my 500i and the other is a wide/west coast style on my 064. The rubber runs up the back of the cover to make a very tight gap where the chain tooth rounds the sprocket. That way the chip hits the rubber and funnels out the back instead of getting slammed into the top of the cover and clogging. The wide covers will eventually pack tight if you are noodling and pulling big chips, the only thing that would prevent that would be running without a cover at all I think. The west coast covers are wider to deal with more chips from the long bars and soft wood, but also to keep your hand safer running a wrap as mentioned above, and to discharge the chips out and away from the sawyer better in odd postions. Just my nickles worth

 

[Thumper88]

My Dolmar is running a normal cover, and the narrower cover is also cut higher and doesnt cover as much area, that combined with not using a rubber chip deflector means it will absolutely blow chips out the back. That saw is nasty anyways, and has an aggressive chain, it is not one you wanna be behind when someone is sawing. The narrower cover clears chips hard and fast but they spray everywhere.

 

[Woodslasher]

From my experience, the smaller covers seem to "spit" a stream of chips out the back of the cover and have a flow of noodles fall out while the wide covers just spray chips out along the last 2-3 inches of the cover and dump noodles. It's like the wider the cover gets, the less velocity and directional control the chips have. As for the op's comment on restricting flow, at least some of the material under the cover is reinforcement, if you look at old 056 clutch covers they are thin, relatively free of ridges/webs, and consequently they are often missing chunks. My two bits, if I'm only bucking firewood and doing some felling I'd pick a "small" cover. If I'm going to be noodling more than two rounds, I'd pick a wide cover.

 

[Wonkydonkey]

I’ve only used std stihl clutch covers. Until I got a 038 (1985/6)and damm those older clutch covers get clogged and end up just throwing chips etc out of the top and back at the log.

your miles may vary But stihl changed the shape of those covers for a reason

 

[Cerberus]

Great replies!! Going to link another current, similar thread here I (shoulda found earlier) found:
https://opeforum.com/threads/wide-husky-clutch-cover.26206/

A youtuber has a couple videos on the 462/500i Stihl covers (regular V XL) but just put out a video comparing the WCS fancy one ($$$) so I figured to post some screenshots:
WCS's benefits-list (on their site they don't even list the weight which I found crazy for such a high-price item, to exclude such an easy, relevant spec, and John mentions it is heavier but it's larger, too -- I have to wonder how much value there is to the whole thing being huge, "hand protection" never even crossed my mind as a benefit..)

Visual comparison (wcs V OEM XL)

Chip-pattern (NOTE that the WCS side is right-side one photo, left-side second photo)

Never had a problem with chip clearance cross cutting the grain but yeah noodling yes but that can be over come with technique cutting nose down as to not be pulling the chain parallel to the grain = smaller chips.

Never cut palms myself sounds nasty clogging up the clutch cover could try cutting some of the back off the clutch cover off like some the chainsaw racing guy's do??

Yeah they are very nasty, have a job next week that's Oak but also Palm and Ficus Benjamina which is sap city I'd rather deal with the heavier Oak pieces...

Hadn't seen any race-covers but it makes sense that zero obstruction would be optimal (up until the choke-point, IE up&over the clutch, which for obvious reasons would "get in the way" / detract from power to some non-zero%) But cutting it off won't work for a work-saw, my thinking is simply grind-out a "triangle" on the rear, keeping the rear-dimension OEM-spec and simply lengthening it + flaring it outwards from the powerhead, as well as of course the interior-wall having:
- long vertical exit on rearmost face, and
- 'choke'/tight spot at close-point to the clutch to 'catch' / prevent chips going in&over the clutch....am paying attention to design here (uncertain if the designers actually put real thought&testing into it...because it'd take no time at all to slice-out a lil triangle and fiberglass-in whatever shapes I want, am setup to do decent jobs of that quite quick and aftermarket covers are insanely abundant&inexpensive...and the mag-alloy surprisingly strong IMO)

Here are two wide covers. One is the WCS aluminum cover on my 500i and the other is a wide/west coast style on my 064. The rubber runs up the back of the cover to make a very tight gap where the chain tooth rounds the sprocket. That way the chip hits the rubber and funnels out the back instead of getting slammed into the top of the cover and clogging. The wide covers will eventually pack tight if you are noodling and pulling big chips, the only thing that would prevent that would be running without a cover at all I think. The west coast covers are wider to deal with more chips from the long bars and soft wood, but also to keep your hand safer running a wrap as mentioned above, and to discharge the chips out and away from the sawyer better in odd postions. Just my nickles worth

Very very well-put! Thanks for posting those pics it's cool seeing where (and how) choke-points are setup, seems the OEM 660 chokes closer to 9 o'clock when the cover would allow for more of 9:30-9:45 if you were free-forming it (I'm unsure if there's advantage to keeping it lower, and suspect there is) so would wanna make an artificial 'choke' as low as you can while still getting it close to your chain...

I’ve only used std stihl clutch covers. Until I got a 038 (1985/6)and damm those older clutch covers get clogged and end up just throwing chips etc out of the top and back at the log.

your miles may vary But stihl changed the shape of those covers for a reason

In the video I posted pics from he mentions how the 500i cover is a step-backwards from the 661 covers, I've never checked out their interiors(the exteriors look slick!) but the regular 660 XL's seem a huge step-up from OEM..