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Message started by Oldfeller on 01/28/11 at 00:08:50

Title: Inelegant Stick Experiment -- cam chain tensioner
Post by Oldfeller on 01/28/11 at 00:08:50

This is an unproven experiment -- do not do this trick until it is proven out.

This post is written at EXPERT LEVEL discussing a potential new rework method -- it is a thought provoker, not a rework method (yet).

proving out a trick like this takes years and years of running time, so be patient

OK, we currently do this:

http://www.hunt101.com/data/500/medium/bit_trick.JPG

and in result we get some retarded cam timing by 7-10 degrees or there abouts by the time we wear it out. This isn't a big issue to us right now but it is there and we know it .... and there isn't anything we can do about it anyway.

http://www.hunt101.com/data/500/medium/new_cam_closeup.JPG

The raised right side shows where the cam is rotated "backwards" by all the cam chain slack being taken up on the left side by the extended cam chain adjuster -- this rotation only gets worse as the second life of the extended cam chain tensioner system rolls on through.

=======================

But ..... what if ???

What if we took out the chain wear on the front (right) side by bowing the stationary cam chain guide outwards?

Photos that follow show a trial mock up of such a system which is done simply to show the concept has a functional pathway to follow and has some results that might be worth pursuing.

I had a motor with a well worn set of guides and a half done chain and some extra fiddle time to play with it. The main challenge in moving the stationary guide forward was that the aluminum housings all have casting draft and the back of the plastic coated steel chain guide isn't flat (it is concave with blockish squarish injection molding features on it). Spacing it out wouldn't be square if you put something square behind it.

Round rod (dowel) stock has good features for the use though -- the half inch round stock shown fits nicely in the groove in the back of the stationary guide, bridging over the squarish injection molding features and forcing the stationary guide into a bow shape with the rod/dowel acting as the string so to speak. A bevel on the inserted end of the rod is needed to "ride over" or "bump past" the injection molded squarish features when you stuff the rod in place by lightly tapping it home.

http://www.hunt101.com/data/500/medium/Installed3.JPG

The round rod self centers on the chain guide groove and since it only contacts the off kilter aluminum housing in a single contact line it is not tilted or influenced overmuch by the casting draft in the housing.

A potential tight spot is created where the chain loads on to the small sprocket -- I think this will rapidly wear into the plastic surface of the chain guide though to the point the stress is relieved. Mind you, these are the original chain guides, so they will need replacement anyway when a new chain goes into place after this second life of the cam chain is used up.

Tensioner has almost all of its travel restored -- 22mm worth or there abouts. You only have 19.3mm of distance until the chain hits itself, so the announcement of "time to tear it down again" should be a nice loud whirring contact noise of chain to chain.

Now -- why might this be worth pursuing?

http://www.hunt101.com/data/500/medium/cam7.JPG

You get cam being advanced a tad at the start of the wear in, instead of being retarded. It will wear in to "normal" and likely not get any further retarded at the end of life than the system does now by the first tensioner protrusion life (first life).

And we won't say anything about the fix being easy or cheap or that somebody could sell a kit with a tube of epoxy and a piece of aluminum bar stock with some nice neat instructions.

We will reserve all of that until the idea proves itself out (or it fails miserably, who knows?)

And that will be years from now as this is my backup engine and my primary engine is doing jest fine right now ....

But, it is a thought to consider -- what do you see that is wrong with it (other than the use of wood of course). It does achieve tensioner reset without requiring a weld up job, it allows the use of used worn guides and it gets your cam timing run all the way back to zero (or slightly advanced) instead of retarding the nuts out of it ....

What'cha think?

:-?

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Oldfeller on 01/28/11 at 00:37:29

And yes, add this innovation to the long list of innovations that were made possible by Serenity donating his old blown motor to the investigative cause.

Serenity wanted him a rework method for the cam bearing death syndrome, he got that plus a bunch more as the work progressed.

=========

Anybody got any extra valve covers? I need two as the engine didn't come with any.

And a large cam end rubber plug (used) if anybody has a used one still sitting around. That's the BIG rubber head plug that gets sandwiched between the cover and the head when you put the two together.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by verslagen1 on 01/28/11 at 08:03:34

I think in this case you want a glass cam bore cover so you can monitor cam timing. 8-)

And put a little white paint on those marks.

1st impression, the plastic on these guides aren't the greatist.
2. You'll be pinching the bottom as the guide is supported bellow the drive gear. This situation will soon remedy itself (see #1)

Sounds like the back up engine should be the tried and true and the test engine installed.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Boule’tard on 01/28/11 at 09:10:47

70535B595A53535A4D3F0 wrote:

..in result we get some retarded cam timing by 7-10 degrees or there abouts by the time we wear it out. This isn't a big issue to us right now but it is there and we know it .... and there isn't anything we can do about it anyway.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Serowbot on 01/28/11 at 09:13:05

Aren't there more stresses on the leading edge (front), than the trailing edge (rear) of the driving gear?...
So,.. the slack is better taken up on the backside?...

... and yes,.. I'm thinking far beyond my head here... so if you tell me I'm wrong,.. I'll agree completely...

... also,.. regardless of slack on the trailing side... if the leading side is tight and the timing marks are lined up... is it still retarded by the stretch?...
... or am I?... :-?...

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Boule’tard on 01/28/11 at 09:30:42

Oh I get it. Oldfeller wants the tensioner to bow the pull side and slack side evenly. Which would advance the timing as opposed to having a straight pull. I don't think it's a good idea because in actual running the chain will want very strongly to pull straight. If there is something rigid holding the right tensioner shoe bowed like that, I think the chain will saw through the shoe prematurely. But let's see how the experiment plays out..

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by verslagen1 on 01/28/11 at 10:23:45

49445E474E5F4A594F2B0 wrote:

[quote author=70535B595A53535A4D3F0 link=1296202131/0#0 date=1296202130]
..in result we get some retarded cam timing by 7-10 degrees or there abouts by the time we wear it out. This isn't a big issue to us right now but it is there and we know it .... and there isn't anything we can do about it anyway.

Why not just bump the cam ahead one tooth at the time you go the 2nd hole on verslagen's tensioner? There's what, 40 teeth on the cam sprocket? 360/40=9 degrees advance. One tooth should almost perfectly compensate for the extra length of chain.
[/quote]
Something's wrong with those numbers, can't say exactly, but something's wrong.

Chain pitch = 0.25"
That's a hell of a lot of stretch to jump one pitch.
Previously, I calculated about .010" chain stretch = 1° of cam retardation.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Oldfeller on 01/28/11 at 10:31:35

http://www.hunt101.com/data/500/medium/Installed3.JPG

Boule's got a valid point about stress wanting to straighten the bowed front guide back out, and it can to a degree. Every big single power pulse will send a tension wave up the right hand side of the chain to the cam sprocket which will pull any available slack out of the front side.

Wood isn't an ideal material, if the idea works it will likely get revisited by the creative among us to seek to overcome the challenges that it reveals. But right now I like it for the fact it will bend to conform if the pressure gets high enough to force it to do so. It will act as a shock absorber to the individual power pulse tension waves, as will the unsupported guide "bow" it supports.

Why wood? Hardwood dowel material is strong (in short sections like this it is very strong, more rigid than the relatively flimsy cam chain guide on either side actually) and it can flex and rebound without loading the shite out of the rest of the system if forces get that high.

Wood is also porous, and will embed a slow setting epoxy bond much better than smooth plastic or metal. Did you notice the stick was epoxied to the guide and to the curved aluminum housing to keep it from going any place? it is trapped by the concave surface of the back of the bowed front guide and can't go anywhere, so the epoxy is just some extra "belt and suspenders" thinking.

Lastly, if the stick manages to get loose and hits a running main gear it gets converted into sawdust rather than breaking some major expensive things.

Lastly, it is so wonderfully inelegant, cheap and simple .... if it works out well it would be a solution worthy of Master Yoda himself.

and maybe I'll finally get my brown hooded robe and full Jedi status ....

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by verslagen1 on 01/28/11 at 10:37:56

4553445941545942360 wrote:

I think gear teeth stress here can be totally ignored.
No evidence of failure... ever.
Chain stress is evident from the wear points in the pins.
At speed, the main load the chain sees is centrifrugal, and the chain will float thru the bend with the contact points at the begin and ending tangents.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by RidgeRunner13 on 01/28/11 at 10:59:09

Just slot the cam gear holes.

I have an adjustable cam gear on my 2.3L ford race motor made by Esslimger Engineering. Makes it simple to adjust cam timing.

And yes, the chain will eat up anything in contact with it on the 'tight' side. 8-)

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Boule’tard on 01/28/11 at 11:36:39

213225243B3630323966570 wrote:

Something's wrong with those numbers, can't say exactly, but something's wrong.

Chain pitch = 0.25"
That's a hell of a lot of stretch to jump one pitch.
Previously, I calculated about .010" chain stretch = 1° of cam retardation.

Whoo boy, here comes a math puzzle :D

Looking closely at the gear on Oldfeller's crankshaft I see it is a 19-toother, meaning the cam gear must be 38 teeth to get the 2:1 ratio. If the chain pitch is 0.25" then the circumference of the cam gear is 38x0.25 or 9.5".

Divide by 2(pi) and the radius of the cam gear comes out to 1.512".

To get one degree of cam retardation, the gear's tangent would have to move 1.512 * sin(1 degree) or 0.0264 inches. To get the 9 or so degrees Oldfeller is seeing, the chain must have stretched (in the distance between gear tangents) 9*0.0264 or 0.238 inches.. roughly one tooth.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by babyhog on 01/28/11 at 12:24:35

I don't know how to spell that sound that Tim "The Tool Man" Taylor makes, but that's what I'm thinking while reading this thread.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by verslagen1 on 01/28/11 at 12:45:30

Math? I got CAD.

Given those gear diameters and 12" between gears...
And the max stretch of .07 over 5" of chain...
max angle is 6.4° with a distance of .168" at the circumference.
No where near a pitch distance and too much advance for good running.

Sure have to wonder how much margin you have with a lancer cam. :-?

(piglet, shhh, I'm trying to keep a straight face)

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by bill67 on 01/28/11 at 13:33:28

Wooden pressure treated wood work better the pressure wooden bother it. ;D

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Boule’tard on 01/28/11 at 13:48:45

4D5E4948575A5C5E550A3B0 wrote:

.. max stretch of .07 over 5" of chain...
max angle is 6.4°...

Pshaw. Are those Suzuki service limits, or Oldfeller service limits? ;)

You could let the timing retard down to negative 6.4° then bumping a tooth would bring you to only +2.6° enabling you to run one of Lancer's hot cams.

grunt grUNNT..

<scratches butt>

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Oldfeller on 01/28/11 at 14:07:09

Having just done it, one tooth is a WHOLE LOT of rotation.

We've had this discussion before, when somebody wanted to take a pitch out of the chain to tighten it up ... an entire link's worth is a whole lot of distance (many times the amounts we are talking for total wear amounts).

-- our wear amount from new chain to dead chain is worth maybe a pins worth of wear distance (little more than 1/8")

-- wear on the guides counts for about as much as chain wear does towards giving "too much slack" to a stock cam chain adjuster's original travel.

NO ONE has ever worn through the plastic on a set of guides yet, that I remember hearing about anyway. Maybe I'll get to be the very first one.

Cracks, yes they all develop cracks during the first run at their jobs and some edge stuff begins breaking off during the second life time -- but no gross wear throughs noted so far. Guide channels are not immortal any more than the silly chains are.

============

And Bill, mine is going to be Rotella oil impregnated pressure treated hard wood -- that's extra special.

And my hardwood rod was cut from a American Magic Hickory Tree, so I will have magic Rotella impregnated Hickory sparkles right in my engine acting magically all the time -- better than your old red pixie dust magic any day.

;D ;D ;D

.... and it isn't going anywhere until one of you jokers finds a set of valve covers and a big rubber cam end plug thingie so I can finish putting it together.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by buttgoat1 on 01/28/11 at 14:40:40

yannow, seafoam would prolly treat that wood better.
just sayin.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by justin_o_guy2 on 01/28/11 at 23:52:21

OF, I didnt read the whole thing, so, maybe Im outta line here, But hey! Thats never stopped me before, right?

Just wanted to say, I spent some time warping on my guide to accomplish that, didnt stuff anything in, but my guide BROKULATED,,& the end O the tensioner fell down & was bouncing around on the gear, still attached to a Very Short piece of chain guide. . It didnt come apart, because of the little wire I had in it, else I woulda had a sproing flinging around,,

Ahd be Right careful there.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by Oldfeller on 01/29/11 at 02:21:01

http://www.hunt101.com/data/500/medium/Installed3.JPG

That's OK Justin, all input is appreciated. Sounds like you had a failure of the left hand (rear) normal moving adjuster guide piece during a second life (or was it third life?) after hand bending it strongly to take up the same slop I am taking up by gently single bending and reinforcing the right hand (front) guide.

You bustulated the other one, not the one I am messing wid.

Now, did you have any major damage to the inner gears, etc, or jest a bunch of noise when yours went?

I'm asking because second (and third) life re-use of the cam chain guides is taking place a lot during these here hard hard recessionary times.

And that left hand large bottom sheet metal guide piece does jest hang out there in space with the cam tensioner spring telling it all the time to go that-a-way and the moving cam chain itself saying go this-a-way and it has a right rough row to hoe by the time it gets to the end of its second or third use life ....

;D

And remember as you go through your various cognitive processes, there is 1/2" hardwood dowel stock, 5/8" hardwood dowel stock and 3/4" hardwood dowel stock all readily available at your local hardware or artsy craftsy store.

I used 1/2" diameter because I had it on hand and I was jest fiddlin' with the idea.
5/8" would likely be about the ideal size with 3/4 being kinda too big diameter wise but a small flat could be put on each side to keep it properly centered with the guide.

Length needs to get shorter as dowel diameter goes up -- larger diameters are stronger and less flexible (if that's what you think you want).

;D

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by justin_o_guy2 on 01/29/11 at 06:47:02

Yeaaa, yer rite,, IDK how I managed to forget, but it was the left side, it hangs from that chrome bolt. I also have no idea just how long it was like that. Reason for goin in was the clutch actuation paddle broke. Wear marks were at almost zero, so, how long was it hanging loose? I doubt very long at all, a completely loose cam chain aint liable to run too long, izzitt? Im pretty sure Id notice a racket like that.

Title: Re: Inelegant Stick Experiment -- cam chain tensio
Post by engineer on 01/29/11 at 13:39:40

I think that the idea is a worthy attempt to solve both the chain stretch problem and the subsequent alteration of cam shaft timing. As several people have indicated the tension side of the chain will always want to straingten out and will increase the wear on a guide that has been bowed. How long will it last is, as you said, a matter of experimentation.

Long long ago when I was a kid I had a primary drive chain tensioner on a British twin wear through what appeared to be a neoprene wear surface and into the heavy cast tensioner. I managed to get a peice of solid industrial grade nylon and I heated up the cast tensioner guide and melted it into the nylon. It stayed put and I shaped the nylon down to the correct contour and the tensioner worked like a charm. The heavy chain slid over that nylon like nothing was there and neither the chain links or the nylon showed any wear.

I got the title for my S40 today but because of the snow the bike hasn't been delivered yet, it might be a month before I see it again. I am anxious to get my hands on some of these parts you guys talk about. That chain looks adequate for the job and so it seems to stretch prematurely but I like to get my hands on things before making any judgements.

I would guess that the Suzuki designers didn't do a better job on the tensioner because they expected the chain to be replaced by the time it stretched enough that it changed the valve timing. Thing is, it should last longer but I love these techniques you guys are perfecting to keep these machines running without spending a fortune on maintenance. I look forward to getting involved in the effort and until then I enjoy reading about everyone's efforts and thoughts.