SuzukiSavage.com - What happened tensioner mods

piedmontbuckeye

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Re: What happened tensioner mods
Reply #15 - 08/15/17 at 15:22:03

batman wrote on 08/14/17 at 16:19:59:

JOG,I believe you'll be waiting a long time. I don't think that idea is sound. Finding a spring of proper strength, in a size small enough to fit in the area, will prove almost impossible. The fact that the softer metal of the tensioner body has to slide back and forth against the mounting stud and the snap ring ,might also cause damage and metal grit entering the oil system.If the new spring is to weak the tensioner will be pushed back against the stud and act as it did ,if the spring is to strong,the pawl will advance ,but when the cylinder expands will the tension of the chain on the back side be strong enough to move the tensioner back ? If not ,there will be no gain either way.

Slightly disagree. I am not sure how the tensioner moving back and forth will create any such wear. Since the tensioner is under constant spring pressure from both sides, it is not just "flopping" back and forth.

Probably, if I had mine to do over, I would have thinned the tensioner mounting lug slightly - the same amount as the thickness of a washer that I would put on after the tensioner, but before the circlip just to make sure that the moving tensioner didn't work the circlip off the mount pin.

Next time I have cover off, I will do that.

See my previous post about what I did, and how it has worked up to now.

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« Last Edit: 08/25/17 at 14:28:44 by piedmontbuckeye »

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What happened tensioner mods Reply #16 - 08/15/17 at 17:15:44 I think the OEM petcock internal spring will work great. Long enough to do at least two.
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batman

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Re: What happened tensioner mods
Reply #17 - 08/18/17 at 16:41:27

The one factor about the way my tensioner is rigged is that the spring pressure applies the same constant force against the rear chain guard and thus the chain, no matter if the bike is stopped /running, cold /or at running temp, at idle or WOT .no other approach can claim the same ,there are to many variables .If I decided to make any change in my tensioner at this point it might be to add a second spring inside the present one to experiment with a bit more pressure and see if it causes more chain stretch. If one chooses to place a rod in the center of the spring ,how do you determine the length? Keep in mind that the guide is curved toward the chain ,but swings from a bolt at the top in an arc .If the chain places pressure on the guide as the motor warms ,in the direct center of the guide, the movement will be 4 times greater at the tensioner.

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« Last Edit: 08/19/17 at 16:50:13 by batman »

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piedmontbuckeye

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Re: What happened tensioner mods
Reply #18 - 08/19/17 at 16:36:01

batman wrote on 08/18/17 at 16:41:27:

The one factor about the way my tensioner is rigged is that the spring pressure applies the same constant force against the rear chain guard and thus the chain, no matter if the bike is stopped /running, cold /or at running temp, at idle or WOT .no other approach can claim the same ,there are to many variables .If I decided to make any change in my tensioner at this point it might be to add a second spring inside the present one to experiment with a bit more pressure and see if it causes more chain stretch.

I want to disagree here. I don't see how the "secondary" spring will vary pressure at all! It will remain constant better than when only the primary spring is used. The primary spring will reduce pressure over the long haul as the chain wears longer, because the spring will generate less and less pressure as it gets longer (Hook's law of spring rate).

On my test fixture, the factory primary spring took more and more pressure as I compressed it. Therefore, I had only to find a secondary spring that was stronger than the original spring had when it is fully compressed in the adjuster when the timing chain is new.

This means that any "back and forth" movement of the adjuster was only the amount machined into the mounting hole to make it a slot. I chose .050 elongation.

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batman

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Re: What happened tensioner mods
Reply #19 - 08/19/17 at 17:24:48

How did you arrive at .050 ? How far is the guide pushed back as the cylinder heats up and the chain goes straighter? The force exerted on the center of the guide due to its curve(in toward the chain) is centered on the guide ,but the guide is bolted at the top and therefore the movement is 4 times greater at the tensioner ,is .050 enough or to much?Is your small spring being stronger than the main , going to increase stretch over time? 10,000 miles should tell.

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piedmontbuckeye Senior Member Offline Go Bucks! Posts: 496 Easley, SC Gender:	Re: What happened tensioner mods Reply #20 - 08/19/17 at 17:32:24 batman wrote on 08/19/17 at 17:24:48: How did you arrive at .050 ? By looking at the pawl's teeth spacing and just plain estimating as to how much movement I thought would be sufficient to counteract the heat/cold expansion of cylinder and head on the chain.
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Re: What happened tensioner mods
Reply #21 - 08/19/17 at 18:01:01

Oh ,you guessed,(another variable), well I guess if I place a washer/spacer of 1 mm behind my spring I will have the same pressure I started with and again have the same result of 1mm of stretch in the next 10,000 miles, according to Hook's law of spring rate. Then again as I have not done this at 10,000 miles I have a decrease in spring pressure(slight) which means I may have even less stretch in the next 10,000 miles ,we shall see.

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« Last Edit: 08/19/17 at 23:24:33 by batman »

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Steve H Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1223 Spartanburg, SC Gender:	Re: What happened tensioner mods Reply #22 - 08/21/17 at 04:42:48 Is that 1mm of stretch or 1mm of tensioner movement?
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justin_o_guy2

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Re: What happened tensioner mods
Reply #23 - 08/21/17 at 05:06:33

It's not easy to envision the cycle of wear the oem design causes, but I'll try to describe it, and then the way the spring mod changes that dynamic.

The jug grows when it warms up. The chain has only the flex in the guides to Give a little, and the tensioner won't give any. The tension wears the pins, stretching the chain. The tensioner spring is always trying to get another tooth, keeping slack outta the chain.
One day, after a ride, it cools down, jug shrinks, and click, the Pawl gets the tooth.

Now, if the whole tensioner was being shoved into the chain hard enough to keep the tensioner spring from being able to make that happen, then the Pawl doesn't catch a tooth and the next warm up cycle, instead of the chain being tortured, it just compresses the end spring.

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Steve H

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Re: What happened tensioner mods
Reply #24 - 08/21/17 at 15:41:38

No chain should ever be stretched tight as it will go. There should always be certain amount of slack.

Look at the drive chain on anything as an example...Have you ever seen instructions that told you to tighten it absolutely as tight as possible?

I have seen instructions that state overtightening will cause the chain to wear faster.

I don't know but I'd imagine that super high chain tension isn't too good for the aluminum bearings either.

Any cam bearing inserts out there that would work to have the head machined for them when the bearing surfaces are messed up?

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What happened tensioner mods Reply #25 - 08/21/17 at 16:37:04 Nobody has found any.
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piedmontbuckeye

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Re: What happened tensioner mods
Reply #26 - 08/25/17 at 14:27:08

batman wrote on 08/19/17 at 18:01:01:

Oh ,you guessed,(another variable), well I guess if I place a washer/spacer of 1 mm behind my spring I will have the same pressure I started with and again have the same result of 1mm of stretch in the next 10,000 miles, according to Hook's law of spring rate. Then again as I have not done this at 10,000 miles I have a decrease in spring pressure(slight) which means I may have even less stretch in the next 10,000 miles ,we shall see.

I wouldn't call my process "guessing." All the tensioner needs is a little of "back-up" room when engine warms up to allow it to not be forcing the chain all the time.

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batman Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 3806 osceola new york Gender:	Re: What happened tensioner mods Reply #27 - 08/25/17 at 15:45:10 Ok, let's call it hoping ,but the truth is you don't know if the tension placed on the chain when the motor warms is even placing enough pressure, at a right angle ,to move the entire tensioner and compress the new spring.
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What happened tensioner mods Reply #28 - 08/25/17 at 16:07:23 Do you understand what a calculated best guess is? Why do you need to pretend it's stupid? What if a genuine engineer said it looked viable?
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piedmontbuckeye

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Re: What happened tensioner mods
Reply #29 - 08/26/17 at 09:53:45

batman wrote on 08/25/17 at 15:45:10:

Ok, let's call it hoping ,but the truth is you don't know if the tension placed on the chain when the motor warms is even placing enough pressure, at a right angle ,to move the entire tensioner and compress the new spring.

If it doesn't back up at all, it wouldn't be any worse than factory pawl set-up,

However, while it would take a lot of experimenting and work, I would bet that the chain when stretched tighter (when cylinder heats and expands) it would put a tremendous amount of back pressure on the adjuster assy. Else, why would the original design have the pawl assy. in there at all? The secondary spring I put in between the mounting post and the back of the adjuster body is only slightly stronger than the primary spring when it is compressed as when it would be with a new chain. Therefore, my "guessed" reasoning is that the assy. and chain WILL be able to push back on the adjuster and compress it some - thus saving the constant tight pressure always being placed on the chain as it was originally designed.

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