I'm thinking that the rear guide doesn't wear so much yet it ages & flexes, and so the tensioner creeps foreward ahead of the chains schedule.

how to measure flexibility of a new vs old rear guide ?

what about a slightly weaker tensioner spring ?

franch wrote on 12/31/69 at 16:00:02:


I had to think about that one for a second...

Try this.  First imagine the 2 points where the tensioner is contacting the chain and where the chain first contacts the gear.  Then draw a straight line between those 2 points.  

The chain will also follow that straight line between those points and I don't think that flex will matter in the upper part of the guide.

The upper part of my rear guide shows NO wear too.

(more below...)

Quote:


I believe the above applies here.  I'll have the front guide out today to check

Quote:


The spring is a thought...

Certainly as the spring extends, it will exert a less and less pressure on the guide, BUT you have to remember the ratchet stop mechanism in the tensioner.  

Every couple millimeters the stop gets locked into a groove in the moving piston.  The piston cannot move backwards, it becomes rigid at each increment, and essentially there is no additional inward pressure on the spring.  

The spring doesn't "bounce" in and out, if you know what I mean.

So, unless the spring becomes too weak to push the tensioner out, the "locked" tensioner will maintain that straight line that I mentioned above.  There should be very little slack in the chain.

As the chain goes around the gear, the centrifical force will pull it outward so that when the chain leaves the gear it will whip out.  The guides and tensioner prevent that by keeping the slack out.  
I think the rachet mechanism is there to prevent sudden surges from getting out of control.  
And the spring has to be strong enough to overcome friction.

Well, well, well...

By the Suzuki Service Manual, the cam chain limit is 5.07" over 20 links or to the outside of 21 Pins.

It is supposed to be stretched tight, and measured with calipers, but even with my Craftsman scale it is about .050" over limit.

Kropatchek wrote on 12/31/69 at 16:00:02:


Trust me, I was a machinist for 12 years so my reading a scale is accurate.  Even these days, I can read it within a 1/32 (> 1 mm)

I used the scale as an illustration, because I couldn't get a clear shot of the dial AND the chain.  Unfortunately the image size is reduced in the post.  You can see the full image here.

http://s21.photobucket.com/albums/b277/gmdinusa/?action=view&current=CamChain...

Do you have the SSM?  I wonder because that's not the way that I interpret those brief instructions.  There is a picture that seems to show "outside to outside", not center to center (or front edge to front edge, whatever).

What is the measure on a new one?  I wish I had a friend at the dealership.

Granted, I don't want to replace the chain, but then if I'm just splitting hairs and the chain is almost out of limit, then I don't want to close it back up that way.

What do ya think?

Kropatchek wrote on 12/31/69 at 16:00:02:


Gee, how'd I miss this topic?

Anyway, I'll do a reread and a recheck today (get a magnifier and study the picture too)

So you're saying the .070" or >2 mm will change the adjuster 9 mm?

Hmmm.

Thanks.

Greg,
You should put this in the tech section. I've been following this thread. Now that I've seen most of it through the pictures, I know what to look for.
Thanks!

verslagen1 wrote on 12/31/69 at 16:00:02:


As I mentioned above, I'm fairly familiar with calipers, I just used the scale because I wanted to illustrate the measurement...I couldn't get the dial in the shot.

Besides, you're cheatin'.  My first calipers weren't digital

But I think that I found another issue that's even better.