Clutch springs weak?

[sawfun]

I have a recent ported 090 that had a bad clutch with two fractions missing though it worked fine. Now with either it or the new clutch it engages fully at idle. Could the saw now have too much low end torque at idle for the springs to hold? Some of you experienced racers run big power saws, do you beef up your clutch springs?

 

[Tuplin86]

Torque won't affect the clutch in that way, as it takes centrifical force to engage. I would check idle speed and your idle bearing. I cannot speak specifically to that saw. But there is either a mechanical issues with clutch or it is idle speed. More experts to chime in soon. Good luck friend

I have a recent ported 090 that had a bad clutch with two fractions missing though it worked fine. Now with either it or the new clutch it engages fully at idle. Could the saw now have too much low end torque at idle for the springs to hold? Some of you experienced racers run big power saws, do you beef up your clutch springs?

 

[Ted Jenkins]

If your clutch is sound and your bearing is in good shape then your issue is with the springs. Stiffer springs mean that the clutch engages at a higher RPM and soft springs mean that it engages just above an idle. I sometimes put stiffer springs in the clutch so that the idle can be turned up a bit and then the saw will idle much longer without loading up. Thanks

 

[sawfun]

Thanks for the help. The idle is as low as it can go and still run and the clutch bearing looks fine also the clutch drum spins fine with no out of round. Where can I get stiffer springs?

 

[jr27236]

Is this the clutch you have?

I took these pictures off the Web after looking up your saw.

 

[Ted Jenkins]

JR has pointed out the clutch you probably have. Most likely the spring is worn out that you have. You could scrounge up a used one or order a new one. If it was me, take the one you have out grind off the end and heat up one coil to make it for the connecting link and try it. The end that you heated needs to be retreated so it will retain its shape. It being a 1/8 inch shorter will be about 5 to 10 percent stiffer. If it works well then consider a new one or get another used one to modify. That type of spring is harder to find than others. I have modified brake springs to use, but only when it is very tough to find the original. Thanks

 

[sawfun]

Thanks for your input, and yes that picture is the clutch I have with 6 shoes. I installed a complete new Stihl clutch with new springs and it made no difference. The old one that had worked before no longer works either so I will have to go with shortening up the springs. Baileys has new OEM Stihl springs listed as in Stock for under $6 so I may go that route. My concern is for getting the spring temper correct after making a new end.

 

[sawfun]

I may add that this engine will lug down and keep pulling a load with the rpm so low it either dies or tries to. I loaded it with a board against the clutch drum and it pretty much makes very little difference, it just pulls with the engine way down in rpm. It just lugs like my 12 valve Cummins.

 

[jr27236]

It sounds to me that the clutch it either bent or possibly something was left out on reassembly? I know you said it spins freely when not running ? Is there even space around the clutch and drum. Below is a ipl picture of the assembly, maybe that will help to see if something is missing or assembled incorrectly .

 

[jr27236]

I have a recent ported 090 that had a bad clutch with two fractions missing though it worked fine. Now with either it or the new clutch it engages fully at idle. Could the saw now have too much low end torque at idle for the springs to hold? Some of you experienced racers run big power saws, do you beef up your clutch springs?

When you say two fractions missing, Are you saying two of the clutch shoes? So 2 out of 6? How did the spring even hold the remainder?

 

[sawfun]

Two frictions on the old clutch are missing, none are missing on the new clutch. The frictions are glued to the clutch shoes. So the shoe is still in place. And yes it is assembled exactly like the IPL picture. Nothing is even close to biNing. Plenty of space between the shoes and the drum.

 

[Ted Jenkins]

The problem with making engine mods is that now the engine behaves differently. In the case of a modified 090 it appears that the engine idles at a different RPM than a stock unit and I have a wonderful stock 090. When I build race engines I am accustomed to do whatever is needed to make it work. When I go cut trees or logs I often encounter enough surprises so do not want any extra surprises. So since you have found good sources for clutch springs go for it. Take any spring you have and grind the end off of it. Then take a quality propane torch and heat up a coil as hot as possible and stick a screwdriver into the last loop prying it out to make a connecting link. You may have to repeat the heating process up many times as it will cool off pretty quick. Once you are satisfied with the shape of the connecting coil heat it up as hot as possible then stick it into a container with ice water. Repeat the last process several times only heating it less and less each time. Now you have it tempered go cut something. However if you have a cutting torch or a better heat source then use that. Thanks

 

[sawfun]

Thanks for the tempering info, that is very useful and likely the road I must take. I have an acetylene torch but would prefer to use Mapp gas.

 

[jr27236]

Thanks for the tempering info, that is very useful and likely the road I must take. I have an acetylene torch but would prefer to use Mapp gas.

If nothing is missing/binding or bent or otherwise. I think this is the only solution to change the clutch spring strength. Good luck

The problem with making engine mods is that now the engine behaves differently. In the case of a modified 090 it appears that the engine idles at a different RPM than a stock unit and I have a wonderful stock 090. When I build race engines I am accustomed to do whatever is needed to make it work. When I go cut trees or logs I often encounter enough surprises so do not want any extra surprises. So since you have found good sources for clutch springs go for it. Take any spring you have and grind the end off of it. Then take a quality propane torch and heat up a coil as hot as possible and stick a screwdriver into the last loop prying it out to make a connecting link. You may have to repeat the heating process up many times as it will cool off pretty quick. Once you are satisfied with the shape of the connecting coil heat it up as hot as possible then stick it into a container with ice water. Repeat the last process several times only heating it less and less each time. Now you have it tempered go cut something. However if you have a cutting torch or a better heat source then use that. Thanks

 

[scallywag]

Have you installed the washer/spacer in the above pic the right way?......Item # 25.

If it's back to front It will bind on the inside spring on some brands of clutch drums.

 

[scallywag]

Try this.... Pull the spark plug, put some load on the clutch drum and pull the saw over, pull it over slow, then hard and fast, it maybe better if you can get a friend to do the pulling and you watch the clutch and apply some load.

 

[sawfun]

Ok, will do this weekend at the gtg. I will also get an idle rpm reading.

 

[VinceGU05]

i would pop new springs in. they may have gone soft and stretched. my 090 spins the chain at idle until its nicely warmed up and comes properly down on idle, and even then the chain kicks around occasionally. i had 1 friction pad missing. i replaced it and was no different the way it behaved.

 

[scallywag]

Looking through some 090 parts today and came across these!.......I never realized these springs came in different lengths.

 

[sawfun]

Turing the idle screw down a quarter turn more and adding the 72" bar seemed to solve the issue. The saw runs perfect.