[GMCnet] How do you adjust a fan clutch?

[KB]

I've seen lots of mention of adjusting fan clutches to get them to engage at a higher temperature, but I've never been able to figure out how to do
it.
Is it just moving the end of the spring somehow (if so, exactly how), or do you have to re-bend the spring end, or ??

Our most recent fan clutch comes on about 195 and off below 180, which is way too low imho (and too loud!)

thanks,
Karen
1975 26'


_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[Ken Burton]

If it is coming on that low, you probably have a Hayden fan clutch. Hayden dropped their fan turn on temperature and that causes the problem on a
GMC. When Ii was working with their engineering group, their engineer tried to get me to modify the turn on temperature. His instruction was to look
at the end of the spring and cut an new slot with a dremmel tool in the holder where the end of the spring was connected.

I had already been through 3 severe duty and was on the 2nd or 3 heavy duty clutch. All of them did the same thing. At that point I did NOT modify
the clutch as their engineering requested. I instead went to the OEM spec Heavy Duty clutch from Delco. I have never had a clutch problem since
then.

So if you wish to modify the turn on temperature, cut a slot next to the existing one and move the spring tab to the new slot.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Jim Kanomata]

Karen,
Take the clutch coil and carefully twist it one way by observing which way
the coil move when you put it in the refrigerator.
You will then carefully twist the coil to go further than before.Thus it
will take more heat to advance.
If not careful, the seal at the hub can start leaking the silicone fluid.
I find it easier to do it correctly when I am doing it, so I might be
reversed.
I only do this on my personal coaches as it is not a very precise method.

--
Jim Kanomata
Applied/GMC, Fremont,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502

[KB]

I did not knowingly buy a Hayden, but of course through the magic of re-branding, could easily have ended up with one.

I tried heating the coil on one of the fan clutches, but never could see it move. Hopefully I didn't damage it in the process.

All our fan clutches rotate the same way: clockwise. The coil, looking from the center pin outward, is also wound clockwise.

So should the slot be cut more to the clockwise direction, or less? I've seen a lot of fan clutches that have two slots, 180 degrees opposite,
so assumed the movement had to be sizeable. My current problem-clutch has two tabs, but a slot on only one of them.
Sounds like if you're cutting a new slot on the same tiny tab as the original slot, it only takes a small movement to change the engagement temp
sufficiently.

I know I could keep trial-and-error-ing it, but somebody here must know which way it should go.
At least I'm getting really fast at changing a fan clutch...


thanks,
Karen
1975 26'

[James Hupy]

Karen, personally, if it is a Hayden, the way it should go is into the
recycle pile. Even GM Delco is not what they used to be, and since Delphi
went Bankrupt and Chapter 11, most of their stuff is farmed out of the
country. I have found that there are 3 levels of fan clutches, standard
duty, heavy duty and extremely heavy duty.
They differ not much in appearance, but in the amount that they lock up.
Standard duty locks up about 60 to 70 % of the driven speed, Heavy duty 70
to 80% lockup, and Extreme 80% to completely lockup. Cut in speeds pretty
much are all over the map, and vary a good deal with each individual
clutch. If you do get one that works well, keep it. You might not find a
new one that works as well as what you have. The last time I replaced mine,
it took three of them before I got one that lasted.
Jim Hupy
Salem, OR
78 GMC Royale 403

[Jim Kanomata]

I'll play with one and give you correct info this evening.

On Wed, Aug 24, 2016 at 9:14 AM, KB <ka...@sonic.net> wrote:

--
Jim Kanomata
Applied/GMC, Fremont,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502

[Dave Mumert]

Hi Karen

Check this thread.
http://www.ford-trucks.com/forums/513583-cooling-fan-clutch-mods-to-engage-earlier.html

It appears the slot needs to be toward the center of the spiral spring, so I would guess that to be counter-clockwise.

Good luck

Dave Mumert

[KB]

Dave Mumert wrote on Wed, 24 August 2016 10:41

> Hi Karen
>
> Check this thread.
> http://www.ford-trucks.com/forums/513583-cooling-fan-clutch-mods-to-engage-earlier.html
>
> It appears the slot needs to be toward the center of the spiral spring, so I would guess that to be counter-clockwise.

In that thread, they seems to be trying to make it come on sooner (lower temp) rather than later, so maybe clockwise to go higher?
But surely somebody here has done it and knows for sure.

Now I have to wonder why many fan clutches have slots on two sides...

[Scott Nutter]

Karen, just get John Biwersi's nylon fan and choose between a heavy duty or severe duty clutch and you will be fine.
Way too much micro engineering going on here..........
--
Scott Nutter
1978 455 Royale Center Kitchen, Quad bags.
Houston, Texas

[Jim Kanomata]

Karen,
The coil if tightened by twisting it clockwise will cause it to to turn on
sooner.Do it gently so you do not damage the shaft and not put your fingetn
on it as the increase of your body temp will cause the coil to unwind.
It does not require but 5 degree of adjustment to respond 10 degree of temp.
Those that are considering rotating 180degree will be in for a
disappointment.

>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Fremont,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502

[KB]

jimk wrote on Wed, 24 August 2016 22:10

> Karen,
> The coil if tightened by twisting it clockwise will cause it to to turn on
> sooner.Do it gently so you do not damage the shaft and not put your fingetn
> on it as the increase of your body temp will cause the coil to unwind.
> It does not require but 5 degree of adjustment to respond 10 degree of temp.
> Those that are considering rotating 180degree will be in for a
> disappointment.

THANK YOU!!!!!