Disassembling viscous fan

[MattF]

erm.........NO

I tried to resist, I really did. Bright blue here we come.

Oh, just as an afterthought, can anyone remind me of the
calculation for working out the measurement between three
points on a circle? My school maths lessons are a distant
memory.

[Chillitt]

a circle doesn't have points...

[BUSHWHACKER]

Does this help??
Let the equation of the circle be

(x-h)^2 + (y-k)^2 = r^2,

and substitute the three known points, getting 3 equations in 3
unknowns h, k, and r:

(x1-h)^2 + (y1-k)^2 = r^2
(x2-h)^2 + (y2-k)^2 = r^2
(x3-h)^2 + (y3-k)^2 = r^2

which you can solve simultaneously. First subtract the third equation
from the other two, thus eliminating r^2, h^2, and k^2. That will
leave you with 2 simultaneous linear equations in h and k to solve.
This you can do as long as the 3 points are not collinear. Then those
values of h and k can be used in the first equation to find the
radius:

r = sqrt[(x1-h)^2 + (y1-k)^2].

Example: Suppose a circle passes through the points (4,1), (-3,7), and
(5,-2). Then we know that:

(h-4)^2 + (k-1)^2 = r^2
(h+3)^2 + (k-7)^2 = r^2
(h-5)^2 + (k+2)^2 = r^2

Subtracting the first from the other two, you get:

(h+3)^2 - (h-4)^2 + (k-7)^2 - (k-1)^2 = 0,
(h-5)^2 - (h-4)^2 + (k+2)^2 - (k-1)^2 = 0,

h^2 + 6h + 9 - h^2 + 8h - 16 + k^2 - 14k + 49 - k^2 + 2k - 1 = 0
h^2 - 10h + 25 - h^2 + 8h - 16 + k^2 + 4k + 4 - k^2 + 2k - 1 = 0

14h - 12k + 41 = 0
-2h + 6k + 12 = 0

10h + 65 = 0
30h + 125 = 0

h = -13/2
k = -25/6

Then

r = sqrt[(4+13/2)^2 + (1+25/6)^2]
= sqrt[4930]/6

Thus the equation of the circle is:

(x+13/2)^2 + (y+25/6)^2 = 4930/36

Understood?

[MattF]

a circle doesn't have points...

I'll rephrase. To work out the distance, from one starting
position on the circumference, that will create two more points on
the circumference, thereby giving three points for an exact 120
degree triangle within the circle.

[MattF]

Understood?

I really should have known better than to ask, by now.
Will I never learn?

[Chillitt]

ah. draw a line through the centre of the circle, get a compass set to the radius, put the point where the line crosses the circumference, then mark with the compass where it crosses it on either side. those 2 points plus the one where the first line crosses the other side of the circle, = 3 equal sections.

[BUSHWHACKER]

I really should have known better than to ask, by now.
Will I never learn?

hehehe!! ahem, sorry.
When I bolted my fan, I just used a felt tipped pen and put marks in three pionts that looked equal distance apart and the same distance from the outside edge.
No science / trigonometry involved.

[MattF]

Cheers chaps. Now rooting through son's pencil case
trying to find where he keeps his compass. If I cock
that method up, I'll use Vince's method. The bolts
will be okay just going through the rear housing and
friction plate?

Cheers.

[mud skipper]

I tried to resist, I really did. Bright blue here we come.

Oh, just as an afterthought, can anyone remind me of the
calculation for working out the measurement between three
points on a circle? My school maths lessons are a distant
memory.

i did this 2 weeks ago and i got it VERY WRONG doh.... i have buggered the whole thing up, hopefully the water pump is OK
i got the mesurment wrong whent ona 100 mile trip and it shook itself to bits, in one piece but rattling
so as we speak i have the front stripped down on the surf and im fitting a Kenlowe fan and Kenlowe atf cooler ( £281 worth ) as its off the road i have stipped out my air con bits and i m commiting the biggest sin of all, i have washed the whole thing top to bottom and inside out, this weekend i will be waxoiling, and fitting on the aforementioned goodies
pics to follow

btw
it looks as if it has a 4 inch lift with the front end stripped, i was shocked at the weight of all the aircon bits, rad, fan and bumpers

[MattF]

What caused it to work loose? Was it an imbalance, or
just the bolts that worked loose?

[mud skipper]

What caused it to work loose? Was it an imbalance, or
just the bolts that worked loose?

the whole thing now has play on its shaft the bolts are still solid

[dave.j.robbo]

the whole thing now has play on its shaft the bolts are still solid

That must have been caused by an imbalance, I reckon. The speed these things reach is phenomonal (?)...

[mud skipper]

That must have been caused by an imbalance, I reckon. The speed these things reach is phenomonal (?)...

well i was cruising at 80 most of the time so a slight inbalance and .............

[MattF]

Okay, now that the panic is setting in, , what bolt layout did
you use? The triangle, or just two bolts, one either side? Also,
did you go alway through the housing, or just bolt the clutch
plate to the back housing?

BTW, you know how you were considering removing your
sway bars? I'm still finding any excuse to drive over $$$$py
surfaces since removing mine. Like a kid with a new toy.

[dave.j.robbo]

Okay, now that the panic is setting in, , what bolt layout did
you use? The triangle, or just two bolts, one either side?

It wouldn't matter how many bolts you use, if they're not in balance, it'll end in tears.

I like the idea of the silicon.