>>>>>
>>>>> Good work Scott. Thanks for all the idler pictures.
>>>>>
>>>>> Yes. Best use an idler designed for the job.
>>>>>
>>>>> Paul Lamar ...No rotor no motor.
>>>>
>>>> Paul & Scott,
>>>> From this end of the engine, the rotation is CW. The idler,
as it
>>>> was
>>>> depicted, is on the driving side of the belt. Using a
spring loaded
>>>> idler pulley in this location could lead to some oscillatory
behavior>>>> unless it has a built in damper. Also, re-locating
the alternator
>>>> to
>>>> the side like this will increase the belt wrap angle on the water
>>>> pump
>>>> and thereby increase the pump bearing load substantially.
So, it
>>>> would
>>>> be important to set the belt tension at the lowest value that
will>>>> prevent slippage. Toward that objective, you would want
to maintain
>>>> the
>>>> belt wrap angle on the driver pulley by moving the idler in the
>>>> direction I've sketched. Finally, using the largest
diameter idler
>>>> that will fit would minimize the rotation speed of the idler.
>>>>
>>>> I've seen some fiber reinforced plastic idler pulleys
recently that
>>>> weigh much less and are probably balanced better than the stamped
>>>> steel
>>>> pulleys.
>>>>
>>>> Aubrey Thompson
>>>
>>>
>>> I'm sorry Paul, I don't have MS Paint. If, in the image, you
were to
>>> rotate
>>> the green circle counter-clockwise so as to cover the heads of the
>>> three
>>> bolts just right of the water pump, and up from the crank
pulley, my
>>> suggestion would be to locate the idler/tensioner in that
location.>>> The
>>> drive belt would leave the crank pulley at about the 12 o'clock
>>> position,
>>> make a wrap around the idler maybe about 270 degrees or so (the
>>> outside of
>>> the belt would ride on the idler pulley) and meet the water pump
>>> pulley at
>>> the 5 o'clock position. the water pump pulley may have 230??
degrees>>> or so
>>> of belt contact---. If the alternator were to mount as the image
>>> shows, the
>>> belt should clear the crank position sensor. I assume the
sensor is
>>> between
>>> the pulley/belt and the cover. If not, I suppose the sensor
and the
>>> driving
>>> magnet could be moved to a more convenient location. John
Pletting>>>
>>> How come nobody has MS Paint? ") One of the few useful programs
>>> that come with Windows. How does one do screen captures without
>>> MS Paint?
>>>
>>> OK lets see if I got this right using Linux xpaint.
>>>
>>> Looks like it will interfere John. Did I do it right?
>>> --
>>> Paul Lamar ...No rotor no motor.
>>>
>>
>>
>> Paul: You get a gold star next to your name for today! JP
>>
>> Thanks JP. To recap the original problem was the belt
>> going to the side mounted alt. interfered with the mag. pickup.
>> First jpg. Aubrey scheme appears to work. Second jpg.
>>
>>
>> Paul Lamar ...No rotor no motor.
>>
>
> I agree the idler must be in between the crank and alternator
pulleys> in order to clear the crank position sensor, as per
Paul's second jpg
> and my picture. So a self-tensioning idler would also have the
> advantage of damping out unwanted oscillations compared to a fixed
> idler pulley? The RX-8 does not have any springs in its two stock
> belts -- just the adjustable idler you see in the pic, and a
standard> adjustable alternator bracket.
>
> Scott Gettings
Scott, would a spring mounted from the top alternator mount to the
idlerpulley work - just a matter of making the brackets. You could
also have it
mounted on threaded rod for spring tension adjustment.
George ( down under)
There are lots of ways to do this, but the space is very limited. A
very small, tensioning pulley (such as the Saturn or Firebird) can be
mounted on a custom metal plate that uses existing front cover
studs/threaded holes. A spring tensioner would have to be mounted at
the right angle, and be heavy enough to supply the correct belt
tension. A fixed idler pulley could also be mounted on the same custom
plate, which would require an adjusting arm for the alternator (also no
big deal).
I'll be finalizing this part of my project soon, and will send more pix.
Scott Gettings
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