Bill,
What RPM do you run at?
I'll send you an Excel spreadsheet if you want.
Are you familar with using a spreadsheet?
I'm sure there are Java script versions on the net.
I just never needed one since I like to calculate suff myself.
I'm not sure I would bother changing from 19.5 to 18's in the rear.
I always liked the big ones in back and small ones in front-even if it did
feel a little bit floppy in a tight slalom. What you might lose time-wise
in a tight slalom, you will proabaly gain back elsewhere on the course.
I'd just change the small sprocket to a bigger one (use an odd numbered
tooth count for best chain life) if you really want to change gearing.
Less HP loss in the chain drive that way too.
A small sproket doesn't present a smooth semi-circular path either. It gets
more like a polygon with corners as the number of teeth gets really low.
More jerky power delivery and more HP loss.
But, like I said before. look at helix and spring rate in the secondary.
8400 RPM, 19.5" and 5.58 should give you 97 MPH at 0.9 CVT and 116.5 MPH at
0.75 CVT.
Even at he lowest RPM one might use of 7700 RPM, you should have 90 and 108.
I personally like CVTs more than any gear box. Easier and cleaner than any
gearbox to fiddle with.
The smooth delivery of power is very nice, especially when one doesn't have
real shocks and has limited suspension travel. 'Course this may more of a
Solo course than road course issue.
Chuck
From: "Jan Schmidt" <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: RE: [F500] gearing ratios
Date: Wed, 04 Jul 2007 12:58:00 -0500
Chuck,
I am using the tall tires (19.5), Kawi, and 5.58 chain ratio, not 5.38.
If I eventually go to 18 inch tires, I will have to get a smaller rear
sprocket, as I think that it will dig into the asphalt, if a tire were
to flex too much. Is there a standard website computer for these
calculations? I suspect that my old belt is too loose, also. In my
opinion, the cvt system is the only complicated parts on these cars, the
rest is pure gravy.
Bill Schmidt 88 RD Kawi
>>> "Chuck Voboril" <[EMAIL PROTECTED]> 07/04/07 10:20 AM >>>
Bill,
Since I didn't notice if anyone else answered you on the gearing change
required, I'll give you some numbers.
17.75" tall tires and 8400 rpm (Kaw?) and current 5.38 chain ratio
should
get you to 110 MPH-if you can actually achieve full overdrive in the
CVT.
Lets assume that you aren't getting to 0.75 in the CVT and have more
like
0.9...thats 91 MPH.
To get to 100 Mph you wouldneed to change to about a 4.9 final drive.
To get to 104 Mph, you need about a 4.7.
Alternatively, someone may have ideas on how to get the CVT to shift out
fully.
My guess is that you are bulding too much sheeve tension near top end
from
too steep a helix or too high rate a spring.
The primary weights may not be correct for the pipes either and you just
may
not be making any HP to pull the secondary open.
I'd work on that stuff rather than changing final drive if the 5.38
works
everywhere else.
Chuck
>I topped out in gearing at an autocross the other day with my 5.58
ratio
>final drive gearing. What ratio would I need to gain another 5mph in
top
>speed? I bet there is an internet site that would answer that for me. A
>125 shifter cart clocked 104 mph at this event!!!!!
>Bill Schmidt 88 REd devil Kawi
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