Hi Larry,
I think that something is amiss here. If the true road speed is 80 MPH,
not necessarily what the speedo shows, then here are some examples of
what the engine revs should be.
Here is a small range of tire sizes for the example.
Tire goes 70.75 inches per wheel revolution, 3.9:1 dif., 5th gear=.821
reduction, times 1.33333 for the difference of 60 MPH up to 80 MPH
Inches per mile=63360.
63360/70.75=895X3.9=3492X.821=2867X1.333=3823 Engine Rev per min.
Tire goes 67.25 inches per wheel revolution, all same as above.
93360/67.25=942X3.9=3673X.821=3016X1.333=4021 Engine Rev per min.
Could it be that you haven't regeared your speedo or adjusted it by the
angle drive to compensate for the lower cable count from the Datsun
engine to the Speedo? I'm pretty sure you don't have it in 3rd gear! <G>
You may actually be going closer to a true speed of 92 miles an hour. No
wonder it's buzzy! You may need a friend in the Highway Patrol or the
Court Clerk!
Paul
PAsgeirsson@juno.com
On Thu, 27 Jan 2000 11:23:21 -0800 "Larry Miller" <millerls@ado13.com>
writes:
>I have the 3.9 in my Bugeye with a modified 1275 and the Datsun
>5-speed. 80
>MPH is around 4500 RPM in 5th. It's still a little buzzy on the hiway.
>I'm
>contemplating a switch to the 3.7.
>
>Larry Miller
>----- Original Message -----
>From: "Glen Byrns" <grbyrns@ucdavis.edu>
>To: <spridgets@autox.team.net>
>Sent: Thursday, January 27, 2000 10:25 AM
>Subject: differentials
>
>
>> After examining the diff. on my Sprite I notice that it has quite a
>lot of
>> play in it. Checking the usual sources I see that replacement gears
>are
>not
>> easily available. Assuming that I can eventually find a
>servicealble
>> differential assembly, what ratios are available and what would go
>best
>with
>> the 1275cc.? The stock ribcase with the original diff. has too low
>a low
>> and not enough high. I expect to cruise the highways much more that
>I
>> expect to climb phone poles and don't really have the resources yet
>to do
>a
>> 5-sp conversion.
>>
>> Thanks to the list as usual for the excellent advice. I've yet to
>ask a
>> question that wasn't answered with wit, wisdom, or both.
>> Regards, Glen Byrns
>>
>>
>
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