I swapped out the 4.22 for a 3.7 rear end in my car, which is equipped
with the 5-speed. Wow! It has transformed the character of the car on
the highway. WIth the ribcase and 4.22, I felt completely out of place on
the highway, the car felt like it was doing something it wasn't designed
to do. I used to drive ~60mph. The combination of 3.7 and 5-speed lowers
my rpm to 72% of original. At 4000 rpm, I go the same speed that used to
take 5500rpm, which according to me calculations should be 84mph. 74mph
at 3500rpm. I ride the fast lane unstressed. (All numbers based on
theory, not the inaccurate instruments of my car. rpm to mph conversion
based on Haynes manual that says 17.3 mph/1000rpm in 1500 with 3.7 rear).
Of course there are tradeoffs. Inclines on the highway will get
me downshifting early, since the motor has less power at 3500 than at 4000
which is what I used to see at cruise.
The long rear end makes for a long first gear which makes for harder
takeoff from a stop. First gear on the Datsun trans is shorter than the
one of the ribcase, which helps to offset this some. This shorter first,
coupled with the 4.22 resulted in a very short first gear that is nice on
steep hills, but is also too low to make any significant speed in the
process on accelerating from a stoplight. I didn't notice this until now.
Now, after taking off, there is rush of forward motion in 1st, that wasn't
there. This is hard to explain, let me try again...if you take off on a
mountain bike in the lowest gear it has, yes - it is very easy to take
off, but this low gear doesn't get you to any useful speed before you have
to upshift...
I have yet to try taking off on an EXTREMELY steep hill in my
neighborhood to test the difference in that respect.
If you do a lot of highway cruising, I would recommend this combo (maybe
not with a 948).
Ulix __/__,__
.......................................................... (_o____o_)....
'67 Sprite
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