Terry, Gazelle in Japan is actually Silvia, maybe that has something to do
with it?!
Also where will I find the numbers that identify my gearbox on the gearbox?
zac
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Sent: Monday, 1 January 1601 10:30 AM
To: [EMAIL PROTECTED]
Subject: Re: Close ratio boxes (Long)
Errol,
Very informative post.
I would like to query just one aspect that you touched on with regard to
FJ20
turbo gearbox ratios as this came up recently on the list. I did a bit of
research into the ratios that were fitted to the Gazelle and the DR30 and
found
that nissan fitted the C71B (22:31) in the Gazelle but all of the DR30
sourced
gearboxes that i have seen and are the more common exported to Australia
lately
have the W71B (21:32) also stamped ZL71B box which has the 3.592 first gear.
Do you think they nissan has done this because of the weight difference
(1040kg
vs ~1200kg) some other reason or is it an urban myth and the importers are
having a lend. (of us)
The DR30 box actually seems to be more rugged and usually not as shagged
(synchros esp) as the Gazelle box by the time we get them in Aus, maybe
japanese Gazelle drivers are rev heads and DR30 drivers are little ole
ladies
(maybe not).
Also one minor thing i noticed about reverse gear ratios, and that is just
about every L4 & L6 nissan gearbox made has the same ratio 3.382 or
something
like that (i'm on the road and i haven't got the book with me.) Do you know
anything about this and why is it so.
The lower gearing of the DR30 box is the problem in the 510 which can partly
be
overcome by using a tall diff, the Gazelle box. I must get hold of a 3.54
diff
sometime when i get my FJ on the road and test the theory behind this. I've
got
a mate with a 5.1 diff behind his FJ20t and it's a good job it never goes
outa
town but can this thing catch and pass anything on the fly (soobies are not
amused) - taking off from the lights is a non event (love that smell though)
but i can't seem to talk him into borrowing a diff from me to see the
difference a CIG 3.7 can do, maybe he thinks it's more for my curiosity than
his benefit (:-.
regards
Terry
> Zac,
> If the input gearset has a lower reduction, (closer to unity) then all the
> gears apart from the 1:1 direct coupled fourth will be taller. This means
> that 1st, 2nd & 3rd close up but fifth gets wider. This is probably the
> cheapest way to close up a gear set but it still has its problems. With a
> 1:1 fifth this makes a good way of changing ratio spread reasonably
easily.
> All 71B option 1:1 fifth boxes come with 22 drives 31 input sets so by
> changing to a 21 -32 set you can lower too tall ratios to give a ratio set
> in between option 1 and 2 etc. Eg option 2 with 22 31 gives 2.348,
> 1.601,1.296, 1.138,1. By changing the input to 21 drives 32 this gives
> 2.539,1.731,1.402, 1.231,1 (just like a taller option 1)
>
> These are the common gearbox input ratios.
> 22:31
> (The most common:- used in K 5 speed, 240Z 260Z, R30 & R31 Skyline, SR20,
> FJ20, CA20.) these are all FS5C71B boxes. From my understanding the codes
> mean F(rear wheel drive) S(overdrive) 5(five speeds) C(closer ratios)
> 71(Main housing type) B(extension shaft & housing type). These boxes have
> typically 3.321, 2.077,1.308, 1, & 0.864 ratios. This is the most common
> box used in Nissan vehicles.
>
> 21:32
> (K 4 speed and other underpowered, commercial or heavier vehicles ( 720 or
> Navara utes, 280C, 280Z, R31-CA Pintara etc) For smaller engined or
> heavier bodied vehicles the above ratios were changed to 3.592, 2.057,
> 1.361, 1, 0.852 by using the 21:32 input set. These ratios allow you to
get
> of the line quicker with a heavy body that is under powered. This box is
> then known as a FS5W71B box. The W being for wider ratios.
> Most turbo boxes are the FS5C71B boxes with the naturally aspirated
> versions having the FS5W71B boxes. If you go to an importer they will
often
> tell you a box is from a turbo or NA vehicle and often get it wrong. The
> easy way is to put the box in first and turn the input shaft counting the
> turns to produce one revolution of the output shaft. (3.3 turbo, 3.6 N/A).
> The main difference with early 5C turbo boxes is the use of heavier
section
> countershaft (38mm diam) and gears. This means they change slower but can
> handle heaps more grunt. The earlier boxes (240K, 260Z etc) up to about 85
> usually had a 29mm diameter countershaft. All boxes from 87 on seem to
have
> the larger countershaft. 85 - 87 boxes can be a bit of a mixture of
> countershaft types.
> The best part of the FS5 (C or W ) 71B boxes is that once you have set up
a
> good set of ratios, you can change the box from vehicle to vehicle by
> changing the bell housing. Eg an L series box to an RB 30, SR20, FJ20, CA
> (16 - 18 - 20), Z (18-20-22-24) by changing the bell housing.
>
> 23:28
> (early Z and fairlady boxes these are not interchangeable with the 71B
> family boxes)
>
> 18:32
> Nissan Vanette and other commercials (if fitted into 5C gear set this
> gives, 4.190, 2.4, 1.650, 1, 0.865 ( a good cliff climbing gearset?)
>
> There are other input sets around, it just means looking out for boxes in
> bits and doing some counting
> Cheers
> Feral Errol
> ----------
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