Re: $300.00 lowering (long)
From: "Jason K Gray" <jason510@worldnet.att.net>
Subject: Re: $300.00 lowering (long)
Date: Tue, 18 Jan 2000 23:03:07 -0900
-----Original Message-----
From: juneor galindo
To: bluebirds@bluebirds.datsun510.com
Date: Tuesday, January 18, 2000 5:22 PM
Subject: $300.00 lowering
>if any of you had $300.00 to lower your dime how would you do it
>coilovers?i need to lower my dime but im on a budget. pegasus has coilovers
>for $65.oo
>thanks
>juneor
The Pegasus $65 kit is just for the threaded collar, doesnt include
necessary 2-1/2" springs or adapter top hat. You would pretty much blow your
entire $300 lowering budget just getting setup with threaded collar+springs,
still doesnt include camber plate wich is pretty much the underlying reason
to get coilovers in the first place and doesnt do anything to preserve
suspension travel.
To lower the front you can basicly do 3 different things (in order of
preference):
1) use a shorter top strut isolator. A shorter top isolator lowers the body
strut tower closer to the spring without consuming travel. Using a shorter
isolator is probably the first thing you should do in the process of
lowering the front. One way to do this is to use a 280zx top isolator, it is
approx 1/2" shorter than the tall stock 510 isolator. Only problem is that
upper metal portion (that holds the 3 mounting studs) of the 280zx isolator
is too large to fit in 510 strut tower so you must cut the 280zx metal down
to 510 size. The 3 mounting studs are same pattern so it bolts in once you
cut diameter down. Takes just a few minutes to reduce diameter with a lathe
of a few hours with a hacksaw. Cost for used (junkyard) 280zx strut
isolators should be minimal.
HOW TO MODIFY 510 also details a method for cutting up and shortening the
stock 510 isolator so it is shorter. If you spend some $$ and get good
camber plates, they will replace the stock 510 isolator altogether with
shorter "isolator" and lower front.
2) Use shorter strut tubes. If the strut is shorter then you can use a lower
height spring perch without effecting amount of suspension travel. The '68
and '69 sedan struts are shorter than other 510 struts so will allow
lowering 1/2" or 1" depending on the year. 280zx struts are also shorter and
allow lowering (see DQ backissue). You could also start with the "long"
later struts and cut a section of the tube out of the middle and weld the
tube back together. You will then need to use shorter strut inserts to fit
in the shorter struts. Possible shorter donors in approx descending length
are 240Z , 280ZX, '85 VW rabbit, sentra, 1st gen toyota MR2 rear. With a
shorter strut tube+insert, the spring perch can be set lower equivalent
amount toward the wheel without effecting travel. The spring perch can be
cut off of the strut tube with just a hacksaw without damaging the strut
tube, either re-weld it in place of make it semi-adjustable like
http://home.att.net/~jason510/280zxstr.htm or go with the threaded
coilover$. For your $300 lowering job, you should spend most of that $$ on
obtaining shorter struts and inserts. This is also a very good time to think
about upgrading the brakes. Doesn't make much sense to spend lots of $$ on
improvements to stock 510 struts if you later plan to upgrade the brakes as
this pretty much requires different struts. See Brendan's webpage for donor
info http://home.earthlink.net/~nutbin/struts.htm
3) Use shorter springs. This should be your LAST option to lower just a bit
more after steps 1 and 2. Shorter springs consume your suspension travel,
increasing suspension bottoming out on bumps (bad). With reduced amount of
suspension travel, you will need stiffer springs. Cutting the already soft
stock springs is a bad way to go. Even though the springs get a bit stiffer
when cut, it is not nearly enough to compensate for the decreased travel.
Get some stiffer springs if you lower by cutting springs any. Do not cut
them so short that they are completely uncompressed at full insert extension
or they rattle. Leave at least 3" of useable strut travel for a street car.
The stock 510 foam bumpstop is rather tall so you can regain a bit of travel
by trimming it shorter or using the energy suspension polyurethane bumpstop.
I have pasted on Chris Salnier's list of low cost donor springs at end of
this post.
To lower the rear of the 510 you basically need shorter and stiffer
springs, cut stock springs are way too soft. Massive lowering of the rear
causes massive problems to the suspension geometry so moderation is the key
to lowering the rear.The diameter of the rear springs need not be as exact
of a fit as the front springs so donor options are fairly wide open.
Suggested rear donor springs are from the front of Mazda/courier and
Mitsubishi pickups, other suitable donors might be found in heavy American
cars with double A-arm suspension, just make sure the OD of the spring is no
larger than 4-7/8" and it should fit in the swingarm. There are undoubtedly
many other spring donors that will work for rear. To regain a bit of travel
on the rear suspension, cut the rubber bumpstop 1/3 shorter. The rear
swingarm is designed to travel through an arc so the outer end is first
pointing downward,sloping away from center of car, then is flat parallel to
the ground and then is pointing upward when under compression. Camber and
toe of the rear wheels are greatly effected by suspension travel. As the
suspension begins compressing from swingarms "downward outward sloping"
toward swingarms "parallel" to ground, the wheels toe-inward from the
static ride height setting. Once the swingarm is parallel to ground and
travel continues so ends begins pointing upward, then the wheels begin to
toe outward. So long as the swingarm swings through "parallel" during
travel, the dynamic toe change from static ride height is minimize since toe
first goes in then out. If you lower so much that the arms are parallel to
ground at static ride height, then the wheels immediately begin toeing
outward as suspension compresses and results in more toe change for given
amount of travel, bad. So, unless you are willing to do the "penultimate"
crossmember modification (see DQ backissues), don't lower the rear
excessively. You should still slot the crossmember to re-camber, re-toe the
wheels even with just moderate lowering (see
http://dimequarterly.tierranet.com/articles/tech_crossmember_slotting.html ,
ignore the 280zx brakes page title).
Later-
Jason K Gray
Wasilla Alaska
510 website http://home.att.net/~jason510/
'73 2-door 510 L16T
In its massive entirety, here is Chris' spring shopping guide.
==========================================================================
BB's
For your swapping pleasure I have created a list of several different
front springs that can be used on the 510. All of the springs listed
will increase spring rate, will need to be cut to lower your car, and
are commonly available in the JY. Also included is the formula from
Fred Pruhn's book "How to make your car handle" (thanks Jason) that
describes how to calculate spring rate as you cut. Listed dimensions
for the diameter of the springs are taken from the center of the wire,
not the OD or ID, this will make it easier to use the spring rate
calculation. The data all came from the NAPA spring book, so things
like free height and load height are approximate. The stock Datsun
spring info was taken from a factory manual (thanks Jason), and can be
used as a rough guide. All dimensions are in inches. It is best to
measure your 510 springs both loaded and free to determine your specific
baseline before trying to calculate rate and ride height changes. All of
the approximate load heights are based on 525lbs on the spring.
I will be doing this for the rear springs too, but expect it to take a
few months... All the info listed below is correct to the best of my
knowledge, I did check all the applications at the JY to confirm that
they looked right. If anyone is more fluent at making the info into a
more user freindly format and posting it on a website, please do so,
just let me know where it is and give me credit for compiling it.
Happy hunting!!!
Spring Rate Formula:
K= (12,000,000*W^4) / (8*N*D^3)
The 12,000,000 and 8 are constants.
W= diameter of the spring in inches. (W is raised to the fourth power in
the formula)
N= number of active coils in the spring. (free coils plus 1/2 coil under
load)
D= diameter of the coil, measured from the center of the wire to the
center of the wire. (D is raised to the third power in the formula)
Stock Datsun:
Spring Diameter - 5.11
Wire Diameter - .472
Load Rating - 89lb/in
Free Height - 14.25 (approx)
Load Height - 8.35 (approx)
NAPA P/N 277-3187 ($52/pair new)
Spring Diameter - 5.04
Wire Diameter - .485
Load Rating - 123lb/in
Free Height - 12.75 (approx)
Load Height - 8.50 (approx)
Application - '88-'92 Nissan Sentra (rear)
NAPA P/N 277-3180 ($59/pair new)
Spring Diameter - 5.27
Wire Diameter - .500
Load Rating - 128lb/in
Free Height - 13.58 (approx)
Load Height - 9.48 (approx)
Applications - '86-'89 Hyundai Excel w/AC, '87-'88 Mitsubishi Precis
w/AC, '79-'82 Plymouth Champ w/AC, '80-'84 Dodge Colt w/AC
NAPA P/N 277-3185 ($59/pair new)
Spring Diameter - 5.22
Wire Diameter - .500
Load Rating - 137lb/in
Free Height - 12.98 (approx)
Load Height - 9.15 (approx)
Applications - '86-'89 Hyundai Excel no/AC, '90 Hyundai Excel w/AC,
'87-'88 Mitsubishi Precis no/AC, '79-'82 Plymouth Champ no/AC,
'80-'84 Dodge Colt no/AC
NAPA P/N 277-3130 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 137lb/in
Free Height - 12.43 (approx)
Load Height - 8.60 (approx)
Application - '76-'78 Honda Accord
NAPA P/N 277-3129 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 148lb/in
Free Height - 13.00 (approx)
Load Height - 9.45 (approx)
Applications - '80 Honda Accord w/AC, '81 Honda Accord LX w/AC
NAPA P/N 277-3128 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 148lb/in
Free Height - 12.31 (approx)
Load Height - 8.76 (approx)
Applications - '79 Honda Accord, '80 Honda Accord no/AC, '81 Honda
Accord - all except LX w/AC
NAPA P/N 277-5187 ($93/pair new)
Spring Diameter - 5.06
Wire Diameter - .562
Load Rating - 158lb/in
Free Height - 14.37 (approx)
Load Height - 9.00 (approx) - measured after cutting off pigtail end
Applications - '80-'85 Olds Toronado (rear), '79-'85 Cadillac Eldorado
(rear), '79-'85 Buick Riviera (rear)
Notes - These have a "pigtail" end on one end that must be cut off.
They are real easy to get off at the JY, bring a long crowbar and you
can pry them off the lower mount, removing them with next to no effort.
Be Careful!!! - Don't try to "help them" by hand if they get hung up.
NAPA P/N 277-5308 ($96/pair new)
Spring Diameter - 5.26
Wire Diameter - .531
Load Rating - 131lb/in
Free Height - 15.60 (approx)
Load Height - 11.60 (approx)
Application - '83-'85 Toyota Celica IRS (rear)
Notes - These are also easy to get off at the JY, remove the lower shock
mount then pry them off the lower mount, removing them with next to no
effort. Be Careful!!! - Don't try to "help them" by hand if they get
hung up.
NAPA P/N 277-5310 ($109/pair new)
Spring Diameter - 5.02
Wire Diameter - .500
Load Rating - 108lb/in
Free Height - 14.50 (approx)
Load Height - 9.63 (approx)
Application - '83-'85 Toyota Celica solid rear axel (rear)
NAPA P/N 277-5277 ($74/pair new)
Spring Diameter - 5.08
Wire Diameter - .500
Load Rating - 115lb/in
Free Height - 14.12 (approx)
Load Height - 9.55 (approx)
Applications - '84-'87 Toyota Corolla, '85-'88 Chevy Nova
NAPA P/N 277-5174 ($87/pair new)
Spring Diameter - 4.97
Wire Diameter - .500
Load Rating - 106lb/in
Free Height - 13.05 (approx)
Load Height - 8.10 (approx)
Applications - '75-'79 VW Rabbit/Scirocco no/AC
NAPA P/N 277-5146 ($87/pair new)
Spring Diameter - 4.99
Wire Diameter - .500
Load Rating - 112lb/in
Free Height - 13.62 (approx)
Load Height - 8.93 (approx)
Applications - '77-'79 VW Rabbit/Scirocco w/AC
NAPA P/N 277-5374 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 113lb/in
Free Height - 13.55 (approx)
Load Height - 8.90 (approx)
Applications - '91-'94 Ford Escort (rear) - except GT, except wagon,
'91-'94 Mazda Protege (rear)
NAPA P/N 277-5376 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 113lb/in
Free Height - 13.95 (approx)
Load Height - 9.30 (approx)
Applications - '91-'94 Ford Escort Wagon (rear)
Later-
Chris of Maine "springing forth with useful info"
'71 wagon "junkbox" driver
'72 4dr - project
'69 1600 Bluebird SSS 4dr 1/24 scale
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