roblop04

Well I bought some stock suspension off an SE-L and I put them on my 200SX... I was tired of hearing the car and dodging every hole on the floor.... now I got some type of problem... the front of the car is higher than the rear.... the car looks like its lifted on the front.... what could be the reasone...

 

bobbyisking

well a b13 at stock suspension and everything, the front "looks" like it is higher, but it's not. the fender gap is higher at the front than the back, but if you measure it with a tape measure, it should be very close the same height. that's part of the reason why springs drop the front a little more, so the gap is closer, and it looks level.

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92 Dark Gray Sentra SER

92 Red Sentra SER

roblop04

I'm going to take pics and post them up.. But just to give you an idea.... I can stick 3 fingers on the back and ill be tuching the tire and the bottom of the fender... now I can stik my whole hand in the front to do the same.... ill be posting pics hopefuly today..

reverm

Yep, that's normal. On a B14 of any given trim level, the front fender gap is about an inch larger than the rear fender gap. The front springs differ slightly in rate depending on the trim level and transmission type though, so if you take say, a 200sx base model w/ a manual trans and bolt on the front suspension from an automatic Sentra SE-L, the difference in rate (around 20 lbs-f/in if my calculations and the figures in these FSMs are correct) will be enough to make the difference even more noticeable.

And no, short of cranking in some forwards rake or making your own fiberglass extensions for the front fenders, there isn't really a way to fix this. Sorry.

roblop04

The SE-L was auto... and I put it on my 200sx ser.....

reverm

The difference between the SE-L auto springs and the SE-R manual trans springs is pretty small - around 4 lb-f/in. So that part about swapping springs would be a moot point.

The front fender gap on your car should be around an inch more than the rear gap, with the car unloaded. The difference will be greater if you have stuff in the trunk.

EDIT: Corrected difference between SE-L auto springs and SE-R manual trans springs. It's 4 lbf-/in, not 8 lb-f/in.

Shawn B

This is (sorta) On Topic I hope.

I am ignorant to the FSM's, perhaps you have them easily accessible on-line?

I would love to have all the stock spring rates for the various models of B13, B14, and B15 chassis. I would include it, citing you as the source, in this section:

http://www.sr20forum.com/driveline-t...ml#post1651579

Can you provide me (us) with this FSM spring information or point me at it? I realize that is a Factory Service Manual, but am clueless from that point. You seem to have this information at your fingertips.

Thanks!

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2004 Tahoe, stock and fully loaded.
'93 Classic - R.I.P. 2007 My mechanical companion. Operation Resuscitation underway....

* The best offense is a good psychosis. *

reverm

The B14 FSM doesn't actually say what the spring rates are for the factory springs. What it actually gives you is the wire diameter, coil outer diameter, free length, and identification color (the two painted stripes in the middle of the spring) for the four different types of front springs and the three different types of rear springs that were used on the B14 chassis.

What I did was take that information and used it to calculate out estimates for the spring rates using the equations listed on this page at eFunda.com (or alternatively you can use their calculator here).

Now to collect the necessary info to plug into these equations. For the basic spring dimensions, I used the B14 FSMs available from www.phatg20.net (the one for the 96 Sentra has the info for all of the springs that came on the B14 in the Service Data and Specifications chapter of the Front Suspension and Rear Suspension sections.). For the figures for material density, poisson's ratio, and elastic modulus, I used the standard figures for 9254 spring steel, which are also available on eFunda.com, here. For the number of active coils, I actually took some stock springs, compressed them on a little jig that I made, and observed the spring through about 2 inches of its travel (All of the front springs have around 4.25 active coils, the rears have something around 6, if I remember correctly).

Front

That's pretty much all the info you need to calculate out the front spring rates. The four color codes for the B14 front springs + their calculated (estimated) spring rates are:

White: 121 lbs(f)/in
Yellow: 125 lbs(f)/in
Pink: 134 lbs(f)/in
Light Green: 139 lbs(f)/in

Reference table of which front springs came from where:

Sentra Base/XE - Manual Trans: White
Sentra E/XE/GXE - Auto Trans: Yellow
Sentra GLE/GXE - Manual Trans: White
Sentra GLE - Auto Trans: Pink

Sentra SE Limited Manual Trans: Pink
Sentra SE Limited Auto Trans: Light Green

200sx Base/SE - Manual Trans: White
200sx Base/SE - Auto Trans: Yellow
200sx SE-R - Manual Trans: Pink
200sx SE-R - Auto Trans: Light Green


Rear

The rears are unfortunately tapered (and progressive rate) on all B14's. This makes it extremely difficult to calculate out by hand. What I actually did was calculate the spring rate 1/2 a coil at a time, treating each 1/2 coil as if it was a single active coil with an outer diameter equal to twice the outer radius of the spring at that time (didn't do this by hand, thankfully. I made excel do it). This means that the figures for the rears are less accurate than the ones for the fronts, but in the spirit of talking, I'll put them up anyway:

White: 170 lb-f/in to 230 lb-f/in progressive
Light Blue: 173 lb-f/in to 232 lb-f/in progressive
Pink: 170 lb-f/in to 230 lb-f/in progressive

Reference table of which rear springs came from where:

Sentra Base/E - either trans: White
Sentra XE/GLE/GXE/SE - either trans: Light Blue

Sentra SE Limited - either trans: Light Blue

200sx SE-R - either trans - Pink


One important thing to keep in mind that these are estimates. I tried to be as precise as possible in my calculations, but I didn't put these springs on a tester. There is a chance that the numbers themselves may be off by a bit.

That being said, I'm pretty confident that the relative relationships between the rates are correct - in other words, I'm pretty comfortable saying that the rear spring rates are substantially higher than the fronts, and that it is possible to stiffen up your front suspension very slightly by getting some auto trans SE-R or Sentra GLE springs (whether you'd be able to tell the difference is another story).

I donno if that helps any. Feel free to ask any questions or poke holes in any of the above.