Geo Metro Suspension Swap (to handle extra battery weight)

[Frank Lee]

I'd go with heavier springs. I think the bags are good when the loads vary a lot, so you can adjust them. But if the loads are always largely the same I wouldn't fool with them.

[almightybmw]

I'm with Frank on this. Bags have 2 purposes: big rigs with varying loads and show vehicles. Outside that they aren't needed as steel springs do a better job more consistently with less chance of failure. Be sure to consider spring wire diameter, as that makes a bigger difference to strength than the coil diameter and length. the latter two are more of a control for bounce and side stresses. Notice some aftermarket coilover setups use 2" or 3" springs with a higher rating vs. the 4-6" stockers? Thicker wire diameter. If the Murano springs are nearly the same length and diameter, check the number of coils and wire diameter. Google some spring sites to calculate load/strength/etc with stock springs and the Murano springs. See what your new height and load rating will be. Don't guess! Try it! (Bill Nye anyone?)

[TestDrive]

Spring rubbers are cheap, but a totally temporary band-aid.
Airbags are a last resort.
In order of preference, here the three main routes to consider.

OPTION 1: Find out what two, custom made, heavy duty rear coil springs would cost.
Probably a lot less than you think.

There is bound to be a spring repair shop somewhere in Milwaukee. Find it. (Local NAPA or a truck repair shop will know their name.) A lot of (maybe most) spring repair shops only handle leaf springs. Even if that's the case though, they'll know who works with coils springs.

You'll need to know:

1. wire diameter
   ...Size of the rod/wire/round stock the coil is made from.
   ...Basically this is the only measurement that will be different on the new springs.
2. coil diameter
   ...Don't recall if it's inner or outer diameter they'll ask for.
3. number of coils/windings
4. uncompressed spring length
   ...Preferably specifications from a manual.
   ...Alternatively measured from an UNCOMPRESSED, new/oem spring.
   ...Yet more alternatively measured from an UNCOMPRESSED, apparently unsagged, used spring.

P.S. While you've got it apart, consider reinforcing the suspension arm. Do it yourself, but ask the guys at the spring repair shop if they think its necessary.
P.P.S. CoyoteX suggested Metro front springs are similar to rear but taller and might work. They might, but could be a bear depending on how far the suspension arm drops once the strut and knuckle control rod are disconnected. (Or whatever the last little bit is before you r&r the spring.)


OPTION 2: Booster springs (obtained from salvage yard) inside existing springs.

This diagram from Autozone

is for a '89-'93 Metro, but it looks reasonably similar to the picture you previously posted.

If you disassemble far enough to get the springs out, you can weld seats for a smaller coil spring to the upper spring seat (#2) and lower spring seat (formed as part of the suspension arm (#18). The main caveat to mounting a smaller coil spring inside the main coil spring? To prevent interference during compression, the inner coil spring windings should be aligned opposite to the outer spring windings. e.g.

Outer spring laid on its side - ///////////
Inner spring laid on its side - \\\\\\\\\\\

OPTION 3: Boost springs (obtained from salvage yard)on struts/shocks


This assumes the scuff mark on the shock/strut in the previously cited picture isn't due to insufficient clearance. Muffler Clamps and large, home made washers could be used as upper and lower spring seats.

[Daox]

I totally forgot about this, but I did swap springs on the Paseo. So, I have the stock set laying around. You should measure your springs up and we'll see how they compare and if they'll fit. The Paseo weighs in at just a hair over 2000 lbs, so they should be a little bit heavier.

Edit: If you can, measure the OD and ID of the spring as best you can. Also measure the diameter of the spring rod itself. That plus the number of windings is a good rough indication of strength.

[bennelson]

I was able to remove the rear-left spring from the Geo.

The spring when removed from the car is:
11" long
3.75 inches across inside the spring (hard to measure - I measured straight across with the top of the tape touching an upper coil, and bottom of tape to measure bottom coil)

The diameter of the spring itself is just a hair over 1/2 inch. (but less than 9/16)

The outside of the spring diameter is is pretty close to 4.75 inches.

The spring is 7 coils.


Also, I measured the height of the car, and then again after removing 4 batteries, which were pretty much right over the rear axel. The difference in height was 1.5 inches. I figure the weight of two of the batts was on this one spring (the weight of the other two batts was on the OTHER spring)

The batteries weigh 70 lbs each, so that means that 140 lbs compresses this spring 1.5 inches, or roughly one inch per hundred lbs, right?

I have some photos posted in my main Electro-Metro thread.

[TestDrive]

Edit note. After posting, I saw pictures of spring in other thread. Disregard questions about variable rate springs.

Originally Posted by bennelson

I was able to remove the rear-left spring from the Geo.

Is the upper spring seat a separate part removable from car like in the diagram? If so, you might get more accurate (inner minimum, outer maximum) measurements for new spring off of that part. Take a good look at that location, the sheet metal of the unibody might want some reinforcement there. (Almost more likely than the suspension arm to need beefing up.)

Might be better if you measured the spring stock diameter with a cheap (vernier metal/plastic dial) calipers. But just over 1/2" but less than 9/16" will probably satisfy guys at spring shop. They'll most likely use heavier stock anyway.

Are the coil windings the same distance apart - a fixed rate spring? If so your 1.5" / 140 lbs spring rate works. Other wise it's a variable rate spring. eg.

1. First 140 lbs spring compresses 1.5"
2. Second 140 lbs spring compresses 1.25"
3. Third 140 lbs spring compresses 1".

Or variation there of.

Have no real idea, but now that you've got spring dimensions, maybe it's worth a trip to the salvage yard to attempt to find cheap HD replacements. If longer but essentially otherwise the same is a choice, consider what the clearances were like getting the old spring out. The previously mentioned metro front springs might be a good option (or a total nightmare depending).

[Bicycle Bob]

The Murano may have different leverage on the spring, or a different gauge of steel.

[Daox]

I just checked my springs. They are roughly 1 foot long, but the wire is only about 7/16" in diamter.

[Tony Raine]

what about air shocks? then you don't even have to mess with springs at all. i assume you have an air compressor at your home. just pump some air in them every once in awhile, and you should be good. and if you get them from a local auto parts store, you can usually get a lifetime warranty

[bennelson]

That all sounds like lots of work.

Here's what I did.

Got a pair of Ford Ranger front coil springs.
Cut them to the length of the Metro stock rear springs.
Jambed them in there.

Works fine. Cheap. Some small amount of pride in doing it myself!

http://www.youtube.com/watch?v=g05SZBzUxW0