Suspension for dummies (B210)

[PineClone]

First, i know nothing about suspension, so i'm going to get the terminology wrong and so on and so forth. But i'm not sure where to start. Some of this (e.g. cutting springs) has been covered here and i can go re-locate that stuff if needed. Here's the deal for my '78 B210 2door sedan:

 

- I want to lower the front end about an inch.

- The front suspension is super spongy

- The rear suspension is super solid. So much so that one time i tried to bounce the rear end by putting my body weight on the rear bumper with my knee, and it bent the bumper. There is very little give in the rear when you hit a bump.

 

Questions are: 

 

- How much coil to cut off the front coils to lower and potentially stiffen the front end?

- What basic shocks/strut configuration is recommended for a nice performing ride? I'm not racing this car, just driving it for fun. Doesn't need to be high end, but i'm not opposed to spending a little money to make it nice.

- What is the cause of the rear end stiffness? Is this the leaf springs? Maybe that is how it is supposed to be. If so, fine.

 

I could take it into a local shop and ask them, but i'm planning to do the work in my garage.

 

Thanks in advance!

[datzenmike]

First, never cut a spring to lower. Springs increase their rate when cut so a one inch shorter spring will be stiffer and not compress as easily and you may end up with 7/8 or 3/4 or 15/16 or who knows? I guess you could keep cutting to get what you want but then end up with a too stiff rate. To avoid this trim the lower perch and support it with a split collar, now you can run your stock spring or cut it to get the rate you want and ride height remains selectable by you. If you can multiply and divide there is a formula so you can work in advance how much to trim a spring to get a certain spring rate then set your ride height with the adjustable split collars. I worked out my 710 spring rate to about 100 pounds per inch, then trimmed it to get 150 lb/in or a 50% increase. Just keep in mind once cut you can't put it back so less is more. You can always cut again.

 

Front too bouncy is not the spring but the shock absorber or damper inside the strut tube. It's job is to resist motion on compression and rebound so a bounce is quickly dampened. Shock absorber oil tends to thin out with age or be too thin to begin with. If you gave the original oil filled dampers inside your struts you can empty them out and run a thicker hydraulic oil. I put 20W motorcycle fork oil in mine and they are nice and firm. If you drive in the winter 15W might be better. It's thicker so it takes more energy to push it through the small valves. That's the whole idea.... to absorb energy. If you take apart and they have been replaced with dry inserts, you have no choice but to buy new inserts.

 

I've done all the above with a few wrenches and an angle grinder in my back yard. Oil was $17, cut off disc was $5 and split collars were $25.

 

 

 

Rear too stiff can also be a shock(s). I've seen then seize up with age too. All you can do is replace them. Unless the rear spring was replaced, but it's unlikely it's too stiff as makers tend to go for a softer ride to satisfy more customers. Worn out shocks on the back can feel stiff if not damped properly. The front has more weight and will bounce more on soft shocks. The back doesn't have as much weight so it is sharper and settles down much sooner. Removing a spring to lower is a no no also as this softens the spring rate and the car will now sag lower on dips in the road. This should always be avoided on a car that is now sitting even lower !!!!!! Instead, slip blocks or spacers between the leaf spring and the axle. A pair of two inch blocks will lower exactly 2" and the spring is unaffected. You may need U bolts that are 2" longer.

 

Tire choice can also affect the ride as they are in effect air filled rubber balls.

 

Any time the ride height is changed the front end alignment is altered. Toe in and camber are affected.

[Dguy210]

Change rear shocks, add a helper spring on the rear.

 

Change front strut inserts, cut 1-2 coils off to stiffen the front (front spring is very soft for ride comfort ~170 from memory).

 

Take a look at front suspension ball joints etc. and idler arm while under the car see if they need to be replaced.  

 

I rebuilt the whole front suspension and refreshed the rear, I also put 280zx front struts and cut the springs down a bit, but I run it a bit stiffer then you probably want. Made a BIG difference in feel and road handling.

 

Overall, you can think of the B210 suspension as very similar to that of a 510 wagon when looking for things you want to modify.

 

Note: I disagree a bit with Datzenmike on cutting springs but he is right in the general things, if you are cutting a lot of your springs you are better with coilovers, but in my experience a little bit seems to be easy and ride ok.

 

Make sure to realign the front tires if you cut the springs.

[Lockleaf]

If you do the math based on spring rates and cut to achieve the rate you want, cutting is fine. But there is no way to accurately determine how far that will lower you. Cutting to achieve ride height leaves ride quality to the fates. It usually goes badly.

 

Otherwise i agree with all the previous

[datzenmike]

You can only lower a finite distance before the strut will bottom out. Coil overs won't fix this. At some point you will need a shorter strut tube like a zx. Or have yours shortened and a shorter strut insert used.

[B210GX]

I cut 1 3/4 coils off of mine Scott. and I do have the 280zx struts/brake combo as well..using the 2"shaft collars for adjustment... but once you get it set where you want it, throw a couple of tack welds on it for safety...

....

Side note, how is your drivers side window squeegee.. I think I have two D/S NOS ones (was told they were for a coupe, they are not). Interested? lmk

 

 

Mike

[datzenmike]

X 2 on the tack weld.

[Icehouse]

The B210 has the same front suspension as the 510 and I mean the exact same parts (crossmember has the motor mounts 1/2" spaced different).   So you can do what all the 510 dudes do.