Suspension advice needed...

[AWDrift]

Here's the deal. I have a 95 fwd talon w/78k on it. I purchased it with 75k on the clock, and it came with Tokico HP series (blues) shocks and unidentifiable springs. These springs are way too low for me (the front fender is 1 finger width from the tire, while the rear is 3 fingers). Also, the ride and handling is horrible. So, I am wondering what would be the most economical way to fix this.

My question is, could/should I keep the Tokicos and just replace the springs, or replace the whole set up? Would some Eibachs or H&Rs solve the problem, or would I need to replace everything? Any other springs would you recommend? I'm looking for a good-performing spring with a drop no more than 1 3/4 inches that hopefully would work with my Tokicos. I am on a budget (I'm 16) so if I could keep the shocks it would be great.

Yes I did search, but didn't find much regarding the re-use of used tokico blues from a severely lowered car...thanks for reading

 

[jtmcinder]

HPs are not very strong. They are fine with stock springs, but not much more. So here's my advice: find someone who will give you their stock springs. You'll learn a lot by doing the swap yourself, spend no money, and can then drive a stock DSM for a while, giving you time to learn what the issues are. Then, when you have $500+ saved up, you can spend your money wisely, instead of making the "Sportlines with AGXs" mistake than many people much older than you have made.

- Jtoby

 

[UCSLugRacerX]

The HP Blues were designed as OEM replacements, and most likely does not match the higher spring rate of your lowering springs. Keep in mind, that you want your shock compression rates to match your spring rates. I had 4 HP Blues on an Integra, and I learned the hard way that they blow out if ride height is too low.
Figure out what you want your car to do, and then hit the search button.

 

[jtmcinder]

Keep in mind, that you want your shock compression rates to match your spring rates.

You might want to explain that in more detail.

- Jtoby

 

[AWDrift]

You might want to explain that in more detail.

- Jtoby

I think I understand what he's saying, however my current lowering springs dont seem very stiff, despite how low they are.

This is pretty much what I expected. I guess the real question is, how long can the blues hold up, and how do I know if they're damaged (besides looking for leaks)?

I'm definitely going to put on some stock springs before winter hits...on the other hand, if I kept the car lowered like it is, maybe I could get out of shoveling the driveway... :laugh:

 

[UCSLugRacerX]

You might want to explain that in more detail.

- Jtoby

Sure thing. Sorry for the late response. Most of the information I will provided is either paraphrased from Carroll Smith from Tune to Win, or Race Car Engineering by Valkenburgh, so I apologize if the ideas seem to mesh.



Matching springs and shocks:
“Bump/rebound ratio is the comparison of peak forces in either direction. For comfort, passenger cars have traditionally used a 30/70 ratio, meaning that only 30% or suspension travel is resisted in bump, and 70% is resisted in rebound—over a cycles to zero. On the other hand, racing shock absorbers may have a ratio closer to 50/50” (Valkenburgh, 35).

For an extreme application example, take for instance your original DSM shocks, (or Tockico HP blues—which have almost identical compression and rebound rates), and then use 700 lbs race springs front and rear.
What happens?
The springs’ resistance during compression will require more force to fully compress during bump travel, or load transfer. At this point in time with the race spring fully compressed, it has potential energy.
After the transition between potential energy to kinetic energy, the spring rates rebound will overwhelm the shocks’ ability to slow the rebounding spring.
The chassis will then be disrupted, and hinder steady state turning, by being shot back-up too fast.

Now let’s look at shocks with too high a compression and rebound rate.
“The more that [shock] compression and extension forces increase, the faster they bring a suspension oscillation to zero” (Valkenburgh, 35).
Consequently, when applied to extremes, “…this can be overdone, however, to the point of critical dampening, where the suspension doesn’t cycle at all but slowly returns to its original ride position without overshooting…[and] it tends to hold the tire off the ground too long—[and] the forces it would transmit to the chassis would be intolerable” (Valkenburgh, 35).
(Whether or not the spring rate matched, or too high, or too low, the effects would be negligible, when coupled with a shock with TOO high a compression and rebound rate. I suppose that fortunately, shock assemblies with such extremes are not too available on our DSM’s.)

Now let’s go back to the 30/70 bump/rebound rates:
“Over a series of bumps, a 30/70 resistance ratio will have the tendency to let the wheel rebound a little less on each cycle. In other word, instead of the wheel falling, the chassis falls, decreasing suspension travel” (Valkenburgh, 36).
If it’s not clear enough, having deceasing suspension travel as you continue to drive over more bumps is a BAD thing.
Keep in mind this set-up is with a “stiff” shock with a “soft” spring. The of this set-up will cause the pogo-effect which is explained above.

(Side Note: Yesterday when I was riding in my friend’s Honda S2000 with Tein R.A.’s, his suspension set-up exhibited somewhat of these characteristics—although for most part, with bump-travel, and load transfer, the forces which disrupt the chassis—did not result in the pogo-effect, nor the reduction of travel, due to successive bumps, causing “over-rebounding” or suspension travel loss. It’s a matter of matching spring rates to shock rates.)

In summation, I’m sure I’ve left out key elements in why springs and shocks should be matched. If anyone could add why they should, or should not be matched, that would be great.


-Andrew

 

[jtmcinder]

Keep in mind, that you want your shock compression rates to match your spring rates.

What I meant (when I suggested that you explain this) was that you should warn people that, as spring rates go up, you want less and less compression damping (in absolute terms). My worry was that people would see the word "match" and think that more compression damping is needed with higher-rate springs.

- Jtoby

 

[UCSLugRacerX]

Sure. That makes sense. (Why didn't you just say that?)
Also, it would be somewhat of a redundant job, for there to be high spring compression and high shock compression
If it's not already obvious, an increased shock rebound resistance, is imparative when coupled with a stiff spring, which an OEM DSM/Tockico HP shock lacks.)