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View Full Version : Progress Springs on EP3 - Do You Have Significant Understeer and/or Bumpsteer Probl?



spydur
07-19-2008, 05:47 PM
I have recently purchased a set of Tokico D Spec's, a set of Progress Progressive Sport Springs and a Progress Alignment Kit for my stock 04 Si (I had also purchased an Energy Suspension Master Bushing Set, but I decided to return it since my car only has 21K on the clock and I learned of the equipment necessary and challenges one can encounter when removing the original bushings). I thought I had worked out a deal to participate in a Saturday installation of the struts, springs and alignment kit at my mechanic's facility, but it looks like liability exposure concerns have stopped that. My mechanic would be happy to install these components during normal working hours at their normal rate (approximately $400 + alignment costs). Being a "Do It Yourselfer", I thought of the DIY threads posted on EPhatch, ClubEP3, K20a.org and HondaTech, I found two strut and spring installation how to's. I then posted a thread last week on EPhatch in which I was basicly asking if it was feasible for me to install these suspension parts in my own garage (thanks to those of you who took the time to share your personal expertise and experiences in your responses).

My car is a DD and occasional autocrosser so I want to install suspension components that will improve the stock handling (improving the appearance by lowering the car is a secondary benefit). I chose Progress Springs do to their fine reputation and historical experience of working with HONDA on suspension components for new HONDA models. I also liked the fact that their springs are progressive and the drop is what I considered to be "reasonable".

While doing my research through Ephatch and other various information sources, I came across some information that concerns me. I read about the challenges that one is confronted with when modifying a McPhersion Strut suspension on a front wheel drive car. More specifically, I read several informative threads on EP3 suspension tuning by MUSTCLIME[/FONT

Direct quotes from one of his treads is:

"The suspension design is greatly effected by ride height....as you lower the suspension the LCA (lower control arm) goes flat and then past one inch of drop it starts to angle up. This is very bad for the suspension when you you look at the side loads (cornering forces). If the LCA is angled up and the weight of the car pushing sideways while the tire is trying to stick to the road, this force will "tend" to push the LCA up more and cause the suspension to blow through its travel. If the LCA is flat or angled down, the cornering loads are directed down the LCA in to the sub frame."

"If you have the HFP suspension, that is a great set up. Because of our suspension design, dropping the EP more than an inch kills handling. Once the front LCA's get past flat (one inch drop), cornering loads push the suspension through its travel and you end up ridding on your bump stops through the turns... Iam sure there will be a couple people telling you that they have a 1.5" to 2.0" drop and their car rails the turns... trust me, take them to an auto-x and watch their cars through the turns. The front suspension will just tuck under and they will have a bunch of understeer."

"If you are just DD your car, here is my advise.... keep your HFP suspension, add some crash bolts in the front and add as much negative camber as you can in te front with about 1/32" toe out in the front.... use 0 toe in the rear. If you really want the car to rail the turns change out the suspension bushings with a energy suspension bushing kit. The stock bushing are very soft , the front LCA bushings are designed to effect toe when cornering.... this sucks unless you are a grandma..... bushing changes are hugh pia and no one can see it,.... but it is one of the biggest changes you can do to your suspension."

BASICALLY HE IS SAYING - IF YOU INSTALL SPRINGS THAT LOWERS AN EP3 MORE THAN ONE INCH IN THE FRONT YOU ARE DECREASING RATHER THAN INCREASING THE HANDLING OF YOUR CAR AS THE LOWER YOU GO, THE MORE YOU INCREASE UNDERSTEER AND HARM HANDLING. IF THIS IS TRUE, THEN THE PROGRESS SPRINGS WHICH LOWER THE EP3 1.8" IN THE FRONT AND 1.5" IN THE BACK WILL [FONT="Arial Black"]DECREASE RATHER THAN INCREASE THE HANDLING OF OUR CARS. IF MUSTCLIME'S THESIS IS CORRECT THEN, I DO NOT WANT TO INSTALL ANY SPRINGS ON MY CAR THAT LOWERS IT MORE THAN ONE INCH! (THEREBY ELIMINATING NOT ONLY THE PROGRESS SPRINGS BUT APPROXIMATELY 85% OF THE SPRING SETS AVAILABLE FOR OUR CAR. THE SUSPENSION STICKY LISTS DROP MEASUREMENTS FOR 14 DIFFERENT SPRING SETS, ONLY 2 ARE LESS THAN 1.0", 3 ARE BETWEEN 1.0" & 1.5" AND 9 ARE 1.5"+, THIS DOES NOT INCLUDE HFP OR MUGEN SPRING/STRUT COMBINATIONS). I DON'T QUESTION MUSTCLIMES THESIS BUT I FIND IT INTERESTING THAT PROGRESS AND SEVERAL OTHER SPRING MANUFACTURES WHOULD PRODUCE A PRODUCT THAT DETRAMENTALLY IMPACTS THE HANDLING OF OUR CAR, BUT THEN SHOW (LOWERING) MAY BE MORE IMPORTANT THAN GO (HANDLING) AND IN BUSINESS THE MARKETING DEPARTMENT HAS MORE SAY THAN THE ENGINEERING DEPARTMENT $$$$$$$$$$$$$$$ !

SO;
(1) HAVE ANY OF YOU WHO HAVE INSTALLED PROGRESS SPRINGS ON YOUR EP3 EXPERIENCED INCREASED UNDERSTEER AND BUMPSTEER (PLEASE MAKE SURE YOUR NOT CONFUSING BETTER FEEL WITH BETTER HANDLING)?
(2) IF YOU HAD IT TO DO OVER AGAIN, WOULD YOU BUY PROGRESS SPRINGS AGAIN FOR PRIMARILY PERFORMANCE REASONS?

v1c10us
07-19-2008, 07:41 PM
i think its more that your car will handle better, but not as good as if the springs didn't lower you quite so much.
Cause you will have a lower CoG and stiffer spring rates which is a +
but as mustclime said, your suspension travel is greatly decreased because the lca can't just go up like it was supposed to. As well as issues with the camber.

keep in mind that not everyone likes oversteer, you might not want your car to be tail happy, I know I do, and if i had a rearwheel drive car id be damn pissed if it had understeer, but some people dont mind understeer, because its easier to contend with and everyone knows what to do when they encounter it.

Drew1d
07-19-2008, 10:07 PM
I think it ultimately depends on what you want to set your car up for.

I think you can get away with a much lower car if the asphault is even and clean around you. But ultimately, sacrifices are made changing your suspension design in general.

If you lower your car more than 2", I don't think your car is going to fly off the road, pirouetting into a stack of boxes. It just wouldn't have the handling potential it could. But even that is a matter of taste and driving style.

I put progressive DC5 springs on my car. I liked them, they were pretty comfortable (progressive spring rate) and the handled pretty well. But I ultimately went back to stock springs. (My roads are crap.)

ep_hatcher_510
07-19-2008, 10:20 PM
i think for 1.8" drop, roll center adjusters would be able to fix it right up.

K-Shark
07-19-2008, 11:05 PM
bump for more input!

considering same exact set-up.

v1c10us
07-20-2008, 01:14 AM
i think for 1.8" drop, roll center adjusters would be able to fix it right up.

theres more than just that involved in it.
The caster angles go pthbbt, you need to fix that, you need roll center adjusters, bushing changes, crash bolts. Not to mention the steering rack rods will be angled up ridiculously, making steering hard, putting strain on the EPS, causing steering rack creak, you can get the inverted tie rod ends but these are known to snap or break and if this were to happen on the highway you'd probably die..

All in all you are much better off with one of a few options if you are dead set on having the best handling car, swift makes custom spring rates and heights, you could lower the car to roughly that of the CTR and get stiffer springs and dampeners. You could get coilovers and keep the drop reasonably mild.
You could get ground control with custom rates.
you could put CTR springs on.
or you could buy a car that handles better already
But if you're not dead set on tracking your car or having the best handling possible then who cares, lower the damn thing, with the exception of buttery soft neuspeed springs that lower the car 2 inches you're not gonna make it handle worse than stock in my opinion..
Maybe you'll get more understeer, maybe you wont have a full range of camber angles for every cornering situation, but are you ever going to be in a situation where that really matters?
if so you need to drive slower on the roads.

!@#$%
07-20-2008, 02:03 AM
It isn't the springs that make the car understeer. There isn't a whole lot you can do to combat that trait in a fwd car. (Sways, tire pressure, corner weighting)

I think lowered on stock tires, it might handle worse, because there is more load put on the tires to grip. My car's handling capability with that setup is very high for a fwd car with only shocks and springs. I see where it could be better, but by no means could my car do what it does now when it was stock.

SandhMan75
07-20-2008, 04:13 PM
I agree w/ !@#$%.... ! My car is lowered on springs and a rear sway w/ bfgs and it handles much better then stock. auto x times prove it aswell. Alot of it is driving style, and things of that nature. Stiffer, and lower is gonna help it handle better, or at least feel more solid!

arthur
07-22-2008, 09:07 AM
lets say, if i want to buy only lowering springs, eibach sportlines or eibach prokit, what d be better?? the prokit only lowers the car 1 inch and the sportlines lower it 1.5´´.

shadowmd
07-22-2008, 09:10 AM
i have the progress springs. had'em on stock shocks for 80k and loved em. now they are on my d-specs and are even better

Heitzke
07-22-2008, 09:15 AM
As correct as Mustclime is, most of us wouldn't be able to tell a difference if we didn't have someone telling us something was wrong. I don't autox, I don't track, and hell, I don't even drive my car that hard. I assume most of these handling quirks would only present themselves under 10/10's driving conditions.

I'm running Progress springs on HFP struts, and have been for almost 2 years now. Does my car handle worse than with the HFP springs? Possibly, but it "feels" like it handles better to me and that's all I know.

spydur
07-23-2008, 12:44 AM
v1c10us

Where do you source CTR springs? I tried to buy used CTR springs and struts approximately two years ago through contacts in England. I could readily locate the parts at a reasonable price, but the shipping was expensive and near impossible. With the devaluation of the dollar since then, no telling what they would cost today.

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