Springs

R

Racescort

New member
I know I've asked this before, but here we go again.

Jon or joeg or anyother Escort driver out there...... what front and rear spring rate are you using?

I finally got my struts and springs off since my season is over, and found that my front springs are only 400 lbs. I thought they should be much higher?

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Doug
ITB Escort
[email protected]
 
Jon got some info from Lee @ Koni about chassis frequency for the B Escort.

I run 600-650 in the front; 900 in the back.
 
Originally posted by joeg:
Jon got some info from Lee @ Koni about chassis frequency for the B Escort.

I run 600-650 in the front; 900 in the back.
Click to expand...

Thanks joeg, that gives me something to work with. I didn't know where to start for a while there.

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Doug
ITB Escort
[email protected]
 
Originally posted by joeg:
Jon got some info from Lee @ Koni about chassis frequency for the B Escort.

I run 600-650 in the front; 900 in the back.
Click to expand...

Joe,

Can you explain chassis frequency?

We are running 550 front and I have 700 rear, Tim has 800.


Diane
 
I haven't a clue as to "chassis frequency". I believe it is a calculation that Lee Grimes did for Jon's car.

Maybe Jon can explain (?)
 
<font face=\"Verdana, Arial\" size=\"2\">Can you explain chassis frequency?</font>
Click to expand...

May I?

It's not really "chassis frequency" that I think is in play here, it's "suspension frequency."

"Suspension frequency" describes the oscillation frequency of the suspension corner if left without shocks (dampers). It is a value based on a calculation considering the rate of the spring, leverage of that spring on the wheel (motion raio), and the sprung weight at that corner.

This frequency is proportional to the spring rate and inversely proportional to the sprung weight (higher spring rate = higher susp freq; higher sprung weight = lower susp freq). Each corner, due to slight differences in these factors, will have a slightly different frequency.

This value is an important calculation because it gives a baseline against which to judge the required spring rates for a given track condition. Lower suspension frequencies are desired for bumpy tracks to keep the wheels on the track (and for smoother rides in street cars) and higher suspension frequencies are desired for stiffer control of the chassis (with consumate loss of traction on bumpy conditions).

Of course, this all ignores the effects fo aerodynamics, which have a definite effect on the frequency, just not consistently across variances in speed.

Note also that shocks do not feed into this calculation. However, once a suspension frequency range is chosen then the appropriate dampers can be appropriately selected. Proper shock selection is very dependant on knowing the suspension frequency.

Unfortunately, when someone asks "what springs should I run?" it's an exercise in futility; unless the cars are *identical* in all factors (weights, suspension motion ratio - design) and is looking to run the exact same dampers, it's hard to say "you need XXX" spring rate. Then, each driver will prefer and react differently to any combination of frequency/springs, shocks, and all other adjustable settings. Suspension frequency will give you a good starting point, but testing is required form that point forward to fine tune the results.

There are many technical books on suspension frequencies, how to calculate them, and general ranges desired for various conditions, and I encourage you to explore that information.

GregA
 
Originally posted by grega:
May I?

It's not really "chassis frequency" that I think is in play here, it's "suspension frequency."

"Suspension frequency" describes the oscillation frequency of the suspension corner if left without shocks (dampers). It is a value based on a calculation considering the rate of the spring, leverage of that spring on the wheel (motion raio), and the sprung weight at that corner.

This frequency is proportional to the spring rate and inversely proportional to the sprung weight (higher spring rate = higher susp freq; higher sprung weight = lower susp freq). Each corner, due to slight differences in these factors, will have a slightly different frequency.

This value is an important calculation because it gives a baseline against which to judge the required spring rates for a given track condition. Lower suspension frequencies are desired for bumpy tracks to keep the wheels on the track (and for smoother rides in street cars) and higher suspension frequencies are desired for stiffer control of the chassis (with consumate loss of traction on bumpy conditions).

Of course, this all ignores the effects fo aerodynamics, which have a definite effect on the frequency, just not consistently across variances in speed.

Note also that shocks do not feed into this calculation. However, once a suspension frequency range is chosen then the appropriate dampers can be appropriately selected. Proper shock selection is very dependant on knowing the suspension frequency.

Unfortunately, when someone asks "what springs should I run?" it's an exercise in futility; unless the cars are *identical* in all factors (weights, suspension motion ratio - design) and is looking to run the exact same dampers, it's hard to say "you need XXX" spring rate. Then, each driver will prefer and react differently to any combination of frequency/springs, shocks, and all other adjustable settings. Suspension frequency will give you a good starting point, but testing is required form that point forward to fine tune the results.

There are many technical books on suspension frequencies, how to calculate them, and general ranges desired for various conditions, and I encourage you to explore that information.

GregA
Click to expand...

So it does have to do with the car and driving style basically?

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Doug
ITB Escort
[email protected]
 
Joe, I can't really remember the exact details on chassis frequency, but I picked up several good articles that describe it very well. I have to plead non engineering background here. That damn doctor thing comes to mind again. It looks like Greg A kind of knows what he is talking about though. Lee Grimes and his buddies at Koni did all kinds of calculations based on car weight and a bunch of things that I didn't even know what I was measuring (they walked me through it on the phone) and came up with this chassis frequency thing. They recommended that I drop down on my rear spring rate to 500#s from the 900#s I was running. I had a big problem with rear end looseness last year but after changing to some custom Koni double adjustables and to the 500# springs I had much less of a problem this year. The different spring rate and struts translated into about 2-21/2 seconds on the track. The calculations recommended running 450# springs in the front as well as the 500#s in the rear. I had 400#s on the front already so just left them as is. I didn't feel like spending the $$$ for 50#s, I'm not nearly that good to tell the difference! Anyway, sorry for the delay in the post, I don't get on very often. It looks like Greg A may have you set up though. If not let me know and I'll find the articles and let you know where to find them.
 
Excellent! I got all the struts off and found that I too have 400lbs. in front, AND I have 500 in the rear,BUT the 500's are only 2in. ID. Jon if you remmember I have to change those coilovers in the rear to the original location. So Im going to have to buy new rear springs and ajustable perchs, and do the work that you and I talked about to make them work.
Jon what spring lentgh do you have in the rear? How do you keep the perchs in place on the rear?

Anybody know someone who needs 2 in. ID 500 lbs. rate. 8 in. long springs?

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Doug
ITB Escort
[email protected]
 
Doug--You need a short 2.5 inch coil over for Jon's-type rear set-up--like a 6 inch free length.

I don't think you will have much luck peddling 2.0 inch coil-overs in the States.

I actually have short 900lb springs that are stock O.D. and I.D. for the rear. Got them direct from the UK. They were relatively inexpensive and available in various rates from Road & Stage as well as LEDA.

The sleeve set-up, however allows you to do easier four corner corner weighting.
 
Doug, Joe is correct, I use 2.5" springs in the rear which are 6" in height. Use an adjustable spring perch setup like I have on the front (remember you can't have the adjustable perch built onto the strut body, it must be separate). At the base on the lower control arm, the flange that holds the stock spring must be banged down and a little additional material must be welded in the make a lip for a 2.5" i.d. spring. The perch will then be adjusted based on your corner weights and the spring will just sit right in the groove that you built up on the lower control arm. Mine works beautifully and Joe has just built his like mine (his looks prettier though, "your welcome" Joe!). I hope this is understandable for you. If not, just let me know and I'll try to explain some more. Good luck. Jon
 
Doug, I forgot to add that the springs are from Truesports and are Eibach's which cost about $115 delivered a pair. I can even get you part numbers if you like. Jon
 
Jon,or joeg,

How does the adjustable perch itself set in at the top. Does it go right around the factory hump(for the lack of a better word.

Thanks for the help guys.

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Doug
ITB Escort
[email protected]
 
Doug, I put the top of the spring right in the top spring "hump" as you call it. I also made a round donut type thing which I bolt into the middle of the top spring perch which holds the spring in place, but this isn't necessary to hold the spring in place. Let me know if you need anything else. Jon
 
I have been reading everything that you men & women have writen , and have a question ?? Is there a difference in spring rates if you run a posi or runnig a welded unit or open diff. The way i figure you would have to run heigher rates in the rear so when using a posi or welded to stop the push in the corners and higher in the front with open diff (kind of like SS) Also some are saying custom Koni`s, where can a person get these for 87-90 EGT ? Because all i see now are Spax which are very good but have to run custom sleeves to fit in steering knuckle!(is it safe)?? Still thinking of car to run and i keep coming back to ford (ran a V8 stang for years in EMRA)but would like to try FWD Thanks for your help
smile.gif
 
Gerard, I've been using those custom sleeves for years with no problem. The Euro Escorts have different front knuckles than the American cars (except for the first few years where the knuckles were the same)
 
Originally posted by Diane:
Gerard, I've been using those custom sleeves for years with no problem. The Euro Escorts have different front knuckles than the American cars (except for the first few years where the knuckles were the same)
Click to expand...

I figured it would be, you see i took a few year ago on Paul B. from EMRA`s black escort the KYB struts he origanaly had in there and cut the bottom part off to make the sleeve to fit the Spax in to it. Real tight fit and figured it would never come apart.
 
Gerard, to answer a couple of your comments/questions: you are correct in that I would run higher spring rates in the rear with LSD or welded diffs. I ran a welded diff for years with 900# springs in the rear and 400#'s in the front. The car handled great and I had popeye forearms. I have since switched to a custom Quaife LSD which I find alot better than the welded diff and have been able to drop down to 500# springs in the rear and have kept the 400#'s in the front. We used a European Escort Quaife and had to redrill holes in the ring gear to match up with the Quaife holes. I have run it now 11/2 years with zero problems and my popeye arms have disappeared. As for the Koni's, I have likewise had them custom made. You are correct in that they are no longer available, but I do have several internally adjustable ones and some from Europe that are shortened and single adjustable. However, over last winter, I worked with Lee Grimes (a good friend) at Koni and had him make me a set of double adjustable struts. The fronts are made out of BMW E30 chassis rear struts which have been modified/shortened to fit into the EGT front knuckles. The rears are Fox chassis Mustang OTC double adjustable units which have the bottom bracket off of an EGT strut welded to them to fit our application. One season with 7 weekends and one test day on them and they were perfect. I dropped 2 sec a lap at my usual tracks. Hopefully this year with a new motor and some more testing with Lee Grimes at Putnam Park in the spring, we will have the car at the front of the brutally competetive CenDiv ITB fields. As far as the Escort for racing, I enjoy the car, but if you are interested in fwd, you might want to consider a Focus in SSC for now then move it into IT when it becomes available. There is alot of after market parts available for the Focus which should make it a fairly competetive IT car when it gets classified. The Escort has NO after market support unless you make it yourself $$$$. Some parts are still available in England but they are only for the earlier Escorts with the 1.6L motor. The 1.9L motor in the '87-'90 EGT has absolutely no help out there. I have done everything custom made to my car. I enjoy the car but will likely get out as soon as I can afford to build or buy a new car. Thanks for the interest. Jon Ricker
 
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