Need a little help figuring something out

[Ron Sutton]

It's not surprising that 600# coilovers feel similar to 575 # big springs, since the big springs are roughly concentric to the shock and would have at least a similar motion ratio.

One of the things to do next would be to cornerweight the car. Getting the ride heights equal does not guarantee that the corner weights are balanced. You'll probably want at least one endlink on the front sta-bar to be adjustable so that re-connecting the bar won't upset the corner weights after you've gone to the trouble of getting them set.

Norm

Both great tips.



Lance you told me you know of a race shop where you can scale it. That will be key. Can you do it before next week's event?

P.S. Norm, the ridetech LCA's move the lower mounting point of the shock out, which, even though it increases the shock angle, did increase the motion ratio a small bit. In the rear, changing from inboard mounted coils to outboard mounted coil overs increased the side-to-side motion ratio a lot, so we needed to go down in spring rate, to keep the same wheel rate.

[SSLance]

Unfortunately I doubt it... I'm struggling just trying to figure out the best way to get the shocks tuned by then for now. Between the shorter fall days, my other commitments, my lack of tire availability (street and\or slicks) and just my flat out lack of time...I'm pessimistic about getting the shocks completely tuned in by Sunday's event.

Hopefully things will work out, otherwise I may be tuning them at the event...which isn't the preferable method under any circumstances...but it is what it is.

I had to buy longer bolts (8" vs 7.5") for my sway bar end links and space the bushings out by about 5/8s" longer than stock with washers to keep the tie rods off the sway bar at full compression. Even then I had to snug the bushing down without the top washer, then pull the nuts, put the washer on then put the nut back on quickly so there was enough thread showing to get the nut on. To put any more adjustment on the sway bar links I'll need even longer bolts or rig up a more suitable adjustable style end link which would probably be the best solution.

[AutoX_a_Truck?]

Unfortunately I doubt it... I'm struggling just trying to figure out the best way to get the shocks tuned by then for now. Between the shorter fall days, my other commitments, my lack of tire availability (street and\or slicks) and just my flat out lack of time...I'm pessimistic about getting the shocks completely tuned in by Sunday's event.

Hopefully things will work out, otherwise I may be tuning them at the event...which isn't the preferable method under any circumstances...but it is what it is.

I had a similar problem when I was trying to dial in my shocks. It's tough get even a good ballpark/baseline tune without a good course to test on. At events it can be tricky too with only 3-5 runs in quick succession (more so with multiple drivers). I went to a KCRSCCA test and tune once and it was great for dialing in my shocks, tire pressures, and sway bars. But, unfortunately, those are usually only at the start of the season.

[SSLance]

I'm contemplating signing up for double duty again this event just so I'll have 8 runs instead of the usual 4. Sure makes for a long day though.

Saw that you signed up Tyler, should be a fun course to run on for us. Have you seen the course map they released last week yet?

[AutoX_a_Truck?]

I'm contemplating signing up for double duty again this event just so I'll have 8 runs instead of the usual 4. Sure makes for a long day though.

Saw that you signed up Tyler, should be a fun course to run on for us. Have you seen the course map they released last week yet?

I am excited to squeeze in one more event before the season ends. My Dad is going to drive the Scout II (couldn't resist the pun) so I will have some friendly competition. The course looks fun! I just hope it won't be too cold. I will be trying out a new gear set in the T5 with different ratios so I hope that works out.

[Norm Peterson]

P.S. Norm, the ridetech LCA's move the lower mounting point of the shock out, which, even though it increases the shock angle, did increase the motion ratio a small bit. In the rear, changing from inboard mounted coils to outboard mounted coil overs increased the side-to-side motion ratio a lot, so we needed to go down in spring rate, to keep the same wheel rate.

Got it.

That would also be in the direction of a higher travel/lower roll setup, right?


Norm

[Ron Sutton]

Got it.

That would also be in the direction of a higher travel/lower roll setup, right?

Norm

Yes. Lance is on a "Tweener set-up" ... in-between a conventional set-up & a high travel set-up. He's traveling the outside wheel about 3", so not high travel like 4"-5.5" we normally do, but more than conventional set-ups that are typically around 1.5"-2".

[UMI Tech]

I've been following this thread and have learned a ton. Based on what I've seen it led me to contact Ron Sutton awhile back for G-body setup help. Our local oval track reopened as an asphalt track after years as a dirt track (they brought clay in 10 years ago and ruined it). Ron helped me convert a local dirt track G-body to a pavement car for an open event. This thing was bad fast right off the trailer and that NEVER happens with a new setup. It's pretty cool how many of the oval track things and auto-x things cross over. Keep up the good work Ron and thanks for the teaching.

ramey

[SSLance]

It's pretty cool how many of the oval track things and auto-x things cross over. Keep up the good work Ron and thanks for the teaching.

My favorite part of what we've done with my car so far is that none of it has hurt it's street driveability at all, so you could say that it crosses over from Auto-x to the street as well.

Take care of the bump steer properly while making the changes and the changes will actually improve the street driveability while making you faster at the track at the same time.

[UMI Tech]

I agree on the bump steer. Some years ago I had a mid-year Monte Carlo in the same division. I spent countless hours tuning the bump steer, massaging parts and so on until it was perfect. The first laps were very uneventful. I pulled in rather irritated that it felt slower. Yeah, slower to the tune of minus three tenths (which is huge). Best improvement I've ever made.

ramey

[83hurstguy]

Nice job with your install!

What's the motion ratio difference between the stock G-body LCA and the ridetech LCA? I'm curious what the wheel rate difference turns out to be with 550 lb/in springs in the stock arm vs the 600 lb/in in the ridetech arm. I was turned off on G-body coilovers by the high spring rates required due to limited travel, but this is encouraging.

[SSLance]

Thanks... I see you are from Kansas City, glad to see another local on here. I don't know how to figure the exact motion ratio difference out, maybe Ron does. I believe he has all of the exact measurements of the different arms and mounting locations. I have them too if you want to figure out the differences between the arms.

You should come out to our autocross in Independence this Sunday to watch us run. It's our last event of the year and there are a lot of fun cars signed up already, along with a fun course design.

[Norm Peterson]

For most front suspensions, there are at least three components of motion ratio. For comparing spring rate to wheel rate, their numbers all get squared and the overall motion ratio is the product of the three component terms 'squared'.

1. Ratio of the length from chassis pivot axis to spring (and/or shock) to the length from the pivot axis to the ball joint
2. Spring and/or shock angle (either the sine or cosine depending on whether you're measuring these angles from the vertical or from the horizontal, respectively)
3. Ratio of the length from the Front View Instant Center to the ball joint to the length from the FVIC to the center of the contact patch

The first two components give you a "ball joint rate", which is not necessarily the same as the true wheel rate even though it's fairly close most times. That last one is what gets you from the ball joint rate to the wheel rate and is generally a small effect. However, it does become more important with larger values for scrub radius (the contact patch force centroid is further away from the ball joint). It's something to perhaps keep in mind for use as a "tie-breaker" if you're on the fence between which of two spring rates to go with.

Keep in mind that any bushing compliance makes this entire line of math an approximation rather than an exact solution. For big springs, even the effective spring location on the control arm is somewhat vague.


Norm

[Ron Sutton]

Hey Lance,

Repost all the LCA dimensions so I don't have to look for them. I need the coil over inward angle too.

[SSLance]

Stock LCA
Center Pivot to Lower Ball Joint 14 7/8"
Center Pivot to Spring Center 6 3/4"
Center Pivot to Shock Center 7 3/8"


DSE LCA
Center Pivot to Lower Ball Joint 14 1/2"
Center Pivot to Spring Center 6 7/8"
Center Pivot to Shock Center 7 3/8"



ridetech LCA
Center Pivot to Lower Ball Joint 14 5/8"
Center Pivot to Spring Center 8 1/2"
Center Pivot to Shock Center 8 1/2"

[83hurstguy]

Thanks guys.

Lance, I'll have to try to make it out. Let me know where you are going to be in Independence with time frames, I'm down in Overland Park. My car was almost ready to go out, been down all summer, but a brand new rear axle seal decided to start seeping last weekend, so it's blown back apart. Definitely interested in seeing your car run in person.

Norm, appreciate the details, I assumed that we are dealing a series of assumptions to get a "best estimate", due to measurement accuracy, the odd G-body angles of a separated spring/shock that aren't necessarily collinear.

[SSLance]

Kansas City Region SCCA autocrosses here most of the time

http://www.kcrscca.org/new/content/m...-drivng-center

MCC - Blue River Precision Driving Center



Directions to site - I-70 to Highway 291 - take 291 north
about 2 miles to Highway 78 (also called 23rd street). Turn right on
Highway 78 and go east for about 2 miles to the Metropolitan Community
College - proceed past the College east on Highway 78 about another 1/2
mile. At the bottom of the hill, there is a road to the right (South)
that leads to their Precision Driving Center.


Admission is free, you can come or go as you like just have to sign a waiver and get a wristband when you first go in. There is a little bit of restrictions about who can be in the "hot pits" during runs but other than that, you can see or do it all while there. There will be 100+ cars out there for the Oct 27th event. I'm signed up to run in Heat 2 which will be on the track probably 11:00-1:00 or so.

If you are planning on coming out or if you have any questions about this, just let me know.

Lance

[SSLance]

I've ordered a pair of these



http://www.sealsit.com/grommet_split.asp

And once they get here I'll prepare myself mentally to cut two 3" diameter holes in my trunk floor up near the center of the shelf above the rear axle.

I just wanted to update this to say these particular seals did not work for me. It takes every bit of a 3" diameter hole to get the reservoir through, which is what I cut with a 3" hole saw.

These seals are 3" in diameter to the outside edge of the metal part of the seal, probably only good for a hole about 2 5/8s" in diameter. Seals-it makes a larger split grommet seal that seals up a 3 3/4" hole but they are $44.95 each, so I passed for now and returned the 3" seals.

They are nice seals and if they'll fit your application, go for it...they just wouldn't work in my situation.

I'm still working on an alternative plan to seal up the holes in my trunk floor.

[83hurstguy]

I'll send you a PM in a bit so your suspension thread stays on topic. Thanks for the details!

[Ron Sutton]

Lance, here is your shock tuning game plan & guidelines for tuning with Triple Adjustable ridetech Shocks

Before you get into full bore tuning ...
A. Do you have a safe place to test? (Meaning safe for you AND others)
B. Start with all the shocks FULL STIFF on all 3 settings.
C. Adjust all 3 settings on each shock to the middle, which is minus (-) 12 clicks.
D. There is no need to adjust the high-speed compression any further for tuning.
E. Track test with "just" shock adjustments & nothing else.
F. Take detailed notes of every change, before every "run".
G. Make 4 click increments in the first round of “rough tuning.”
H. Use 1-2 click increments for “fine tuning” sessions.

Make these tuning changes in this order:
1. Soften the low-speed compression on the fronts … until you get the car "loose on entry" when braking & turning & back up ... or go until you run out of adjustment.
2. Stiffen the low-speed rebound on the rears. You will gain grip back on entry. Go until the car gets loose again on corner entry turning & back up ... or go until you run out of adjustment.
Step #2 will also provide more grip on corner exit. Pay attention to when it affects grip on entry & middle.

3. Stiffen the low-speed rebound on the fronts to help keep the nose pinned down in the roll through zone. Go until the car gets loose on corner exit & back up ... or go until you run out of adjustment.
4. Stiffen the low-speed compression on the rear shocks until the car gets loose anywhere & back up ... or go until you run out of adjustment.
Steps #3 & #4 will help the car turn better "mid-corner" when you're "rolling or coasting" with no brakes or throttle.

The middle of the corner is the highest priority. If the car won’t turn well in the middle, the entry & exit are inconsequential.

Please do these in this order & take lots of notes. You won't be able to remember all the details accurately. I don't know any top race teams that don't use "run sheets" to keep track of changes, results, etc.

Then, send me a report of each run, with all 4 shock settings, the handling results on corner entry (braking & turning), Middle (coast) & Exit (throttle roll on & steering unwind) ... and the differences from the previous run.

You'll learn first hand what changes do ... I'll guide you on what everything means to us from what you send.

-------------------------------------------------------------------

Then, go back through the same process, but fine tune with 2 clicks, then again in 1 click increments until you find the best balance.
• Experiment with a “little here & a little there” strategy.
• Experiment with a “less here & more there” strategy.

Once you’re “happy” with the handling … this is your baseline set-up. Write it down & place it in a vault. Whenever you find yourself “out-to-lunch” with tuning … go back to your baseline.

If after more events & testing, you improve on your shock settings, make that your new baseline. Write it down & place it in a vault. Whenever you find yourself “out-to-lunch” with tuning … go back to your baseline.

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Fine tuning for day, track, conditions, etc.

Loose Entry:
• Stiffen the low-speed rebound on the rears. You “may” gain grip back on entry. If it gets better, go until the car gets loose again on corner entry turning & back up ... or until you run out of adjustment. If it gets worse … stop & back up to the baseline setting … and move on to the next step.
• If still loose, stiffen low-speed compression on front shocks until the car grips up on entry. Don’t go any stiffer than needed, as this may tighten up the roll through zone.
• If still loose on entry, reduce rear braking force with adjustable proportioning valve.
• If still loose on entry, try braking softer & longer.
• If still loose on entry, the cure will require a stiffer front spring or sway bar rate.

Tight/Pushy Entry:
• Soften low-speed compression on front shocks until the car frees up on entry. Don’t go any softer than needed, as this will make the car loose on entry.
• If still tight/pushy … soften the low-speed rebound on the rears. Go until the car gets loose again on corner entry turning & back up ... or until you run out of adjustment.
• If still tight/pushy … stiffen the low-speed compression on the rears. Go until the car gets loose again on corner entry turning & back up ... or until you run out of adjustment.
• If still tight/pushy on entry, induce rear braking force with adjustable proportioning valve.
• If still tight/pushy on entry, try braking harder.
• If still tight/pushy on entry, the cure will require a softer front spring rate.

Loose during “roll through zone” only:
• Pinch yourself, because you’re dreaming.
• Are you sure the car isn’t loose, or pushing, on entry causing the car to get loose in roll through zone only?
• This is great news … brake softer, but the same length & increase the roll through zone speed until the car comes back to neutral handling. If it get’s tight, you may need to brake slightly harder to decrease roll through zone speed & cure it.
• Ok, if it is really loose in roll through zone only … soften up the low-speed rebound valving on the front shocks.

Tight/Pushy during “roll through zone” only:
• Stiffen low-speed rebound on the front shocks until the car frees up in the roll through zone.
• If still tight/pushy in the roll through zone, stiffen the rebound on the front shocks until the car frees up in the roll through zone.
• If still tight/pushy in the roll through zone, soften the low-speed rebound on the rear shocks until the car frees up in the roll through zone.
• If still tight/pushy during “roll through zone” only, brake harder, but the same length & decrease the roll through zone speed until the car comes back to neutral handling.
• If still tight/pushy in the roll through zone, the cure will require more than shock & braking adjustment.

Loose Exit:
• Stiffen the low-speed rebound on the rears. Go until the car gets tight on exit … or loose on corner entry …and back up ... or go until you run out of adjustment.
• If still loose, soften low-speed rebound on front shocks until the car grips up on entry … or gets tight in the roll through zone. Don’t go any softer than needed, as this will tighten up the roll through zone.
• Do not soften the low-speed rebound on the front shocks UNLESS the roll through zone is awesome AND the tires spin the instant you touch the throttle.
• If still loose on exit, experiment rolling the throttle on later or slower.
• If still loose on exit, the cure will require more than a shock or driving adjustment.

Tight/Pushy Exit:
• If any adjustment range left, stiffen the low-speed rebound valving on the front shocks. Go until the car gets good on exit ... or go until you run out of adjustment.
• If still tight/pushy on exit, soften the low-speed rebound on the rears. Go until the car gets good on exit ... or until it hurts the entry … or until you run out of adjustment.
• If still tight/pushy on exit, experiment rolling the throttle on later or slower.
• If still tight/pushy on exit, the cure will require more than a shock or driving adjustment.


Keeping Accurate Tuning Notes:Here is the common way in racing ...

a. Everything is from full stiff.
• - means softer
• + means stiffer
• HSC is High Speed Compression
• LSC is Low Speed Compression
• LSR is Low Speed Rebound

b. After the first setting, we always write the change clicks AND the total clicks

c. If you start by softening all three settings by 12 clicks, we write it like this

LF:
HSC -12
LSC -12
LSR -12

RF:
HSC -12
LSC -12
LSR -12

LR:
HSC -12
LSC -12
LSR -12

RR:
HSC -12
LSC -12
LSR -12

---------------------------------------------------------------------------

d. Then from there ... if you stiffened the low speed rebound 4 clicks only on the front shocks, we write it like this:

LF: LSR +4/-8

RF: LSR +4/-8

That means we stiffened the low speed rebound 4 clicks ... and ended up at 8 clicks from full stiff.

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e. If you softened the low speed compression by 4 clicks only on the front shocks, we write it like this:

LF: LSC -4/-16

RF: LSC -4/-16

That means we softened the low speed rebound 4 clicks ... and ended up at 16 clicks from full stiff.

--------------------------------------------------------------------------------

This way, at any point, you know what the total is.

Make sense?