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Coilover choice: Ohlins vs ??

58
43
Exp. Type
HPDE
Exp. Level
Under 3 Years
TX
600/750 gives you a much higher frequency in the front vs the rear. The car will pitch a moderate amount and will have some understeer (with no other adjustments). Given that you should find that the rear is compliant enough to get power down better than with the OEM setup. Keep an eye on your front tires, I suspect they will wear faster than before relative to the rears. Don't go too much on the sway bars, use them to tune steady state (mid- turn) and then use the dampers for turn in, turn exit. With little to no aero you can run a higher compression : rebound ratio. Instead of the traditional 2:1 or 3:1 rebound to compression, try 1.5:1 rebound to compression and increase rebound based on the stopwatch.

I would be excited for data points if you can relay any feedback once on the track, or even city driving. I spun a rod bearing back in may and I am waiting on a new motor (ford is warranty-ing my motor) so my suspension project is delayed. I will have potentiometer data for the factory setup once I am back in action. It would be good to have comparative feedback to include with my baseline.
 
424
259
sfo
600/750 gives you a much higher frequency in the front vs the rear. The car will pitch a moderate amount and will have some understeer (with no other adjustments). Given that you should find that the rear is compliant enough to get power down better than with the OEM setup. Keep an eye on your front tires, I suspect they will wear faster than before relative to the rears. Don't go too much on the sway bars, use them to tune steady state (mid- turn) and then use the dampers for turn in, turn exit. With little to no aero you can run a higher compression : rebound ratio. Instead of the traditional 2:1 or 3:1 rebound to compression, try 1.5:1 rebound to compression and increase rebound based on the stopwatch.

I would be excited for data points if you can relay any feedback once on the track, or even city driving. I spun a rod bearing back in may and I am waiting on a new motor (ford is warranty-ing my motor) so my suspension project is delayed. I will have potentiometer data for the factory setup once I am back in action. It would be good to have comparative feedback to include with my baseline.
I run the same MCS package racing only no aero nearly a streetcar in SCCA touring class.
I don't think my car pitches at all and nor does it porpose. What is the mechanics of pitching? The front rates are so much higher than stock or PP1 that should resist pitching and it seems to do so. Wear tires? Yeah massive!!! I was cording new hoo hoo A7's in about 3-4 short sessions with SCCA so they are not full four 20 min sessions/day like an HPDE. I had to run the max class legal Ford FP bar in the front, near max legal camber and lower the car to min legal to control the roll and I think my tires will be OK. I run tires square and do not find too much understeer. I'm still dialing my suspension in and think a got more time to be made up. Shocks I don't know what they do so left them at the rec starting points. I'll get around to playing with them soon but I fee victorious just trying to get ahead of tire wear...I think.
 
58
43
Exp. Type
HPDE
Exp. Level
Under 3 Years
TX
I run the same MCS package racing only no aero nearly a streetcar in SCCA touring class.
I don't think my car pitches at all and nor does it porpose. What is the mechanics of pitching? The front rates are so much higher than stock or PP1 that should resist pitching and it seems to do so. Wear tires? Yeah massive!!! I was cording new hoo hoo A7's in about 3-4 short sessions with SCCA so they are not full four 20 min sessions/day like an HPDE. I had to run the max class legal Ford FP bar in the front, near max legal camber and lower the car to min legal to control the roll and I think my tires will be OK. I run tires square and do not find too much understeer. I'm still dialing my suspension in and think a got more time to be made up. Shocks I don't know what they do so left them at the rec starting points. I'll get around to playing with them soon but I fee victorious just trying to get ahead of tire wear...I think.

What car do you run? Lots of things make a difference, roll center, roll couple, etc. Pitching is the fore and aft (longitudinal) chassis motion. When you accelerate and you have a higher front ride rate the car experiences a longitudinal acceleration (squat) and the car pitches backward. When you come off the throttle or are hard on the brakes the car can pitch forward (dive) depending on your total front ride rate.

Depending on your chassis and your aero balance some setups become pitch sensitive. Aero can be particularly sensitive and as the car pitches you can upset your aero balance (not ideal). With no aero your car is less sensitive to pitch and so you do not have to worry about it as much. Typically an amount of pitch is acceptable to "tie down" a corner of the car, and produce predictable aero performance.

You asked for mechanics... you're gonna get mechanics :p

""In general a lightly damped vehicle will exhibit two modes of vibration: a "pitchy" bounce and a "bouncy" pitch, each with its own center of oscillation and frequency. The "pitchy" bounce has its center of oscillation outside the wheelbase and the "bouncy" pitch has its center of oscillation within the wheelbase.

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""In addition to controlling the unsprung mass on rough surfaces (as discussed under Ride/Handling Compromise), the damper comes into play on turn entry and exit-the transient phases of cornering. During these phases the vehicle has a rolling velocity which creates damper velocity and force. A similar situation exists with pitch due to acceleration or braking. Roll and pitch occur simultaneously in racing as the driver works around the "g-g" diagram. The effect of the dampers is to change the loads (and load distribution) on the wheels during transients. These load changes in turn result in changes in the lateral tire forces, changing the directional stability and control, particularly near the limit of adhesion.""

Soft ride is generally incompatible with the stiff springs that are required to control body motion in roll and pitch under the high lateral and longitudinal accelerations found in race cars. For those cars that operate on bankings (or with high aero download) the problem extends to heave (pure vertical motion of the body) as well. Good ride in the passenger car sense also dictates the relationship between front and rear natural frequency which is usually in compatible with roll stiffness requirements.

In some suspension designs there is a significant change in ride height with longitudinal acceleration so it is necessary to make sure that the correct dynamic CG height, h, is used. This ride height change is due to suspension geometry effects and ride/pitch effects that are variously called anti-dive, anti-lift, and anti-squat

In racing applications overall lift and pitching moment are usually combined into separate front and rear lift acting at the respective axle locations

In general, steer that results from wheel ride (bump) motion and body roll (and pitch) motion is undesirable. With most types of steering and suspension systems some steer with ride travel is inevitable. The reason to run zero bump steer is very simple: If the wheel steers when it runs over a bump or when the car rolls in a tum, the car will travel on a path that the driver did not select. ""

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20
26
Exp. Type
HPDE
Exp. Level
3-5 Years
Jacksonville, FL
Wow, where did the time go. Way overdue to provide an update here on my progress. So, all new suspension parts have been installed. Did this all myself (what better way to really understand the suspension?). Took me forever doing it an hour here and there. In addition to the bits I was planning to go with, I ended up adding tie rod ends and tension arms for good measure. The stock ones just looked so out of place with the shiny new SPL LCA. Anyway... in summary, here's what's been installed and I'd like to hear any thoughts on my question at the bottom regarding setup/adjustment before I get it aligned.

MCS dual adjustable dampers w/remotes on front and rear
600/750 springs front and rear
Vorshlag camber plates (camber and caster adjustable)
SPL front LCA (adjustable length and spacers for ball joint offset)
Whiteline front and rear swaybars and endlinks


after I got that on I decided to add:

SPL front tension rods (adjustable length and spacers for ball joint offset)
SPL outer tie rod ends (spacers for ball joint offset)


I've got it lowered to just about where I think I want it now, and have let it settle out a bit, sitting at about 1" lower than stock, measuring 14.25" in front and 14.50" in rear (center of hub to highest part under fender); from pinch weld to floor, that puts me at about 4" in front and 4.5" in the rear. Just high enough that I can still get my quickjack under it.

I've got camber set at about -2.9 with room for a little more without cutting the strut tower. I had planned to cut/enlarge the strut tower holes to allow me to run more camber adjustment, but decided to hold off on cutting for now. (I think that might move the car into a different class in NASA or SCCA?)

I left caster setting at stock. The vorshlag plates do have a single adjustment setting that increases caster about 1degree.

Toe was way way out due to the camber change so I pulled it in myself to get it to about 0 (required four completed turns of the inner tie rod to get it there).

I bought the Tenhulzen two-wheel alignment tool to mess around with for fun and to see if I could make some adjustments on my own but caster is tricky to read on it. I'm somewhere between 6-8.

I was pleased to see everything fits really well. Tight but well. I'm running the 8x11 Apex EC-7 wheels with 25mm hub centric spacers with 305's up front and they fit like a glove. VERY little space between inside sidewall. The MCS damper allows for an adjustment at the top of the two lower bolts so the damper can angle out (for even more camber I assume) but I have to leave it completely straight (like OEM) in order for the tire not to rub on the damper. Even as it is, I probably have only a little more than 1/8" clearance. Maybe a problem as tire pressure increases on track? And I can't see how I could fit a 315 as someone had suggested unless I add another small spacer. Anyway, I get full turn range with no rubbing on wheel well liner.

Next step is to get it to the alignment shop for a final alignment.

Before I do, am wondering if I've done the right thing with my initial adjustments on the LCA, Tie rod ends and tension rods.
First, I adjusted the lengths of the LCA and tension rod lengths to be as close to stock as I could to start there.

Now we come to roll center adjustment. Both the LCA and tension rods as well as the outer tierod ends have washers to adjust the height to re-align the roll center that changes as a result of the lowering. Since I'm lowered a bit more than an inch, the tech at SPL advised me to use both of the spacer/washers to lower the LCR at the wheel/ball joint. I think they are 1/8" each so about 1/4" total. Doing so gives the LCR a moderate slope down from chassis to wheel. For the tierod ends, I set the spacers such that the tierod angle was as close to parallel with the LCR as possible which meant using all the washer/spacers provided. Wasn't sure what to do with the tension rod spacers so spaced it about the same amount, maybe a bit more. My understanding is that will account for some of the lowering as well as effect dive characteristic (and length adjustment can be used to adjust caster as well).

The mechanic I use is going to do the final alignment and setup for me and I'll ask him about the roll center changes but before I do, am curious if you all have any thoughts on how I've set it to start. Knowing my mechanic, I expect he's going to tell me I should have just left it at stock height and not mess with it at first and he may be right, but I figured I'd start with getting it at about the height I'd like and see if I can tune it from there as the starting point. Maybe a bad idea. Yes, I know that too many adjustments can be opening a can of worms...

I've learned a lot so far. Appreciate your thoughts.
 
Sounds like some great progress.

I’m not sure about the roll center correction so others can chime in there. When you get it and camber where you want I’d strongly suggest to build, borrow, or buy a bump steer gauge to set your tie rod ends up. I built a simple one to do my car and not only did it require much fewer spacers than spl indicates, 0.02” was the difference on my car between readings that were acceptable and ones that were not. Eyeballing it cannot get you the bump curve you are after. It’s a process, but with all the nice parts you have installed you might as well finish the job off right.

A pic of my gauge in case you have interest to build one yourself:

16C6BB5D-7D39-4139-B80C-E21FA326839C.jpeg
 

Bill Pemberton

0ld Ford Automotive Racing Terror
5,549
4,081
Exp. Type
W2W Racing
Exp. Level
20+ Years
Blair, Nebraska
Sounds like a great set-up , and similar to mine -------big fan on the MCS set ups. Running dual adjustable dual remotes on my Boss S, though I have only had a chance to run them a couple of times with Covid and getting some upgrades on the car ( fuel cell being done at Chicane 23 ).
 

xr7

TMO Addict?
417
411
Exp. Type
Autocross
Exp. Level
5-10 Years
Minnesota
Scootsmcgreggor - did you check both sides, or run the same shim stack on both sides?
 
Scootsmcgreggor - did you check both sides, or run the same shim stack on both sides?

Just did the same shim stack on both sides after setting up one side. Ideally would have done both sides separately but was also not sure if I'd keep these alignment settings so decided to do just one side and copy for now in case I change the alignment and need to do it again anyways.
 

xr7

TMO Addict?
417
411
Exp. Type
Autocross
Exp. Level
5-10 Years
Minnesota
I'm going to be doing mine this winter, it will be interesting. Probably will build a home made jig also.
 
20
26
Exp. Type
HPDE
Exp. Level
3-5 Years
Jacksonville, FL
Appreciate the help guys. Have a quick question related to my build. Not sure I should post it here, but you’ve been very helpful and I’m in need of a quick decision.

I have a lot of homework to do regarding NASA time trial and classing and the impact that modifications have on it. I started to do some research, but I have a quick question that I thought you could help with.

Will replacing the rear lower control arm bushings with spherical ones impact the time trial classing of my S550?

Having my car aligned on Friday, and my mechanic really wants me to make that change swapping out the rear rubber bushings. He’s race prepped mustangs for a while and thinks it’s a big performance improvement which I suspect it is. My question is should I have him do it now or wait until I better understand how it might impact time trial class?

I have the bearings and he says it’s a 5 to 6 hour job, I’m inclined to Weight on it and just have him do the alignment and leave them alone for now until I better understand it but appreciate your input.

if the rules are pretty clear that it makes no impact I would have him do it while it’s in the shop considering schedules etc. Thanks.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
5,549
4,081
Exp. Type
W2W Racing
Exp. Level
20+ Years
Blair, Nebraska
Have you gone to members.drivenasa.com and checked out the rules Classification /Calculator? That should help you a ton, but assume you have not gotten a Time Trial NASA license yet? Go down to the Super Touring /Super Unlimited classification section and plug it in. I would use ST2 or ST3 if you are just guessing at your Class. Good luck.
 
Not sure on the class implications but that rlca bearing is one of the best handling and predictability mods I’ve done so I hope you can put it in for
Your class or say F it and do-it anyways.
 
20
26
Exp. Type
HPDE
Exp. Level
3-5 Years
Jacksonville, FL
Have you gone to members.drivenasa.com and checked out the rules Classification /Calculator? That should help you a ton, but assume you have not gotten a Time Trial NASA license yet? Go down to the Super Touring /Super Unlimited classification section and plug it in. I would use ST2 or ST3 if you are just guessing at your Class. Good luck.
Thanks Bill. I’ll do that. Correct, no license yet. Am just thinking ahead and probably overthinking it. Thanks.
 
2
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Mid Atlantic
Does anyone have feedback on MCS RR2 Remote Shocks?

GB33, have you had much seat time with these fitted?
 
20
26
Exp. Type
HPDE
Exp. Level
3-5 Years
Jacksonville, FL
Just completed first track day with the new suspension. Wow. It’s a different car. Still have to get the adjustments right and get seat time but so far so good. By the way, I did end up replacing the rear LCA bushings for good measure. Car feels like it’s on rails.

It was a private track day and so had several long sessions and at the end of the last two, got the axle temp high warming as the diff was getting too hot. It was almost 90 degrees out and the track was hot. I’ve read the various suggestions such as running heavier fluid and wrapping the exhaust to keep heat away as much as possible but it seems to me that that the only real sure solution is to bite the bullet and put in a differential cooler. Thoughts? Any recommendations on which one and how difficult is installation? Thanks.
 

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