I found this table there especially interesting and simple as far as "tuning": What I don't fully conceptualize is how to get it "just right" between spring stiffness and shock settings, especially when my shocks are single-adjustment for compression and rebound. And then let me add this quote to the mix... it seems to be at odds to what we have been doing to improve handling and control -- stiffer springs, bigger anti-sway bars, and firmer shocks! One of the shock tuning guides says: "In general, stiffening one end of the car will reduce the mechanical grip on that end. In other words, when you raise the spring rate, increase sway bar size or stiffness, stiffen the bump or rebound of a shock, install firmer bushings, etc. you will reduce the grip on that end and decrease traction. To increase grip you must lower the spring rate, decrease the sway bar size or stiffness, soften the shocks, use softer bushings, etc." but maybe that doesn't apply if you do it on both ends of the car as we have done...? I'm no expert on the mechanical-physics principles of this stuff, but I am *sure* my car handles better with all the stiffening/firming changes I've made.
1 If we stiffen the springs for an axle, no matter if it is the bar or regular spring, that end will carry a larger portion of the moment of roll, thereby reducing grip for that axle. But this is in relation to the other axle, not really the sum of the grip for the whole car. Therfor used to BALANCE the car. As a tire is heavier loaded the µ coefficient is falling off, which is the reason for the rising-load-grip loss. 2 However, stiffening the car does mean heavier load of the tires but also more unloading as it creates more abrupt load changes. Therby ALTERING the total grip potential while driving. Softer setting EVEN OUT, road irregularities and chock loading of the tires, and is creating a better overage grip. What governs the spring setting is the tire in use. Or, harder spring will heat the tires more. A There ARE a second reason for harder springs and that is the CAMBER problem. When the car roll, we got +camber, which we do not want. The wrong camber creates "load transfer" within the tire contact patch, therby reducing grip for the same reason as weight transfer over a single axle. Regards Goran Malmberg
Gorans' post is correct although probably more technical than most will relate. Bottom line: If you had a perfectly balanced car (never happens) and you increased the spring rates or sway bar rate in the front, you will lose mechanical grip as a percentage of total grip on the front and increase in the rear. In my case, I went to the track a few weeks ago and found that my 250# springs in the rear were too soft. In heavy power applications, exiting corners, from the apex to corner exit I had power on understeer (also known as tight, pushing, etc.) The shocks are already adjusted properly to suit the springs, so the fix is to increase rear spring rate to keep the car from squatting with power application and lifting the front tires. The Sprint car guys call this forward bite and I have way too much right now. An increase in rear spring rate will "prop" up the rear and balance the car in power on situations. Once I change springs and dial in the shocks again, I may find I need to adjust elsewhere. Note that increasing rear spring rate will decrease rear grip as a whole and transfer grip to the front. Not that the car will be slower by this decrease because overall grip will increase and the car "should" be faster. Tuning suspension is a fine art, but is based on everyday physics. In the racing world you rarely if ever achieve a perfectly balanced car. The trick is to tune it to the parts of the track that matter most, i.e. corners that lead onto long straights or corners where you carry lots of speed. If you got your car to handle great everywhere but 1 second gear corner that leads onto a short straight, you'd be set for the day. John P.S. None of this really matters unless you are at the limit. An ill handling car could feel great at 80% of it's true ability.
Just to avoid misstakes. My inlay was meant to give Mike C an explanation, as he was wondering about springs and grip theory. Goran Malmberg
Wow, i LOVE the direction this thread is going! A lot of GREAT information (and links). This is probably true but also we must remember the public roads here in New England are horrible whereas the track is obviously a smother surface. So this is why 'dialing down for the street' would be a good thing. i can not stress enough how bad the roads here can be.
I should also mention that my analysis is very much track, or hard sportscar driving oriented. Many people have more cruising oriented demands, but such condition is a totally different story. F,ex my shock setting is mostley in bump direction, while rebound is set softer so that the tire grip recovers fast after a bump. While a strictley smoth ride setting is the reverse. Goran Malmberg
Gang, if you haven't figured it out by now, Mr. Malmberg also knows what he is talking about as well. Think of shocks as dampeners, because that's what they are. They control the speed at which a spring compresses and releases. With that in mind, stiffen the spring, and less bump setting will be required and more rebound will be required. Input the same force to a stiff spring and it will resist compression and act slower than a soft spring, therefore needing less "bump" dampening from the shock. Conversely, once compressed, a stiff spring is going to have a strong desire to return to it's original length and do it in a hurry. Thus, it needs more rebound dampening than a soft spring. Many make the mistake of trying to tune the car too much with shocks, and they do have their place, but only after the car is sprung correctly, scaled correctly, and has the proper sway bar rates. Dialing in too much bump to a car sprung too softly will make it thump around like it has welded rods for shocks and loose traction whenever you encounter a bump in the road. Generally I will try a set of springs and tune the shocks to the spring package and track surface. Once set up, if there are handling issues that can't be tuned away with sway bars, tire pressures, etc. another set of springs may be in order. Do a spring change, re-scale, back on the track to dial in the shocks, etc., etc., blah, blah, blah. You get the point. It's not hard, but it can be time consuming even if you know the right changes to make the first time and know what changes will effect what aspects of the handling. There's a reason crew chiefs and engineers get paid big bucks and the teams that have big bucks usually end up in victory lane. Again, have fun, John P.S. Any questions just fire away. I'll try my best to get you pointed in the right direction.
Remember, folks, when messing with your shocks, you want DAMPING. DAMPENING is what happens when the oil leaks out!
ARGH! Don't remind me as at Lime Rock it appears my front passenger side shock DAMPENED the rim because the compression adjustment knob came off.
ok, found a site and i made a brief reference sheet (attached below). Image Unavailable, Please Login
Hardly a guru, at least with 308s, but I am running 6" at the rear and 5 3/4" in the front measured at the lower rocker panel. My measurements are within 1/8" tolerance side to side with respect to scaling the car to achieve the cross weights I was after. I don't have my set-up notes handy, but I do remember the ride heights. Therefore, I am running 1/4" rake at the moment. I haven't spent a ton of time tracking the car to tune it. Maybe 10-15 laps one day last month. I have some other things that I am doing to it this winter and will get it on the track to sort in the spring. John
More QA-1 spring problems. The fronts have acquired so much of a set, though they've been on less than a year, that I'm finally out of adjustment. I love the way it looks, but another couple of months and my front fenders will be hitting the tires. After the problems I had with their springs on my rears (ends not cut perpendicular to the springs' vertical centerlines and eventually wearing through the shock bodies and the QA-1 distributor wouldn't even replace the springs) and now this, I URGE EVERYONE TO STAY AWAY FROM QA-1 SPRINGS. Rediculous. I'm not even going to TRY to have them replaced under warrantee -- I don't want them. I'm buying Eibach's in the same 300# 10inch. Both Eibach and Varishock springs are known to have more resistance to set.
Amazing that they would even be selling cr*p like that. I've have had eibach springs on my car for 5 years without so much as a hint of a problem for what ever that's worth.
Hey Mike, I have had Eibach's springs on Varishocks for the last 6 months and I am very pleased. My origanal shock order came with QA1 shocks but in the wrong length 12 front 14 rear (another story) so I bought Eibach (10-300fr,12-250rr). These springs do settle but seem to have stopped. I actually have my ride height set a little high compared to some of you guys due to the fact that my wheel tire combination was hitting the fender lip under heavy loads. I think my frame rails are 4" from the ground. I am however running out of adjustment. You may not run into this problem because I believe your ride hieght is lower than mine. I think 12" spring would work up front but you would have an akward period until the springs settled. The best solution and what I will do if there is any further settling is to buy spring perches. These will effectively add 1 to 1 1/2" to the spring and that is all I would need. Hope this helps. Bill
Mike, Sorry to hear that. You must have gotten a bad batch. My QA-1s have been fine. They settled a little the first week, but haven't moved since I scaled the car in August. Maybe I got lucky. Try Hyperco springs. They are all we would use when I raced. Eibachs are good as well, but given the choice, I would buy Hyperco for the same money. Good luck, John
I hadn't thought of that before, but for less than $40 for the pair (www.hrpworld.com/index.cfm?form_prod_id=330,41,363_510&action=product) that's not a bad solution... but for me I really want to get rid of the QA-1 springs since with the amount these have compressed, I think the quality isn't there.
John and any others??? I'm wondering if I can intrude of this 308 based suspension discussion and ask you what you think about a setup I have on my Maserati racecar? I think my questions will still be of interest and applicable to the current discussion. I've been driving it for about 2 years now and this year I had a pro who's been doing setups on Porcshe racecars for years set the car up with zero spring/shock changes and take a look at it to give me some advice. The coil overs are only adjustable for height. Are questions ok? Bob
Thanks. OK here goes. Let me start with a little bit of background on the car. It is a cup car that Maserati built in the mid 90's. It's sized about like an M3 and with me and a tank of gas it's 53/47 f to r. It's 3030 lbs wet. It has Bilstein coilovers but the compression and rebound are not adjustable, just the ride height. Struts in the front and multilink in the rear. Everything on the suspension is adjustable with solid bushings and uni-ball links. The front is a single Eibach and the rear is a two piece spring with an aluminum collar for coupling the tender spring. The guy who did the setup (alignment and corner weighting) for me at the beginning of this year said its setup way too stiff (springs and valving on the shocks) for the tracks I use. Lime Rock, Watkins Glen, Summit Point and Pocono. He also said I need more drop in the front for sure and possibly the rear as well. My suspension only drops 1" in the front when I lift the car and the springs don't compress very much when I let it back down. It was strange to me that he's not suggesting adjustable valving on the shocks. He says I don't need it just different settings and different sprints of course. My concern is if it's not right I have to take everything apart again and re-valve them again. He does have a lot of experience with Porsche race cars. Still it seems odd to me? I have a lot of problems with bumpy turns, Lime Rock is just horrible in some spots in this car. I also have trouble with the car when I push hard through 4 in the infield at Pocono and one turn at the Glen (I forget the name) hard right uphill in the carousel? At times the rear gets into a bouncing rhythm and I have to let off (not good) because the rear wheels will get air born. I've also destroyed 3 left front tires at the Glen but not while driving. They always split in the garage a day later. The tires (Pirelli slicks) are not running too hot and are at about 30PSI. We started at -3.5 camber in the front and dialed it back to -2.5 but it's still doing the same thing at the Glen. I'm leery of just having the shocks re-valved. It's not that I'm going to do setups for each track. I just want to be able to find a happy compromise which I currently don't have. Changing springs with new corner balancing is going to be enough tuning without having to actually remove and change the valving on the shocks each time. Sorry if this too much at once but what do think? Bob S. If you guys want me to start a new thread just say so. Thanks.
What spring rates are currently on the car? Also what is the inclination angle of the shocks and struts? I can guess on the fronts, but I have no idea of your rear configuration. John
not familiar myself with the Ghibli however a quick search netted this... http://www.maserati-alfieri.co.uk/alfieri-ghibliopencup.htm may or may not be helpfull. is yours pre or post 95'? hopefully others can chime in with some solid help.
John, I think I have that documentation here (somewhere?) from my setup at the beginning of the year. Let me dig a bit and if not then I'll go out to my winter garage and get the info again later this week. I have the valve specs as well. The inclination angle may be tougher but I don't think that's changed from stock in the rear. The front should be available from his alignment readout notes (I hope). It's a bit of a weird front strut camber adjustment plate at the top. It's offset and to effect camber changers you remove the nuts, drop the threaded studs down out of the strut tower, rotate the entire top of the strut by one or more set of adjustment holes and then re-insert the studs up through the top of the tower. This has the effect of changing the camber and caster simultaneously but not independently. My setup guy didn't seem to think it was a problem though. I am curious though about this guys recommendation to go with a fixed valve setup. He has a great reputation so I'm certain he knows his stuff and he said it was a waste of extra money for me. Your thoughts? Bob S.
Hey thanks for your efforts. I actually supplied a lot of that technical info to Enrico for those pages. There's a lot more information that's just not documented publicly and then there were the 97-98 Italian GT series of races. Several of these cars were upgraded (more like sorted out and completed) for that series. Forget about Maserati knowing anything. They flushed any people who knew anything about these cars some time ago. Their historian, who's been there forever, Mr. Cozza wasn't even aware of the "1996 Evoluzione Kit Documentation" as listed on Enrico's website in the link you provided. I gave Maserati a copy for their archives. Bob S.
