so i changed my suspension setup again.....

[rdyzz]

anyways i was using ground control and koni setup before. running 5kg front and 7kg rear with no rear swaybar due to wheel lift at hard corning. it works ... anyways my quest was to be able to lower the car more (1 finger gap) and have sufficent stroke 3" +. my modified rears with the koni cartridge from the front of a corolla works just fine. however my fronts did not have enough stroke to be lowered to the point of 1 finger gap. if lowered to that point it had maybe 10mm worth of stroke.. and the shortest koni race cartridge was only 15mm shorter. so i would have to cut my strut housing 15mm shorter. it did not make sense for me to go this route because what if it still did not have enough suspension stroke. so i ended up calling up D2... yup D2, to see if they could sell me only just the fronts. well they did. after reading many mixed reviews on them i finally got mine today. the changes i made were i ended up using my ground control 5kg spring instead of the 7.5kg that came with it.

i'm not sure how long they will last, but my impression right now is that they exceed the ground control/koni in comfort and handling. not just that but they ride way smoother and softer than my old cusco coilovers ever did. they are not bounchy like the koni's. this might be due to the fact that i changed to way softer springs. even if they blow i there is a guy on mr2oc that can rebuild them for cheap, and revalve them better then D2 ever had them. im saying the D2's are decent and might be good if they actually used softer springs. yes i know, but this is comming from a guy that has owned many set ups. no i have not owned anything crazy like full race dual resorvior stuff, but i have owned tein flexs, cusco comp s, lowering spring gr-2 setup, ground control/koni setup. and these cheap taiwan coilovers paired with softer springs has exceeded anything i've owned. however the quality and longivity of the item has yet to be experianced.

so the current setup is D2 coilover with eibach 5kg spring in the fronts and corolla front koni and ground control 7kg in the rear (swaybarless). my setup is for street tires and not meant for slicks if i were more serious i prob would not even use the setup i am using. my car would not be lowered to 1 figer gap and it would not have a full interior lol.

[eage8]

you were using front MR2 cartridges weren't you? changing to GT-S ones might have helped... I don't think my travel is nearly that bad, but I haven't actually checked....

I'm at about 1 finger... http://userpages.umbc.edu/~migol1/RX...rollasized.jpg

[rdyzz]

even with the corolla struts the strut body is still a fixed height. even at the last height setup the most annoying thing was bottoming out on mild sized bumps.

[kwint]

Yeah, D2 seems to have mostly positive reviews from all different car drivers. The OTS rates are said to be pretty comfortable as well.

[rdyzz]

pros..
ok so after autocrossing with them and driving on the road with them. i still feel they are pretty decent for the money. they worked great at the track. just went to a test and tune yesterday and my car was about 1-2 seconds slower then 200whp cars with stickier tires (starspecs, azenis) im only 100whp (if that) and using 195/50/15 yokahoma s.drives. the car rolls somewhat still and thats the whole point. because i'm mainly tuning my setup for street tires.

cons..
the main thing i dislike about the D2's is that i dont think thier 32 way adjustments work as well as it should. full stiff did not do much to the compression valving. it felt like it had the same amount of compression/bump dampening as on full soft except with slightly more rebound dampening. atlest on the koni's the adjustment did somthing to the bump dampening. i can see why they used a very stiff spring. so basically the spring is doing all work of the compression valving while the rebound controls the springs stored energy. i dislike this for one reason, bumps. yes it does bottom out from hitting decent sized bumps on the highway. due to this the longivity of their product is questionable. as i said however i did not get this because i knew they were the best or thought so. i knew their short commings and mixed reviews. however i wanted to lower my front more and there was no other option cheap enough. anyways i know a shock guy that can rebuild these and make them work.

[eage8]

Originally Posted by rdyzz

atlest on the koni's the adjustment did somthing to the bump dampening.

the majority of single adjustable dampers only adjust rebound damping, including konis.

[rdyzz]

Originally Posted by eage8

the majority of single adjustable dampers only adjust rebound damping, including konis.

i thought their bump dampening did go up some. i have no solid info on this other than the fact of when my koni's are on full soft it is less rough then when it is on full firm. leading me to think that some degree of compression/bump dampening is also increased kinda like a 10/90 deal. 10% increase in compression 90% in rebound. thats what my butt dyno is telling me anyways. as far as using the best, it doesnt much matter to me. i do like things to just work, due to that fact that i am not a professional driver or posses such skill level i could never take full advantage of the best equipment. however one of the things i love to do the most is corner that is why i love suspension debates or discussions.

[eage8]

yeah, you certainly got me thinking about what to do with my rear suspension setup. It seems if I make it stiff enough with the sway bar to be able to slide when I want it to... it also slides around when I don't want it to :P

I'm currently back onto the softest setting on my 20mm whiteline... and it's ok for high speed courses and the middle setting is ok for low speed courses, but the last course I was on was half high speed and half low speed and it didn't work well :P

I've been thinking getting some ground controls with much stiffer springs and maybe a bit stiffer than normal in the rear and leaving the whiteline with the softest setting...

or I could go with a smaller bar, for which the only choices that I know of are the 19mm Ultra racing bar or the discontinued TRD bar which is about 19mm and hollow.. which probably would be best, but also impossible to find...

Or I could just go your route... but probably a bit more extreme, something like 500F/500R or 600R (in in/lbs)


I'd actually like to go a bit higher with the ground controls than I am right now. Just because right now my control arms are pointing a bit up... which is bad for your roll center.

[canadianae92]

good to hear, was thinking of picking up a set of d2 coilovers this summer

[eage8]

Originally Posted by eage8

Or I could just go your route... but probably a bit more extreme, something like 500F/500R or 600R (in in/lbs)

just got off the phone with Ground-Control. I ended up going with 525 lbs front and 600 lbs rear springs. (metric: 9.3k Fronts with 10.7k rears)

[rdyzz]

nice. should let us know how that works for you. i'm also running .15 degree of toe-out up front and rear. my car is still a street car so nothing to crazy for alignment. since your in a class i'm not sure you can do this, but with the pillow ball mounts up top. i pointed them so instead of adjusting camber side to side they go diagonally to add caster. so far i got anywhere from 3.5 to 3.9 of positive caster from doing so.

off topic...
i see this helps in 2 ways especially if your running wider wheels. 1 it adds caster of course, but 2 it changes the scrub radius somewhat since it moves the pivoting point inwards more, effectively shifting your scrub 1 inch or so outwards. so if your car was designed for a 6.5" wheel with a +42mm offset wheel. having the weigh sit in the middle of the wheels. and then you did what i did and got +25mm wheels that are 8" wide. all a sudden you got 38 more mm of wheel. and while 2 more mm are in the inside 36mm of it extends outwards. now all a sudden that extra 36mm you just add doesn't benifit as much because not that much weight is on it. so shifting the scrub radius will help with tprque steer and stability. or so im lead to belive... its even worse when you dont get wheels that are wide both ways. if you just had a 6.5in wheel and shifted the offset to a + 10. all a sudden since you shifted the offset outwards only, and did nothing to add width to both sides. your suspension is still designed (if all is stock) to have the weight sit directly in the middle of the +42 offset which would mean it sits 3.25" of the way on your wheels. so if like i said you only changed offset to a +10 but still remained a 6.5" wheel, you will have most your weight only sitting 2" of the way in instead of 3.25" of the way in. which will = torque steer and other problems as well.

here is a rough diagram of my suspension measurements and how changing pivoting points would affect strut andgle and scrub radius.

[eage8]

Originally Posted by rdyzz

nice. should let us know how that works for you. i'm also running .15 degree of toe-out up front and rear. my car is still a street car so nothing to crazy for alignment. since your in a class i'm not sure you can do this, but with the pillow ball mounts up top. i pointed them so instead of adjusting camber side to side they go diagonally to add caster. so far i got anywhere from 3.5 to 3.9 of positive caster from doing so.

my current alignment:
front
0.15" toe out
-3.4* camber
stock caster

rear
0.1" toe in
-2.5* camber

that's still very much in development though, I haven't played around with it that much. how that I have more predictable springs, the rear toe will probably change.

I currently have camber plates on order (they were back ordered from tein) and I was going to do exactly that. and I mentioned that to the ground control guy and he recommended against it. He sent me some info that I'll post in a bit about caster which was interesting.

[eage8]

Tech Talk - Caster

A short dissertation on CASTER, the most misunderstood of the three front wheel alignment angles, with regard to production based roadrace cars.

Of the three main front wheel alignment angles, camber, caster, and toe, it is certain that caster is the most confusing and most subtle, and therefore the most misunderstood. This subject requires a working knowledge of racecar front end geometry as found in one of the many books available, some of the best of which are listed below.

Camber is the angle at which the top of the tire is tilted in, as viewed from the front of the car. As the front tires are turned left and right, the camber changes slightly because the pivoting points for the tire are not vertical as viewed from the side. If the car has positive caster, as most every racecar does, the topmost pivot is behind the lower pivot and this causes the tire to tilt in more at the top as the tire is steered inward. This small amount of negative camber gain is the most common reason for the popular misconception that a lot of caster is a good thing.

While it is true that most cars DO handle better with more caster than the factory spec, and many handle well with as much caster as possible within the limitations of the body structure, it is definitely a fallacy that "more is better".

The most confusing thing about too much caster is that the car can FEEL better, but actually be slower on the track. This is aggravated by the possibility that the car can feel so much better that the driver actually goes faster, even though the bumpsteer and corner weights are made worse. This occurence is the driver's problem for not going fast enough to begin with and there are books for that too.

Changing caster primarily affects four things, high speed stabilty, camber gain, bump steer characteristics and relative corner weights (wedge). There is no disagreement that high speed stability is a good thing, so extra caster is a plus there. Camber gain with extra caster just happens to be in the direction we want, more negative, so that's good too, however the amount is usually greatly overestimated as shown in the example below. Bump steer however is affected adversely, but this can be changed, however I have seen many racers get caught out by this one. Corner weights are the big problem with too much caster, as extra caster definitely affects an otherwise balanced racecar for the worse.

What occurs with extra ("too much") caster is that more and more weight is transferred off of the outside front and inside rear tires, while this may at first sound good because taking the load off the outside front CAN be good, the reality is that the outside rear tire will be doing too much work in the middle of the turn, so steps then taken to alleviate this will cause a corner entry push. Additionally, on any rear wheel drive car the inside rear tire will be light and won't come off the corners well. Remember we're talking about a well balanced car here, not a car where this extra caster covers up a sway bar or spring problem.

There's nothing like a good example so here are some actual numbers from the use of data acquisition, a set of electronic scales and an alignment machine. With caster + 3.5, camber -1.5,when the tires are turned 7 degrees as typical for sharp hairpin, the camber gain was 0.35 degrees (not much!) however the corner weights changed by 22 on just the outside rear tire. With caster +5.0, camber -1.5, and 7 degrees toe-in, the camber gain was 0.50 degrees (still not much), but the corner weight changed 35 lbs. on the outside rear tire, which is just too much. The most interesting item in these examples is actually how little the camber gain changed. This stuff applies equally to FWD and AWD cars, but for slightly different reasons.

This page is for thinking purposes only, and of course you may find totally different results, but all engineering students who feel typically argumentative are cheerfully advised to get out of the computer lab and race something, instead of E-Mailing me about why their theories disagree.

Books: Race Car Engineering by Paul Van Valkenburg, any Carroll Smith book, How to Make Your Car Handle by Fred Puhn, and the new Don Alexander book is way better than the old one.

[rdyzz]

my reasoning for running more caster is so i can run less static camber. so you get more braking and acceleration out of the tires. did not realize that caster only affected that much camber gain.
i'm kinda wishing there was a drop spindle for our cars....


hymm very interesting. i guess i will have to test both setups to see which is faster. its just to bad that you really can't. atlest not on an autocross course anyways since the corse is never the same with every future event.

[eage8]

can you post a picture of your caster plates?

I'm interested to see what angle they ended up at.