Mike Kojima is authoring very good series on suspension tuning in SCC. Good reading for anybody interested as much of it was written for a Sentra. Our bretheren on the Altima boards were nice enough to digitize the first 3 sections...

Part 1
http://www.nissanclub.com/forums/sho...d.php?t=193317

Part 2
http://www.nissanclub.com/forums/sho...d.php?t=193955

Part 3
http://www.nissanclub.com/forums/sho...d.php?t=196222

I'm hearing part 3 may have some inaccuracies that only SAE members might catch.

 

lots of good info in there, even though it goes over the head of most of the people reading it. Kojima is good at that!

now to figure out how to modify my control arms like he's doing

 

Thats some good reading, its explained very well. This needs to get stickied when its all complete.

 

If someone has these magazines and doesn't mind scanning the article, I'd much rather see that than a poorly retyped copy on a website somewhere.
I'll be glad to buy the current issue, but doubt if the back issues are still on the shelves around here (and I obviously don't subscribe to it)

 

Good write-ups, and it goes along the same lines that I've been attempting to do. At the moment I have a balanced setup (on most courses, at least), with camber plates being the next step.....get some more of that front rubber on the ground!

it's too bad more people on here don't understand how important handling is....everyone is so busy jerking off to their dyno numbers and their 20" wheels.....

 

Errr, look more at the article. we need more than camber correction. look more at the modified control arms.

that's the ONLY part of that article that I haven't severely modded on my car, and I'm still having nasty front tire wear issues...
oh well.. screw it. I'm gonna mod the 240 now.

 

I saw part 1 on the newstand, bought that, and subscribed right then. I'll scan em all when it's finished.

Agreed Matt, we need to fix our control arm geometry. Is Blemco up for that? Or who's near Austin and wants to contact SPL about fabricating some parts for us? In race config my ride height is 3.8" below stock and my arms are pointing towards the sky. I have little idea how I've butchered my roll center but it can't be good.

 

I'm not dropped that low, so a camber adjustment should really be sufficient IMO. For the guys 2-3" low on coilovers, the control arm alteration would be more necessary....

 

I contacted SPL on seeing if it was possible to fab up adjustable front control arms for a Maxima. Needless to say they weren't interested...

The market on the org would be poor, maybe they would sell all of 3~5 sets IMO. These also don't come cheap either, at SPL they cost $700~$900 per set. Come to think of it, Im not even at the level were I could justify something like this. I may just do the available suspension stuff for a Maxima to keep me occupied. But the more I think about it I may just end up getting something lightweight and RWD for a track car.



Those are nice though, shame they have to be installed underneath the car.

 

all this stuff to do.. its never ending... but its soooo fun! I would like to do some AutoXing. Im tired of the 1320. Its fun going to the track but i would like to try auto xing. I need to get some tires that i can dedicate just to track racing. Irish, what kind of rims are you using for the track?

 

if you were going to spend that kind of money on a control arm you might as well try to convert the whole front suspension to SLA like these mustang kits, http://www.miracerros.com/mustang/t_suspension.htm, im not sure if thats entirely possible with our front axles being in the way but that could be sweet in a maxima, too bad i have no money to try it

 

Great link. I'm limited in geometry changes I can make but it might provide an idea or two to work from.

 

It's not that hard. My fiancese's stratus of all cars has that setup front and rear. I was amazed when I saw it. Such a great start to a suspension package ruined by crappy spring rates and weak swaybars.

 

I read Kojimas articles- for people who don't know hes actually a Nissan Engineer, and is verrry knowledgable about cars. I meet him a few times, and even did a clutch on a NX2000 in his garage in SoCal.

I'm thinking of trying to swap the tie rod ends from mounting at the TOP of the knuckle to the bottom to get rid of some of the bump steer. My controll arms are straight out maybe just a little bit pointing up, but my tie rod ends are pointing way up.

I meant to ask Mike about that change but I been bussy and I don't wanna bombard him with tons of Emails. Basically after moving down the tie rods so they attach from the bottom I will have parallel arms with tie rod ends and it should reduce my bump steer by far.

What are your guy's thoughts on this idea ?

 

go for it.
don't bother reusing the tie rod ends..
just buy some HIGH QUALITY 1/2" heim joints, and a 1/2" diameter grade 8 bolt that's 4" long. get a few washers, about 3 nuts, and a length of 3/8" sch40 pipe. the ID on the pipe will be very close to the bolt diameter, but should fit. if not, just go up to some 1/2" sch 40 or sch80 pipe and you'll be fine.

Once you have all the parts, run one nut and a thick washer down the end of the bolt, then drop it into the spindle from the top with a couple inches of it sticking out the bottom of the spindle.. stick another washer and bolt on the bottom of that and crank it down REALLY tight so the bolt won't twist in the spindle and throw off your alignment..

then you can just stack spacers on the end of that as necessary to get the spacing you need for the heim joints.

oh.. you'll also need to make some tie rod ends.. I use 3/4" DOM tubing with a 0.120" wall thickness.. you can tap a 14x1.5mm thread into one end of it and weld on a 1/2" fine thread nut to screw the heim (w/jam nut) into, or buy some weld-in tubing inserts..

Errr.. hell.. I can make you a set, but it'll be a while before I get a chance. I just got done with another shipment of heim joints and won't need to order any more for a while... probably be around $100 for all of it if you want me to do it.

The problem with doing that is that you change the arcs that the steering rack and control arm travel on. this will partially correct the bump steer, but will throw other issues of the geometry off when you do it.
some of this is covered in either page 2 or 3 of the SCC articles mentioned above. This is why they modify the ball joints on the suspension as well. lower the tie rod ends, and you need to lower the ball joint pivots by approx the same amount.

*Heeeeey!! I just thought of something!!* we're lucky on 3 gens that the ball joint just bolts in to the control arm and we can pull the joint off, replace the studs with longer ones, stack some washers on the ends of the joint, and voila!
http://autozone.com/servlet/UiBroker...3d801f58ea.jsp
http://www.rockauto.com/ref/BeckArnl...ml?1013841.jpg

 

You don't think the stockers are going to work when flipped to under the knuckle ? this would even out the tie rod ends with the controll arms. I need to finish up installing my ES bushings this week sometime- only got the drivers side done, so I can give the tie rods a shot, I have an aligment machine at work so aligning the car isn't a problem for me, and I have to do it anyways as I noticed my alitment is now off with the ES bushings.

I'm trying to imagine the setup you have in mind and it reminds me of something we did in my triends Wrangler with his tie rods after he installed a big lift kit on it. 100 bux aint nothing , but I would love to see this setup so I can see what exacly you are talking bout.

I have camber plates so camber adjustment is possible on my JIC FLTA2s- and currently I run 1.25 deg of camber up front and 1 deg of camber on the back- negative ofcourse, with no tire wear issues.

Lucky 3rd gen SOBs, you can eassily remove your ball joint and modiffy it.

I will try to take a picture of my car so I can show you the arcs of my tie rods vs controll arms- my arms are pretty much horizontal with the ground maybe just a little bit pointing up- 10-15deg at the most, where my tie rod ends are more like 30 deg pointing up. I thought if I reverse the mounting of the tie rod end I will make the arcs more even and lessen the bump steer.

 

Sure.. it will change the bumpsteer, but will not eliminate it. I don't know why, but even with Eibach/Tokicos I had ZERO visible bumpsteer issues.. at least none that I recall. now when I jack the car up, it goes from straight to about 10 deg out on both sides. eek!!

I've got them centered as well as I can so that when I push the car down, the toe goes in. when I pick the nose up, it toes out.. this makes for more stable braking (especialyl at high speeds!), but makes the dynamic alignment settings go whacko when the car is leaning in a corner. outer side toes in more because it's compressed, inside toes out because of the extension. this is one of the reasons our cars like to get real twitchy when you're throwing them into a corner. you turn the wheel xx degrees, then as the body starts to lean, it turns into the corner MORE.. woah. fun stuff.

I'll try to take some pics of the tie rod setup I have on mine. I had some somewhere, but can't find them now..

reversing the tie rod ends won't work because they are tapered, just like the shaft on the ball joint pictured above.. in order to make them work, you would have to recreate the exact same taper from the other direction. takes a machine shop to do that.

 

heh..
http://projectnissan.com/shopping/pc...idproduct=3794
one guy complained to me about $100 for them..

 

Thanks for the links. More information on this stuff is always welcome. Now I've got about 27 pages of Word document to print out, read, and hopefully digest.

Thanks for the heads-up regarding part 3 (in particular). Maybe I'll spot something, maybe I won't. Anything that I can't make sense of or struggle to get through becomes food for further discussion.

On edit, I'm interested in seeing the damping discussion of Part IV.

Norm

 

As soon as the Aug issue comes out I'll scan all and put up on soundmike's website.

I'm interested too in the damping discussion. I based much of my damping research on Turbo Mag's 11/04 issue which did a 7pg article on Tein Flex vs WRX vs Sti rates. SPL's site shares their custom Z32 rates. Also, ATI of MI is one of the most knowledgable tuners in the whole USA. Lots of good info on their site ATI site

Oh, and few pages after Making It Stick pt#3, on pg 136-137 they highlight Ed Flores of Progress Group and his skills. He was one of the designers who developed the 3G coilovers with Cheston for Catts.

 

Either the ATI linkee no workee or I'm not very good at guessing what the '***' should read.

Regarding Part III, I did find a couple of things.

The boldfaced portion is not entirely true, at least not as it has been written. The component of load transfer to the outside wheels that occurs due to suspension roll stiffness does increase, but the contribution to lateral load transfer that comes through the roll centers is decreasing at the same rate, and the total load transfer remains the same (as long as vehicle weight, CG height, track, and lateral g's remain constant). The overall front:rear distribution of this lateral load transfer can normally be expected to change as roll center heights are altered, though, and with it, handling balance.


Instantaneously this can be made to be true at one or two suspension positions, but I don't think that it remains precisely so over the full range of suspension travel. The knuckle rotates about the IC, which is not a fixed point. The outer tierod end is constrained to rotate about the inner rod end, which is a fixed point as far as bump/rebound is concerned. IOW, where the tierod construction line intersects either the LCA or UCA line will drift off the FVIC point a little. It's a close approximation, however, and the greatest deviations should occur at the maximum bump or rebound positions.


Norm

 

"***" = "T E T" as in accurate technologies.

 

Sept issue just arrived. No part IV to speak of. Tons of pages dedicated to budget drag cars which we don't care about.

 

heh.. move your mouse one inch north before clicking on this forum and THEN say that.

 

I said BUDGET. Nearly nothing for the Nissan community is inexpensive compared with the Hondas. They're talking complete blown rides for < $4K.

 

Its too bad he messed up his tire pressure thing. If you add air to the fronts and remove air from the rear...you will increase rear grip and consequently understeer

 

If it were only that clear. On the one hand, you're shifting the lateral load transfer distribution forward by effectively stiffening that end with respect to the rear, which moves you toward understeer. But on the other hand, less pressure in the rear tires tends to make them run at higher slip angles (and lower slip angles up front with the higher pressure there), for an influence in the oversteer direction.

Norm

 

Theorize all you like....go try it and come back

 

you can go either wya with it, honestly. I've tuned my car for severe oversteer at auto X by dropping the rears to about 18psi in the past.... I've also jacked them up to about 60.. I leave my fronts around 42psi to keep the sidewalls from rolling over since that's my biggest problem. I tune understeer/oversteer with the rear pressures.

both ways work, just depends on how far you're willing to go with pressures.

 

I run 45 front 35 rear...car is perfectly neutral. If I drop them to 32, the car understeers. If I raise them to 38, the car will oversteer.

 

depends on the tires/ car, i cant get anything but understeer with my rear tires above 36 but it oversteers when they are below 36, also my fronts are at 42 usually

 

I've found the rear pressures to be a black art. There's sometimes a large range where nothing seems to change especially if the suspension isn't perfectly setup. On my sticky S-02's for instance I've gone between 30-60psi with no discernable difference in grip. 300-400 treadwear tires however had a much smaller range. Low will deform the contact patch and usually goes away with some warning. High will raise the edges of the patch causing more snap oversteer. So many different tires with different sidewall constuction (read many Yokohama's) don't work by the regular rule.

 

In part one, they are saying that adding front sway bar decreases understeer, but we all know that, at least in Maximas, the rear sway bar is used for this purpose. Can anyone explain that?

 

Which sentence in part 1?

 

In many cases, adding a bigger front bar on a RWD car will help cure the understeer tendencies. That's why the SCCA allows larger front sway bars in stock classes for Solo II.

I've also seen it help on FWD cars as well, but only in the case the stock bar is way undersized to begin with and the body leans so bad under cornering that it's bottoming out the outside corner.

 

There we go. I was about to say that it depends on what the car's limitations are to begin with, but I had no idea of the specifics.

 

Sta-bars actually accomplish two effects. The obvious one is that they reduce roll, which generally improves the camber situation (and hence grip) at the end whose camber curve is less favorable (generally the front) more than it helps the other end. The other effect is that it attracts lateral load transfer to that end, which reduces the overall grip of that pair of wheels. The overall effect is sort of an algebraic sum of these effects, if you take it in terms of slip angles.

If, for example, the outer front wheel goes into several degrees of positive camber with a way undersized front sta-bar, you might well gain more from the improved camber situation on the front wheels relative to the rear (ending up requiring less slip angle at any given lateral g) than you lose from the increased LLTD (which requires a greater slip angle), and the result would likely be less understeer. If you start with a much stiffer bar, the loss due to LLTD will overcome the gain from improved camber, resulting in heavier understeer. Either way, up front the effect of a bar is the net difference between effects that are working at cross-purposes. There are other effects that might gain from stiffening the front sta-bar, but this is perhaps the pair with the greatest effect.

That's what makes a rear sta-bar such an effective mechanism for reducing understeer (up to a point, anyway). The reduction in roll, however slight it might be, still improves front grip relative to the rear (reducing its slip angle requirement). The increased LLTD is now out back, reducing its grip and making it run at a slightly higher slip angle. Both of these are working in the same direction of less understeer/more oversteer.

Norm

 

Damn good explanation, Norm.

 

Thanks, good explanation.

So, when we add RSB to our Maximas (and not overtighten it) these two affects add up and not just decrease understeer but also increase the maximum g-force the car can handle before it starts to skid?

 

Nope. It will help initial turn-in response and prevent understeer, but whether it helps total sustained grip depends on other factors (e.g. tires and pressure, front camber settings, spring rates front and rear).

For example, if you take a car with coilovers that have stiffer springs in front than in rear, a RSB might increase total grip levels. The same RSB on another car with other aftermarket springs might actually decrease total grip levels.