AE86 Suspension and effects

[aaronlee133]

Hey everyone,

Before I go into my question is anyone else having this issue with posting and/or the search function? I think it began ever since the forum was updated not to long ago. I keep getting the following error message: "The specified search backend doesn’t exist."

Having said that, I apologize if this thread is duplicative elsewhere. What I wanted to know was starting with a base AE86 chassis, how do certain suspension modifications, in isolation, effect the car characteristics? and i dont mean struts and springs. I understand the general of it, e.g., large rear swaybar equals more understeer, etc but what I'd like to know is your personal feeling of how the car changed and what you feel differently. For example, and if you did purchase a sway bar (front or rear, and brand), what did you feel/notice different? If you added a chassis brace (brand, and front/rear/strut/frame) what did you notice differently (and no textbook answer, please)... I'm really curious to hear people's feedback and whether they were happy with that modification. lastly, if you had conflicting upgrades e.g., added this and then added that and it ended up cancelling out one another.

Thanks fellas,
-Aaron

[Deuce Cam]

Search doesn't work.

Here's my grip street car take.

I'll start off by saying that with everything else being the same, imo, generally speaking, lowering the car decreases grip and turn in feel. It's because of the rear suspension design. One can get away with around a 1" drop without much of a negative affect, but it gets worse the more the car is lowered after that. Good for drifting though.

Hardened bushings increase response/feedback, and provide a more solid/consistent feel at the expense of compliance. These affects increase as one goes from hardened rubber->polyurethane->solid heim joints. I've had a mix of all to certain degrees. On the street I prefer all rubber bushings (trd, cusco, or oem).

I've tried a few sway bars. I had 24mm whiteline front and 18mm whiteline rear both adjustable and set to full soft. There was less body lean and the chassis seemed more responsive to steering inputs. Overall there was more under steer and less grip on my setup. The rear felt more stable. I changed to a 23mm cusco front sway and everything felt the same. Then I put the oem gts rear sway bar back on which equated to a little more body lean, but perhaps less stability and more grip (still under steered though). Finally I'm back to oem gts bars front/rear (22/16mm) which I prefer - lots of lean, but grips nice.

I've had a few front strut bars. IMO the round cusco/style bars are the worst since they flex the most. One can grab the cross bar by hand and easily flex it. However, when installed correctly (i.e. with suspension fully hanging/drooped) they all slightly increase: steering effort, rigidity, and feel consistency in a turn.

Wheels/tires: I've never used really wide or low offset wheels. I've also never tried stretched tires. Increasing the track will increase stability, but hurts turn in feel. With tires one generally wants a good width/height ratio to get the best performance and feel. Compared to the wheel width, a nice square tire profile without too much height is ideal imo. That way one will get the most out of the package and also get good turn in feel/response. From my experience I've found that having wider wheels in the rear (compared to the front) increases under steer.

[aaronlee133]

Thanks Deuce!

Your feedback was exactly up the alley of what I was looking to hear!

I'm currently running the full Protean bushing kit including new bushings and end links for the OEM GT-S front and rear sway bars. Interesting to hear that you went through several variations but came back to OEM bars for grip.

Regarding the strut bars - you mentioned in your opinion that the round cusco seemed to be the 'worst'. In terms of sway bars in general tho would you say it affected understeer/oversteer at all or simply just the rigidity and steering effort?

Have you any chance ran rear stiffening braces at all?

Thanks again! Super helpful.

-Aaron

[Deuce Cam]

I lied, forgot that I still have prothane end link bushings front/rear, but everything else is rubber. Reason is rubber end link bushings seem to wear out faster under hard use.

A front strut bar that is installed correctly will net some rigidity. You might also notice a small increase in steering effort with a manual rack, but negligible.

Sway bars are more noticeable in terms of under steer/over steer. I only tried an og whiteline 18 mm rear sway on full soft. (They changed the design years ago and are now 20 mm, unfortunately.) I'm pretty sure all others are 20 mm +... Anyway, I never had a large enough rear sway to get over steer bias from that alone. However, I always noticed under steer with larger front sway bars. It's not uncommon for sways to reduce grip, but it depends on the overall setup. Usually more tire can take more sway.

When I had a hatchback I had an amt tri bar. It was legit and made the car feel similar to a coupe, but they're no longer available. Swangbiz made a similar tri bar, but I don't think they're available anymore either, unfortunately. IMO rear strut bars like cusco, etc. are a joke.

[gotzoom?]

Without knowing what you plan to do with the car and which tires you plan to run, feedback will be of limited value, but here's my experience with the car, which is mostly track driving.

Unfortunately, most of the shock/strut suspension kits that say AE86 on the box are junk. Yes, they will be better than a 30 year old stock suspension, but they are generally designed to feel sporty rather than actually be sporty. You'll see tons of people raving about this suspension or that suspension, but the reality is that most have no point of reference and are simply looking at the difference between a 30 year old suspension and what they bought. If you want to make the car go fast, your only real option is to cobble something together after doing a lot of research and measuring. The front is pretty easy. Koni makes the 8610/8611 strut inserts that work well and can support any springrate that makes sense to run on the car. If you can find a set, the SP Tec coilover sleeves are by far your best option. They cost a little more than the aluminum sleeves you'll read about, but the weld job is $50 vs $150. They will also be welded to the strut tube so they don't spin when you adjust the collars. The rear is more of a problem, and where you want to spend your money. Probably the easiest way to go that works relatively well is to get the TRD blue rear shocks. They aren't stupid expensive and they work ok. The adjustment is a bit course and they have a bit too much compression damping, though. Stay away from anything meant for a Camaro or Mustang unless you can easily revalve them. The damping is much too high and they are designed for much more motion ratio than we have on the AE86. I'm currently running QA1 Promastar single adjustable rear shocks that have been revalved. They work better than the TRD shocks, but they are still not great.

With regard to springs, my advice is "don't believe the hype." Everyone swears by the 8kg/6kg setup, again, because they don't know any better. 6kg is much too stiff for good rear grip. I am running 4.7KG rear springs with Hankook RS3's and I'll go as high as 5.5kg with DOT-R tires. For the front, I think you can get away with 8kg, but you should probably go lighter. Getting the balance is important, so you will probably need to experiment with rates to get the balance the way you want. IMO, the single most important mod to the AE86 suspension is Whiteline adjustable front and rear swaybars. They give you the ability to fine tune the balance better than any fixed swaybar. I also like the fact that they are easy to adjust at the track so I can tame inside wheelspin in tight corners, etc.

Wheels have a bigger impact on handling than you might expect. The factory wheels are positive offset, so that tells you the hubs and front geometry are designed for positive offset. When you run zero offset or negative offset wheels, you introduce something called scrub radius. it basically means that the front wheels no longer pivot on the center of the tread. The impact on handling is that the car will feel "numb" at center and it will feel like the turn effect is delayed. You'll turn the steering wheel and the car will start turning after some delay. It's more of an annoyance than anything, but it makes it tricky to be precise when you're at the limit of the tires.

Other setup advice that I have: Make sure you do not have any rear thrust angle. You'll need adjustable rear links in order to dial it out. Even a tiny amount of thrust angle will make the rear unstable. Depending on the tires you run, you may need more camber than seems sensible. For example, I run 4.5 degrees of negative camber with Nitto NT01 tires. I really need 4.7 to 5.0 degrees, but I can't get more than 4.5. That much camber makes the car very darty and not much fun to drive on the road, though. A good limited slip diff is also a must. I recommend the Tome T-traxx 2-way. It works well and will improve grip. I feel it works better than the TRD diff that everyone raves about.

Hopefully that gives you some more to think about.

[aaronlee133]

Very insightful.

What I'm planning to do with the car is mild fun - some auto-x, and the occasional HPDE in between. At the moment I went ahead and installed the entire Prothane bushing kit. The only bushings I didn't replace was for the stock tension rods since I'm using T3 rods in place of. For struts I'm running full stroke bilstein monotones with Tanabe springs. The spring rates on these are very mild and close to stock (+20%-30% stiffer): 2.8F/2.6R and lowers the car ~ 1in F/0.7in R.

When I purchased the car I thought about what it was I wanted to do and that's when i decided to go with a mild suspension build, which only lowered the car slightly so as to not disrupt too much of the geometry.

I'm currently running Volk TE-37's 14x7 0-offset and Azenis RT615K. And your comments re: numbing effect is interesting as I haven't had time to drive the car since rebuilding it but now I'm curious to see how it feels since I previously had watanabes that were +14.5 offset on this same suspension.

Getting to the heart of the matter was simply that I used to track an RSX-S and had a lot of suspension mods: tein coil overs, camber plates, J's racing roll center adjusters, chassis stiffening brace, Mugen front/rear strut bars, rear camber adjustment arms, and an oem type-R rear sway and OEM Type-R LSD. At the time I was younger and had just started working so in short I threw a lot of money at it. As I started going to track events and learning more about car/handling characteristics etc, I began to realize that I should have taken my time with the suspension build. And then slowly but surely, I began to experiment and remove items until I got it to where I liked it. So fast forward to today, I haven't replaced any of the sway bars (other than bushings and end links) nor added any strut or chassis stiffening items. I am not familiar yet as to how all this effects a 4-link rear and the 86 chassis in particular and once I start taking the car out and have a pref on what I want the car to do I was going to refer to this thread as a reference i.e., i want the car to do this more. based on feedback, i may want to....

I def like your insight on the spring rates.Interesting you delved into that as I remember hearing the rave on that combination and from my track days i thought, wow, 8K/6K??? That seems a lot for such a car.

[oldeskewltoy]

For struts I'm running full stroke bilstein monotones with Tanabe springs. The spring rates on these are very mild and close to stock (+20%-30% stiffer): 2.8F/2.6R and lowers the car ~ 1in F/0.7in R.



I'm currently running Volk TE-37's 14x7 0-offset and Azenis RT615K. And your comments re: numbing effect is interesting as I haven't had time to drive the car since rebuilding it but now I'm curious to see how it feels since I previously had watanabes that were +14.5 offset on this same suspension.

Getting to the heart of the matter was simply that I used to track an RSX-S and had a lot of suspension mods:

As I started going to track events and learning more about car/handling characteristics etc, I began to realize that I should have taken my time with the suspension build. And then slowly but surely, I began to experiment and remove items until I got it to where I liked it.

So fast forward to today, I haven't replaced any of the sway bars (other than bushings and end links) nor added any strut or chassis stiffening items. I am not familiar yet as to how all this effects a 4-link rear and the 86 chassis in particular and once I start taking the car out and have a pref on what I want the car to do I was going to refer to this thread as a reference i.e., i want the car to do this more. based on feedback, i may want to....

I def like your insight on the spring rates.Interesting you delved into that as I remember hearing the rave on that combination and from my track days i thought, wow, 8K/6K??? That seems a lot for such a car.

I have a somewhat different perspective.....

First, are your Tanabe springs rated linear, or variable? A life time ago(back in 1998) I was using Bilsteins, and variable rate TRD springs. the sensation was NOT a comforting one. In essence because of the variable rates, the car was unstable while transitioning.

Because of that experience, I wrote Moto... here is his response - http://club4ag.com/tech-data/dampers-ch ... u-in-mind/


I'm now running custom wound linear springs 5.3kg/mm front, and 3.5kg/mm rear that ride at about 3/4" down. With a front to rear ratio of 3:2. I've driven a few AE86s with 8kg/6kg (ratio of 4:3)rates, and they are far more inclined to oversteer, I find the 3:2 ratio more neutrel. As for sway bars, I'm running a 24mm front bar, with the stock rear bar... again this is more neutrel then many other AE86s. As for dampers, the Koni's are very good, another option would be HTS, I'm running their full stroke versions - some adjustment allows you to "tune" the final feel to your liking. As for bushings, I'm a big fan of rubber, I'm running mostly TRD high density rubber, the only exception to this is my custom adjustable lower control arms are running urethane bushings.

[gotzoom?]

I agree with OST on using linear springs. Progressive springs make things too unpredictable for my liking. One thing you'll need to get your head around is that the RSX has a suspension that was designed to make the car handle well. The AE86 suspension design is from 50 or 60 years ago and was not designed for performance. Nearly 10% of the car's total weight is unsprung, and that is not good for handling. It does make the car a lot of fun, though. I also have a Miata and generally the Miata stays home while the Corolla is at the track. The Miata is faster, but I have way more fun driving the Corolla.

You made a good choice with the Bilsteins. They can easily be revalved to suit your needs. They are set up for a sporty feel ie: they have a lot more compression damping than rebound damping. This is easily changed with a revalve. You can also have droop limiters installed inside the shock to keep the rear springs captive. I'd recommend that, as bad things happen if the rear springs can move around. you'll need to measure in order to tell Bilstein how long of a droop limiter to install. I'd use the ziptie trick to do that. Put the car on jack stands so the rear wheels are off the ground, then jack the rearend up until the springs are both captive. Disconnect one endlink on the rear swaybar. Put a ziptie on the shock shaft and slide it down until it hits the shock body, then lower the rearend and measure the disstance between the top of the shock body and the ziptie. One thing I forgot to mention is that you need to remove the pinion snubber (bump stop directly above the pinion flange, bolted to the body of the car) when you lower the car a lot. If you're using Swift or TRD springs, you'll need to remove that and cut 2 "ribs" off the bump stops that are in the middle of the springs. You could also remove the factory bump stops completely and put bump stops over the shock shafts when you install the shocks.

You'll probably want at least 2.5 degrees of negative camber up front. That helps the car turn better and you'll get better front tire wear. You need to be able to rotate the tires in order to slow down cording the outside shoulder on the rear tires. There is no rear negative camber, so you'll wear the outside shoulder fast, in the rear. I don't recommend running a stagger wheel setup for this reason. It's also unnecessary on this car. When you autocross, you need to disconnect one endlink on the rear swaybar or you'll get a lot of inside wheelspin. I experience inside wheelspin in tight corners on track too. It's just a product of having a live axle, so there isn't much you can do about it. You'll need to take the wide line through tight corners to reduce the wheelspin. The "Miata line" doesn't work so well on this car, unfortunately.

[Deuce Cam]

Gotzoom, aren't the ae86 billy's rebound biased (they feel that way)? The specs are:

Front: 1285/725 (Reb/Comp)
Rear: 1695/740 (Reb/Comp)

I also prefer linear springs. At one point I had the progressive megan drop spring set which was ok on the street, but still felt a little weird at the limit. I think they were passable because spring rate was moderate (4.5/4k). After installing ae86 specific bilstein shocks I tried the progressive espelir drop spring set (3/2.8k) which had the same drop as the megans (roughly 1.85"). That setup felt very unpredictable at the limit plus bump stop contact on all 4 corners under different conditions. Basically, don't lower the car more than 1.5" with full length shocks unless you're using at least 4K springs, otherwise you'll get lots of bump stop contact.

I'm using oem springs now with the bilsteins... although over damped it's surprisingly good. With with my modest wheels and azenix rt615k I've never had this much grip before. However my wheel setup is staggered... and I have to run them reverse (wider up front) otherwise the car plows. Overall it's good for the really twisty mountain back roads in my area with poor surface conditions, but would probably suck on a track. I want to try more spring rate and get the ratio front biased again.

[totta crolla]

I felt the front Bilsteins to be over damped in compression and under damped in rebound, this using 190lb springs.

[gotzoom?]

Just the raw numbers don't tell the story. You really need to look at the dyno plots to see what is going on. Nearly all "sport" shocks are heavily compression biased. The good news is that Bilstein shocks are easily revalvable out of the box. You need to send them to Bilstein, since they require a special chamber to gas pressure charge them, but they have a standard shim stack on the pistons that is easy to change.

[Deuce Cam]

Déjà vu. I still have a lot to learn. Thanks guys.

[aaronlee133]

Great information and thanks for the feedback guys.

The springs I'm using are variable (more dual rate than progressive). The progressive coils are wound tightly together and are located on the the top and bottom. The center portion has evenly spaced coils, which is the linear rate.

Moto's email is very concise. I had to read it a couple times as there's so much info packed into that response.

And just to clarify, the bilstein I'm using are the B6 (HD) models (non-rennes model). Thus far the combination feels pretty stable and predictable' neutral with a hint of oversteer but I have yet to push it and assess it at its limit. The full stroke HTS is what I had initially had in mind. However, and at the time I wanted to order, I was told they were backordered with no definitive date of re-stocking.

I have new top hats and not running camber plates at the moment since I wanted to experience the car as-is or rather as-was. Additionally, I didn't know which way i wanted to go i.e., short-stroke or full with which coil over set so I decided to simply get new top hats.

OST/gotzoom?/Deuce: when you guys ran linear springs may i ask what brand those were? Eibach?

Thanks,
-Aaron

[Deuce Cam]

As far as linear springs, I've had oem, eibach front coilover (8k and 6.7k), and trd rear 5.1k. I've also had the swift rear 6k that t3 sells, but they're not full linear. Aside from oem, imo the trd, swift and both eibach springs were too stiff unless one plans on doing a lot of track events.

Btw I have the same bilstein shocks

[gotzoom?]

I'm running 550lb Eibach springs up front and TRD 4.7kg uncut rear springs. I don't recommend running that combination unless you have my full setup, though. QA1 springs are quite a bit less than Eibach, so take a look at what they have to offer. For the most part, spring steel is spring steel.

[Deuce Cam]

Just felt like ranting and decided this was the place...

After perusing www.trdparts.jp - for the first time in a over a year - I determined that there are very few parts still available for ae86... All the rear springs and all bushings (aside from engine mounts and front end link) are now discontinued. The only only other parts still listed are: adjustable short stroke race shocks front/rear (and the short fixed fronts), rear standard length fixed oil shocks, and acrylic rear quarter windows for the 3dr. Everything else is history. I suppose it was just a matter of time...

[oldeskewltoy]

OST/gotzoom?/Deuce: when you guys ran linear springs may i ask what brand those were? Eibach?

Thanks,
-Aaron

custom made to my specifications

[oldeskewltoy]

Just felt like ranting and decided this was the place...

After perusing http://www.trdparts.jp - for the first time in a over a year - I determined that there are very few parts still available for ae86... All the rear springs and all bushings (aside from engine mounts and front end link) are now discontinued. The only only other parts still listed are: adjustable short stroke race shocks front/rear (and the short fixed fronts), rear standard length fixed oil shocks, and acrylic rear quarter windows for the 3dr. Everything else is history. I suppose it was just a matter of time...

New? product... comes with rubber... not urethane, or hardmount





http://page15.auctions.yahoo.co.jp/jp/a ... t386498315

[Deuce Cam]

Interesting. It's too bad there's not a closer pic of the bushings, but they look fairly promising.

Cusco might still sell rubber replacement bushings for the oem links also. I bought front/rear trd control arm bushings in early 2015, and although they weren't cheap new, they were still a lot cheaper than the cusco equivalents.

[gotzoom?]

The Godspeed and other similar designed rear links are like that too. They have a spherical bearing with the outer race made out of some kind of plastic type material. They work well and are a bit quieter than full metal bearings.

[Deuce Cam]

It's hard to say without a closer pic, but I think what ost posted is a solid rubber bushing with a crush tube in the center, and a race on the outside so they can be pressed into the link. I couldn't transfer the pic, but if you click on the link ost provided and scroll down they have a stock photo showing links from some other models, and they're spherical bearings look completely different.

[jondee86]

Hardened rubber version...



Pillow Ball version...



Tension Rods...



Lateral Bar...



Hard Rubber engine mounts...



Tie Rod Ends...



Got some nice stuff Got no idea on the prices though.

Cheers... jondee86