I finally got around to swapping in an LSD in my 87 base FC. Its other mods were streetport, ported intake manifold, ram/cold air intake, five lug swap, springs and struts, 300zx wheels and 225/50/60 summer tires, a GXL rear anti-sway bar, rear steer eliminator bushings, front camber adjustment slots, aluminum hood swap and about 200 pounds of crap removed from the chassis.



I had the suspension dialed to be pretty neutral before the swap. Some light trail braking could be used to counter the natural turn-in understeer on turn entry, and then all braking could be released to allow the car to glide tightly through a turn at around .8-.9G. But power could _never_ be put down early in a turn, unless I wanted to spin out into a ditch or just spin the inside rear wheel.



So I put a GXL LSD in the other day and it had 15 foot-pounds of static friction between the output shafts, measured with my torque wrench. It had about 110k miles on it and was probably half worn-out, but I wasn't complaining. The open diff had less than one foot pound of friction between the shafts, so it was an improvement.



After installation, the rear felt MUCH more stable, like I put a rudder on the car or something. Power could be put down right away, almost before the apex of a turn, and if traction broke, the car would just go sideways slightly but not spin the inside wheel like before. But the LSD caused some understeer to come back. The car wouldn't glide as hard through a turn like before.



The fix: adding a tad more rear toe-in using the adjustment cams on the front of the rear trailing arms. This increased the slip angle of the outside rear tire in a turn, reducing understeer. The car is great now and just like before, but with that stable feeling that it never had. I can drive it pretty damn hard now and wring it out like the sports car it should be.



So anyways, if anyone cares, when you swap in an LSD to your base model FC, you can get rid of some of the understeer it causes by dialing in some toe-in to the rear wheels.



https://www.nopistons.com/forums/pub...IR#>/bigok.gif

How about on an '88 T2? I've heard all this stuff about there being this toe thing in the rear end that'll turn the tires inward or some crap, similar to the all-wheel steering of a Mitsu 3000GT VR-4 or 300Z.



What's up with that? My professional drift buddy last night was saying how me having aftermarket suspension thats set stiff helps because the toe on the rear tires won't even "activate" until a great deal of pressure is put down on the shocks or something. *shrugs* I'm clueless.

that is a completely different topic, what your 'pro' buddy was talking about was the dtss system. it's called dynamic track steering system or some b.s. do a search and many good topics will come up on it. fluid dynamics eliminated it because it can at times make the car 'unpredictable.'



fluid, my first car was a gxl and i never noticed how much of a difference having a limited slip makes until now. i now have a sport and it's night and day. i'm looking forward to swap in my turbo rear soon. good info

great news, I really need to get rid of my open diff... the car does spin out pretty easy since most of the rest of the suspension has been changed and stiffened up.. one wheeler peeler sucks

I concur, the LSD is a major difference, and that's noticeable in normal street driving.

yeah my t2 really had that stable feeling, it never ever felt bad ever. even spinning into the bushes it felt composed https://www.nopistons.com/forums/pub...IR#>/wacko.png



why do you have a big rear bar and a small front? i'm reading about the speedsource its cars and they dont run a rear bar at all?

Spring rates, shock stiffness, anti-sway bar thickness, front and rear camber, rear toe angle, LSD or no LSD, tire pressures, and front / rear weight bias affect a car's tendency to understeer or oversteer.



With stiffer rear springs or shocks, you can eliminate the rear anti-sway bar and keep the neutral handling. Generally, a thicker rear bar will cause the rear to rotate more in a hard turn. If it is too stiff, the rear will rotate all the way around in a spin (oversteer). Stock FCs (all that I have driven, at least) have some pretty substantial understeer before about .5 g lateral acceleration when the DTSS kicks in and adds some toe-in to the outside rear hub.



You can use many combinations of the items mentioned above to affect the car's neutrality, and if you already have comparitively stiff rear springs / shocks, you might be able to get rid of the rear anti-sway bar. Also, track cars usually get set up to have some slight understeer while autocross cars (mine) can get away with having a loose rear end due to the lower speeds on the course and smaller consequences of spinning out.



I ran w/o the rear bar for a couple weeks, and the FC felt like my old Integra as far as handling balance. I have tokico HP nonadjustable struts and Eibach springs, so I was unable to choose a stiffer rear shock setting or spring rate. Adding the stiffer rear anti sway bar not only reduced body roll, but helped the car to rotate around turns instead of pushing and plowing.

I'm using 5-way adjustable Tokico's and I have them set at 4, and I'm using Eibach springs too. I was cornering a couple days ago and I wasn't pushing myself, mainly cause it was my 1st time on the road, but later on when I pushed myelf a little harder, I could feel the car understeer on the 90 degree turns. Should I soften up the front or something? Loose front stiff back = less understeer/more oversteer?

try entering the turn slower and getting on the gas a bit sooner

yeah thats right you auto-x, need more rotation for that https://www.nopistons.com/forums/pub...#>/biggrin.png

My AutoX setup sucks at higher speeds. I remember my first open track day. I used my tried and true AutoX suspension settings and the car was too loose.



I tried running w/o a rear swaybar. It seemed to rotate better in the slow turns but made the car too loose for the faster turns.



Now I just do like Mike said go in slow come out fast.

I've noticed that my FC understeers a lot more with higher steering angle (turn angle of the front wheels), and I think this relates to insufficient front caster. I'm going to play with adding a little more front caster on autox days. When it doesn't push at high speeds during turns, it will push badly at autox speeds for a given front negative camber setting. I've found that my best front traction for cornering at 40+ mph is had with about a degree of front negative camber, while I can't seem to get enough negative front camber dialed in for 20mph cornering (my strut tower slots max out at around 2 degrees).



Regarding pushing on turn entry: I like to think of this as "turn in understeer", and it can be overcome by entering the turn just as you're coming off the brakes and the nose of the car is coming up. This creates a very brief trail braking situation that loads up the front tires more than the back when they are turning in and naturally have a much higher slip angle than the rear tires, which haven't begun turning. Higher slip angle on the front tires = pushing and plowing, hence the ability to overcome understeer with more negative toe in the rear. https://www.nopistons.com/forums/pub...IR#>/smile.png



By doing brief trail braking on turn-entry, I have found myself to be able to use up my traction budget more of the time (be at the limits of the tires more often in a turn). Making a turn on a correct path, or line, on the edge of traction, requires a delicate balancing of the chassis in a certain way.

You got it. Softer spring, anti-sway bar, and shock rates in front, as well as higher tire pressure and less weight in front and some rear toe-in and mild front toe-out, and of course (probably the most important one for track events) adding some front negative camber will all reduce understeer. If you have wider tires in back than in front, this can cause more understeer than if the tires were the same size.



Regarding driving technique: I realized my biggest driving mistake and got much better after taking a couple trips around a course with the local FD top time guy. I swore he was going to spin the car a few times but his technique allowed him to keep it under control at a much higher speed than I thought possible. And I didn't scream like a little bitch either!

What rate springs are you using and what size tires? -2° front camber is telling me you are using either some really high profile tires or really soft springs.

They are dual rate eibachs that are about 80/160. They pretty much suck, but came with the car and are an improvement over the stockers, in only for the drop in ride height. I'd get the racing beat spring and sway bar package if I had five hundred bucks at my disposal.



My tires are 50 series BFG comp t/a's with a relatively soft sidewall. Once I get some real race rubber, I'm sure my setup will need to be adjusted.

Deal with the springs you have and save your money until you can afford a set of coil overs. I made the racing beat mistake myself. I ended up selling them at a loss 6 months later for a set of coil overs.

That's a really good idea. Lol. I'll remember that when I get $$ some day. https://www.nopistons.com/forums/pub...IR#>/smile.png

I put the RB front sway bar in and the GXL rear bar. The car pushes too much. Do you think an LSD swap would take care of this? I'm talking about autocross. My problem is that I don't get out enough and each time I change or adjust something, I can't get enough time to tell if I need to change the part or change my driving style or what.

If your car is "pushing" it is understeering. LSDs increase understeer. Swapping in an LSD would make your car push more. If you want to run an LSD, the remedy I would choose would be to trade the RB front bar for someone's RB rear bar and get a GXL front bar instead of the thicker RB one (softer anti-sway bar in front and stiffer in back).



I think a lot of people swap in a thicker front anti-sway bar just because it's better than stock, but don't realize that without balanding it with a thicker rear bar too, it will cause understeer, and that is not good for being fast around curves.

Yeah, I put in the RB front bar after reading peoples recommendations of making the car neutral... but for autocross, it feels worse. I'd like to upgrade to an RB rear or what you said, just try a GXL front. I noticed that running without any front upper strut tie bar, I get some of the turn in back as if its reducing the understeer. One more reason for not going with an RB rear bar was to try and keep the inside wheel planted for better traction since I have the open diff. I could be way off on that but I think the sway bar would affect that.

I agree that putting on a stiffer rear bar will cause the inside rear wheel to get lighter in turns, and if you have an open diff, the wheel will spin more often when putting power down.



If I were you, I'd get the LSD and a stiffer rear bar, and return the front one to stock. I'm still using my base model front bar and I just might remove my GXL rear one in favor of something even stiffer. The LSD causes significant understeer compared to the open diff. My car still has some slight understeer despite my toe angle adjustment. The car's balance is pretty good for fast road driving, but not good for tight autox driving.



Ah, the neverending tinkering of suspension setup. https://www.nopistons.com/forums/pub...R#>/tongue.png

what kinda toe are you running up front? going to zero toe in the 1st gen did wonders

Dammit j9fd3s!! your avatar is screwing with my head.



FYI- I am running a Racing beat front and rear sway bar. I have a hard time making my car rotate. I remedied the problem on short tight courses. I run 36 PSI rear tire pressure and 26 PSI front. This is with my hoosiers and my coil overs so of course every car is going to be different.



Try playing with tire pressure. Oh yeah and if your running street tires you are going to understear no matter what.



I was just Autocrossing my mini with Falken Azenas and it was pushing everywhere. I switched my front tires only to a set of Kumho V700 racing compound tires and the understeer was gone.



There are so many variables to deal with your going to find out that you just need to set your car up for what feels best for you.

Funny, I dont notice understeer on my car. Maybe I'm so used to it, I dont recognise it. Or maybe I'm just not going fast enough https://www.nopistons.com/forums/pub...#>/biggrin.png

In an Autocross situation you WILL understear with street tires. Its the ability to manage the understear or slow down enough to minimize understear that makes it tolerable. I could never race in a street tire class nor can I understand why anyone would want too - other than for budget reasons.

lol, i know! mine too!

I guesstimate it to be at 1/8" toe out in front and 1/4" toe in on the rears.



I think I'm going to take the stock rear subframe camber link, cut & thread it with a stud, and adjust out some of the natural negative camber that the rear wheels get with lowered suspension. I hate doing things that remove traction, but yeah, understeer sux and I'm stuck with street tires for the time being. There's probably a degree of negative camber on the rears as I speak . . and my street setup is the stock camber in front . . which aint very negative.



Two weeks at the next autox, I'm going to take down some built F bodies in their slicks with my street tired FC NA! Muahahaha. (I only wish)

I've never ran with any R compound tires, just the Azenis sport street tires. I imagine if I did, I wouldn't want to go back either.



I keep thinking its banzai with the avatar https://www.nopistons.com/forums/pub...#>/biggrin.png