Unintended "drifting"

[snakebit]

I was entering the interstate via an uphill, double-apex, decreasing radius ramp that I have driven nearly every day for the past 20 yrs. I took my usual line and had the throttle floored by about the 2nd apex. I didn't stomp on it, but eased into it. But this was the 1st time taking this turn this aggressively since installing the coldside.

As I drifted (4-wheel) onto the highway, the rear abruptly stepped out!:ack2: Fortunately, I caught it and had it straightened out in less than a second, but this was really unexpected. I have driven my 350+ hp V8 Volvo wagon many times here and never gotten a hint of this. I have driven other short-wheelbase cars here (Civic and CRX) but being FWD, they only plowed when pushed.

Needless to say, I'm feeling a bit extra cautious about taking my usual curves in the "usual" fashion.:nono:

I know I should really get to a track or big empty lot and wring the car out where I can safely spin it if I lose it. But I am curious for your feedback - do any of you find the stock "Hard S" suspension setup on the NB to be a bit tail happy? I know my 1st gen RX7 became much more controllable at the limit after I stiffened the front bar; I wonder if Mazda also dialed in a bit of oversteer into the Miata for the fun factor. I would be very interested in finding out what sway bars you are using for a nice, neutral balance.

Oh, and a big salute to all you Veterans!:cheers2:

[Tom @ Fast Forward]

I have the Torsen LSD and found that good tires (225-50/15 T1-r) solved the problem of unexpectedly stepping out. I have since added the RB sway front and rear to kill the bad lean coming out of a hard turn. Then I added the 12/10 JICs to finish it off. I would say that the main help was the Torsen (stock on my 10AE) and tires.

[snakebit]

I have the Torsen LSD and found that good tires (225-50/15 T1-r) solved the problem of unexpectedly stepping out. I have since added the RB sway front and rear to kill the bad lean coming out of a hard turn. Then I added the 12/10 JICs to finish it off. I would say that the main help was the Torsen (stock on my 10AE) and tires.I have the Torsen too. Did the RB sway bar set create more or less understeer? I will go to 205-50 tires when the Goodyear F1s wear out, but I don't mind sliding a bit as long as I can control it. I just like the handling neutral or maybe with a touch of understeer, now that power oversteer is readily available thanks to the coldside.:biggrin:

[mike whitehouse]

Actually, the NB has less tendency to oversteer than the NA. Mazda revised the rear suspension for the NB to increase its controlability. I have a 10AE like Tom's but unlikes his, mine is stock. One thing you didn't mention was the tires.

Different tires have different breakaway characteristics. My Bridgestone RE-01R tires will drift much more consistantly than the Falken Azenis they replaced.

PS look at my aviatar. :)

[99mx5]

Another option is to have your car aligned to a more aggressive setup.

[Tom @ Fast Forward]

I was told that, with the front RB sway, the rear should have stayed stock. But then, I tend to over do things. :) I have been told by several experts that the 12/10 JICs are way too stiff and not good on the street but my wife and I drove it to Cleveland and back in June and enjoyed the ride. On the track, I love the whole setup. Only difference for the track is that I put on the 225-50-15 RA-1s in place of the T1-rs. if I were you, I would not hesitate to go 225-50/15 in place of the 205s. They made my speedometer dead accurate. Stock tires and the 205s are about 5% slow.

[snakebit]

I've never noticed the F1s to have particularly sudden breakaway.

I think I may need to be more aware of my driving habits after years of FWD cars. With FWD, you can wait longer to unwind the wheel as you get on the gas; the car will just understeer under power. I'm going to be more conscious of when I start widening the line, probably should be doing it earlier than I'm used to.

Or maybe I hit a patch of something slick. In any case, I'm grateful for the Miata's quick steering!:sweatdrop:

[mike whitehouse]

snakebit,
Yes, the Miata is a great dancing companion!

Also, I have driven Tom's car both on the street and at an autocross and I agree that it is both very liveable on the street and handles well. The extra power does take some getting used to. It wasn't until my last run that I actually starting driving and not drifting.

[Tom @ Fast Forward]

Mike,

Was that before or after I did the suspension?

[mike whitehouse]

Tom,
I think that was after, unless you changed it since January. I drove it in Sierra Vista Jan 07. Ari ran the event on the way home.

[Tom @ Fast Forward]

It was after. I did the JICs last year.

[Serpico]

Tom,

What's your ride height set at to allow those 225/50/15s in the front?

I have the RB 1.250" front sway and stock rear bar and it did create a ton of understeer on corner entry, so I changed allignment and went with more negative camber up front than the rear and it's pretty neutral now.

I ended up at -2.0*front and -1.7* rear
a little toe out up front and a little tow in in the rear
max caster up front

It's great for autocross but a little twitchy at or ABOVE highway speeds..... :)

*Snakebit, a lot of guys recommend removing or disconnecting the rear bar to help get rid of the tail-happiness

[Tom @ Fast Forward]

We set the JICs to the same ride height as the 10AE had stock. We measured center of axle to the wheel well cut and installed it back identical. I don't remember the number as it was a year and a half ago. Sorry. Maybe somebody with a stock 10AE will measure for us. The 10AE was significantly lower than my 05 with it's stock suspension. I do believe the 10AE had the sport suspension Bilsteins and springs.

[snakebit]

I were you, I would not hesitate to go 225-50/15 in place of the 205s. They made my speedometer dead accurate. Stock tires and the 205s are about 5% slow.I can't afford new wheels right now. 225 would be a bit wide for my stock 15X6 wheels, dontcha think?

[99mx5]

Tom, I have a '99 sport with Bilsteins if you need the measurements.

[Tom @ Fast Forward]

Ari,

Please do. then I'll measure mine and see how close it is. I think the 99 Sport and 10AE have the same suspension?

[99mx5]

Measurements from center of wheel to fender lip on stock Hard-S suspension.

Front:13"

Rear: 13-3/4"

Hope this helps...
-Ari

[mike whitehouse]

On my car a 10 AE;
the front is 13 inches
the rear is 13 5/8 inches.

This like Ari's was wheel center to the top lip of the wheel cut out.

[Tom @ Fast Forward]

Hmm,

I remember it being two different numbers front and rear but I just measured 13 on all four corners? The good news is that, with the JICs, it is independently adjustable in a couple minutes. Loosen the nut and turn. I keep threatening to visit a friend in Mesa with corner scales and do it right.

[99mx5]

I too had both both front and rear RB sways and liked them alot (thats when I recommended them to Tom). I installed them when I installed the coldside. I always attributed the sliding to the extra power. I then made a few tests to determine the difference between the RB, the stock bar and no rear bar. I found that turns that I could confidently make with the stock bar were really loose with the rear sway bar. I then removed the sway bar and found that I could take the same turn faster but with more lean. I also found that the rear swaybar complements an upgraded suspension, such as Toms. This is probably why he doesn't experience the looseness that I have. I've been told that my car raises the inner front tire when I take extreme turns without the rear swaybar.

[BlownMX5]

+1 on no rear sway bar. I have the JR tubular (hollow) sways and my last time at the track, I tried disconnecting the rear bar with the front bar on medium. I liked it so much I just left it that way. For me, I just realized that under steady-state cornering, the rear slid first. Unhooking the rear sway corrected it perfectly.

[Tom @ Fast Forward]

Nope. It's got nothing to do with that. I just don't drive as crazy as you do. :)


I also found that the rear swaybar complements an upgraded suspension, such as Toms. This is probably why he doesn't experience the looseness that I have. I've been told that my car raises the inner front tire when I take extreme turns without the rear swaybar.

[99mx5]

I tend to use all the travel... on the throttle :)

[pat conlon]

<snip>... if I were you, I would not hesitate to go 225-50/15 in place of the 205s. They made my speedometer dead accurate. Stock tires and the 205s are about 5% slow.

Tom, remember, you installed the 3.636 ring, and that's why your tall tires evened out your speedo.
I don't think snakebit has done this...

Carry on...

[Tom @ Fast Forward]

Pat,

Actually I had the problem with the stock diff. When I installed the tall gears, I installed the corresponding speedo gear and had the same error. Then I did the bigger tires to correct. My 05 had the same 5% error. I have put the GPS in several Miatas with similar results.

[bogey]

When I went from the 195/55/14s to 225/40/16s, my speedo is much closer to accurate. I was reading about 9% high and now I am about 4% high.

[pat conlon]

Thanks Tom and Bogey, I did not know this...

[snakebit]

I too had both both front and rear RB sways and liked them alot (thats when I recommended them to Tom). I installed them when I installed the coldside. I always attributed the sliding to the extra power. I then made a few tests to determine the difference between the RB, the stock bar and no rear bar. I found that turns that I could confidently make with the stock bar were really loose with the rear sway bar. I then removed the sway bar and found that I could take the same turn faster but with more lean. I also found that the rear swaybar complements an upgraded suspension, such as Toms. This is probably why he doesn't experience the looseness that I have. I've been told that my car raises the inner front tire when I take extreme turns without the rear swaybar.What size RB front bar are you using, 1.125" or 1.25"? Are you also using the RB control arm mounts, RB frame braces and RB end links?
I was hoping the FM 1" front bar would do it, but if the RB bar is the sh*t, then I'll go for the extra $$ and labor.
I'm currently running w/ the stock front bar and no rear bar and it still feels too loose. Holding the throttle and steering wheel steady through a turn, I can feel the rear wanting to break away first.

[99mx5]

I have the 1.125 RB bar (P/N: 54103) and the sway bar brace kit hardware only without the cross brace (P/N: 54122) and the heavy duty sway bar mounting brackets (P/N: 54110). I am using the factory end links and have the sway bar on the soft setting.

I also have the car aligned 1/32" toe IN at each corner and -1 camber with +5 caster on the front and -1.5 camber on the rear. My shocks and springs are the factory sport package Bilsteins.

I have read that the RB end links are not good.

[tann3r]

The 1.125" RB tubular front sway bar both stiffer and lighter than the 1" FM bar. If you install the bar correctly and regularly lube it, there is little chance of tearing out the mounting points. All of the torn mounts I have seen were due to the bar binding.

I'm currently using the 1.125" (stiff setting) RB bar paired with the non-sport rear bar (11mm) and tein basics (7/6) and find it very neutral at the limit.

I find it odd that the rear suddenly stepped out on you though. the power delivery of the coldside is very linear. I think you may have hit a patch of loose dirt that initiated the slide.

Like Ari mentioned, I'd suggest an alignment. Its cheaper than the front sway bar and I think you can get the balance where you want it. A good alignment goes a long way.

[snakebit]

The 1.125" RB tubular front sway bar both stiffer and lighter than the 1" FM bar. If you install the bar correctly and regularly lube it, there is little chance of tearing out the mounting points. All of the torn mounts I have seen were due to the bar binding.

I'm currently using the 1.125" (stiff setting) RB bar paired with the non-sport rear bar (11mm) and tein basics (7/6) and find it very neutral at the limit.

I find it odd that the rear suddenly stepped out on you though. the power delivery of the coldside is very linear. I think you may have hit a patch of loose dirt that initiated the slide.

Like Ari mentioned, I'd suggest an alignment. Its cheaper than the front sway bar and I think you can get the balance where you want it. A good alignment goes a long way.I got the "Lanny alignment" as recommended at Miata.net:

Rear
Toe: 1/32 inch (0°4.5' or 0.075°) IN per side
Camber: -1.75 degrees

Front
Camber: -1.2 degrees
Caster: 5.0 degrees
Toe: 1/32 inch IN per side

Seems much like what 99MX5 (Ari?) has. My springs and shocks are also factory "hard s", so with the RB bar I should be as fast as Ari (I wish).:driving:

[Tom @ Fast Forward]

1.125" tubular with Brian Goodwin's brackets. The brackets were a bear to install but they don't look like they will break any time soon. :)

[99mx5]

LOL! Thanks! Actually, autcrossing has taught me what my car will do at the limit. After knowing the limit, all you have to do is stay just below it. :driving:

-Ari