RX-8 rear stability at track events
 

Ran a track event this past weekend at Hallett, Ok in the DD 8. The car is mildly modified, stock shocks, Eibach springs, MazdaSpeed swaybars front and rear, Azenis on stock wheels (38# hot pressure), Carbotech pads (8's and 10's), MS intake, RB race pipe, HKS single side exhaust and custom tune. The rear end is very light at corner entry and and has very low grip. It tried to come around on me a few times but I was able to save it. Any advice on adjustments I could make for some more rear grip at corner entry? This shows up after straightline braking and as I'm beginning my turn in. I'm thinking some more camber (didn't have time for an alignment) but don't know what else to try, less rear bar maybe?

Also, had fuel starvation in extended high g LH turns anytime the tank was about 3 gallons from FULL. Any CONFIRMED reports that the 2009 pump is solving this?

Thanks,
Michael

i dont know of any confirmed reports on the 09 pump. but there are confirmed reports on this walbro pump:

http://blackhaloracing.com/products-...ce-fuel-pump9/

Advice from the new guy.
 

If I understand, suspension is stock except for sways and springs.

If I compare what you are looking at to my whopping 2 track events, I can tell you I have not seen this. There are better folks out there, and I am not familiar with that track, but I can turn right at 80 MPH into turn 1 at Roebling, and the car behaves well, it rolls like a son of a bitch, but stays planted. I have the G-Force Plus tires at about 34 cold, 38/39 hot. I also, due to the stock, and old (70,000 miles) shocks, need to give the rear a chance to settle before the turn. If I did not do that, I would expect a very light rear end to try to pass the front end on the outside of the turn.

Best I got right now.

Mike

Do you know where your alignment is at since you lowered the car? I don't know what has to be taken apart to lower the car, but it may have been reassembled with rear toe out. This could give you a handful on the track.

Lowering tends to add camber, so you may actually have a little too much if you were more aggressive before lowering.

Another possibility is the factory shocks. They may not be able to dampen the higher spring rate properly, and have worn out. Depending on how you're turning it, you may be compressing the outside rear all the way. When you get to the bumpstop - wham, spring rate goes essentially to the moon, and that could be causing your looseness.

Three possibilities I can think of, I would put money on the first or third before too much camber.

It was doing the same to me on cold tires, I've never had that problem until I added the set of sway bars, I have a hotchkis set, front on the stiffest setting, rear on the middle, I was considering switching back putting the front on the middle setting and the rear on the softest.
I'm not ruling out my driving technique (or lack there of), maybe I should have been on the brakes sooner and let off smoother before turning in.
Oddly I didn't have this problem once the tires were warmed up, and it only happens when I come down a straight, hit the brakes hard for a sharp turn, the backend always got a little light, but it's never tried to come around on my until the sways.

mines been pretty stable around the 90mph sweepers at buttonwillow. Im on tein s-tech and koni yellows, and potenza re-01r tires at 35#s, i would also like to add that im not using any front lips or rear wings. Once the car is settled into the turn it stays true to the line.

I think an alignment will really help in your case since dropping the car probably has messed up the geometry. When i got my first initial alignment after the spring/shocks one of my rear corners had postive camber lol

a) you're on factory shocks

b) the OE fuel pump is likely fubar, sometime they come this way new even

c) some rear toe-in and rear camber may help, but until you get some decent shocks you'll be chasing your tail in circles. Some more front bar might help too.


....

I've done five or six track days in my MY09. The only time I've hit fuel starvation is when I got below a quarter tank of fuel.

Thanks for the help so far. The Koni's arrived today. We'll see what that does. Toe plates should arrive later this week and after that I can do a real alignment. THe fuel cut is really hurting the lap times though. The car has about 35k miles (2005 model). Maybe I'll swap for the '09 model and report back afterwards.

Be careful with the toe plates. You have to start with a square alignment and adjust both sides equaly otherwise the chassis will crab. It can be done though, just takes care and determination. :)

And so not worth it ;)

Nothing is easier than a nice 4 wheel laser alignment rack :)

WTF does that mean? The experts on here are so vague its stupid sometimes.
Sounds impressive tho. LMAO

He's at Hallett having fun, not a comp racer like you.

Which Hallett event were you at?

We have a thread for that ya know?? ;)

https://www.rx8club.com/gulf-rx-8-forum-32/2010-hallett-motor-racing-circuit-high-speed-touring-193524/

PS -- i've had fuel starvation before but not at Hallett. I wonder what you're doing differently?

um, it means that if you're not careful, you can end up with the total toe you want but it might be uneven side-to-side...that will result in the car basically crabbing sideways. what is so hard to figure out? :dunno: maybe spend less time making snarky comments and more time thinking.

My car doesn't lose it in the corners Mr Snarky. hehe
Guess what I should say is , so many over spring, under shock,over sway bar, to much stagger on wheels and tires, no realignment, not enuff brakes, then wonder why it doesn't handle as well as it did stock with good tires.
A definitive thread on how to set up a good suspension for full race, HPT, Autocross would be very beneificial to all. Instead of comments that have no bearing except to the class they are racing. My apologies if that, was unintended. Then there is the power upgrades to go with it. WHEW

One last item, How many RX8 buyers are young, have driven Mustangs and Trucks and never knew ya had to align the rear wheels too? :)

Who exactly is having the problem here, you or the OP?
Secondly, if you want help, you had better be kinder to those that reply.

WOW...;)

Typical

So vague it's stupid or so stupid that it seems vague? You decide ..... :lol:

I have a set of laser toe plates. Pretty amazing to have adjusted toe numerous times then eventually put it on the rack for a double check to find out the car is within 1/16" of a perfect alignment. The key is to measure total toe, adjust one side only and get it where you want it (1/2 delta), then adjust the other side to match. It may take several attemps of adjusting, settling the car, and remeasuring.

To reduce oversteer, less rear bar. I run the MS front bar and the stock rear bar with new holes drilled 3/4" inboard of the original holes. This is assuming you have a proper rear alignment which means just a bit of toe-in and just a smidgen more camber than the front. (-2.0 F, -2.1 R for me.)

I have factory shocks with MS springs and PT sways and I didn't experience any rear end looseness during the track day I just did on friday.

though I did have an alignment done a few weeks ago.

I ran Hallett this past Sunday.

I'll be working on the alignment and will post some updates after the next event.

I would suggest using the stock rear sway bar and I have had a lot of luck with the 09 pump upgrade.

On the subject of toe plates and issue of crabbing, I just use a string from rears out to front to avoid crabbing. I tied a loop in my string to hook on the rear muffler tip. Don't laugh! really works. Hook the string around muffler tip; pull across rear tire up to front. holding string taut at the front tire, move inward until string touches front of rear tire and check where you are relative to front tire. Of course you want to be even both sides.
Sounds cheesy but its faster and cheaper than running to a laser shop everytime you tweak something. Did this for years in rally. Start with a rack alignment, then can try some things this way.
(OK so I'm cheap! Also too many idiots running the laser racks.... rather do it m'self ... more fun too.)

love it!!! My kinda guy!
OD

Are your sway bars adjustable? Less rear bar or more front if they are. When I was playing around with the adjustments on my Progress sway bars I felt what you described when I reduced the front bar and increased the rear. Reducing the front to the softest and the rear stiff gave me your problem. I ended up with the front on the middle of 3 positions and the rear on the stiff. The car is well controlled now.

How much negative camber do you have in the front and rear?