Snap Oversteer

[wlfpkrcn]

Hi Guys,

We are running a second gen RX7. It gets an intermittent wicked snap oversteer in fast corners. I suspect it might be bottoming out, but not entirely sure. Always in fast (4th gear) corners. Right at apex it will slide and you think you have it and then it is gone. The corners we have had problems with- 10 at Infineon, and 1 and 8 at Thunderhill. We are still sorting the car and have only run a couple events. It has happened to me and my partner. The incident this wekend ripped off the spoiler, damaged oil cooler and Radiator. Looking for an answer before the next event

AD shocks
Speedway bar
F-450 R-275
Torsen
4.10

Any thoughts or has someone gone thru this with their second gen?

[seckerich]

Have the rear steer bushings been changed out? What is rear ride height at the rocker? Do you have the rear bar connected?. Other than these causes your spring rate should never do that.

[wlfpkrcn]

Yes rear steer has been eliminated.
Rear toe 0
Min ride height 5"
No rear sway bar
All suspension bushings have been replaced (no stock rubber)

[seckerich]

Put the car on stands with the springs off the rear and see when it bottoms. It should hit the rear arms on the floor pan before the shocks bottom.

[wlfpkrcn]

Thanks Steve. I will pull the springs and see what i come up with

[dickita15]

There is a trick where you put zip ties on the shocks before a session at then check them after the session to see how much travel you are using. This will let you know how if it is really bottoming.

[Mazmarc63]

The rear is to low. Look at the tunnel on the inside of the car where the storage bins used to be. You will probably see the floor pushed up slightly. This is where the long locating links are making contact under compression. As soon as they hit, you play pitch and catch.

I had this exact condition about 12 years ago at Sebring and two very smart young men showed me the errors of my ways. The same two (now older) men that just helped Mazda win the Grand Am GT Manufactures Championship yesterday!
As a data point, may I suggest using a slight rake front to rear. I generally use about 3/4 inch. Another data point...I use 500/250 spring rate, no rear bar, a string width toe in in the rear and about 2 deg negative camber. On the front, I use a big Speedway bar with a secret (right Steve?) bend in the arms, and set to ultra stiff, slightly less than 3/8 toe out with about 2.5-3 deg negative camber.

Don't forget to reset all your toe numbers after you jack the car around.

And oh yeah, Steve learned everything he knows about Mazdas from those two guys from Sunrise, Fl.

[seckerich]

The rear is to low. Look at the tunnel on the inside of the car where the storage bins used to be. You will probably see the floor pushed up slightly. This is where the long locating links are making contact under compression. As soon as they hit, you play pitch and catch.

I had this exact condition about 12 years ago at Sebring and two very smart young men showed me the errors of my ways. The same two (now older) men that just helped Mazda win the Grand Am GT Manufactures Championship yesterday!
As a data point, may I suggest using a slight rake front to rear. I generally use about 3/4 inch. Another data point...I use 500/250 spring rate, no rear bar, a string width toe in in the rear and about 2 deg negative camber. On the front, I use a big Speedway bar with a secret (right Steve?) bend in the arms, and set to ultra stiff, slightly less than 3/8 toe out with about 2.5-3 deg negative camber.

Don't forget to reset all your toe numbers after you jack the car around.

And oh yeah, Steve learned everything he knows about Mazdas from those two guys from Sunrise, Fl.

Snitch!!! Very lucky to have all these years working with Speedsource. Good advice here. Now all that is left is the family fight with my wife Vicki working on the 70 and me working on the 69. 69 will win the championship.

[racingralph]

i also know those two guys , got our shocks from them. your right , raise the back of the car up . i start at 6" with the shortest tires , for the rear . ralph . ps , i was told i didn't know much about these cars..wow.

[Mazmarc63]

Ralph, Ralph, Ralph...

Don't listen to those detractors. Just being in the SE racing a Mazda for the last decade, you learn details by osmosis.

I was reminising with MVS last month about these cars. I built my car 14 years ago and just won the CFR Championship with it in '09!! The engine in it is 12 years old!!

And the Mazda goes hummmmmmmmmmmmmm.

[seckerich]

It was 13 years ago you gave me a ride in yours and made me start building them. You are just a bad influence.

[monsterbronco]

You are just a bad influence.

i totally agree with this statement!

[wlfpkrcn]

Thank you guys!!! I will get it checked out and set up properly

[Rob May]

Ralph, Ralph, Ralph...

Don't listen to those detractors. Just being in the SE racing a Mazda for the last decade, you learn details by osmosis.

I was reminising with MVS last month about these cars. I built my car 14 years ago and just won the CFR Championship with it in '09!! The engine in it is 12 years old!!

And the Mazda goes hummmmmmmmmmmmmm.

That engine is one fine piece!

[monsterbronco]

so i was under the car last night and sure enough there are dents in the floor... whoops. guess the rear needs to get raised

[Mazmarc63]

But you arent the one that asked the question.

Hey wlfpkrcn, let us know what you found.

Keep up the good work, Wes.

Hey Stick, Q'd 2nd, finished 3rd in the enduro last weekend. She still goes good.

Try to figure out exactly what year that was you built that thing. Shouldn't be too hard.

[lateapex911]

Also, keep a close eye on those ADs. They are known to lose gas, and have other issues.

[wlfpkrcn]

Also, keep a close eye on those ADs. They are known to lose gas, and have other issues.

The AD's get topped before every event. None have lost pressure to this point.

I did find that we had the incorrect springs installed as well. Should have done some research before installing them they were 400lb springs not 250. We bought a pair of 250's and they are now in the car. Ride height has been increased as well

[Eagle7]

I did find that we had the incorrect springs installed as well. Should have done some research before installing them they were 400lb springs not 250.

That would do it. Glad you found it.

[seckerich]

The rear is to low. Look at the tunnel on the inside of the car where the storage bins used to be. You will probably see the floor pushed up slightly. This is where the long locating links are making contact under compression. As soon as they hit, you play pitch and catch.

I had this exact condition about 12 years ago at Sebring and two very smart young men showed me the errors of my ways. The same two (now older) men that just helped Mazda win the Grand Am GT Manufactures Championship yesterday!


And oh yeah, Steve learned everything he knows about Mazdas from those two guys from Sunrise, Fl.

Those same guys just won the Grand Am GT Team, Manufacturers, and driver championship for Mazda at Miller this past weekend!!! Sleeping on the porch now after the 69 beat the wives 70 team.