Cal Club Autocross Forums

I have WAY too much oversteer when coming out of a late apex turn. I need to calm the rear end down somehow, but keep my rear tires and tire size (cant go bigger). I run a good street tire- Dunlop Direzza D1 Star Spec. I frequently go on long cruises and dont want to run an R compound tire. I am going to lower the rear of the car 1" which will help slightly with weight transfer. I was also leaning toward stiffer front springs. What else can I do to help out my oversteer issue? I have a 67 Nova with 450 lb-ft of torque and a multi-leaf spring rear setup and I dont want to run traction bars. Thanks in advance!

give less throttle ... put some cement sacks in back ... which is what someone told me they did after putting a small block in a Miata,

Why can't you go bigger with your tires?

Can't fit much tire in those cars without at least mini tubs.

If there is a rear sway bar, you probably don't want it.
If you can soften the springs in the rear you probably do want to.
Lowering the rear can help sometimes.

I'm not sure unsecured ballast is something we can endorse. *cough*

In the old Mopars, I've found that stiffening the front with bars and springs and softening the rear (no bar or tiny little bar, light springs). Makes it better. Then you rotate it with the throttle as necessary. My critics in the old car world all whip out the whole neutral handling balance whatever BS about bringing up rates proportionately. They miss the point of what the setup changes are trying to do...

What are your alignment numbers in the rear?

What are your alignment numbers in the rear?

Funny man...

Max Hayter wrote:What are your alignment numbers in the rear?

probably pretty close to zero camber and zero toe. (it's a live axle rear Max, pay attention }:) )

Max Hayter wrote:What are your alignment numbers in the rear?

Say what?

You could bend the axle tubes for a bit of neg camber, but toe-in would be tough.

I bet Addco makes a big american iron front bar.

Max for post of the year! haha.

With that much torque, and street tires there really isn't too much you can do besides getting very good at controlling your right foot. Anything you do to even half way solve the problem would probably become a sever compromise everywhere else, ie if you stiffen the front and soften the rear enough to make a real difference corner entry understeer going become paaaainfull. Then you start eatin tires at both ends. I'd say set the car up as neutral as you can, and give yourself as much pedal throw as you can to help modulate the power.

A BIG front bar will help settle the back end down, but Marshall is basically correct. It'll be a compromise.

I think you should try driving around it first.

Mike

How wide are your tires in the rear?

I would also recommend more front bar, and less front shock rebound, if you have that adjustment. Both will help power application at corner exit, without really affecting comfort on cruises.

You've got way more power and lateral grip than the car had from the factory, so it's possible you're getting into some funky bad binding part of travel in the rear suspension. Because of this, I would hesitate to suggest softening or lowering the rear of the car too much, lest it get to that part of the travel even sooner.

try moving the engine to the back seat location

WOW this got interesting! I appreciate everyone's input.

I cant run a bigger tire because these little Novas dont have room. I run a 245-45-17 now out back, and a 255 would be pushing it. I have a 1" front swaybar on the car (no rear), and a 1.125 bar in the garage so I could try that out. I have a rebound adjustment on my front shocks so thats easy to play with at the track. I was hoping for an easy solution but I think a little trial and error with changing basic parts and keeping my right foot tame will have to do!

Jeff Ringer wrote:try moving the engine to the back seat location

I have a spare engine I could put in my back seat- that would save the work of moving the existing one! Do you think if I buckled it up I would pass tech?

Or maybe put a passenger in the trunk...

You're going to find that patience is the single best fix for that car autocrossing.

And really focusing on corner exit technique--Smooth throttle and unwinding the wheel is going to pay big dividends.

And then eventually you'll be like me and buy a Honda.

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Bigger Tires

... you'll find lots of worn fender liners among our AX'ing cars ... from using tires that are just a bit too big. Just a fact of life in the solo community. ;)

If you don't have a limited slip differential already, I'd get one. I know on my Crown Vic (also a big, torquey American car) since I have an open differential, it will just spin that inside tire away and make the back end loose.

245's for 450ft-lbs seem way too small. I make similar power with a lighter rear end on 295's. I'd really have to lean into the pedal to get power induced oversteer.

Slab side body with mini skirting.... A 1967 Nova is one of the most tire restricted muscle cars ever.
I was kinda surprised he's fine running 245's.

Soft sided drag racing tires? Will limit cornering speed, perhaps a good thing, but allow better acceleration?

Mako Koiwai wrote:Soft sided drag racing tires? Will limit cornering speed, perhaps a good thing, but allow better acceleration?

:unimpressed:

You can't run real drag slicks. One, if you didn't have bead locks they would unseat... Two, they have such bulgy sidewalls they'd never fit on Bryan's car...

People have used DOT drag radials at autocrosses especially in cars like this. Mixed results. I think the Dunlops are about the best street tire for his application... It is what it is. I think it can still be fun and a great training tool for precision driving. And great fun for us to watch!

In HS, I had the 69 Barracuda. My friends had a 66 Chevy II, a 68 Nova, a 70 Camaro, and a 67? El Camino. It was a nice pack of cars even if they all wore bowties but mine.

I thought maybe the bulge would just be at the bottom of the tire, ie. no clearance issues? Perhaps use more pressure then one would typically use for drag racing ... sort of in between.

The bulge is huge on a "real" drag slick. The street versions aren't as bad.