1st gen push

I run an 84 chassis with a panhard rod and turn in spacers. I seem to have the only ITA Rx-7 in the SFR that pushes (not bad, but enough). The real problem is that tire pressures become critical. If I'm off by more than 1 PSI, the push comes on hard and my times drop 1+ sec per lap.
As for relocating the holes, the GCR says traction bars are free. Do our upper axle links qualify as traction bars?

Tak
#29 ITA SFR
 
Tak-


To comment on your thoughts, but in reverse order.....
It sounds as though you are running the upper links. The story goes that the rear end, when lowered to the ride heights we run, goes into a binding situation. (This is a twofold issue, from what I understand ...the links and the watts link both contribute. The axle gets twisted as it gets lowered) Take a look sometime and you'll see that the upper and lower link follow different arcs. The upper links are effectively eliminated in certain scenarios, and the upper location is provided by a new third link, and is considered a traction control device under the ITCS rules. The smae rules allow any material (air, even) as a bushing, so while the upper links are retained, they are located with extrememly soft materials, which really means that they are just along for the ride.

The third link is designed to provide the proper geometry.

If you were talking about retaining the upper links, the free bushing rule would allow you to create a bushing that would allow you to alter the length and/or angle of the link, as long as the link was not modified in any way. I imagine you could do this with machined delrin/aluminum casettes, among other similar solutions.

To directly answer your question about the top links being considered traction devices, I don't believe so.

Also, can you describe your push? High speed? Low speed?, On throttle roll off? Mid corner? On throttle pick up? Corner exit?



------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
Jake-
Just to clarify, I run a panhard bar, not the stock watt's link.
The (mild to moderate) understeer comes after turn in, as power is rolled on. In a long sweeper (say turn 2 at Thunder Hill, CA, ~180 degree, 90 mph) the push begins about 1/3 of the way around. Rolling on throttle makes it worse, jabbing the throttle brings the tail out (too much). Very light brake dragging with throttle on usually solves the problem--just a lot pedal dancing! Doesn't seem to matter what speed, it does the same thing at Laguna turn 2 (~180 degrees, 45 mph)

If you would like to get more detailed, drop me a line ([email protected]).

Tachi (aka Tak)
# 29 ITA SFR SCCA
 
I have a limited slip in good working order. No wheel spin or chatter exiting slow corners. A little wheel spin if I hop a curb.

Puzzling aint it?

Tak
 
Originally posted by Tak:
...the push begins about 1/3 of the way around. Rolling on throttle makes it worse, jabbing the throttle brings the tail out (too much)...
Click to expand...

Tak,

My chassis set-up skills/knowledge are good, but not great. Having limitations in knowledge and budget have forced me to learn to drive cars with certain 'quirks'.

Obviously a car that is balanced in all types of corners under all conditions would be ideal. However, since that is very unlikely. My theory is to get a car that is close and predictable. The rest will have to be made up with my technique.

This is sincere advice, not some smartass answer, my apologies if it comes across that way.

If rolling the throttle on makes the push worse and jabbing the throttle makes it loose then you need to find the sweet spot somewhere between rolling and jabbing
wink.gif
.

Many times every car on the grid will be less than 'perfect'. The biggest difference will be what each driver does with what he has to work with.

Best of luck! Seat time and a longer throttle throw can make this easier.
 
Tak

Does your Panhard rod have adjustable height? If so, this will have an effect. testing should reveal a new personality.

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
Hey everyone, lots of good replies and questions to my original post. I will be running the hpde at Sears this Sunday with Nasa. What are some quick and easy fixes for the understeer? I will try some toe-out and differant tire pressures, maybe 30# in front, 34# rear? What say you?
 
I'd try an additional 2# split in tire pressure towards the rear. This would be the quickest fix. 30/34 would be okay if you are currently running 30/32.

What happens if you soften the front bar one hole?

Does it have this same behavior when turning right and left? Turn 2 at Laguna is a left hander, not certain about the other corner you were talking about.
 
I got rid of my push by dropping the nose 3/4", dont know what ill do when I camber the rear end a pinch, it'll probly be pushing again.
 
Originally posted by 7'sRracing:
dont know what ill do when I camber the rear end a pinch, it'll probly be pushing again.
Click to expand...

Uh oh... get ready for the rules nerds onslaught!!!
biggrin.gif


Seriously though, everyone should check the camber on their rear housings. Our replacement housing (after a crash) had positive caster on both ends and some toe out on the drivers side.



------------------
Scott
It's not what you build...
it's how you build it

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E-mail me for deals on
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Sunday's Infineon event went well. The car had less push, ran 30psi front, 34psi rear. The chute is great, very narrow opening between the berms on entering, but you can run on the inside berm, it will make the car hop, the no-no's on the outside berm don't do much for the handling, but you can run on them and not get into trouble. It's downhill so you pick up speed, a very late apex on the turn at the end of the chute (7?), great place to do a little power slide. Lots of fun, but not as challenging as the standard course.
 
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