5 replies to this topic

[bmarshall1]

I had an issue where my rear end was very loose (no jokes please  ), a new set of Toyos and 2 turns up in the front seemed to have cured it (apparently Toyos aren't 25 session tires in spite of what people say).

 

I am doing some adjustments and have a question: how does raising/lowering the front affect toe in?

 

Lastly, my current settings are 3/8 toe out in front and 1/8 toe in rear, 3.2 camber and 2.8 camber Fr /Rr respectively.  Caster I don't recall but maybe 5-6?

 

Currently the handling is fairly neutral with a bit of rear end rotation on some corners.

 

--I am thinking going down one turn in front and bring the rear camber to match the front to improve overall grip, then test the set up, is this a good plan or should I be doing something else? I am a more set it and leave it kind of person.

 

Rake is neutral to about 1/8 higher in front, corner balance is 50/50,ride height is about 4 3/4 from pinch or about 7/8 between top of shock and bump stop.  Sebring is my home track (bumpy), and I am a mid to back 2/3 of the pack driver (I need to work on consistency).

 

Am I heading in the right direction?

 

[Alberto]

where in the corner is it loose?  entry, middle when you start apply throttle, exit?

 

Toe

3/8" toe out seems like too much.  I'd back that off to 1/8 or 1/16.  I measure in mm and aim for 1 or maybe 1.5mm toe out on each front.  rear usually 1 mm toe in.

 

Camber

Measurements will depend on the calibration of the tool you use to measure but...  I run about -3.5 to about -3.8 degrees all around now.  I used to try and run -2.5 to -3 in the rear under the premise that I'd get better tire wear from very old threads that I read.  I experimented with more camber in the rear and found that the car had more grip and less looseness in the rear.  I.e. it put the power down better.  Hence the -~3.5* rear camber.  

 

YMMV

 

Hope that helps.

[FTodaro]

I do not know for sure that 3/8 toe out in the front is to much. There is a theory out there that the more camber your run the more toe out you need in the front. Think about rolling a tire with lots of camber on the inside edge would it not want to track to the inside. On the rear you can get away with less toe in IMO 1/16 to 1/8 max. for my VVT.

[bmarshall1]

Thanks guys, I have searched and read many, many, threads regarding set up and Tadaro hit the nail on the head with his comment, whether it be true is another question.

 

The car was loose about mid corner on, no trail braking and an old tired motor so likely not overpowering the tires.  In fact if I can get on the throttle sooner it seems to hunker down and increase the rear grip.  I am sure some of it is my style (or lack thereof).

 

On the other hand the tires were 20 heat cycle toyos.  I feel the old tires along with the seemingly many off-camber corners at Sebring was the issue, so... new tires and raised the front a few turns and now the car seems nicely balanced with a slight amount of rotation, but I wonder if I am giving away some overall grip/balance with this set up?

 

After new toyos and 2 turns up in front it is not bad anymore.

 

I start out at 28 and end up around 33/34,  is that about right?

[Alberto]

regarding heat cycles, yeah, the RRs start to become more difficult to drive after ~15 heat cycles.  They can still turn good lap times in the right hands but you definitely have to work at it.  After what I learned last year with my coach (Matt Cresci), I mostly stopped using them around 15 heat cycles - although that is track dependent.  A technical track like Sonoma, no.  A big open track like Thunderhill, not as bad.

 

Experimenting with setup changes good tires is enlightening.  You get to learn for yourself what a change of 0.5 degrees of camber feels like.  Trying to get good data / experiences when using tired, heat cycled tires is difficult.  I think Ross Bentley wrote something about that.

[bmarshall1]

Good points Alberto - I was working more to keep the car on the track vs. working to go faster.  After installing new tires I was able to practice brake and turn in points vs. keeping on the track.  I will start a thread regarding getting a  Driving Coach.