Understeer help

[andy21]

I had someone `toe out` the front a degree or so. That helped.

Flat flooring for a couple of hundred quid, that'll sort you out.

[Nick Woods]

Quoting elie boone: 

All Caterham data about rake is without driver.

Ok , but therefore that must assume a certain value for the weight of driver and/or passenger which may or may not be appropriate for the person who actually uses it.

 

For example, the unladen rake of my car is higher on the drivers side than on the passengers because it was set up to be correct when I drive it solo. When I'm in it the rake is the same both sides, but when I have a passenger its a little lower on that side. As I drive it solo more often than not , and drive it harder when on my own I wanted it set up that way. One of the car mags (ISTR it was Evo) used to run a 7 and they had it set up to be correct with a passenger on board as that's how they used to run it most of the time

[Guest]

Quoting sforshaw: 

Nobody has mentioned driving style .......

 

Stu.

 

It is my first Caterham with only 6 months under my belt so I would be interested in any info you might have please.

[Pelico]

Driving style: Possibly entering the corner too quick.

 

On one of the Motorsports events training days I was advised to break hard to enter slowish, go for a late apex, feel the front wheels grip and then bleed the power in.

 

 

Mind you I am a rubbish driver 😬

 

The more talented might trail brake at bit

[SLR No.77]

If you've been used to front wheel drive cars you need to adapt your style slightly, also an LSD will tend to accentuate "pushing" the car straight if you accelerate hard mid corner ... until the back end breaks out! Try to get on a track day with an instructor who knows Caterhams

 

Stu.

[Richard Price]

Quoting andy21: 

I had someone `toe out` the front a degree or so. That helped.

One degree

I'll bet it also wore the inside edges of the tyres, and scrubbed speed off in a straight line.

I'd say parallel to 0.25° to out.

 

Leebert, did you say what type of LSD you have. If it's a plate type diff, then too much preload can induce understeer and then snap to oversteer. My own car originally had a ZF diff with too much preload. Once corrected, the understeer was reduced, and it has a much more progressive transition to controllable oversteer.

If its a suretrack or quaife, then it's not the LSD causing understeer.

 

Camber is also worth checking, the recommended "road" settings from the factory are good for tyre wear and stability, but not so good on the limit. The harder you push, the more negative camber works.

 

However, I'd agree with Pelico, driving style can have a huge influence. Too much speed into a corner, too aggressive, and too much power on the exit can give the impression of understeer.

 

Whilst many folks will recommend using a rear ARB to counter understeer, I've only ever found it made the rear unpredictable.

 

 

 

[7 wonders of the world]

Assuming springs are correct and dampers in good order I would disconnect the rear ARB, and concentrate on the basics, tyres, tyre pressures, corner weights, rake, geometry and for initial set up use the orange front ARB.

 

Than once your in the ball park you may wish to fine tune by using the rear ARB to add a fine degree of balance.

 

Keep it simple, alter one thing at a time test and repeat and record what changes you make along with the results. This way you can always back tract using the data your producing should you need to.

 

 

[Richard Price]

With wide track and standard springs and dampers, I use a red front ARB, and no rear ARB.

It's good on the road and quite competitive on sprints and hillclimbs.

 

 

[Guest]

Lots to think about there. Thanks for all your comments

 

The LSD is a Titan that was refreshed almost a year ago by the previous owner IIRC. I don't have any details of ow it was set up unfortunately.

 

It is quite possibly driving style as the car feels really nice when I'm not driving it hard. I think it would be a good idea to get some more miles under my belt and some track time with tuition. Apart from hiring a 7 a few years back, I've not driven a RWD car. I've put a booking form in for Dunsfold and hope to do a track day this year. Looking forward to getting even more enjoyment out of the Seven