rear end traction

[Robfo]

Hi, i hope someone can help me. I've got an evo2 with c hubs and short wishbones. When coming out of corners the rear end of the car steps out. I can get over this by putting a little less power on but it slows me down and if i use a little too much power the car can nearly do a full spin.
I have let other people drive my car and they always comment on how nervous the rear end is coming out of corners.

Front: 40wt 2 holes. Shocks mounted in the middle hole on the top. 3deg kickup. diff set to be free but does'nt slip. 1.5deg camber 0deg toe in. Droop: bottom of c hub is slightly below the chassis level.

Rear: 40wt 2 holes. Shocks mounted in the middle hole on the top, inner hole on the bottom. Wishbones mounted in the upper holes. 1.5deg camber 2deg toe in. 3mil spacer infront of the wishbones for wheelbase. Diff set loose so it slips slightly. Droop: Bottom of c hub level with chassis.

Hope someone can help.

[cobra81li200]

Basically, you have the choice of reducing the rear spring rate, adding front droop or shortening the wheel base using rear wishbones. All this will make more mass transfer under acceleration.

On my SD I used a softer spring and moved the rear wishbones 1mm forward when alban came (remember he could not drive the car with the setup i was using previously), and you saw the result, the car was very good.

[Robfo]

Yeah i have moved the wishbones forward from std, opened some holes on the rear (i was using 1 hole). I'll have to play with the front droop.
Thanks, helpfull as always ;D

Any xray specific help would be very useful aswell

[Robfo]

Oh i forgot to say, the rear end is normally reasonably planted at the start of the race. But becomes unstable towards the end.
How do i set the car up so it does'nt overheat the tyres?

[cobra81li200]

oh, that's a major point you should have mentionned it. Then you should do the contrary to the wishbones, move them backwards to have less weights on the rear tyres, they won't heat as much. Try also less rear toe (how much did you use). If this makes your car unstable right from the begining, then get back to the previous setting and try drilling the rims with more and bigger holes to let the air circulate between outside and inside the wheel.

[steven bough]

I must agree,that ive always suffered with ovesteer with my T1R,if i use 3deg caster i get oversteer into corner if i use 6deg caster i get ovrtsteer exiting the corner.The way i try to get around it is the sme as you (be slower & smoother At the corners)-but i also feel if i could sort this problem ,then i feel i could go a lot faster around corners,instead of having to be on my tip toes incase the rear brakes loose..

So Rob-When you find the answer please let me know as well-& visa versa if i mamage to sort it (i.e i will let you know...

Stev

[Robfo]

If i find the answer i'll tell you.
But i think i'm more likely to find out the meaning of life!

[whoopass]

I run 2 deg rear toe, the rear shocks in the outer most hole. Both upper holes for the kickup. I also run the bridge cut in half then hung over the end of the diff housing to create more shorter rear camber link positions.
The rear end on mine is pretty sorted, in fact I only change the spring rate (usually Stiffer) as the temp is so cold currently and as previously mentioned it is unlikely the tyres are overheating (i am assuming you are racing outdoor tarmac?)

Try running a longer rear camber link, this will reduce traction and increase stability. Run a softer spring on the rear to the front. make sure the droop is set correctly and that the shocks fully extend when unloaded.
hope this helps.

[al]

it was on carpet :)

[Robfo]

I've only run it indoors on carpet and rubberised floor. Its too cold to go outdoors brrrrrrrr im freezing just thinking about it ;D
I'll try running the shocks in the outer hole. i'm pretty sure they are overheating as this only happens 2 to 3 mins into the race

[whoopass]

sounds like it, you may need to look at your tyre/insert combo, maybe run a harder spring, harder wheel so the rear tyres are not working so hard? but the first few laps will be like the end of the race currently! bit tail happy

[Robfo]

Ok, thanks for the help. I'll post the results of the changes after sunday.

[SMTCA Focal Point]

I had that regularly. I solved it by moving one side cells forward one slot. It balenced the car up that little bit better. It wasnt far from being good before I did that.

[MikeS]

Silly question but not sure from your posts, is it the front or the rear tyres that are "overheating" and what tyres/inserts are you running?

[Robfo]

Thanks for everyones help i really appreciate it.
I raced at the HPI winter series yesterday and played about with the setup all day. This is what i ended up with:

Front:40wt 3 holes open. Shocks in the outer holes. 3 deg kick up. diff set to be free but not slip. 1 deg camber 0 deg toe in. Droop, wishbones level with chassis level. 5mm ride height

Rear 40wt 2 holes open. shocks in middle holes at the top and inner holes at the bottom. upper holes used for wishbone mounts, 0 deg anti squat. 2 deg camber 2 deg toe in. diff set to be free but not to slip. Droop: bottom of c hub level with the top of the chassis.
I used the one way pulley as a one way.

This setup gave me loads of rear end grip under accelaration and lots of steering. Setup this way the car feels a little nervous on turn in but driven properly i think it could be very quick around the track. I felt i could be very aggressive with the car without being worried about it suddenly loosing grip or oversteering in or out of the corners so it is a big improvement on my earlier setup. ;D

One question: When your shocks are on your car do the springs float on the dampers or are they held in place firmly. To get the required amount of droop and ride height i had to have my rear shocks set with a little preload (maybe the wrong word?) on them.
I have always set them so the spring have a little float between the top and bottom of the shocks when the wheels are off the ground in the past. As i have been racing for some years i understand that if i want harder springs i need to get harder springs and not just compress them so they feel heavier. Is preload ok? Maybe i should ask in the touring car area as this part of my post is'nt Xray specific?

[SMTCA Focal Point]

One question: When your shocks are on your car do the springs float on the dampers or are they held in place firmly. To get the required amount of droop and ride height i had to have my rear shocks set with a little preload (maybe the wrong word?) on them.
I have always set them so the spring have a little float between the top and bottom of the shocks when the wheels are off the ground in the past. As i have been racing for some years i understand that if i want harder springs i need to get harder springs and not just compress them so they feel heavier. Is preload ok? Maybe i should ask in the touring car area as this part of my post is'nt Xray specific?


If your springs are floating as you say, in my opinion you have too much droop as the chassis should be supported at all time by the springs and not allowed to lift off under cornering etc. Perhaps others will disagree. I would also be interested in there responses.

[John Stones]

Floating Srpings? wha?