Two things (possibly one) I noticed on the video in sports while the rear seemed to be on the verge of pogoing, the suspension also tracked very well over the curbs. I'm also curious if you've tried different tire/wheel combo........wondering what a more compliant tire might do?

Now Ange whgile it was fun to see someone else bombing round with Miata / MX5s but that video is rather dangerous!!!!! As a two stroke fanatic watching the video and hearing the Ba-iiiinnng downshifts is dangerous and could cause me to do a rotary conversion...................this coupled with listening to the screaming RX8's in car during Grand-Am telecasts on US TV reminds me to much of my 1 2 5 Road Race bike.............which was waaaaaay fun.

OK back on topic.


Tom

nah no neg on the rear, although it would be nice

im running -2deg on the front

Ange,
Just been looking at your youtube vid.
Have you been tampering with your diff as it looks very much as if you are running a touch of negative camber there?This is turning into a very informative thread....
Dave

I'm sure the perfect Ute set up is not what the coupe set up would be.

On our D-Sports Racer the car was somthing like 76 inches wide, the pick up points for the left and right suspension were only about 18 inches apart , so as you can imagine the control arms were long and this resulted in the car running no sway bars at all (as I managed a class lap record with it the lack of sway bars didn't seem to matter).

On a MX-5 Miata show room stocker I once tried some bigger sway bars at an autocross and while the bars helped the cornering and turn in it also caused the inside rear wheel to spin. The solution would be a limited slip diff, not going back to the smaller bar but the diff wasn't legal in for the road racing class ............so if I could have legally fitted bigger bars the laps times would have been slower due to the wheel spin.

I won't do the explanation justice but the whole idea behind sway bars is that the grip level for the pair of wheels (front or back) is increased by limiting excessive roll / weight transfer, now you can overdue this. All those cool pictures of 911's cornering on three wheels............... a softer bar would keep all the wheels on the ground. For the hotchkiss (sp) rear axle the principles are the same, the trick is having enough wheel travel in droop so that the inside wheel isn't being lifted off the ground due to limited travel. In some cases a car will be faster with no rear bar, you just have to test it.............when it pours rain, if it's a race day I will disconnect both bars on my car as they are to stiff.............understeers in and can't put power donw on exit..............for a track day I'm to lazy to be bothered.



For the sake of this thread a rear bar might keep the car off the bump stops which then would make the lack of a LSD a problem. I also wonder what the weight distribution is on a standard UTE and what sort of ride height difference front to rear is needed to get thing set up well. I tend to favor softer springs in conjunction with sway bars, the softer springs in the rear would allow a little more rearward weight transfer and the sway bar would limit the excessive roll caused by the softer spring.

Also Ange brings up a good point R compound race rubber tire construction will have a big effect on how the car handles as they generally have a stiffer sidewall then street tires.

Tom

the only change that i could feel on the race track was that with the 14mm rear bar
i had to wait until the ute was completely settled (sitting flat) before i applied any power.
any slight (and i mean slight) bit of acceleration would result in the inside rear wheel spinning (even with a good lsd)

once i removed the rear bar i was able to apply the majority of the utes power once i could see the corner exit
with good exit grip and speed. infact if i apply too much it will power oversteer,
which tells me that my rears are both well planted as the lsd isnt giving up one the inside wheel anymore

no difference in body roll could be felt with & without the bar
nor did it effect the way the front behaved

i guess the most important thing to note here is that my findings
are when cornering on the absolute limit of my tyres (r-spec) on a racetrack

so my experiences will be irrelevant to most on this forum

ANGE,
Thanks for the reply.
I understand (could be wrong) that unloading the inside rear could also be a front end problem. (i.e opposite corners are coupled). So too much anti roll in the front, too high front spring rate, or on front bumps??
with a 14mm rear bar did you notice the front inside wheel lifting?

Bryan

i fitted a 14mm rear sway bar to my ute, and found that initial turn in felt better (at road speeds)
but on the circuit it did nothing for body roll and just helped to unload the inside rear wheel in corners

i also believe that the overload leaf in the standard spring pack does horrible things to handling
(much the same as hitting the bump stops) and if your doing ciruit racing you'll need to add at least one
full leaf as the rate of the remaining 3 leaves is too soft.

good shocks make a world of difference but again too stiff on the rebound and they'll unload the inside rear
(i run koni reds on full soft)

these mods will reduce body roll (if the fronts sorted) but will not stop power oversteer obviously

heres how mine handles
youtube link

Tom,
It's interesting you talk about adding a rear sway bar.
I would have thought that with the Hotchkiss rear end, where ride and roll rates are coupled you would have more then enough anti roll from the leaf alone?
And given how light the 1200s are, the height of CoG, surely it wouldn't require a high spring rate in the rear.
Whats the thought behind going a rear bar?
Cheers

Bryan

Solid info there Tom!!
Makes we wanna go play with my suspension just for the hell of it!

I do have one more question; When the motor comes on boost, what sort of horsepower jump are we talking..............if you are already cornering near the limit and the motor jumps 20 or 30 horsepower then even after upgrading the suspension you would still have this issue.

As for suspension upgrades, I don't know utes but the basics are same as for any car. Believe it or not err on the soft side, the car won't have that snappy feel but will corner much better with a slightly soft set-up versus the urban myth oxcart springs.

As for actual set-up I'd say the rear springs are very likely more than stiff enough since Utes are designed to carry a load. For sway bars on the coupe I'm using 7/8 inch front and 5/8 rear. ( I think this equates to 21mm and 15mm) With a ute I would try adjusting the ride height so that the back is slightly lower, shifting the weight to the rear. While on the subject of rear suspension you need to see if you are cornering on the bump stops, if the car is doing it alot the spot where the stop his the chassis rail will be polished clean or you can put a dab of white grease on top of the stop do a skid pad test (if you can find a deserted parking lot) and see if the grease ends up on the chassis. You need to see what the car does in steady state cornering. As for Dampers any good quality brand will work.

The Carroll Smith "Tune/Prepare/Engineer to win" Books will help a lot, Tune To Win in particular. The reason I bring up the Smith books is in it he says fix the end that isn't working. In you case address the rear of the car first. First you need to do two things determine is this a "boost" induced problem or is your car cornering on the bump stops? If it's a boost issue that can be cured by you pretty easily with you're right foot, if it's cornering on the bump stops as Benny pointed out you need more travel. The cure could be changing the ride height if it's way to low or using a shorter bump stop. Next as you don't like the amount of body roll the car fit a set of sway bars. Finally how do you like the ride? If you're OK with the ride then the one issue you have mentioned will be cured by the sway bars.

Finally read up and make adjustments one at a time; A car has three phases you need to isolate, Transient (Turn In), Steady State (mid corner) and Power-On Exit. You may have to compromise on one phase to get better overall performance for a particular car. For example on my coupe with 73HP at the wheels turn in and mid corner speed are more important then exit as there isn't enough power to have issues on exit. Compare that against a 400HP 3500lb car, which isn't going to obtain the same corner speed, and the exit will be most important.

Tom