Inside wheel is spinning after putting in coilovers.

[lightyear]

Now that i have front suspension travel the car is leaning into the corners (causing excessive inside wheel spin).

The old front coilovers where a bit dodgy and only had about an inch of travel, which held the car flat around corners.

Should i look into upgrading the diff to a better lsd than the viscous? Or try and set spring tension harder and put the front sway bar on full hard? I just can't afford the $1500 for a good diff. Can the viscous be rebuilt to work better?

[project.r.racing]

bigger front sway bar?

[Matty]

The viscous LSD is famous for its ineffectiveness, and wearing out quickly. I'm amazed you haven't blown it up in fact... (the 1.6 R&P actually)

Raising/softening the front will be causing more weight transfer on the rear which is your problem. I think you've already ditched the rear sway bay. If not, try this first. Then stiffen the front bar. Or get a proper LSD.

[Okibi]

I think you've already ditched the rear sway bay. If not, try this first. Then stiffen the front bar. Or get a proper LSD.

I say make sure you have your rear sway bar and if possible upgrade both the front and rear.

[lightyear]

I have the whiteline adj 25mm swaybar on the front. I will put the rear whiteline swaybar on, but have to fix the broken bolt. I just thought if i screw the spring platform up it will help make a stiffer spring to reduce body roll. Everyone said that diff was useless, but it had been working fine with the car as it was. I had a look at sdpics photo of my car and there is a noticable difference in body roll.

[Matty]

adding the rear bar will make it oversteer more.

Increasing perch height will (for a couple of reasons) increase weight transfer at that end, so if you're talking about the front then that will increase understeer/decrease oversteer.

m

[lightyear]

It's not oversteering, as only one wheel is spinning. I will put the rear one on and see how it goes. I can always take it off again. It had understeer on turn 3 but that could have been due to the oil on the track.

[Okibi]

adding the rear bar will make it oversteer more.

Increasing perch height will (for a couple of reasons) increase weight transfer at that end, so if you're talking about the front then that will increase understeer/decrease oversteer.

m

It could snap oversteer more at the moment you have one rear tyre planted on the road. It will slow your lap times down if your power is spent going no where.

Adding a rear sway with stop the car cocking it's leg like a dog and spinning up the inside wheel as much.

If you're getting oversteer with the stock sways then don't remove them, get your alignment professionally set.

[Matty]

Adding a rear sway with stop the car cocking it's leg like a dog and spinning up the inside wheel as much.

Uh, no Dave, adding a rear bar will make it lift the inside rear more...

[greenMachine]

Adding a rear sway with stop the car cocking it's leg like a dog and spinning up the inside wheel as much.

Uh, no Dave, adding a rear bar will make it lift the inside rear more...

I'm with Matty on this one.

The answer to this question is three words - L...... S...... D...............

From those lap times the car is putting out some serious Kws, tweaking the suspension settings will only go so far. You really need to ensure that the power is going to both rear wheels, not being spent spinning a wheel and converting rubber to noise and smoke. Simple choice really: spend $$ on an LSD and go quicker and have longer lasting tyres, or spin the tyres and wear them out quicker, losing time while doing it.

Or, just drive slower ...

My 2c. Feel free to put it to the LSD cost

[manga_blue]

No matter what you do with your suspension you'll still need a better diff. There's this: http://mx5cartalk.com/forum/viewtopic.php?f=44&t=37468

[Okibi]

Sure a better LSD will help but we're talking about body roll when pitched into a corner, the body roll takes weight off the inside rear wheel. Less force is pushing that tyre against the road making it break traction and spin.

I still do not agree with removing the rear sway bar.

"The bar resists the torsion through its stiffness. The stiffness of an anti-roll bar is based on the fourth power of its radius, the stiffness of the material, the inverse of the length of the lever arms (i.e., the shorter the lever arm, the stiffer the bar), the geometry of the mounting points, and the rigidity of the bar's mounting points. Some anti-roll bars, particularly those intended for use in auto racing, are adjustable, allowing their stiffness to be altered by increasing or reducing the length of the lever arms. This permits the roll stiffness to be tuned for different situations without replacing the entire bar. The stiffer the bar, the more force required to move the left and right wheels relative to each other. This increases the amount of force required to make the body roll."
http://en.wikipedia.org/wiki/Sway_bar

I know Matty is full bottle on this stuff but until anyone can present a logical explanation as to why the rear sway bar isn't working as it should then i'll stick to my guns.

In my NB I upgraded both my sways before I got my LSD, with the stiffer rear sway my car lifted the inside wheel a great deal less.

[lightyear]

I know i need a better lsd, but what some people are forgetting is that with the old suspension (that did not let the body roll), there was no issue with single wheel spin. Thats why i was thinking of screwing the platforms up to compess the springs a bit might help.

[Matty]

I know Matty is full bottle on this stuff but until anyone can present a logical explanation as to why the rear sway bar isn't working as it should then i'll stick to my guns.

Weight transfer is a function of centre of gravity height, cornering acceleration and track width. It has (almost) nothing to do with body roll - a go-kart still gets weight transfer occurring.

Weight transfer happens from the inside to the outside pair of tyres during cornering. Whether it goes to the outside front or outside rear is a function of the relative roll stiffness of the suspension at each end. Say you had an infinitely rigid rear suspension, then all the weight transfer would occur to the ouside rear wheel, and none to the outside front.

A sway bar is in effect a roll-stiffener for that end of the car. Yes it reduces roll stiffness, but (as said) that has very little impact on weight transfer*. But it does mean that more weight transfer happens at that end of the car.

Adding a rear sway bar (increasing rear roll stiffness) is going to want to cock the inside rear wheel up. This has two effects in this case:
1) the inside rear becomes unweighted, so it has less traction, and with an open diff you then have less ability to accelerate the car.
2) the outside rear gets more weight on it. Tyres have a coefficient of friction that decreases as you put more weight on them. So the upshot is the rear has less grip (and at the same time the front gets more grip because there is less weight transfer going on there) - so you end up with oversteer.

Conversely, removing the rear sway bar gives the rear more complaince, so weight transfer goes more to the outside FRONT tyre, and the opposite to the above happens (more grip at the inside rear, less weight on the outside rear).

*increasing roll stiffness can improve overall grip because you decrease the camber change on the tyre, an effect which improves their traction, but with double wishbones this is a minor effect.

[Matty]

I know i need a better lsd, but what some people are forgetting is that with the old suspension (that did not let the body roll), there was no issue with single wheel spin. Thats why i was thinking of screwing the platforms up to compess the springs a bit might help.

First, you're dealing with a tricky setup, and what I wrote above applies to a linear system (one that doesn't bottom out or have progressive spring rates etc).

I'll bet that with your old front suspension (very little travel) that you were bottoming out the outside front - this increases the spring rate on that corner massively, so all the weight transfer goes to the outside front --> understeer and good rear traction.

I have no idea what changes you made with new coilovers - can you please expand?

Screwing up the front perches will not compress the spring more - the spring compression is just a function of how much weight is going through it. Nor will it change the spring rate. It will only have the effect of raising the front of the car.

This will:
1) decrease your static negative camber (less front cornering grip, but better braking grip)
2) reduce the chance of the front bottoming out. (more front grip)
3) raise the front roll centre hieght, and decrease your front roll couple (which will lead to more weight transfer at the front, which will lead to less front grip)
4) increase the centre of gravity height, which will reduce overall grip.
5) increase body roll, which will cause a camber change which will reduce overall grip.

In a nutshell, it will make a difference, but I can't predict what the outcome will be...