Torque-steer

[fyrstormer]

I've gotten my Yeti to handle almost the way I want, but there's one last thing that's causing me some grief: torque steer. When I hit the throttle hard, the vehicle veers to one side. I've checked the wheel bearings and they're not binding, so it must be something about the way the suspension articulates under hard acceleration that's causing the torque-steer. I can counter-steer, but only if I remember it's a problem and I catch it in time. Has anyone else come up with a good solution for this?

For the record, I have both diffs open, the stock swaybar in the rear, and the stiffest EXO swaybar in the front.

[Coonburger]

Have not had that problem... Mine is locked front and rear, and under throttle it goes perfectly straight. Even when the front was open, it went straight....

[binaryterror]

Could be from the chassis rear link placement, move those to see.

Could also be too light of a sway bar in the back.

I'd remove the front sway too just to see what that provides, but shouldn't in a hard launch change the torque.

[CamaroTom]

It's because of the open diff in the rear. When you hit the gas one rear wheel is trying to spin faster than the other. A locked diff would solve it.

It's kinda like a powerful fwd car with an open diff, when you hit the gas it tries to pull steering wheel to one side.

[fyrstormer]

Locking the rear diff isn't really an option for my intended terrain and driving style. I would've thought the 100k diff oil would keep it in-check, but perhaps I need thicker oil in the rear diff. I wish Associated would re-stock their 200k oil already; I tried the 500k stuff and it's way too thick.

How would changing the rear link position affect this problem? I'm not familiar-enough with how four-link suspensions work for the suggestion to make sense to me.

[cmbscx10]

I'll do some research but how do you run an "Open Diff" in the back? Ditch the locker and diff housing for a front one? Would that even work?

[EeePee]

This is pretty easy if you know a few things about open diffs and solid axles and suspension stuff. The driveshaft is rotating. The pinion is trying to climb the ring gear. There is resistance. That can be seen by the chassis leaning over. That then means weight has been transferred. That means one tire is not on the ground as much as the other. Open diff transfers power to the wheel that is more willing to spin. That mean speed difference between tires. That means torque steer.

[fyrstormer]

Originally Posted by cmbscx10

I'll do some research but how do you run an "Open Diff" in the back? Ditch the locker and diff housing for a front one? Would that even work?

Ditch the locker and replace it with a spare set of internal gears for the front diff, which are also the same gears used by the EXO in both of its diffs.

Anyway, it's not completely open, that would be if it were packed with slippery grease. I'm running mine in a limited-slip configuration with 100k silicone oil providing resistance against diffing-out.

[fyrstormer]

Originally Posted by EeePee

This is pretty easy if you know a few things about open diffs and solid axles and suspension stuff. The driveshaft is rotating. The pinion is trying to climb the ring gear. There is resistance. That can be seen by the chassis leaning over. That then means weight has been transferred. That means one tire is not on the ground as much as the other. Open diff transfers power to the wheel that is more willing to spin. That mean speed difference between tires. That means torque steer.

I understand that part. What I don't understand is how changing the linkage pivot positions would alter this behavior. There are three forward pivot positions to choose from for the upper links; I'm currently using the middle position.

[EeePee]

Anti squat, which has an affect on what the chassis does, and the axle.

It is your civic duty to try the other two positions.

[binaryterror]

I move those squat links all over and you can learn a lot and really change handling.

I also use the Dlux truss, for even more adjustment and a way better axle mount point (stock is too low).

[redsawacs]

Torque steer can be mitigated by removing torque......

Hey, I'm just stating the obvious - HORRIBLE option, but an option all the same - LOL

[fyrstormer]

Originally Posted by EeePee

Anti squat, which has an affect on what the chassis does, and the axle.

It is your civic duty to try the other two positions.

Since the difference will probably be too minor for me to notice through casual observation, can you tell me which direction I should move the forward upper-link pivot points to increase the anti-squat effect?

Originally Posted by binaryterror

I move those squat links all over and you can learn a lot and really change handling.

I also use the Dlux truss, for even more adjustment and a way better axle mount point (stock is too low).

I think I may have heard of that part a while ago in relation to the Twin Hammers, but I can't remember for the life of me who makes it or where it's sold. Link?

[EeePee]

It's not that minor and no, I won't.

Increase or decrease, you don't even know. Learn, my friend. It's good for you. Try em both, experience it.

Dlux makes Dlux products. Vendor's section.

Maybe Binaryterror will be more helpful.

[fyrstormer]

I found the truss on SuperShafty. I can't tell just by looking; how much does it raise the rear upper-link mounts compared to stock?

Y'know EeePee, even if I know what the adjustment will do, I can still experiment to confirm whether that adjustment accomplishes what I want it to accomplish. You could tell me which direction to move the links to increase the anti-squat, but I'd still have to try it and see for myself, except I wouldn't be going in blind, with no idea what to expect. Why should I rediscover knowledge that already exists? I get paid to figure out things that other people haven't figured out, I'm not going to waste my time figuring out things other people already know in my free time.

[fyrstormer]

Well, I managed to find a helpful article online: Tuning 4 Link Rear Suspensions for the Drag Strip

So it looks like moving the forward upper-link mounts down will increase the anti-squat effect. Interesting, because I took one look at the kit-stock recommended setup with the forward upper-link mounts in the highest position and I just knew it wouldn't work well.

[EeePee]

Okay, but it's your hobby, no? What's the big deal? I'd really like to see someone go in blind, like I've done, experiment, and learn, and then help others. I can link you to two huge threads here on RCC, one of which I helped a ton of people, but I now like to drop morsels of information and get people to expand themselves. Grow.

Fine, here's 2006: Anti Squat and Suspension Tech

[fyrstormer]

Don't worry, I have plenty of ways to grow as a person. I do RC as a hobby because it's (usually) *less* stressful than other areas of my life. Experimenting blindly and hoping for a positive result is extremely stressful and not fun at all, because there's all this tinkering involved and I have no idea if it will do any good or end up being a waste of time. I did enough blind experimentation when I was first getting into the hobby.

If you're concerned about people parroting information they heard without ever checking to see if it actually works, you don't have to worry about that from me. I disagree with conventional wisdom due to my own personal experience on a regular basis.

[EeePee]

Sounds good, mate.

In the time it took you to respond, you could have tried upper and lower holes.

[fyrstormer]

Nope, because I'm at work right now. I'm planning ahead so I can make the most efficient use of my limited time between getting home and doing chores.

Anyway, I ordered the rear Dlux truss, so if moving the forward upper-link mounts down a notch doesn't give me the effect I'm looking for (or causes clearance issues with the MIP rear driveshaft), I'll move the rear upper-link mounts up a couple notches instead. Looking at the other truss options available, i.e. Vanquish and STRC, it doesn't look like either of those offer extra mounting points, or even any static additional height.