So in my experience, new bushings don't make any difference with bump steer. Maybe a *tiny* bit with torque steer, but not much. I was told by some that they would. Luckily they make handling noticeably better, but still....I HATE the bump steer on MINIs.

My friend has a totally souped up JCW with all the modification goodies -- lowered, new springs, camber plates, poly bushings, sway bars, etc., etc. He said that the bump steer was gone when he did his suspension mods, but when I drove his car today it had nearly the same bad bump steer that all MINIs seem to have. I honestly don't think there's a whole lot that can be done about it, based on that; and I also think that many might have wishful thinking about their mods helping with it. I don't mean that in a rude way, just in a based-on-experience-with-my-car-and-others'-cars way.

Thoughts?

I think he is a bit overly optimistic. The engine bushings help torque steer more than anything not bump steer. I have a Mini-madness poly bushing for my lower engine mount. It definitely helped in the torque steer department!

I'm pretty sure he is talking about control arm bushings, not engine bushings.

Headlands,
when you say you are having bump steer issues, you are referring to driving down a smooth road at a constant speed and then hit a bump with only one side of the car and the car jumps to that side of the road? Because bump steer is when your front wheel moves up or down, the arc of your tie rod changes and can pull the tire in or push it out causing your toe to change on that one wheel. This is usually exaggerated on a lot of lowered cars due to the factory tie rod angle being out of geometry and can require a spacer for the tie rod to bring it back to the factory location so the geometry is back in spec.
Or are you referring more to when you are accelerating and hit a bump and the wheel jerks to that side? That would just be a powerful front wheel drive car and sticky stiff side wall tires. Help me figure out what the conditions are that you are experiencing.

The definition of bumpsteer is often confused on internet messageboards....that's my observation.

The lack of suspension travel/compliance is often confused with bumpsteer.

- andrew

It's actually both of those things. I just often feel like the steering wheel is jerking around in my hands when I hit bumps, and I've experienced the exact same thing with 3 other MINI S/Clubman S cars that I've driven. It's not remotely confidence-inspiring! From talking to other people I know that this is simply the way the MINI S cars are. Some reviews I've seen specifically mention it, too.

My car isn't lowered...my only mods are better shocks/struts, a rear sway bar, and front control arm bearings. None of these things made these issues worse at all -- they improved them ever so slightly but really not by much.

I can see how stiff sidewall tires (low profile) and a powerful engine could contribute to this, unfortunately much more in the MINI than in other sports cars I've personally driven (Mazdasport 3, BMW M3, BMW 335i, VW GTI).

The R56 does not actually have much bumpsteer, the R53 is much worse but even then it's not a big deal. Bumpsteer is caused by the steering tie-rod and control arm having different lengths and/or not being parallel, and as such the wheel will change toe during suspension stroke. A car with significant bump-steer generally shows it during aggressive cornering maneuvers when the road surface has significant undulations, as such causing a sudden change in the tires slip angle and a jolt of direction change through the chassis.

I have a feeling you're trying to describe something else. Changing dampers, spring, and control arm bushings would of course have no impact on bump-steer, but they would all have influence on ride and handling. The R56 does have significantly more torque steer than the R53 due to the reduction in anti-dive [not as much torque steer as a SRT-4 or MS3, but way more than a GTI]. The fact that you have a Clubman means that the longer wheelbase will inherently make the chassis less responsive and more stable. Can you try to be more precise with your description of what you're observing?

Thanks,
Ryan

Hi Ryan.

Seems I may have the terminology wrong. What I'm describing in my car (plus 2 other R56 S's, 1 JCW R56, and 1 R55 S that I've driven) is that the steering wheel jerks around in my hands when going over bumps. It's not every single bump...I just know that it happens a lot, both during acceleration and when I'm not accelerating. I know that the R55 and R56 have tons of torque steer, but this is something very different as it's not necessary to be accelerating to experience it. It happens whether one is going straight or turning, but again not all of the time.

One concrete example is being on the freeway and driving in a lane that has a ridge in it, going lengthwise. The wheel will move around in my hands as if it's trying to figure out how to handle the ridge -- I've seen other people in this forum describe this exact behavior. Or on regular streets the wheel will jerk around trying to navigate a bump, but again not all bumps (for example, this doesn't happen on speed bumps). I wish I could be more exact with what exactly triggers it, but I've seen many posts where people describe this very thing.

My car did this before I had any of these suspension modifications, and like I said I have noticed it in other R56 cars that I've driven (all were stock except for the JCW which was heavily modified). It feels just as out of control as torque steer.

That description does help a bunch. I know the feedback you're feeling through the steering wheel. Indeed the R56 does suffer from that, as does the current BMW 1-er and 3-er. I believe it's a function of there being too little anti-dive and its interaction with the scrub radius [which is a function of the steering axis and wheel offset]. Your tire selection will also play an enormous part in this. The effect is technically torque-steer, though some people will call it tramlining to distance the feeling from powertrain-induced phenomenon. The irony of all this is the R53 has virtually none of the steering feel problems the R56 has. It was the primary reason I sold my R56, to be blunt.

The biggest improvement you can make to the tramlining/torque-steer problem is to install ALTA PSRS offset control arm bushings in a "half-n-half" position to add anti-dive and increase caster. Adding caster will make the steering wheel snap to center, giving more authentic steering feel immediately off-center. The anti-dive will change the angle of attack on the control arm and thus the torque acting upon the control arm relative to its pivot axis.

The second big improvement to the problem is to install tires that don't suck. This can be tough to quantify, but essentially you want tires that don't try to follow imperfections in the road, don't hunt around during accel and braking, and offer generally consistent feel under all situations. Tires that have awesome steering feel help tremendously. The Falken 615 and Kumho MX [now both pretty old] both offer amazing steering feel and are pretty minimal in terms of tramlining [from what I remember]. Don't get Sumitomo HTRZIII, most Pirelli's or Continential's, and the awful BFG KDW2. The Yokohama AD08 is supposed to be excellent, but I have no first hand experience. For what it's worth, the Dunlop SP Winter Sport 3D have excellent behavioral characteristics despite being a snow tire.

I hope that helps,
Ryan

Thanks much, Ryan.

It's frustrating to me that that they would worsen the steering feel in the R56/55 from the R53. WHY!? It sometimes makes me want to sell this thing, and I've only had it for 4 months. I don't care what anyone says: it's not a good thing to have at all. Plus the R53 still had that "slot car feel", so this shows that it's possible to not have these problems and still handle like a slot car.

What do you mean by "half-n-half" for the control arm bushings? I have the Madness poly bushings, so is there an adjustment to make to help this situation? Is adding caster a big job?

I have Dunlop SP Sport Signature tires and have a feeling that they "follow the road" like you're saying. Damn, they're only 3200 miles old so I'm not too keen on replacing them already, but if it'll help make this car feel like I'm actually in control of it at most times then maybe it's a good investment. Is there an all-season tire that you can recommend?

Again, it's SO frustrating to me that BMW would make the unfathomable decision to have this be much worse on the R56/55.

Ryan,

All very good info, when looking for tires you must also remember that in general the stiffer the sidewall the more chasing the tire is going to do. That is why the factory runflats are so bad, there is no side wall flex so its as if you had a solid tire and that is going to follow every imperfection in the road. The more compliance you get in the tires the less there will transmit the road back to the wheel. Everything is a compromise though, you go to soft side wall then you loss steering feel. But non runflats do help a bunch.

I thought bumpsteer was just something that comes with a gocart.

I just had a long talk with Danny at Mini Corsa. He said a strut tower brace might help, and to make sure that the alignment is perfect. We talked about camber and there is of course a tradeoff either way, so I need to decide about that. He said that the poly control arm bushings should help a lot with this, too, so it's also his suspicion that the alignment is out of whack.

The ALTA PSRS bushings can be rotated to add 0-1.5 degrees of caster

Thanks Jarid Mounting the PSRS in "option 2" position is my recommendation for the R56.

While a solid polyurethane front control arm bushing will at least keep the arm stable, it doesn't fix the inherent geometry problem. An offset bushing is the only relatively easy way to fix it.

Regarding tires, there are tires all over the performance spectrum that do and do not exhibit tramlining [following the contours of the road]. Generally, the wider the tire and the closer to a slick it is the more it will tramline, regardless of sidewall stiffness. That said there are max performance summer tires that are very well behaved. It all depends :P

Technically go-carts can't have bumpsteer as there is no suspension. Since the chassis is the suspension, [and the resulting absurdly high wheel rate] you get lots of tire bounce and varying contact patch, which will cause varying levels of grip through the course of a bumpy corner.

Cheers,
Ryan

Lowering the rear of the front control arm mount would reduce anti-dive, not add to it. So more load transfer through the springs.

Can you explain the interaction between torque steer/tramlining and anti geometry? I don't have much experience with torquesteer.

- Andrew

Well, since I'm not going to go through the cost of buying and installing all new bushings after buying and installing the Madness polys, then the question I ask you is this: is it possible to adjust the camber in another way (i.e. the more traditional way of removing the plastic pin dealie)? If so, what are the tradeoffs with camber adjustment and how much would you recommend adding for someone like me who is not a racer but sometimes does very spirited, fairly aggressive street driving?

Andrew, you are correct, lowering the rear mount would reduce the anti-dive percentage. My mistake. The advantage of reducing anti-dive percentage would be to reduce the binding on the suspension arm, which appears to help torque steer and tramlining. For what it's worth, I modified the front suspension on my track-car R53 to reduce the front anti-dive, and while it requires greater spring rates to offset the would-be added suspension movement under braking, the steering precision and overall grip improvement were big pluses.

Going back to my R/C racing days, we would reduce anti-dive and anti-squat to increase mechanical grip on low-grip tracks. When I ran less anti-dive up front, I wouldn't need as strong a servo to turn the front wheels because the suspension wasn't bound up as much.

Food for thought,
Ryan

Interesting, thanks. My experience with anti-dive and anti-lift is from the Subaru WRX....reducing anti-lift would make a major difference in front grip powering out of corners.

- Andrew

Sounds like spot-on experience.

I have both

They both helped, but the PSRS didn't help as much as I was expecting.

ALTA say that their PSRS in option 2 adds anti-lift. Wouldn't anti-lift help with powering out of corners? not anti-dive....

Alta has the description wrong though...same thing with their PSRS kit for Subaru....many on that side have noticed that.

- Andrew

I see....

I love this site

Technically karts do have (a sort of) suspension as their chassis are designed to flex, along with tire pressures, torsion bars, camber/caster, and ride height adjustment that all make a difference in the performance of the "suspension". Karts can experience this phenomenom! Agree with previous posts that if you do have poly bushings all around that a majority of your problem is coming from your tires. Try adjusting your psi first. For instance the difference between my oem Pirelli's and my track day Hoosiers is a huge impact on how the car feels, and 5 psi difference on both sets of tires is a very noticeable difference as well! But keep in mind that psi needs to change for performance or longevity.

Today I tried adjusting the pressure of my tires. I experimented with a few settings and settled on 35 psi for all four. It does make a noticeable positive difference, indeed! It feels a touch sloppier on the curves, but barely noticeable, and the tradeoff in not feeling like someone else is taking control of my steering wheel is worth it in spades.

Hard for me to imagine why MINI recommends 38 psi -- even only 3 psi less makes the car much easier to deal with.

This car has been a great learning experience in many different ways. Unfortunately, the driver's course I tried to sign up for at Willow Springs next weekend is full, but I'm looking forward to taking a class at some point and learning even more.