Once temps reach about 15 deg F, the Poly bushings become very very hard .

I have yet to pull these apart, but I am curious to see what they look like after 35K miles of driving...at the track, in salt and snow etc.

One potential down side that has been discussed is range of motion, but that may be isolated to a poor design rather than the material itself. One truth is that poly will wear away if it rubs along side another component...which can happen if range of motion isn't studied. As I wrote above, I am very curious and in particular, to see what the boring looks after being driven thru all the crap this winter has thrown my way.

I care about range of motion and drivability on the street, then track. When it's hot, I don't really notice the harshness. In four weeks or so I will remove these and take a few pics.

 

Michael, it's been quite a while since our paths last crossed!

Would you mind elaborating on your statement above? Curious to hear your rationale or logic on that topic... Thanks much. Hope you are doing well...

 

COOL!

 

Nice to see read a reply from youTony!!! How's life? I'm headed back to the Old Country soon...

Anti dive alters side view roll centers. So, dive is first resisted by geometry and not springs and dampers. This will cause bushings and control arms to intitialy resist dive - these components will absorb load before springs and dampers. Essentially this can complicate spring and damping setups and how a car feels and responds on and off the brakes. anti squat works the same way.

I've used anti-squat devises in the past, but never anti-dive - only because it wasn't available. I'ver never studied any of these in particular, just read a lot and talked with a few engineers about it.

Like anything Tony, it's a compromise and the tuner gets to weigh which ones work for his crew and which ones don't.

I can get more specific, but I've been told recently that I'm pedantic and I'm hogging threads. So let me know if you want more info and I'll PM you.

 

I call bs... from a pure... lurking in the threads learning craploads of stuff from your posts perspective... keep posting please regardless of what you are "told".

 

Alrighty then!

When load is transfered thru the bushings and cohntrol arms, the suspension is said to 'lock up' momentarily. This transfers loads quite quickly to the front tires...not really a great thing. But, after the above compnents have resisted all the load they can, the springs and dampers become loaded. This creates a cycle in which the tires are loaded quickly, then unloaded as the load transfers to the springs and dampers and then the tires are reloaded again.

I'm not an engineer, so the term loaded and unloaded suits my brain, but this is probably not the correct term - its all weight transfer.

Also, anti-dive works in roll to a certain degree as well...how? I dunno, but like all things with cars in motion, no one force acts on a car in one axis alone. So I imagine that as a car with anti-dive rolls into a turn, some resistance is carried by bushings and control armsa rather than springs and dampers...that's a guess, but probably not far off.

 

Yes, MEB, please keep posting. It's nice read conversations between customers and vendors that know what they're doing (you, txwerks, and dmh).

mb

 

Meb mentioned range of motion. This is something that yet has been discussed with the exception of my past post. Why has no one reported about this with any of these bushings? Still, to date, those of use who don't own the Altas have not a clue of how they are made and what they are made of?
I asked Meb to check binding with his inserts when he was in the process of removing them. I have a feeling that they may bind.
I still hear Don speaking of Delrin bushings, though I am still here to tell you that delrins will absolutely NOT work in the Mini.
Seems that I have been the only one that has actually studies the motion of our front control arms. It's not what most think.

 

If there is any uneven wear in either the boring or on the dowel portion of the P flex bushing, the story has an ending. This wear characteristic will absolutely confirm binding.

 

I'm a theory guy, they race for a living...but I did sleep at a Holiday Inn last night Thanks for the kudos mbcoops!

 

On dive and anti-dive, I'm not sure I buy the arguments and here's why. What you're talking about is how the torque from the (mostly) front brakes interact with the fore-aft roll center. With braking, you're already loading the crap out of all the suspension points (otherwise all those fancy springs and brake systems would spin around and flop on the ground). The act of changing one or more contact point by a few degrees, mm or whatever can have a large effect on the roll-couple, but not really do squat to the magnatude of the forces transferred by the suspension bit.

And I don't know if it was here or else where, but the Alta bit uses a SS shaft that goes through a hole in what appears to be delrin sphere. The sphere is captured in the Al housing. I'm guessing it's a press-fit of the two halves to capture the sphere, but I don't honestly know. As installed, there is no range of motion issues, but the suckers are stiff that's for sure! I don't know if that will be an issue, I'll let you know in a bit.

Matt

 

How do you figure?
1) Delrin is used by Alta's PSRS , H-Sport's camber plates, REs' rear damper bushings, and the lower control arm bushings I used last season.
2) The only one!

 

Michael, if you get any grief over expressing yourself as you have, then I'm at fault also for asking you... I've learned much here on NAM, but it takes a discerning eye to weed through a lot of noise to find some the valuable nuggets; and I've found more than a few from your posts.

Enjoy Italy! I'm leaving for Taiwan in a few days myself...

This range of motion subject is important, and I look forward to learning more about it, and what our current offerings provide. With regard to Delrin, I believe what Greg (onasled) was referring to was strickly about the front control arms - with a full Delrin replacement, and the corresponding impact to motion...

 

BMW chose to have the axis of the control arm hex shaft point somewhere other than the rotation center of the ball joint, but they did, and that's why the control arm bushing has a funky motion. It goes throug a little arc.

Matt

 

100% correct. A solid Delrin bushing does not provide the range of motion our front control arms require.
I have witnessed it firsthand.
Greg, if you didn't replace the other side yet, maybe you can post a video of the motion with your bushing and the Delrin.

The Alta PSRS is not solid Delrin, as the Doc has pointed out.
If you have solid Delrins in your front lower arms, have you tried to pivot them on the frame with nothing else attached?

Exactly. Solid Delrins do not allow for said arc.

 

Lack of reading comprehension...and defensiveness
onasled: "I still hear Don speaking of Delrin bushings, though I am still here to tell you that delrins will absolutely NOT work in the Mini."
When or where did I ever say I had solid Delrin front lower control arm bushings? They are part of the package that Alta has -- nothing more; nothing less. In post #66 I simply stated an order of bushing material choice.
The truth is the opposite of what onasled proclaims: Delrin will and does absolutely work in the Mini.
The spread of disinformation is infectious…

 

but the shape as well.

Matt

 

Delrin may work in the MINI, as long as it's not being used as solid front lower control arm bushing.

 

could also be used to make some bitchen' black cup holders! I'm sure there are a million uses!

Matt

 

Basically, anti-dive uses geometry to increase the effective spring rate seen at the contact patch during braking (converts torque to lift), so if you are already running very healthy spring rates it can hurt the ability to absorb bumps (resulting in loss of traction) under heavy braking.

This essentially makes one end of the car behave differently on less than glass-smooth surfaces when under different levels of power or braking, which some would describe as "less predictable."

Note that the usual rule of thumb is the stiffer the springs are, the less anti-anything is needed (because there is less pitch to control and it is easier for things to quickly get too stiff), and percentages are generally kept under 30%. Thanks to the magic of leverage though, they can be well over 100%, which is easily observed by traction or ladder bars' anti squat actually lifting up the back of a RWD car under power. Anti-lift reduces weight transfer, which may be useful for straight-line traction in FWD applications. And Whiteline is well known for their reduced anti-dive kits for 4WD Subarus (which decrease both anti dive and anti lift). For all we know, the PSRS "anti lift" feature does the same.

Delrin was used in the wheel bearings of Mattel's first Hot Wheels cars to give them a speed advantage over archrival Matchbox cars. It's from 1952 so is one of the newer synthetic plastics (Bakelite was from 1909 and Nylon from 1939).

 

black and white exist in print, but perhaps not in real life...

...adding to the anti-dive...60% or of the Mini's weight sits over the front axle. Anit-dive will make the weight transfer under braking more severe. BFG9000, I don't think anti-dive adds to spring rate. It actually "locks" the suspension by transfering load thru bushings and control arms, and not springs and dampers. This is my understanding and one of the reasons behind unpredictability. Anti-dive is being controlled via geometry and the resistance to dive is therefore resisted by this leverage, and not the springs/dampers.


As BFG9000 wrote, the stiffer the spring and dampers, the less likely a need for anti anything exists. And this brings me to an analogy I used here once before, the 'zero' car. Four wheels arranged in a perfect square with equal weight distribution over each wheel. This is an intersting way of analizing changes to suspension. Add to this analogy two extremes; one with infinitely soft springs and another with infinitely hard spring - pipes if you will. These three mental images allow one to build the perfect car...which doesn't exist.

The point here is that if a car is designed properly, anti-anything is not necessary...it is trying to fix a much deeper problem while adding to the list of problems...it will not allow the suspension to operate the way a suspension is supposed to operate. And it affects more than just braking.

You all know I am not an engineer, and I am prone to making mistakes because I am old. But I do rely on an engineer whom I consult with on occasion. He stated to me that anti-dive should not be used on front wheel drive cars period - this assumes that front wheel drive also means a fairly heavy weight bias up front. The conversation was a long one and I remember about 1/10th of what he spoke about. I came away from the conversation with an image of a car under braking so severe it caused the back end of the car to flip over the front. I believe this is the leverage BFG900 spoke about???

If you like to experiment, try the Alta piece in the position that adds anti-dive. You can always change it back. I am not suggesting that the Alta piece is poorly engineered, only that anti-dive from what I've read, from what I've been told, is not desirable. I've used anti-squat devises in my past on front wheel drive cars and although these help traction under severe acceleration, the affect is basically reveresed and weight transfer coming out of corners was rather abrupt - the LCA's front pick-up point was lowered.

 

in the chassis books. But I'm still baffled how you think a 1/4" change in bushing location is going to have a huge change in loads compared to the normal loads on the contact points under hard braking.

Also, all cars have a certain degree of dive (or lift) built into the design of the existing suspension. Just by the fact that the Cg is above the road surface and the contact patch is at the road surface indicates that there is a torque during braking. Weight transfer increases the torque of the front relative to the rear, increasing the net torque for rotating the car in lift. What we're talking about isn't the inclusion of anti-dive into a virginal perfect suspension, but a modification of an existing design.

And Michael, I'm just baffled by the "inta-lock" description of anti-dive. The individual bushings don't care where the forces come from, so why doesn't this happen on application of the brakes? What's magic about the forces from anti-dive that would cause this?

As for the vocabulary of what goes on, there are a million ways to skin that cat. One COULD say it acts like a stiffer spring, in that roll-resistance is increased (otherwise there wouldn't be any "anti" in the "anti-dive"), but this isn't entirely accurate. What's really going on is the coupling moment is decreased.

Matt

 

I was staying on topic Don, as per this thread heading "Powerflex front control arm bushings installed " I was speaking of front control arm bushings, nothing more. Don't feel defensive please! I respect you knowledge with this stuff.
I'm still not sure if you are saying that these in solid Delrin "..will and does absolutely work in the Mini." Are you stating this?
The only other place that I would not use it is in the trailing arm bushing in earlier models. Can't say the same for the later models as I have no personal experience with them.

 

Got it. I don't think either of us understood what the other was saying.
I'm just saying Delrin can work in the Mini not that it will (because it won't) as a solid piece for the front lower control arm bushing.
This is a good discussion so meb, onasled, and Dr. O please keep it going.

 

Definition: A tuned-in front suspension characteristic that converts braking-induced forces in the suspension links into a vertical force that tends to lift the body, thereby reducing dive under braking.

According to all that I have read, if the LCA pick up points are horizontal with the ground, there is no anti-effect. So it does not have to exist nor is it magic. I don't have Milliken's book in front of me, but read the chapter and talk with a couple of suspension engineers and then lets get back to discuss. It's not baffling, but does involve fairly complicated force vector diagrams to plot and understand. This is not my area of expertise and therefore the reason I consult with folks whom do this for a living.

Matt, lets be clear, I'm not an engineer, but I am here to help and share information. Just becaue I cannot fully explain a phenomenon, does not mean that it is not true and just because Alta says it works doesn't mean it does. These debates help all of us to further our understanding for the dynamics at play under and thru our cars...you chose to use the word magic as if I were selling snake oil. Why?