Good to hear...yes,very expensive suspension re-dos are! I'll be very carefull second time around.

Have you decided to stay with the stock front bushings? I'm reinstalling new stock bushings in place of the Powerflex bushings. The P-flex bushings make the already quick steering nervous as well as adding to horrid comfort over RR tracks for example.

 

I've got the Alta PSRS system sitting on the table. We'll see how I like them. I curious about the anti-dive.....

Matt

 

...hmmm, didn't know that was one of the benefits. How does it work? Anti-dive characteristics may at times affect [a] suspension in odd ways...I need to check up on this. But, I did employ anti-dive with great success on my 1981 Ford Fiesta.

Do you plan to install these soon after receiving your ball joints?

 

Here is a thread about it...on page two someone who has them on his track car starts to talk about the benefits and changes he has noticed.....just thought it might help

http://www.motoringunderground.com/f...ering+response

 

I read that review a while back. I would wait until one of the racer types here test this unit. The review was a little off in a few places; adding caster slows steering response, does not make it quicker. SAI is the axis about which the steering turns.

This is a highly anticipated piece, however. The Power flex units in my car feel hard as rock when the temps go below zero...today was the worst ever. K-huevo warned me...

 

yah, just throwin it out there in case you hadnt seen it

 

and the higher it is, the more camber you induce as the steering is turned. So that should help cornering some as well. Especially as I'm camber limited, as it's a street car. So WTF, I'll give them a try, and if they really aren't for me, I'll sell them off in the bushing mount. But I didn't mind the increase in NVH with the camber plates, and I think that bush contributes more to transfer of impact to the unibody... We shall see.

The lower temp warning from Keith, and Don's comments about not havinging them take a set at the track were what swayed me from the poly.... Stock would have been fine, but where's the fun in that?

Matt

 

Exactly, expirimenting is fun...I enjoy the process as much as the results...sometimes the process is much better than the results

Yes, camber gain is a reputed benefit. Lots of caster will wash out SAI as caster raises one wheel and lowers the other. The outside wheel raises, the inside lowers. This also places more load on the inside rear tire. some folks find this beneficial, but in an opposite lock condition, the weight is moving to the wrong wheel. I don't know where the threshold is with the Mini, but I did experiment with caster with my 99Si - a car with fairly poor high speed tracking. It helped a great deal, but turn-in was noticably slower...not really slower, but much harder to induce given the greater steering effort. So getting to an apex required a lot of concentration.

Matt, how is caster adjustable??? The front of the A-arm is fixed...if the rear pick-up point is lowered, caster is increased and this may indeed be how anti-dive is introduced. There are also side view roll centers and I know little about these. But if I remember these determine among other things, dive and squat. I would have thought lowering the front pick up point would reduce dive...what do I know I just cannot imagine how this works without reducing the articulation tolerances in the ball joints...and, wouldn't the position of the strut have to move in sinc with this at the strut tower?


Also, does it appear as though camber and toe are affected as caster is changed?

 

Thank you, didn't mean to minimize your contribution

 

Michael and Matt,

Have been following this thread only from the posts #70 and above, so may not have the whole picture.

For what ever this is worth, I lowered my MINI 3/4". In the front, I lowered the outboard ball joint pick up point and raised the inboard ball joint pickup points enough to restore the front roll center to approximately the stock position. I calculated that I reduced the front anti-dive geometry a small, and probably immaterial, amount.

I agree with Michael and Keith that the hard control arm bushing, in my case
Delrin, really does add a "twitchy" element to the steering response. We never get really cold here in Seattle, but I am aware of the deterioration in front end compliance on cold days.

Am running 4.5 degrees of castor. Was hoping to squeeze in a little more next week at my annual pre-season alignment. Maybe I should not. Any suggestions?

Regards,
John Petrich in Seattle

 

Hi John,

Haven't read much from you lately. I don't have any suggestions, but nice to read you are performing some out-of-box mods. 4.5 deg caster...doesn't feel like a lot more than stock???

I do have a question, have you tried to move the lower control arm with the strut disconnected? I'm wondering if you have any binding - purely speculative on my part.

My intuition tells me that tilting the control arm will also move the front view roll center's location fore and aft...

 

Michael,

Am on my way to work. So will post later tonight if necessary. A couple of comments:

1) The process is fun, but you know, I'm getting tired. A lot of anxiety and heavy thinking goes into these developmental processes.

2) After the last post, looked up my alignment specs and see that my castor is actually 5.2 degrees. I misremembered and think that I'll sit tight on that number.

3) Yes, yes. Have run the control arm thru it's full range of motion (ROM), with no signs of restriction. Your comment on the BC coil over link tells the story: With uprated spring rates the actual arm motion, in bump and droop, is not as full as the stock ROM. So, I don't think that I'm binding the ball joints. Have removed them this week after 2 1/2 years of service in this configuration. Inspected them and saw no sign of "trauma" or much wear at all. Am replacing them as a matter of course.

Have a good day. Track day tomorrow where I am volunteering as a corner worker. Yippee!

John Petrich in Seattle

 

The PSRS has the bushing off-center. The instructions show two rotations that it can be installed. One increases negative caster about 0.75 degrees with some anti-dive, and the other increases negative caster about 1.5 degrees with no anti-dive. I think I'll try the 0.75 with some anti-dive for the heck of it.

John, you are way beyond me in sorting out what's up with the Mini suspension. The only reference point I have for your question is Don Hollingshead (dmh) said "run as much negative caster as you can get" for the track. I'm sure talking to him directly would be much more fruitfull than me spouting re-runs!

Matt

 

so does anyone have any suggestions for changing out the stock megan springs? should i just go with 375 375? i have a mcs. i also have a webb ex bar if that makes any difference. i dont have any suspension experience so i dont really know where to go to stop bottoming out. thanks

 

you can keep the 335# springs in the rear and use 375# springs up front with no problem...or even a little lighter up front.

 

I still haven't had any trouble at all with the 375s up front -- feels good, works well -- but I have an MC.....isn't an MCS slightly heavier in the front?

 

John, you are way beyond me in sorting out what's up with the Mini suspension. The only reference point I have for your question is Don Hollingshead (dmh) said "run as much negative caster as you can get" for the track. I'm sure talking to him directly would be much more fruitfull than me spouting re-runs!

Matt

Matt,

Don is a prince. He emailed me and said: "Six is a reasonable target. Try that. If you really like castor then bump it to seven." I'm drilling a couple of holes tomorrow morning and going for 6.5 degrees.

Oh, happy driving season,
John Petrich in Seattle

 

I have the MCSC and I'm running with the 375/375 as KurvHugr suggested. Very happy with how it's performing and have not had any bottoming out.

 

Post a photo or two of your modified control arms? That would be way cool!

Matt

 

I second that request John

 

Matt and Michael,

Attached are two photos that tell the story. The "correction" is not to the control arm, per se. The "correction" is to the inboard and outboard balljoint pickup points, which in turn, restore or correct, to near stock, the control arm geometry and return the front roll center and camber compensating geometry to near stock.

The first photo depicts the outboard balljoint and the 3/8" lowering spacer that lowers the outboard balljoint. The second photo depicts the inboard balljoint and the approximately 3/8" shim stack that raises the inboard balljoint.

Of course, nothing is easy. These balljoint mounting changes cause misalignment of the steering arm and a bump steer problem. So, put together a bumpsteer "correction" from BMW Z-3 racing parts available from Bimmerworld, James Clay. Another story.

Hope this helps,
John Petrich in Seattle

 

Thanks John! Wonderful job in progress.

This may help...if you know where the roll centers are, then you also know where the instantaneous centers are. If I remember, the tie rod end centerline must always point to the instantaneous center if bumpsteer is to be avoided...I'm pretty sure of this, but let me double check. This should give you another reference point.

 

Ya dropped the ball joint 3/8", add 3/8" spacer to the tie rod end at the steering knucle. Everything should be about the way it was! (yeah, it's cheating!)

Matt

 

Michael,

There are a couple of ways to describe the bump steer situation. I didn't get too particular in this situation. The steering knuckle and rack mounting are solidly defined and I am not going to try "correcting" those. I just eyeballed the angle of the tie rod and made it parallel, again, to the front control arm when viewed from the front of the car. That was as far as I was prepared to go in this particular area. A rough, first order correction. Figured that with up rated springs, the suspension wouldn't go as deeply into bump as with the stock springs, so the bump steer correction wouldn't have to be as perfect as stock.

Matt,

Yes 3/8 + 3/8 = 3/4. However, I plotted the various angles for the roll center; stock and lowered without a correction, and lowered with correction to satisfy myself that I was going in the correct direction. So, lowered the car by 3/4" and corrected 3/8" at each balljoint. Pretty simple first order correction.

John Petrich in Seattle

 

I shimed the tie rod ends on my old 1981 Ford fiesta to help eliminate bumpsteer - worked fine too. I offered the info above as a double check...or for amusement since you already have the RC locations plotted.

...in related news, the 2001 to current Acura/Civic plateforms require steering rack realignment, I big headache. Apparently these plateforms do not like lowering and shims are not enough.

Nice work John and thanks for sharing and my comments are only meant to be helpful.