Want to continue the discussion on rear strut upper mounts by supplementing my posts #11 and #17, above. It has been almost two months and I have had 4 track days to experiment.

The

 

Want to continue the discussion on rear strut upper mounts by supplementing my posts #11 and #17, above. It has been almost two months and I have had 4 track days to experiment.

The posts are accurate as they stand. The Madness upper mount bushings have functioned perfectly, and I am very satisfied.

That said, it became clear to me that the last traces of rear end yaw and pitch in unusual track situations (HEAVY down hill high speed braking to a crawl) were caused by the front struts hitting the bump stops. Am using stock struts with H&R sport springs. I cut the front and rear bump stops down by over 1" and find the car rock solid, now. Amazing. All those old excuses that MINI is a short wheel base car and that the track is rough in that area were bogus. In other words, the rear end instability was not caused by rear end suspension problems, short wheel base, or a rough road but caused by the front struts hitting the bump stops and the front spring rate hitting the sky. Again, the combination of a high speed down hill heavy brake area is uncommon on the tracks I've driven. So many tracks are relatively flat, or those with elevation changes don't commonly terminate in heavy braking to a slow speed. The down hill braking situation is common on the public roads, but not everyone puts the car to the test. Think about your front bump stops.

As a result, I have reinstalled the monoball rear strut upper mounts that I had removed a year ago. Have "softened" my rear anti-roll bar a bit to compensate for the increased roll stiffness that came with the reduced compliance by substituting out the Madness urethane bushings. The car feels better in transitions, as one would expect.

Will have 4 more track days in the next 6 weeks. Am eagerly anticipating the opportunity to put the new rear suspension settings to the test. Am hoping that the "softened" rear anti-roll bar settings will tame that little bit of twitch that I feel at 110 MPH in a rough surface high speed turn and let me "trust" the car more. But, don't want to lose the fast rotation in a couple of tight, slow speed sections. And, am dreaming of the crisp suspension response in transitions that comes with solid or near solid suspension components.

I'll post the results of the monoball upper mounts in a few weeks.

Regards,
John Petrich in Seattle

 

I'm glad you're having better luck with your suspension setup John!

If you want a "crisp" suspension, you need to get rid of the stock shocks. Solid suspension components will make a VERY small difference in comparision (plus they are noisy).

Trust me, you'll LOVE the way the car feels after switching to better shocks.

 

Mitch,

We've PM'd and I agree with your assessment of the value of high quality shock absorbers / struts. New struts for MINI are my project for this Winter.

My post in this thread was intended to address the very limited topic of rear strut top mount bushings and the interplay with driving technique and crazy variables such as bump stops. I am still very much on the steep side of the driving learning curve and am rapidly learning to differentiate among the variables of driving skill/technique, track surface, car set up, and suspension component characteristics as they affect track performance. Keeps me thinking when not actually on the track.

Am looking forward to that "crisp" performance that you have been talking about. Must be a beautiful thing. Want to pick your brain more in the future. You may have additional ideas when your MINI actually gets delivered. Oh joy!

Regards,
John Petrich in Seattle

 

John, whenever I see you post, I go straight to that thread because you always share some good stuff!

From my experiences, bump-stopping in the MINI is no fun, and can be quite scary. When I have some clear roads, I take my canyon commute quite hard. Ledas, along with the Webb plates, made for some serious bottoming-out. I don't think I've ever been so scared in my life, at least in a car.

John, where did you get the monoball upper strut mounts?

EDIT - Sorry, just went back to the first page... and saw that you had them made (modified)! Remember about what the cost was? Thanks.

 

TonyB,

Sure glad to hear from you, too. I've got a lot to say about bump stops but unsure whether it is proper to continue on this particular rear strut thread, start a new thread, or PM you.

What do you think?

John Petrich in Seattle

 

John, I hope my post didn't come across the wrong way. I think it's great that you're trying lots of things on your MINI. (makes me wish I wasn't running ours in the stock class).

My only point was that shocks make a big difference. For example; you probably wouldn't need to cut down your bumpstops if you had better shocks. Etc....

Keep up the good work John! You got a great car there!

 

Mitch,

No, no, no. I wondered later if I should have made reference in the post to your as yet undelivered MINI. No, no, no didn't mean anything negative at all.

I'm laughing now. In fact, I was hoping that when you and your wife get your car that you would think further about suspension improvements in earnest and will share any new thoughts with at least me, if not all of us.

No, no, no, ............no, no, no.

Regards,
John Petrich in Seattle

 

Hahaha! Gotta love internet communication.

(no back on topic!)

 

New thread or CC me on whatever you send Tony

 

John (got your PM), all.... I agree, a bump stop thread is in order. I'm a running late to work now. If no one does so, I'll try to start one later in the day. If someone does, please let me know!

 

Tony, Sid and Mitch,

I'll wait for Tony to start a thread. He is very good at that. Then I'll repost the substance of my PM. I'm dying to hear what people think.

John Petrich in Seattle

 

https://www.northamericanmotoring.co...ad.php?t=73465

 

A follow up on Post #27.

I have been experimenting with mono-ball suspension attachments for a long time. Ran into problems when I substituted mono-***** for Maddness Urethane bushings for the rear upper strut mount. The problems were most dramatic with threshold braking. The rear end would yaw and pitch like crazy, not just a 'little' but 'a lot'. Very unsettling for the car and driver. The wild gyrations disappeared for the most part with the Maddness Urethane bushings, but I was tip toeing a bit as well. Thought that the struts might be 'bumpstopping' so I cut down the bumpstops. Worked like a charm. All the gyrations disappeared and I re-installed the mono-ball bushings. No problems at first, Post #27, and no problems 3 track days later despite all the things I've tried on track to try and unsettle the rear end.

I'm convinced that there is no problem with mono-ball rear strut bushings, per se, for those that want them. I doubt that there is any real advantage to these zero compliance bushings compared to stock bushings or Maddness Urethane bushings with stock struts, like my installation. The mono-ball bushing could be a significant enhancement for a high end track oriented strut system. That, however, remains to be seen. It's aftermarket struts for me next year. Maybe I'll find out.

Regards,
John Petrich in Seattle

 

John, thanks for the follow-up! I don't think it's ever been clarified, but has the bumpstopping been in the front, rear or both?

On a side-note, I just returned from a Seattle and Victoria trip that was very pleasant! We stayed with a high school buddy of mine who as a nice place in Snohomish. You live in a beautiful area!

Thanks again for your diligent follow-up on this important issue.

 

Tony,

Nice to hear from you, now that you are back home. Knew about your trip, but hesitated to complicate your travels by inviting you to come by for a beer or 7. We live very close to Snohomish. We bike ride a lot in that area.

Regarding the bumpstopping, I think the primary problem was the front bumpstops. At least, the violent motions seemed to start with hitting the front bumpstops. However, the violent rebound backwards, likely compressed and bumpstopped the rear struts, and as a result sustained the fore and aft oscillation. Reminded me of some Disney production: The Wild Ride of Mr Toad. I just cut both front and rear bumpstops down. See this post from our local BMW website: http://www.bmwpugetsound.com/vbb/showthread.php?t=31605

Am going your way on September 7 and 8 for track days at Laguna Seca and Thunderhill. Cannot wait. Have revised my rear sway bar and have high hopes of finding more high speed stability. Then, it's coil overs for Y2007. Want to spend money. My wife will be overjoyed.

The best to you,
John Petrich in Sammamish near Snohomish

 

I never really felt that the rears were an issue, especially for me (much of the weight loss is in the back). As you might have seen in another thread, I'm contemplating putting linear springs on the front of my Bilstein PSS9's; probably 350 lbs. They come with progressive in the front, 320 lbs, I believe. They are barrel-shaped, and are the limiting factor in getting more negative camber...

At this time, I will go with H-Sport's new camber plates, which should net me nearly .75" of travel gain over the Webb ones.

John, I did think of you when I was up that way! Time was really tight, so while it would have been nice, it would have been rushed (like you thought), and not exactly ideal. We will return though as my wife really wanted to travel to the top of the Space Needle, but due to an elevator issue and a looming flight, we had to get a refund...

Have a blast at Laguna Seca! I'll be working from home on the 8th (Friday). If you'll be driving through the San Jose area on that day, let me know, and I'll see if I can meet you somewhere...

 

Are there any other bushings out there besides MM? A little pricey compared to other bushings. All we need is the dimensions; there has to be another "OEM replacement" bushing with the same dimensions. I would think the strut rod and bushings would be similar, just the actual mount would be different. Anyone?

Frodo

 

I emailed Energy Suspension and asked them if they make any shock mount bushings. They sent the following links. The second link is very amusing and as long as you have the proper measurements you might find what you are looking for.
http://www.energysuspension.com/pages/univ1.html
http://www.suspension.com/BODYMOUNT.html

Also, this guy claims he works for ES and wants to know what bushing we would like to see.
https://www.northamericanmotoring.co...d.php?t=107773

Frodo

 

Have had a few thought provoking PM discussions with Frodo, a.k.a. Chuck, about the rear strut bushing options. Sounds like he has done some interesting research. I've kept those links for the future. As a result of the discussioin, I removed my rear strut monoball bushings and replaced them with my spare Madness bushings. Ran the Madness rear bushing setup on the track yesterday.

Was looking for any symptoms of rear end instability in the context of transients into a fast sweeper corner, heavy braking (I mean "heavy" braking) over a rough surface, and some quick lateral weight shifts thru a chicane-like segment. Nothing. Could not distinguish between the feel of the monoball bushings and the Madness bushings. In fact, my heavy braking area was one area where I feel the car was very planted and I performed measureably better, but I don't exactly know why. Was planted with the monoball bushings as well.

On the street, the Madness bushings are noticeably less obnoxious in terms of cabin noise and chassis shaking when driving over concrete seams, and those little "turtles" that demarcate the lanes.

At this point, I'm keeping my monoball bushings in the spares box and going to continue using my Madness bushings in my dual purpose car. Don't think extreme measures for the rear strut bushings are particularily helpful and not worth the cost.

Thanks Chuck for the stimulus to rethink my setup.

John Petrich in Seattle