I had recently installed an electronic oil pressure gauge, using small copper tubing run from a "T" fitting at the factory mount location to the gauge sensor. I wasn't comfortable with engine movement and that soft copper tubing - believing that over time, all that flexing would eventually snap the copper tube, so I purchased PolyFlex bush inserts for the top mount, the transmission mount (the big one near the airbox), and the bottom mount.

Purchased from Moss. Relatively easy install. A jack helps when doing the transmission mount.

Silly me believed initially these replaced the rubber bushes - not so. The factory rubber bushes remain in place, and these slip into and over the voids of the rubber bushes.

Results:

Engine movement is well under control now. Where you could measure movement in inches, now, to my eyeball, appears less than an inch.

With the factory bushes, one could feel engine movement and vibration only rarely.
With the PolyFlex's in, vibration is constant at idle - not unpleasant at all in my opinion. This sensation promotes a feeling of "aggressiveness" IMO. You can definitely SEE and feel vibration at idle with no load on the motor. The rearview mirror buzzes a slight amount.
However, as soon as you put the car under load and start moving, the vibration disappears.
I hope this next part makes sense:
Shifting gears feels MUCH more precise on my 2003. Previously, I would occassionally miss a gear when trying to shift quickly. It was frustrating and I feel it was caused by tranny/engine movement - like third gear wasn't where it should be, like trying to hit a moving target, if that makes sense? Now, each gear change feels like where it should be - no "feeling around" the shifter into the gear you're hunting for. Just bang, bang, bang right where they should be.

The improved shifting is well worth the effort, and the piece of mind in not snapping the oil pressure line is a bonus! I'd do it again in a minute.

Its my understanding that 2005's have an "improved" upper mount? There is not a PolyFlex bushing available for this mount.

I also changed out the rack-n-pinnion bushing. A tight area to work in to be sure! With my sway bar and Hsport springs, my handling was already great. Slight improvement in steering response. Probably not worth the effort of busting up your knuckles changing it out? This bushing also requires greasing it up before installing-- messy. I'd probably forego this one, if I were to do it again. Then again, if someone doesn't have an already tighten-up suspension, it may make a world of difference?
Ciao!

 

The shifter mechanism is mounted directly to the car body, and cables/rods activate the gear box, Dont understand why the gear changes were a problem . I mean sure the box itself moves around a bit but I cant see it being enough to cause cable/rod issues?


John.

 

I hear ya, John, and don't know either ... But I'm definitely hitting my gears better. No doubt in my mind.

 

BluMiniMe,

Good job and a worthwhile modification. Have performed similar mods and agree with your description of the slightly increased "buzz", a.k.a. low frequency vibration, at idle and slightly above. I have stopped noticing the very small amount of rear view mirror vibration. The changes are so subtle that my wife doesn't notice.
As for the shifting, I've noticed the same. Entirely spontaneously, a couple of track rat friends have remarked positively on the firm and tight shifting when they track my car. Not sure what they expected.
I have taken a couple of runs at installing the Powerflex bushing in the large transmission mounting bushing on the driver's side of the car. I picked up an objectionable amount of vibration no matter what I did. A number of passengers noted it and wondered what was up. I don't think that the transmission bushing change resulted in any perceptable improvement in engine movement, torque steer, or any related impact. I removed mine and recommend that people pass on that particular bushing as well as the steering rack bushing.
A couple of other track rat friends have commented exactly as you have about the lack of value from replacing the passenger side steering rack mount bushing. Lots of work, and no impact.
I have gone further and replaced the entire large rubber bushings with Delrin inserts, top and bottom. Expensive and difficult with little if any tangible improvement beyond that provided by the PowerFlex bushings in limiting the engine movement. I think that you are there with little benefit from further modifications to the engine suspension.

Regards,
John Petrich in Seattle

 

If you have any flex in the engine mounting at all (and you'd absolutely hate to drive on the street without any flex in the engine mounting) you'll need to put a flex joint of some sort in your solid copper gauge line or the flex will cause it to work harden and split.

Had to pull a Formula Ford pilot out of his burning car one time because he used solid copper line to plumb the fuel line from his bulkhead mounted electric fuel pump to his carburetor. He forgot about the engine movement and sure enough the line work hardened and split allowing the electric pump to merrily spray gasoline all over his engine. It made a nice fire but we didn't have any marshmallows at the time so it wasn't an unqualified success.

We did have a word with the Tech inspectors about it.

 

I'm sure you're right 'Tuna. I will look for a place to mount the sensor on the engine somehow so it will move with it. Thanks for your advice Good call.

 

Petrich, when I hear descriptions of the various bush locations (recommended, and not), it's easy to get a little confused as to where exactly you are talking. Would you have any photos to share? Some of these spots are a pain to get to, as mentioned, and I'd like to focus my efforts in areas that will at least make a perceived difference. As you might recall from previous disucssions, I've done a fair share of experimenting here, and it's frustrating to spend a couple hours and end-up with way too much vibration, and then a couple more hours to reinstall the stock bush... Really apppreciate you paving the way on this front! Thanks in advance for your time...

 

Tony,

Nice to hear from you again. Have to talk more sometime about all of your experiments. Unfortunately, our camera has taken a dump. Expect a fix soon. But must use words rather than a photo.

The easy stuff: The rubber bushing, located on the passenger end of the steering rack, the one that fixes the rack to the front subframe is the tough one. Replacement doesn't seem to make a difference to many different people who have replaced it. The large transmission mount, located on the driver's side at the end of the transmission, is the one where my attempts with the PowerFlex inserts have only caused vibration and no noticeable improvement in "stability". So, out they came.

The hard part without the photos: The bushings that I ended up replacing with Delrin inserts are those large black rubber bushings for the engine stabilizers. There are two; one visible when the hood is open, attached to the passenger side strut housing and another underneath the engine attached to the front subframe. These are the bushings that I presume BluMiniMe was describing when he reported on his bushing modification results. I didn't detect any appreciable "improvement" with the Delrin inserts, over the yellow inserts, but there may be some decreased compliance overall. Don't really recommend the Delrin path due to the cost and uncertain benefit in my rather ordinary setup. However, the balance may shift in favor of the Delrin bushings with reduced engine block rotation in the case of a higher output motor that uses NOx, turbo, twinscrew, etc.

I think that I addressed your questions. If I didn't, pse try again. It's summer and my brain is too hot.

Regards,
John Petrich in Seattle

 

Ah, my memories of delrin:



Where yellow below, I tried Delrin there also, but way too much vibration!



For those who don't know, this goes here:



I now just have these 4 spots with PowerFlex bushes (2 large yellow inserts, and 2 purple smaller ones)...

John, thank you. So, if one were to ask you what bushes are worth swaping-out, and with what, what would you recommend, difficulty aside?

 

I only added inserts to the large mounts. I didn't do the smaller purple ones.

The bushes for the topside mount (attached to the strut tower) also came with large washers that sandwhich the new yellow inserts from the top and bottom.

 

Tony,

Great photos. Yes, those are the bushings that I was talking about. Looking closely at your photos, I cannot tell whether you had installed Delrin bushings in the small ends of the braces as well as in the large ends. I ran a series of experiments where I substituted Delrin for both the large and small bushing, top and bottom. The vibration was intolerable. The CD player wouldn't even work due to the large amount of vibration! One by one, I replaced the small end Delrin bushings that I had installed with the purple PolyFlex bushings from the kit. After replacing both small end bushings with the purple PolyFlex bushings, the vibration dropped to tolerable levels and I felt that I had attained maximum practical reduction in engine block rotation.

Looking at your photos of the Delrin bushings, and at photos from other people's installations of the PolyFlex yellow inserts, I don't see any large washers between the steel strut that extends to the engine block and the bushings. I have installed 3" steel washers on both sides of my Delrin bushing and spread the steel strut a little bit so it would slide over the whole thing and bolt down. My rational for the large diameter washers is to spread the load on the bushing from the steel strut over the largest area possible. This appears especially relevant when the yellow inserts are installed. It is common to see the center of the insert pushed down by the steel strut and to see the outer perimeter of the yellow insert mushrooming half way out of the rubber bushing. It seems that the beneficial effect of the yellow insert at stiffening the rubber bushing could be reduced by the mushrooming on the outer half of the insert.

That's my story and I'm sticking to it.

Regards,
John Petrich in Seattle

 

BluMiniMe,

An accidental double post. You and I were posting at the same time. I'd recommend that you try the purple bushings. I have measured the relative compliance of the purple bushings vs the stock rubber bushings, and there is no comparison.

Fine on the large washers. Must be a new addition to the kit, long overdue.

Regards,
John Petrich in Seattle

 

I know I must have a better photo somewhere, but I too have a larger fender washer on the yellow insert. However, I have just that one at the top, not on the bottom, and none on the lower bush at all, at least not
yet.


Thanks for the clarification John. You have Delrin on the two large bushes, and the purple PowerFlex on the smaller ones... Heck, I might need to try that again. I think I'll buy two extra metal bush holders from MINI so I don't have to keep removing and installing these suckers (very tight fit)...

Oh, did you see this:



https://www.northamericanmotoring.co...ad.php?t=49589

 

Ok, do I leave in the stock pads on the transmission mount when putting on the polyflex bushes or not? I followed bills web space thing and it says remove them, and did not look like they were in there at the end. PLEASE HELP.

 

I took em out as per bill's web space. The poly inserts should not fit with the stock stuff in place, they are replacements. As opposed to the lower engine mount, which are inserts.

Holy thread revival btw.