[Cloud9...68]

I've received my full alottment of spherical, solid, and delrin, as the case may be, bushings from Racers Edge, and have found, as I was warned, that there is a lot of variation in the sizes of the openings in the suspension pieces into which the bushing fit. Some fit nice and tight, but some are alarmingly loose and sloppy. It has nothing to do with the bushings themselves - they appear to be of excellent quality, and the same bushing that fits tightly into one arm, is quite loose in the opposite one, which confirms the variability is in the suspension pieces, not the bushings. This makes sense, given that Porsche didn't have to have very tight tolerances on these pieces, since they all got stuffed full of nice, forgiving, squishy rubber bushings at the factory.



So my question is, what's the best way to improve the fit of the bushings? Karl of Racers Edge says to use Loctite, but upon researching aluminum adhesives (my issue is primarily with the anodized aluminum monoballs in the front A-arm and the rear banana arm), I've learned that Loctite is not the ideal material for bonding aluminum, for a variety of reasons. The family of methyl methacrylite ahdesives is what people recommend for applications such as aircraft components, where aluminum-to-aluminum bonding is very common, and of course quite critical. These products are a little pricey compared to adhesives such as Loctite and epoxy, plus they tend not to be locally available, but I don't mind spending a little extra money to get the best possble result for something as critical as my suspension components.



Since I assume this must be a fairly common problem, what have people who have installed solid bushings done? Am I over-thinking this? Is Loctite OK, given that the bushings are held in place by the through-bolts? Thanks.

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[tamathumper]

Are you looking for adhesion or just filling irregularities?



My company makes many plasticizers and adhesive resins, and I don't mind asking the chemists in the R&D lab (100 feet away) what they think. They (and I) enjoy the odd out-of-the-box question.

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[Cloud9...68]

Thanks the the offer! To answer your question, I think I need both adhesive and filling properties. Ideally, the bushing should fit so tightly into its opening that there is zero movement in any direction of the bushing's casing; all the movement should be confined to the bushing's spherical element. Given that several of mine have a small space between the outer wall of the bushing casing and the inner wall of the opening (there must be a technical name for this opening...), which is causing undesirable movement of the casing, I think a need a material that will snugly fill the gap, yet not be so brittle as to crack under the stresses of cornering at the track, and never, ever, come loose. If both the bushing and the opening were perfect cylinders, I probably wouldn't need any adhesive properties in the fill material, but given that this isn't the case, I would think that adhesive properties would also be desirable for the material. Thanks again; I'm anxious to hear what our R & D folks recommend.

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[tamathumper]

Can you do me a favor and send me a picture of exactly what we're talking about?



In this kind of circumstance, a picture is worth a thousand words, and when they find out it's for a Porsche, they'll be even more apt to chew on it for a while.

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[Cloud9...68]

Our younger daughter took the only digital camera that I know how to communicate with my computer (I'm not the most computer-savvy person in the world, and I knw even less about digital cameras) on an outing, and she won't be back till Sunday, so I'll see if I can piece something together for you.



Here's a picture of some of the bushings:



Banana arm monoball spherical bushing



Here's a picture of a front control arm that a bushing almost identical to the one shown above needs to fit snugly into:



Front control arm



I'm sorry I'm mixing the rear trailing arm bushing with the front control arm (shown in the second image above with the stock rubber bushing fitted), but the picture of the rear bushing is better than of the front, and I couldn't find a good picture of a banana arm. But the idea is the same - the cylindrically-shaped bushing needs to fit snugly into the opening in the suspension arm, which you can see in the second link. Thanks again for the help.

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[tamathumper]

No worries, we're off tomorrow anyway, so I won't be able to ask any questions in earnest until Monday. I hope that's not too late?



By the way, I just wanted to ask for clarification on your first post above... LocTite is a brand name, actually an entire product line manufactured by the Henkel corporation. Henkel is a big customer of ours and we sell them a boatload of different resins, additives, adhesives, etc.



When you say LocTite, you should probably follow that with a product identifier or a three or four digit number that specifies which product in the LocTite line you are referring to, as they have very different properties and uses, for instance the products in the Industrial line (as opposed to the DIY Consumer line) cover: Bonding, Coating, Concrete Repair, Flooring, Gasketing, Lubricating, Machining Compounds, Potting & Encapsulating, Repairing, Rebuilding & Restoring, Retaining, Sealing, Surface Preparation, Thread Sealing, and Thread Locking...



I'd be very surprised if you wanted to use an industrial adhesive to affix the bushings to the structures, as with these glues you will never, ever get them back out. I double dog dare you to get them out without machining them away... But if you do decide to go that way, one of their ads on their site says their products are trusted on everything from "race cars to porches", so you've got both bases covered.





By the way, how does a solid bushing with a rim at each end like those have fit into a cylindrical hole? I can see how a rubber one might be compressed and "pop" into place once fully inserted, but the solid ones?

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[Cloud9...68]

Yes, I'm aware of Loctite's vast product line. I didn't provide the product identifier because Racers Edge (from whom I bought the bushings), didn't either, so I went into my research on this stuff unclear as to what type of adhesive I should use. Looking through Loctite's product line, I didn't see anything that appears to be suitable to the aluminum-to-aluminum fit I'm interested in enhancing. And in researching this on the web, I ran across more than one discussion which stated that Loctite in fact doesn't make anything for bonding aluminum.



So, I've come up with three candidates for the job: Extreme 310, Partite 3750 (made by Parson Adhesives), and 3M Scotch-weld 2216. I spoke to someone at Extreme, and she told me that 310 could be removed by heating it to about 250 degrees, although I'd like to get a second opinion on that, because I share your concern about gluing my bushing in place and never being able to get them off. I want them to hold solid under extreme cornering conditions, but not to form a permanent bond to my suspension arms. So I'm still researching.



As far as how the bushings go in, they're in two parts, in that one of the rims is screwed into the body. To install, you remove the cap, push in the bushing, apply some Loctite 271 (see, when I know the type, I'll specify it ) which is supplied with the bushing, screw the cap back on, and torque to about 100 lb-ft.



With all the racers who have installed solid/spherical bushings, I'm surprised I haven't seen the topic of their fit come up before.

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[tamathumper]

These guys (chemists) live for this stuff, so it's fun to get them to go all ninja about the difference between the products and what do you really want to achieve. I'm going to assume you want to *fix* (as in "affix") your bushings in place, in that you want them to be snugly held without extraneous motion, and you want them to be "rock solid" - (which in no way stipulates that you want to *adhere* them in place, meaning that with these materials they will become as one, inseparable unit, or "solid as a rock").



I already bet they're going to say use an epoxy to fill in and then re-machine the arms to fit the bushings - the epoxy (think JB Weld times two) will be heat and chemical resistant, hard as a rock, and once cured won't adhere to the bushings themselves).

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[Cloud9...68]

You have the scenario pretty much correct. The bushings need to be held snugly in place in their suspension components, such that the only thing that moves is the spherical bearing inside the bushing. I don't mind adhering the bushing in place (as opposed to just having them press fit), as long as there is the opportunity to remove them in the future should I need to replace them for some reason. So, a very strong industrial glue that could be removed by heating would fit the bill.



I'd prefer not to have to remove the rear trailing arms to have them re-machined to fit the bushings. Maybe it's just a philosophical thing, but I'm proud of the fact that I was able to drive the old bushings out without having to remove the arms (I still don't know how I did it; must have been the drugs <img src="/forum/images/smilies/968/tongue.gif" class="smilie" alt="" /> ), so I really don't want to break open the brake lines and remove them now. At this point, I'm leaning toward a methly methacrylate like Extreme 310 (available on eBay for a reasonable $10), as it seems to have the properties I'm looking for. But, as always, I could easily be swayed by data...

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