Neatix spring plate bushing glue
 

So------there I was standing with my new Neatrix spring plate bushings and the tube of glue that comes in the kit and I thought to myself,-"Self,where on earth does one put the glue for best effect ?". It seems to be a very small tube for a lot of surface area.

Can anyone give me some pointers please?.

It is superglue and it goes on the metal tubes on the spring plates. Stuff dries quick so do one bushing at a time. Spread it on, slide the bushing on. Just apply it where the bushing sits on the tube as it butts up against the spring plate.

Thanks for the answer Kurt, is the glue just to hold the bushing in place for re-assembly or does it have any 'structural' purpose The originals were bonded onto the spline, but how much glue do I use with the new ones.

i had heard, and was directed by reps at smart racing that the outter fit, the race in the body should be the "tighter" of the two contact surfaces. they did not supply or recommend any glue. they did however state that the inner surface (the tube on the spring plate) should be the the "hinge" surface of the spring plate rotation. meaning the outter should stay set in the body and the inner race required sanding to fit tight but not bind when installed.

i may have had different products but it made since to me. the bushing if tight on the spring plate will rotate in the body, and area i would not want to be a friction contact surface. the spring plate seems a better surface to take this stress.

i will attach the smart racing link with a detailed direction on spring plate bushing install.

Isn't that just for the urethane bushings? Even if you sanded down the neatrix rubber bushings I still think they would bind in the torsion bar tube.

As for the super glue keeping the bushing from rotating on the spring plate tube, I think this is the idea in theory, but in practice I think the bushing is going to rotate.

I really don't think that you want the bushing to rotate in the body of the car.

Chuck's (Elephant Racing) Poly Bronze bushings have spindles that you put over the spring plate stem. These spindles are round and they rotate inside the bushings. One of the problems with the spring plate stems, is that, they are not truly round. This makes problems.

Good luck,
David Duffield

I bucked conventional wisdom and did not glue my Neatrix bushings to the spring plates. It seems to me that requiring the bushings to rotate in the races (the body and the end-cap) just puts more friction into the system and takes away from the functionality of the design. The goal of these bronze and eurathane bushings is to reduce friction, I don't see why you would want to add more into the system.

Like the factory rubber bushings, neatrix is supposed to accomodate spring plate rotation through deformation. That means the neatrix should be glued to the spring plate. It remains stationary in the outer mounts through friction.

Failure to glue the neatrix would likely result in the spring plate rotating in the neatrix bushing ID, creating a friction surface that slides instead of deforms. This will cause the rubber to wear faster than if it is glued and merely deforms. It will also increase the friction of the bushing.

That said, I suspect the glue is not adequate and breaks free for most installations.

Thanks Guys, perhaps I will scout around for some stronger, or less fragile,glue.Chucks explanation makes perfect sense.

Anyone know how to weld rubbery stuff to metal (I mean deliberately of course !)

your right kurt, i used urethane. my bad.

matt, you used urethane too correct?

Check out: http://www.lord.com/Default.aspx?alias=www.lord.com/adhesives
These guys supply the adhesives for the big three, I used to work there...Truly amazing stuff!

Hmm, I am not sure if the factory bushings remain stationary on both the spring plate and the race in the body. When I check the factory service manual, there is supposed to be a lubricant over the rubber on the spring plate (rubber preserving glycerine to be precise), so I think the mechanism is one of the rubber bushing rotating within the race in the body as opposed to just having the rubber act in shear between the spring plate and the body race. This makes more sense to me when I look at the angles of rotation involved during normal suspension movement, which seems to be higher than the relatively thin rubber bushing could absorb without fracturing. Plus, I think that the immensely sensible (and cheap) engineers who designed the 911 would not have gone to the trouble of making that nice smooth race in the body, along with nice smooth bushings, complete with a retainer plate that is so nicely positioned via standoffs from the body if they really wanted the thing to not rotate in the body races. They would have used nice square pieces of rubber and clamped it tighter than a cow's arse in mosquito season....if you catch my drift.

So then on the subject of Neatrix, I think that the gluing allows the replacement bushing to replicate the factory motions, in terms of glue, I was going to use PL400 (aka gorilla snot) which has been known to hold whole buildings together.

I used it on the Welt bushings. I haven't been back in there since 40k mi ago. So far so good.. and you don't just use a rag to remove the snot from your hands.

Dennis, everything you say is logical. But, you are contradicting one of the best minds in the 911 suspension business, namely Chuck Moreland. I don't know where he gets his information other than simply analyzing the components, how they work and building a better mouse trap.

My own experience says that the race, as you call it, gets rusty and provides a poor surface for the rubber to rotate in. To be sure, it breaks away at some point in its life and wears terribly after that. That's apparently when the moisture gets in to cause the rust.

I'm gonna have to agree with Chuck for the time being as I don't think the cheap engineers at Porsche were trying to design a rubber bearing lubricated by water.

Oh, and on the deflection, I didn't believe that at first, but I know that it's static on the front for sure. Stands to reason the same thinking went into the rear. The amount of angle the front goes thru including lifting the car is quite a bit and similar to the rear, all in a smaller rubber thickness. It could be that it DOES deflect that much.

Help me understand your theory better.

Having taken quite a few of these apart, I can tell you the ID of the torsion bar tube is not a smooth surface. The spring plate rubber is often sufficiently stuck to the torsion tube that it is difficult to pry apart using tools, let alone move freely in suspension travel. Upon liberating the bushing, chunks of rubber are often stuck to torsion tube and spring plate cover that are very difficult to remove.

Glycerin is specified as a rubber preservative, not a lubricant.

The proposed square bush would prevent indexing of the spring plate/torsion bar assembly which is required to set ride height. Hence a round bush was used.

I glued mine on.
 

Based on the original design, the bushing did not rotate on the tube so I tried to duplicate that with my repair, although I question whether the glue will hold. Mine came off in chunks. In fact, I had to use a torch to get get some larger chunks brittle enough to chip off.

I left a small amount of rough surface rubber on the tube and against the back wall to provide some friction against the new bushing. I figured if it was damed determined to stay attached to the metal, the rubber against rubber would provide more resistance to rotation than rubber against a smooth metal tube. That and the glue seems to have done the trick.

Can't argue with the logic, and the idea that the rubber bushing acts in shear would be supported in Frere's book where he gives a bit of text about the decision by Porsche to move from Fluidbloc (lubricated) to Silentbloc (bonded, in shear), in what I thought was referring to the front A arm bushings, which are obviously acting that way.

Now a couple of questions. First, why did Porsche bond the bushings to the trailing arm at all? Seems it would be easier to have a slip on, replaceable unit...but then again, it may have been so that they could mold them in place with no clearance on that surface.

Second, what effect would lubrication have at all...namely, would it cause irregular motion, essentially disturbing the smooth action of the suspension and hence something to be avoided (pertinent to me as I lubricated my bushings with Dow 111 silicone grease!). This seems to be alluded to in Frere's book, where he suggested that the Fluidbloc's were rejected due to their irregular action under stress.....

Third, is the desireable position to have a low friction bushing arrangement (hence the shear of the bushing would not enter into the springing rates/motion/action)? That would lead me to think that the Elephant Racing bronze/poly bushings are the right answer....at least with regard to suspension action.

Lastly, how much of the high frequency NVH (noise, vibration, harshness) is filtered out by the relatively soft rubber of the factory bushings. Reason is I am trying to prepare a "touring" 911 for the wife and I to use for driving around in our twilight years and do not want too much NVH in our lives....are the urethane/poly bushings really only suited for track or high performance use or are they "nice" for the street?


PS - I have only disassembled 4 911's, in all of them the rubber bushings looked pretty chewed up and torn circumferentially. Struck me that they were actually trying to rotate in the housing and not being all that successful....hence my idea as to lubrication. The races in all cases were in pretty decent shape wrt smoothness, I may have been lucky.

In searching for info on rear bushings .. and came across this. Why not ressurect a thread or two?

The theoretical answer to the above question is that for isolation to occur, there needs to be a stiffness mismatch between the steel and the rubber. A factor of 10 or more is preferred, and a factor of 5 is still decent. So if the steel part has a stiffness of 25kN/mm, the rubber should ideally be no stiffer than 2.5 kN/mm.

I work on chassis structures, and we go the other way - the ride & handling folks tell us how stiff of a bushing they need for ride & handling, and we try to get the steel structure stiff enough to provide isolation with their bushing rate.

It's alive! (The thread that is.)

Here's what I can add from first hand experience. Netrix bushings are a fine effective solution. Especially for those with street cars.

I ran the Netrix bushings for about two years. During those two years, the car saw track and street use. The car rode well, without any obvious "sticktion" issues. Eventually I pulled the bushings out. (Not because there was anything wrong, but because I had scored a set of brand new G50 spring arms.) To my surprise, the Netrix bushings looked great! They had many, many years of service left.

Stiction. Hmmmm..... The resting weight on a front tire is, let's say 400 lbs. Let's say it's 600 lbs on a rear tire. When we hit a bump, those figures go, momentarily, to some pretty massive figures. Two or three or six pounds of "stiction" is going to make a difference? Or one pound (imagine hand-rotating a "stiction" joint without any spring or shock interference). Do I think "stiction" is something for non-Formula 1 teams to worry about? Nope.

I have Neatrix bushings on my spring plates. Very nice. I saw absolutely no good reason to glue them to anything. A thousand dollars says the outer surface does not move relative to the body, regardless of whether you glue it or not. And what if it did? Heck, if it did, it would help fight rubber bushing compression/sag over time. But that's just another thing I won't worry about. I expect these bushings to give excellent service for many years.

In all fairness, I would like to have Chuck's special, superduper skookum polybronze units. Perhaps some day. They are spendy, but I think they are a good solution. In the meantime, my Neatrix units will serve just fine. With no glue. In all the reading I have done on this issue, and all the various opinions and justifications and theories about deformation and blah blah blah, I think the glue idea is comical. At best.

I use silicon grease. Slipperiest stuff I know.

My experience with Neatrix bushings goes back to my 78SC. After the initial installation, I pulled the springplates for reindexing several weeks later and found that the inner bushings had become lodged in the tube (I used the glue supplied with the kit). This would suggest that the outer friction (bushing to tube) is great enough to break the glue bond (bushing to springplate).

Ulrich

Same thing happened to me on my 86 after one drive to check ride height. I needed to re-index and found the glue did not hold. I believe I posted a question about this at the time and the answers I got back were to lube the bushing to springplate interface and forget the glue. Did that and so far, no issues.

Silicon grease.

The stiction case is really about bushings that slide, and not rubber bushings that deform.

However, the force of friction equals the friction coefficient multiplied by the normal force. In this case, the normal force is the weight resting on the bushing.

That means that the 2 or 3 lbs or friction force you feel when the suspension arm is disconnected and hanging in the breeze becomes much greater when the weight of the car is resting on the bushing. And as you point out becomes greater still when the bushing is loaded in a turn or bump situation.

To illustrate this point, consider a tire resting on the road - no car attached. You can easily slide the tire over the road surface with only a few pounds of sideways force. Now attach a car to it to increase the "normal" force. Takes a lot more force to slide the tire.

The exact same thing happens with bushings.

Personally I like my new 935 spring plates with the heim joint and no bushings at all. I had the weltmeister poly graphite bushings. I remember spending hours sanding them down to make them fit the torsion and spring plate tubes. Getting them back out was not much easier.

Been reading on this issue for some time and am about to install my Weltmeister Neatrix bushings from our host. These seem MUCH harder than the old rubber I've been scraping and burning off. In addition, it has a hard,shiny surface with some sort of lubricant on it. Bottom line...does not seem suitable to be glued in. The instructions discuss a lubricant but also say it's not required. My came with no glue or disucssion of glue. I guess I'll clean the surfaces up as much as possible and hope for the best.

The only lubricant I used was soap and water on the outside of the bushing, just before inserting it into the torsion bar tube. Rather than use the glue that came with the bushings, I used a Permatex two-part epoxy to bond the bushing to the spring plate.

Only rubber bushings get glued. Plastic ones get lubricant.

I've wondered about this also. The 356 community seems to install the rubber bushings without any glue and lubricates them both inside and out. Seems to me there are several schools of thought on this.

Chuck's correct- where the rubber bushings are used, it is the deformation of the rubber that allows for suspension movement. There should be no movement between the bushing and the metal on its ID and OD.

We know this for two reasons and I'll use the SWB case to illustrate it. The SWB bushings consist of a rubber bushing around a steel tube. The steel tube is fixed to the control arm. And when I say fixed, I mean, that when you change it out, it takes a blowtorch and an air hammer to get it off, it's FIXED to the tube. The outside of the bushing is another steel tube that gets held into the crossmember with a pinch bolt that is tightened down when the suspension is in droop.

The original factory workshop manual actually contains a warning about this. They tell you that when the pinch bolt is tightened with the suspension in droop, you can't let the arm subtend more than 20 degrees of motion, or you will rip the bushing.

Now, Chuck's polybronze bushings, or roller bearings are a different story: these are intended to be lubricated. As far as plastic bushings go, these were the only alternative 40 years ago, but today there are modern solutions that provide correct geometry, limit bushing compliance, have a much more linear friction gradient and are easier to service.

304065 is correct, to avoid any confusion he is describing the front control arm bushings. And specifically he is describing 65-67 control arm bushings, which are different than the later parts.

On the spring plate bushings, there are comments above about them feeling lubricated when new. This is not intended as a lubricant in operation, but is an artifact of the bushing production. This is a mold release agent - it coats the mold before the rubber is injected. It prevents the rubber from sticking and allows it to be removed from the mold.

The mold release agents will interfere with the adhesive used to bond the bushings to the spring plate. Failure to remove this is one of the reasons the adhesive sometimes fails in operation.

On the Elephant Racing spring plate bushings, we wash them before packaging to remove the mold release agent. Literally, we have an old dishwasher for the task!

To supplement our cleaning, our instructions call for cleaning/degreasing the bushings and scuffing the ID with provided abrasive cloth to ensure clean rubber to get a good bond with the provided adhesive.

There is absolutely no doubt Chuck has it nailed. His product comes with very specific detailed instructions on how to install. Stray from it at your peril.

neil

OK, just ordered and rec'd my actual Neatrix busings from our host who initially shipped the PG version. I did not know it was the wrong type so installed it and was astounded how loud/squeaky they are. Now preparing to go through this whole PITA again with Neatrix. Here's my question...can I follow Chuck's process on Neatrix bushing to minimize the noise or is that only applicable to Elephant's spring plate bushing? Goal is NO SQUEAKS....
If I understand Chuck's position the pressure of the interference fit keeps it from moving...correct? I've been doing some checking to find some glues but does not seem that anything can stand up to the sheer forces on this bushing.

Yes. The neatrix and elephant bushings are very similar.
Clean off the waxy mold-release compound, and super glue them onto the spring plate. I used several tubes of super glue. Better safe than sorry. Regular cyanoacrylate (sp?) superglue works fine.