Neatix spring plate bushing glue

[Breeang]

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?.

[Rot 911]

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.

[Breeang]

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.

[juanbenae]

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.

[juanbenae]

http://smartracing.net/pdfdocs/4512XX_bushing_install.pdf

[Rot 911]

Originally posted by k911sc
http://smartracing.net/pdfdocs/4512XX_bushing_install.pdf

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.

[Oldporsche]

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

[MichiganMat]

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.

[Chuck Moreland]

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.

[Breeang]

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 !)

[juanbenae]

your right kurt, i used urethane. my bad.

matt, you used urethane too correct?

[Biff]

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!

[Dennis Kalma]

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.

[RoninLB]

Originally posted by Dennis Kalma

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.

[Zeke]

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.

[Chuck Moreland]

Originally posted by Dennis Kalma
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.

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.

[autobonrun]

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.

[Dennis Kalma]

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.

[burgermeister]

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.

[Dixie]

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.