Neatrix bushings. Glue or no glue???
 

I'm replacing a few things on the rear suspension and part of the job is the spring plate bushings. I purchased the Neatrix bushings from Pelican, PEL-PP909976, and the single review for the product makes mention of super glue. My package didn't include superglue, and the instructions make no mention of it's use.

I also purchased a hardware kit from Elephant (didn't buy rubber bushings there due to shipping costs to Canada) and I did review the install instructions for the rubber bushings that they sell. They call for glue.

Then I read this old thread

http://forums.pelicanparts.com/porsche-911-technical-forum/194410-neatix-spring-plate-bushing-glue.html

Many are sure you do not need to glue. But Chuck says you should, and I'm fairly certain he knows his stuff. Perhaps the rubber bushes Chuck sells work differently from the Neatrix product?

Anyway, The product I have in my hand makes no mention of glue, nor did it come with any. Do I proceed without or am I going to regret it?

The Elephant rubber bushings are closer to stock than Neatrix, but both function exactly the same way and both require that the spring plate not turn inside of them. That means glue. I'm skeptical of the ability of super glue to hold it, however. I used 2-part epoxy.

Any thoughts on why the Neatrix instructions make zero mention of it in the install instructions? In fact they even go so far as to suggest a lubricant can be used.

The Delrin bushings i just installed in my 944 spring plates mentioned to lube freely as well ... although i installed the hard rubber ER ones in my 911 with crazy glue as recommended by Chuck !

Cheers
Phil

These bushings get glued to the spring plate. They do not get lubricated like the Polyurethane, Polygraphite, Delrin, etc. The only time anything is used is after the bushings are glued to the arm, some liquid soap can be used when installing the arm back into the car.
They are designed to twist like the original factory rubber bushings. It seems they stopped supplying the glue with the bushings. Most of the time the glue did not survive and was dried up in the tube.
If you apply a lubricant you will end up replacing them. Follow the same installation as the Elephant Racing rubber bushings. http://www.elephantracing.com/documents/911-2290003-2290004rubber-spring-plate-bushing-instructions.pdf

Pelican Parts - Product Information: PEL-PP909976

Chuck says the same thing about the Neatrix bushings.

Neatrix spring plate bushings glue? [Archive] - Early 911S Registry

Bearings are lubricated, bushings are not.

I glued mine (ER rubber) to the spring plates, and used some silicone grease on the perimeter. I left the spring plate cover lightly snugged up until the car sat on the ground, and then tightened the spring plate bolts - this way the bushing isn't clamped in until the car is at ride height.

Knock on wood, I have not had issues with the glue failing. I track the car frequently and drive 5 - 10K miles on our lovely Michigan roads, so the bushings do get a workout.

YMMV

I really question the glue holding anything. I bet the shape of the torsion tube (slightly tapered) along with the clamping force of the plate causes a friction to keep things as they should be. Super glue really doesn't have the shear strength to be of any value.

well thanks for the responses. I've decided to do as you all do and glue them. Even though I'm skeptical like Ben that it can serve a purpose. On the other hand, it cant do any harm.

Interesting tip from burgermeister. I'll do the same.

Don't use silicone grease, just use the liquid soap as Elephant directions state. It should be clamped firmly and the silicone will allow slip which the rubber is not designed for.

Just "thinking out loud" Re. shear strength..

For the ones I could find with specs CA glues generally list it in the 1000 - 4000 psi range. 1000 psi is a nice round number.

The torsion tube is about 2" diameter, and I think the bushings are maybe 2" long - that gives about 12 square inches of surface area per bushing.

So the shear strength of the bond is around 12,000 lb, at a distance of 1" from the center of rotation. So about 1000 ft*lb would be the torque it would take to break the rubber loose, and you've got 2 of them, so 2000 ft*lb per side. Given the length of the semi trailing arm (about 1.5 feet), it ought to hold about 1300 lb of weight on one wheel with just the rubber in shear and no torsion bar in the picture ... not sure what the stiffness of the ER bushings is, but I'm going to guess one can't support the entire car on just the bushings in torsion. I think that one would hit the bump stop before that happens.

Obviously one isn't going to get a perfect bond, and high temperatures will weaken it somewhat - but it seems there is ample headroom in the CA glue. Or I need more coffee because I screwed up my calculations ... wouldn't be the first time.

The "superglue" holds. I'm not saying the glue is what keeps the bushing from rotating, as the guys make a good point that the tapered nature of the bushing cover clamps the bushing onto the torsion tube when you fully bolt it down on the chassis mounts.

My most recent experience is replacing perfectly good rear Neatrix bushings on my '87 Carrera with polygraphite bushings. The Neatrix were installed ~2002 when I first rehabbed the suspension with new bushings, torsion bars and shocks. Drove it that way for ~5 yrs and then installed the poly bushes. I had to cut the bushings off the trailing arm once again, same as I had to do for the original bushings, as the superglue was still holding. The bushings were subjected to track driving and R-comp tires, so they were put to the test pretty good

mea culpa - I just slipped the Neatrix rubber on when I did mine - no glue

It seems fine (or I am too insensitive to detect the looming horror)

given the spring rate of any torsion bar, I have never understood how the twisting of the rubber (Silent-Bloc or whatever) can make a difference in the spring rate... maybe it does??

The rubber bushings do make a difference in the wheel rate. The stock ones, together with the inner (I actually measured mine) are worth close to 1mm of torsion bar diameter, the somewhat stiffer ER & Neatrix ones probably a bit more than 1mm.

So if you switch to a bearing setup, you will need to go up a size in torsion bar to keep the same wheel rate. That said, a 1mm difference in torsion bar diameter would be pretty difficult to tell from the drivers seat. Maybe if it was front or rear only, one could tell the balance was off a bit during track use...

I have had a rear suspension knock that I can NOT seem to rid from my car. In frustration, I removed the year old ER spring plate bushings. Believe it or not, super glue is very capable of holding bushing in place, I had to destroy mine removing them. You need to follow the instructions - clean, rough, etc. , but it will hold.