Rick K

I want my car to be a great street car that's a good performer on the track.

For now, the car will maybe do 2 to 3 DEs a year, tops.

I'm beefing up the torsion bars to 21/28s - and while we're in there, going to replace the springplate bushings in the rear before having it aligned.

So, are polybronze worth the extra $ over neatrix ($50 a set vs $250 a set)?

Not sure I would notice the performance difference in bushings given my skill level, but, I wouldn't mind spending a few extra bucks if it means that it will be a more permanent solution and my alignment settings are more likely to hold. Not sure how long the neatrix stuff will last given the kind of driving I will be doing.

Any opinions/experiences are greatly appreciated. Thanks, Rick

Amber Gramps

Check out Steve Weiner's website. He has a section on this. I don't touch my wimpy old street suspention on my cab without a call to Steve. He will walk you thru the entire build.

http://www.rennsportsystems.com/

jester911

I just did this upgrade last winter and I went with the polybronze.
I track my car more than you do but for me it didn't make sense to have to redo this in a few years with the work and cost involved.

I discussed this over great length with the mechanic that does the stuff I can't or don't have time for and he agreed that it was best for me.

So Doug is right in that you should discuss this with Steve or a mechanic you trust. You need to go thru all the pros and cons with someone to make a good decision for you.

911S3.6

The polybronze bushings are WAY worth it.
I got mine (from Steve Weiner/ Rennsport Systems) when my old rubbers were shot.
The car is transformed. Transitions in turns, the car is supple and fluid.
no squeaking, creaking - occassionally need to lubricate the accompanying zerks fittings. (every 5000 miles or so... if you track the car, probably 10K if not).
Add some monoballs in the rear trailing arms and front struts and you are in for a surprise.

hope this helps,

Nick

JCP911S

If you want your car to hammer over bumps, crunch and squeek, and bind up, by all means go with the neatrix.

If you want the car to feel smooth, buttoned down and quiet, go with the poly-bronze.

It's really a mater of taste

KeithC2Turto

I'll stick up for Netrex.

I to plan to track only a hand full of times a year.

PB's are very nice. However, the porsche enginiers were pretty smart. I choose Netrix. Stock style bushings are good enough for me and I know they are going to best isolate noise and harshness.

Another concideration could be that putting PB's in the rear without addressing the rear inner arm bushings is kind of like only doing half a job as the old rubber inner bushings will still continue to contribuit to toe change under load. Then, spherical metal bushings are the only consistent choice. These will contribuite to added noise transmission into the cabin.

Both are solid choices.

r911

But Keith, you are comparing apples and oranges. The stock mounts are rubber. Neatrix is not rubber. You can get away with Neatrix on the rear if you absolutely must save money.

Nor is the limited use the issue. Just sitting the car's wt. will distort the Neatrix bushings (or rubber ones too). It is time on the car, not whether the car is moving or not that is the issue. Also, the Neatrix will negatively affect street driving, not just DEs, AutoX or racing.

I have had Neatrix on the front & rear of my car ever since I inherited the bushings from the PO. Polybronze did not exist when I bought the car, or when I serviced the Neatrix bushings by re-lubing the Neatrix in front & rear to save $$. The harshness and squeeking quickly returned. I finally saved up enough t$$ o buy the F Polybronze. I plan to install them later this summer.

Trust me - if you can possibly afford the parts and DIY (or if you are paying a shop to do the work) either get the A-arms refurbished with rubber or get the PolyBronze. The Neatrix stuff is garbage and JCP911S put it exactly right.

Again, you can get away with it on the rears.

Let me make this very clear: Keith is absolutely wrong when he says that Neatrix will best isolate noise & harshness. In fact, it is the worst of the three solutions for NVH.

KeithC2Turto

Randy,

Respectfully, you sound very sold on the PB's. They are a great product from what I have read and judgment I have made from looking at their design.

I do not mean to repreesnt my self as an expert.

It sounds like you have not yet put the PB's on your car and may not have a full set including rear inner arm mono ***** and front shock uppers.

I admit, I have not had the opertnity to drive simmilar set up cars with Stock, Netrix, and PB rear bushings for a direct compairison.

Based on the streingth of your statement you must done so or read somthing somewhere that said Netrix hurts handling.

Did the cars have spring/sway/shock/tire/airpressure setups that were close enough to be able make a fair and reasionable compairasion?

Were the inner rear arm bushings replaced with solid ball joints or where they still the old stock rubber/metal set ups?

Puting PB's on and not replacing the inner bushings is only doing half the job.

Also, are you sure you even have Neatrix on your car?

If so, you are not suposed to lubricate them from what I understand.

In fact, they are suposed to be glued on the arm and the larger external surface is suposed to be sufficent so in will not slip once installed.

See the PB web site for example.

Unlike Stock or Netrix, PB's have to be lubed a couple of times a year. Not a big deal but if neglicted could become an issue.

I did not know there was a Netrix front bushing. I could not find any such thing when I was looking for a stock style replacement.

You say that Netrix is not rubber.

I have had a set before and do have a set of Neatrix here wating to go in the rear and they sure look like rubber to me.

They look very much like the factory rubber type bushings (but not worn).

The front is a different issue. There is not any value replacement bushings and the PB's are about it unless you have ER rebuild them with stock style Rubber which it is more expensive.

The Weltmister's softer restoration bushing is the only value replacement option up front. However, they should be lubed and can squeak.

Thus, if the fronts are bad, going PB's front is a likely a best practices option but for many.

However, getting a new set of front arms with factory rubber bushings or having ER, who makes the PB's, rebuild them with factory rubber style is a good option for most stock drivers and in keeping with maintaining the value of a stock car.

I am sorry, but saying the PB's will have less noise transmission and harshness compaird to a stock rubber bushing in good repair goes against my basic machanicaly understanding. Better that a wornout factory set up, I can accept.

Again, I am not an expert.

I used to know the man that developed Netreax. He was a national SCCA autoX champ for severl years in an early 911 (w 2.7, E cams, Solex carbs). He was one of the best Porsche experts/builders I have known of. He was also the first to crack 1g on street tires for a magizine test in a street legal 911.

Thus, I would find it hard to think Netrix bushings are is as bad as you claim.

I have had the replacement 'nylon style' bushings on a 72 w 2.8 twin plug I built and on a 72 911S I restored to factory Sport Purpose specs before PB's were around and they are harsh and can squeak. Not the Netrix.

It is my unprofessional opinion that if the factory front bushings and rear inner arm bushings are serviceable, which is often so, then Netrex rear bushings are a best practices replacement for a street 911. And still a solid choice for someone that just goes to a couple of DE's or autoX a year.

If the fronts are out, PB's seem to be a good choice. The Weltmister restoration bushings are a value replacement in the front but not w/o possable issue.

However, one should not forget the rear inner bushings or the bushings on the sway bars and there links. One might add the front upper shock mounts to this list.

I bought new shocks, torsion bars, all new bushings for my sway bars, new rotors, pads, fluid, brake lines, larger 86 Carrera sways... Adding $1000+ for PB's front, rear, and including inner rear arm mono ***** was not necessary when $50 Netrix would get me back to servicable condition.

Yes, the PB's would have been a better track option. (Not the total best as they still have a flexable poly component to them.)

Further, I made an educated guess that staying with stock style rubber bushings would take a little bit of the "track" out of my suspention for a dual purpose car.

Again, there is no reasion to think Netrix will hurt a cars handling, ride quality, or squeak like you claim.

They are a very acceptable way to maintain one's car.

Please, I am not an expert, nor do I mean to play one on the internet.

Good luck and I hope you fully enjoy your Porsche.

KeithC2Turto

PS, Rick, 21/28's in an unconventional combonation. 21/27 in light 911's and 22/28, or 22/29 is more commonly seen on a street/track car.

r911

My view of Neatrix is based on using them in my own car. My problems are similar to those reported by others, particularly on Pelican where there is a voluminous amount of discussion on this. Mine are not rubber - maybe they make a rubber version, but I don't know about that. You CAN get Rennsport (Steve W.) or Chuck at Elephant Racing to refurb your arms with rubber.

Chuck says that his PB work as well for NVH as the stock rubber -- others who anyone would rcognize as an expert have told me the same. However, I have not yet ried them personally.

Nothing personal but "there is no reas[i]on to think Ne[a]trix will hurt a cars handling, ride quality, or squeak" is just not supportable. Many have stated the opposite, just as I have. I urge you to try different types over time.

I have also tested my Neatrix equipped 911 (1973) with my other 911, a 1975 stock rubber suspension car (which weighed a bit more) back to back over the same bumpy & twisty road, driving each within 10 minutes of the other, and switching which one went first. You can do a better comparison only by using identical cars, and double blind. The '75 was a lot quicker, tho nothing like my Boxster S. It also did not squeak and was more comfy.

It is not entirely clear to me what your opinion is based on, but apparently it relies on reading about the different types. That is fine, but the crux of science is experiment.

Ed Hughes

IMO, Elephant's Poly Bronze design excells on ANY 911. You don't have to track the car every month to get the advantage of one of those few designs that actually improves on what Porsche did originally. Think about it, Polyurethane to act as a dampener, and then metal to metal to facilitate the rotation of the a-arms or trailing arms. The best of all worlds; a design that works whether you're on a track or on your favorite twisty.

Secondly, they are probably the easiest bushing repair from an installation standpoint on the market.

Thirdly, lubing them once or twice a year takes all of 5 minutes. If every required periodic maintenance item on a 911 was this simple, there'd be a lot of shops out of business.

KeithC2Turto

Randy,

At your suggestion I went back and searched topics with Netrix in the title. There were only 4 posts and I read them. Yes there are a lot of referances in the body of other posts so I guess what I read was only a limmited sample.

Netrix is not a pice of junk as you seem to claim and your position supprizes me. I think very highly of the PBs.

Most seems very happy with the Netrix and even raved about them. Several had them for a couple of years and had no issue. There was only one that had any squeaks and I suspect they were installed with lube of some kind and not glued.

The lub would not only creat potental for squeaks but may even brake down the rubber.

The PB's are a great product. For a track car they are amoung the best and because of the added Poly component are are easy to install and the only real streetable track bushing in my opinion.

PB's do require perodic lubing where the stock and Netrix are maintance free. Not a big deal.

The only better track set than PB's up would be a roller bearing set up but this would be difficult to fit and require each spring plate and torsion tube to be machined round and to exact size to install. This is the brilance of the PB's.

I know the maker represent that PB's ride as well as stock. I do not think they squeak nor add much, if any noticable amount to harshness and I do not think the maker would make any clam that there product is better as to NHV as do you.

However, PB's do not have the give of stock or Netrix bushings and the lack of compliance would have to be transferd somewhere, much of it might be transferd to shocks, some should be to the chassis.

Many components make up ride quality. I changed the tires on my ML 320 and had a much nicer ride from just a tire change. Shocks, spring & sway rates, tires, and all the other bushings make a significant contribuitions to the ride quality.

The biggest chalange to Netrix is the effort to compress them into place and install. If installed correctly, they do not squeak. (No lube & glue it to the spring plate.)

You stated: "Let me make this very clear: Keith is absolutely wrong when he says that Neatrix will best isolate noise & harshness. In fact, it is the worst of the three solutions for NVH."

That is a very aggressive and bold statement.

I still think Netrix or good condition stock bushings will best isolate from noise and harshness. PBs are great but there is alwas a trade off, less compliance has to come at the expence of somthin else. I do not think they degrade the ride to a point that is significant and they have solved the problems of the old hard replacement bushings of past.

Now, I am focused on the rear. The front has a lot less weigth and there is much less rubber in the stock set up. PB's here should even less noticable if at all.and are still a great choice. Like wise the gain from suspention control will be less. Shock tower flex and upper strut bushings may offer as much opertunity for imporvement.

I am done, belive as you will sir.

Ed Hughes

Well don't take this the wrong way, but your spelling leaves a lot to be desired. I'm surprised you found even 4 threads with "Netrix", which you use consistently in your posts, so my guess is that's what you searched with. It's NeAtrix...

You may want to check Pelican too, as there are probably 25 times the number of technical 911 threads there.

Lastly, a PB bushing probably DOES indeed ride better than "stock" on the street. If you consider all of the SC's, Carreras and older that have decades on the stock rubber bushings, with compressed/deteriorated rubber, the ride of a car going to this upgrade will certainly improve. I speak from experience; I changed 20 year old/110K mile stock bushings over to Elephant PB's 4 years ago, with no other mods done at that time, and it was the single best upgrade I've done still to this date.

r911

Well, that is always a good point, and commonly people make the wrong comparison (old X vs. new Y) - happens all the time with tires. We should really try to concentrate on comparisons of new vs. new (if we can find them).

Just thinking about it (and I pointed out that danger above) you'd imagine the rubber would have more give (compliance) on a bump and hence have a better ride than the PolyBronze. Several experts - not just Ed - have stated it is the other way around however. Also, Chuck has posted on Pelican why he thinks the PB give a better ride - it has to do with stiction and the ability of the PB to rotate easily (unfortunately, that may require the additional expense of the "cuffs" for the front bearings).

Yes, it is a strong statement: Let me make it again:
Neatrix is clearly the worst of the three solutions for NVH."

I'm glad to hear Keith or anyone back up their statements with personal experiences, even anecdotal ones, or better, with comparisons like the ones I did, with scientifically designed experiments, theoretical analyses or back of the envelope brainstorming. But the proof is in the methods used to obtain the information. I can't tell exactly how Keith formed his opinions.

One thing my PhD adviser said to me a long long time ago, and that I subsequently passed on to my own graduate students: "The first thing to read in a [scientific] article is the methods section - if that is inadequate, there is no reason to waste your time reading the conclusion."

rnln

There is one thing Keith mentioned but seem like no one pays attention. Keith said his Neatrix is rubber, not plastic. I think this answered all the confusions between Keith and Randy.
It's strange. This is the second time I read about "rubber Neatrix", but when I asked more, then there is no response.

Keith,
May I ask where did you get your "rubber Neatrix" from?