Is polybronze the way to go?
 

Hey guys, I've got a couple weeks of free time coming up and one of the projects I wanted to tackle on my 911 is replacing the 30 year old worn out A-arm bushings, and rear torsion bar bushings with new ones. It appears that OEM bushings, and even aftermarket rubber bushings are unavailable, so I'm looking in to other options.

I use my car as a daily driver, with the occasional weekend fun run on mountain roads, and I'm trying to find the right product to suit my needs. I've looked in to the polybronze bushings, and I'm impressed by the engineering, but I'm wary of going "full polyurethane". I've heard horror stories in general (not necessarily pertaining to 911's) about people "refurbishing" their suspension, thinking they are doing a good thing by installing polyurethane bushings, and ending up with a car that is just too rough for city streets. I don't want that to happen, I want to be able to drive my car daily.

So in the end, do you think polybronze bushings are the choice for me, or is there some other direction I should be headed in?

SmileWavy

jonbot,

I can not speak for you, when I decided to redo my bushings, I thought aboutt he same thing.

I do touring, autocross and the occasional DE.

I ended up putting Neatrix in the rear. The Polybronze was an attractive alternative, but ultimately cost won over the polybronze.

I was going to replace my fronts, but upon inspection, I did not think replacement was warranted. If I needed to replace them, I would have went with PolyBronze as I have no facility to machine urethanes to fit. An alternative would have been to give the car to a local speed shop who can do the machining and have them install urethanes.

Maybe I helped a bit?

Look at elephant racing site...they have all the info...they replace a-arm bushings with stock bushings if you send them. They also have their polybronze setup which is highly regarded.

My '73 911 came with polyurethane bushings that squeaked like hell. I replaced them with Polybronze and, considering the purpose of the car (mostly autocross), I'm very satisfied. The ride is a little harsh, as you'd expect with stiff torsion bars, but no "resonating" into the chassis and NO SQUEAKING. However, it was somewhat of a challenge to get them to fit properly and work smoothly. I would call the low-friction mounts essential.

That being said, if I were only going to do street driving, I would probably have the control arms reconditioned with stock rubber bushings. Elephant Racing can do this, as can Smart Racing Products and probably others. Note that aftermarket rubber bushings like Neatrix are in no way similar to the reconditioned control arms.

While you have the control arms off, consider replacing the ball joints and tie rod ends if you haven't done this already. Consider having the car corner balanced after you get it back together.

The horror stories about polyurethane are true. They squeak and ride harsh. I would advise you to stay away from polyurethane bushings.

PolyBronze is not a polyurethane bushing. It is a bronze bearing encased in a polyurethane jacket. Rides smooth and no squeaks.

PolyBronze is the right choice for -

a) performance, they are the best handling option available
b) DIY, you can install them yourself
c) people willing to give them the occasional squirt of grease

Your alternative is to replace with rubber bushings. You can't DIY this for control arms. You can DIY this for spring plates. These make sense for people that need a zero-maintenance product and are willing to trade out performance to get it.

Both products give good ride quality.

this is probably worthless


I have Welt black street bushings all around. It's a very harsh ride for city streets and overkill for even LA streets.

I rode in a 911 with Neatrix rear and Welt black in front and was surprised that it's 75% less harsh. It's actually doable for city streets.

My car has 21/27 T-bars and the other had stock '72 S T-bars.

Is polybronze the way to go? Yes. I made the very expensive mistake (labor-wise) of replacing rubber A-arms with polyurethane, and even after a week of driving, they began to bind and squeak. The next week I had polybronze (Elephant Racing) bushings installed. My handling improved as well as my ride. Harshness? You'll get a harsher ride out of the plastic than the steel (or whatever the polybronze is made from).

Equate it this way: which rides better as a road bike - plastic or steel? Steel, of course.

My next project is the inner swing arm bushings along with some bigger rear torsion bars and revalved rear shocks. (save me a pair, Chuck). I figure my ride should be stiff but controlled.

I personally stopped at Elephant Racing and looked at the poly bronze bushings while attending Jerry Woods class...in my opinion that's the way to go. However, I'm not expert in suspension set up, just looking at it logically.

It may cost more, but the quality is on the money...or is it the other way around!
There's a metal bearing that the bronze bushing rides on, hence the occasional greasing. However, the grease nipple makes that a simple job.
I'll be getting these when the time comes.
Chuck is also very customer oriented and will answer your questions and is very accommodating as we just showed up without an appt.!....Damn Hawaiians!SmileWavy

On my bimmer I have urethane bushings...no bearings and the ride is harsh, so I'm used to it, but looking at Lafant Racing's (sp. is for chuck:D) set up I doubt it will be as harsh and there's a lot less stress/friction on the mounting point.

I have poly bronze and monoballs - not harsh at all - just direct and precise

Elephant. Done.

Replaced front A-arm and rear springplate bushings with Polybronze and installed trailing arm monoballs. Of course, replaced a whole bunch of other stuff "while you're in there".

After approx. 10K miles of street, some autox and a couple of DE's, I am very happy with the Polybronze. Installation was straightforward. Chuck Moreland was very helpful whenever I had questions. Overall, the ride is stiffer (not bone jarring), but I think that's due to the struts and torsion bars not the bushings.



1987 911

Ditto even on the horrible roads of Western NY.

The only problem I have with the polybronze is that on the rears I can't get my grease gun on the fitting far enough to actually inject grease. The zerks on the poly bronze busings don't stick out far enough. Has anyone firugred out a fix?

Is it possible to get longer zerks? [fittings]?

Grease gun tips vary in diameter. Larger ones can cause clearance issues to the spring plate cover. If this is the case, touch one side of the tip to a grinder to thin it a bit.

just go for polybronze
 

i have the project done early this yr with polybronze f R monoballs plus revalve dampers fr bilstein also change the 22 29 torsion bars retain the stock sway bars for 87 carrera car drive very smooth in street actually I track the car most of the time,I will have to tell you it worth the investment.

you can buy a flex hose for your grease gun at any auto parts store that will fit

Google "flexible grease gun hose"

I just put polybronze in my '88 Carrera (front and rear) and I am very happy with the results. I put 20k miles per year on this car so the ride quality is very important. I only have 150 miles on these so I can't speak about wear, but the ride quality is great.

That isn't the problem. It's the tip on the flexible hose that is a little to big (long), at least that is my problem.
It's a bit tight but I manage to get grease into them. If I had to do it again I would position the zerks slightly different.

If you have the money PB is the way.

I know what ya mean, as I have just one that is a bit of a PITA. I've tried a few different tips (none work very well) on flexible hose and manage, but in hindsight, I would position that one at a slightly different angle (although the other side is virtually the same position and has no problem). I like 'em!

Wow, thanks for all the info guys, this is really an important subject to me, and I appreciate all your input, I'm reading through everything you guys say.

To me, the suspension defines the whole attitude and feeling of the car, and I just don't want to make any decisions I might regret. I wasn't aware that Elephant racing provided a service to replace the rubber bushings, that's pretty sweet. Right now, I'm kind of leaning towards this service, but I'm still trying to weigh out my options.

One concern of mine with the polybronze is the 1 year/5k mile lubrication interval. It doesn't sound terrible right now, but I wonder if it would became an inconvenience for a daily driver.

Another thought I have is what happens down the road if the bearing races need to be replaced, how difficult is it to remove them after they have been epoxied in place for years? I'm just trying to think about it from all angles.

For your application, I would stick with the original design. I think Smart Racing also replaces the rubber bushings.

I have the elephant polybronze set up and like them so far but my car is set up for more track than street.

For a long term, maintenance free solution, I don't think you can do better than the original design.

Don makes an excellent point. Mine's not a daily driver, so it's just one of the annual maintenance items...another "to do". Most of us are in there doing something else anyways, so it's no big deal to hit 'em occasionally. If one doesn't DIY though, and really puts some miles on each year, that's certainly a valid consideration in spite of the benefits. I don't ever relish the idea of replacing a pb bearing, but the same is true for rubber. One benefit not mentioned about pb bearings imo, is how easy they facilitate reindexing the rear torsion bars. When I put everything back together (euro height), I got her close enough first try and then adjusted, but if one did need to change the rear height by reindexing, it'd be much easier imo. My setup is similar to Clubsport's: 22/29 t-bars, Bilstein HD/Sports, polybronze bearings, monoballs, strut brace, lightened a bit, and some other stuff...fantastic for the streets I travel, and I wouldn't change a thing.

ps: Maybe it's changed, but I thought the relube interval was more like 10K miles (I do it sooner). I hadn't thought about the epoxy aspect...I've had mine several years, and did 'em the old way (shimmed and pressed on) with no problems whatsoever.

For a car that sees mostly street use I'd go with Netrix or factory bushings. I've used the Netrix bushings before. They are quite, don't need constant greasing, are inexpensive, and hold up great.

The grease maintenance should not be over magnified, its not that big of a deal, it takes just 30 minutes.
It just needs to be done.

Its not for the concourse car since the bushings (and the parts around it) tends to get a little greasy over time.

I went with polybronze on the front and neatrix on the back on my 911 daily driver. Suspension now just feels like a new stock suspension. Not harsh at all.

This worked for me (so far) ... it is cheap and quick, if nothing else.

http://forums.pelicanparts.com/porsche-911-technical-forum/371046-front-lca-rubber-bushing.html

This assumes our bushings are still elastic and not brittle. Chuck Moreland can also rebush your A-arms with original-style bushings if yours are toast and you want to stay stock.

If rubber is not to your liking and if you are riding on the torsion bars like I was, I can't imagine PB bushings making the ride any worse. You will loose some front ride rate going to PB bushings - not sure how much, but 10% might not be that far off. Next summer I might take mine apart again to measure it. Too damn cold now....

this may also give you some idea http://forums.pelicanparts.com/porsche-911-technical-forum/331261-revalve-upgrade-suspension.html

[PolyBronze] "Suspension now just feels like a new stock suspension."

- according to Steve Weiner, who should be unbiased and has seen a LOT of setups, the PolyBronze will feel BETTER than a new stock suspension. The only downside appears to be the need for a bit of grease once in a while.
-- From a reply to a question by me in the last few days -- should be easy to find if you search.

It's really not a big deal. Every time you change the oil, just grease the bushings. Of course, you will need to buy a grease gun if you don't have one, but such is life...

ianc

This is not a big deal. Up to about the '80's, all cars had zerk fittings that needed the occasional pump of grease. You did the greasing when you changed the oil. 1-2 pumps per fittings and you were good to go.

I still have my grease gun.

PolyBronze-No
 

The previous owner had installed a full PolyBronze setup in my 87 Carrera, Cool, I thought untill I tried driving on Seattle streets! Not comfortable and noisey as hell! All kinds of rattles and bangs.
I replaced the whole setup with new factory rubber control arms, and bushings, front and rear it is like a new car now, literally.
In my opinion, not acceptable for street use, great for a track car!

John
1987 911 Carrera

Are you sure they was the PolyBronze? You must have had som other issues if thats the case.

Absolutely sure, I saw them with my own eyes, and I know the mechanic who installed them.
This car is extremely well maintained!
You are not driving in Seattle!
JT

No, not in Seattle, but the roads where I live are no ballroom floors.
They should not rattle and bang, not if properly installed, which is not as easy as one might think.

Hmm...there's got to be more going on here imo. Seems to me that "comfort" is more related to the stiffness of the torsion bars, shocks, etc. than with the movement of the rubber bushings or pb bearings (more freedom of movement imo). My car is "firm", but certainly not uncomfortable, and as far as noise, not a single rattle or squeak regardless of the road conditions.

I have 22/31 bars and neatrix/polybronze. Mine is not a daily driver and is mainly used for sunny weekends. 1,500 miles max pa.

My ride is harsh for the road, not too much, but harsh nonetheless. Handling probably suffers on the road.

I do find greasing the polybronze a PITA! They should be done every 1,500 miles? So, definitely out for a daily driver (IMHO).

If I did it again? I would stay stock (unless I did lots of track work).

Of all the things I have done to my suspension in term of degrading comfort I would grade them in this order:
1. Low profile tires
2. shocks (I run Bilstein Clubsport)
3. torsionbars
4. swaybars
(5. PB bushings.)

Number 1 and 2 had the biggest impact by a huge margin. PB I would say almost improved the comfort.

LOL!!!
I was thinking the same thing...how difficult can greasing the nipples be?
I remember having to grease like 5 nipples just for the front suspension.

Strange that the PB would be noisy since it moves on a bearing...unless it wasn't greased?

The A-arm rubber bushings isolates 2 of the 3 noise paths from the balljoint into the car body. Usually 25-50Hz and up. The PB bushings would not do this.

OEMs spend quite a bit of money, time and effort on bushings (there's even variable rate, directional, hydraulically damped ones) to isolate noise and tune the ride. I'm not knocking PB's, but there HAS to be some detrimental effect for noise when compared to a rubber bushing (one that's working correctly, not one that's bottomed out on the torsion bar). May be perfectly acceptable based on roads and owner preference. I bought a set myself, though they are still in the box....and I'm still on the fence about installing them sometime. For now, the rotated factory ones seem OK.