cheaper polyurethane bushings for e36. anyone else besides powerflex and UUC?

[paradox96]

does anyone else make polyurethane bushings for e36?
powerflex charges way too much for their stuff.
I used to mod 240sx and I could get 4 times more polyurethane than I would get from 2 powerflex control arm bushings.
I mean the whole kit for 240sx is around 130$. kit by energy suspension.

I will be on the phone with energy suspension tomorrow to see if they will be making anything for BMW.

[YAOGinanM3]

does anyone else make polyurethane bushings for e36?
powerflex charges way too much for their stuff.
I used to mod 240sx and I could get 4 times more polyurethane than I would get from 2 powerflex control arm bushings.
I mean the whole kit for 240sx is around 130$. kit by energy suspension.

I will be on the phone with energy suspension tomorrow to see if they will be making anything for BMW.

Why would you want to inflict poly bushings on your street driven BMW and passengers? Poly bushings require frequent lubrication and regular replacement when used in the wrong places (like RTABs) and makes your car noisey and harsh riding. Poly is not the best material for many of the bushings on the E36 chassis especially if street driven.

HTH!

[Brent 930]

No poly on a street car?

Rubbish.

Other than motor and tranny mounts I only use poly for my rear subframe bushings (going AKG 95A soon) and RTAB's, which are PF.

Try AKG Motorsports.

[YAOGinanM3]

No poly on a street car?

Rubbish.

Other than motor and tranny mounts I only use poly for my rear subframe bushings (going AKG 95A soon) and RTAB's, which are PF.

Try AKG Motorsports.

Let me ask the question this way. Why would you want more NVH and higher maintenance for no measurable improvement in objective performance? Remember this is for a street car.

[pbonsalb]

The problem with performance parts for BMWs is volume. Less volume means less competition and together that typically means higher prices. I use AKG diff mounts, Powerflex subframe bushings and RTABs, and have been using Powerflex FCAB but have a set of UUC bearing bushings that I will try next since the Powerflex now have about 40k miles and are cracking. Unfortunately, the last time I checked, Energy Suspension made only front swaybar bushings for 23, 24 and 25 mm bars.

[turbosporttsi]

Let me ask the question this way. Why would you want more NVH and higher maintenance for no measurable improvement in objective performance?

If the bushing is used in a stationary position, it requires no maintenance and doesn't degrade. (Softer, bonded bushings are a different story.)

For me, the poly allows better feel of the car's motion. There is no way to quantify feel. Obviously, retaining the suspension's intended geometry under load is always a good thing as well; something that rubber has a very difficult time doing.

But this is all from an autocrosser's perspective. If the car is purely a street car, I see nothing wrong with poly if used in the right places. The pros and cons will be up to the individual.

does anyone else make polyurethane bushings for e36?
powerflex charges way too much for their stuff.
I used to mod 240sx and I could get 4 times more polyurethane than I would get from 2 powerflex control arm bushings.
I mean the whole kit for 240sx is around 130$. kit by energy suspension.

I will be on the phone with energy suspension tomorrow to see if they will be making anything for BMW.

Unfortunately, most poly bits for these cars are a bit pricey. AKG Motorsport has good pricing on some of their parts. I have their rear subframe bushings and would recommend them.

[YAOGinanM3]

If the bushing is used in a stationary position, it requires no maintenance and doesn't degrade. (Softer, bonded bushings are a different story.)

Yes poly can make an excellent bushing material if used in the right places primarily stationary modes for isolation of heavy or high mass components and as an isolator for parts that swing on a single plane through the axis of the bushing but never in a location where the poly bushing would need to allow movement off axis of the bushing tube or for multiple axis use.

But the question I asked was why would you want to increase NVH on a street car for no measureable gain in performance?

For me, the poly allows better feel of the car's motion. There is no way to quantify feel. Obviously, retaining the suspension's intended geometry under load is always a good thing as well; something that rubber has a very difficult time doing.

Yes poly does increase compliance but at the cost of increased NVH. But you can achive the same thing with OEM type bushings of higher hardness ratings. Poly can let you feel closer to what the car is doing but the price you pay for this is a constant increase in NVH. If a poly bushing does not increase NVH then that bushing is not be capable of transmitting increased feedback. The relationship is 1:1.

But this is all from an autocrosser's perspective. If the car is purely a street car, I see nothing wrong with poly if used in the right places. The pros and cons will be up to the individual.

So what are the correct locations you think that poly bushings can be used on a street car if driver wants to maintain OEM like levles of NVH and what advantage do you think a poly bushing offers in this case?

Unfortunately, most poly bits for these cars are a bit pricey. AKG Motorsport has good pricing on some of their parts. I have their rear subframe bushings and would recommend them.

Poly bushings are very inexpensive to produce and require almost no tooling. The only reason they are expensive for BMWs is that the OEM bushings they replace are complex pieces that require tight tooling to produce so the poly bushing makers raised their retail prices to increase profit margins. There is not a huge market for these products in the first place and the market is full of poly bushings because people figured out how inexpensive it is to produce poly bushings.

Why, what is better about the AKG rear subframe bushings?

[paradox96]

I really did not notice any difference between BMW and 240sx bushings. exact same design of bushings. just different shapes and sizes. I replaced all bushings in 240sx with energy suspension bushings and rode it 15000 miles. I really liked the steering wheel response. did not have any cracking or noise issues, but I lived in dry climate. almost no rains. sway bar bushings did show signs of wear after like 10000 miles. This may be ghetto but I think I will put some small rubber bags around front control arm bushing bracket to keep the shit and water away from grease.

[Hova]

This may be ghetto but I think I will put some small rubber bags around front control arm bushing bracket to keep the shit and water away from grease.

http://www.amazon.com/Pennzoil-7690-.../dp/B000KKJQLO

[YAOGinanM3]

I really did not notice any difference between BMW and 240sx bushings. exact same design of bushings. just different shapes and sizes. I replaced all bushings in 240sx with energy suspension bushings and rode it 15000 miles. I really liked the steering wheel response. did not have any cracking or noise issues, but I lived in dry climate. almost no rains. sway bar bushings did show signs of wear after like 10000 miles. This may be ghetto but I think I will put some small rubber bags around front control arm bushing bracket to keep the shit and water away from grease.

I found that marine grade synthetic grease works very well showing minimal wear, it sticks and does not wash off.

[Hova]

I found that marine grade synthetic grease works very well showing minimal wear, it sticks and does not wash off.

Read post 9

If you have the time, and recourse's, you can make your own bushings as well.

http://www.usplastic.com/catalog/def...arentcatid=795

[YAOGinanM3]

Read post 9

If you have the time, and recourse's, you can make your own bushings as well.

http://www.usplastic.com/catalog/def...arentcatid=795

Oh you beat me to it. We used to pour our own poly bushings using metal reinforced fiberglass forms. Not as pretty as the our later tooled molds but they worked just as well and the molds were cheaper.

[Brent 930]

Let me ask the question this way. Why would you want more NVH and higher maintenance for no measurable improvement in objective performance? Remember this is for a street car.

Whatever increase NVH I'm getting I could drive my car across the US and be just fine. More maintenance?

[turbosporttsi]

But the question I asked was why would you want to increase NVH on a street car for no measureable gain in performance?

Just because the increase in performance cannot be measured doesn't mean that it has only negative qualities. NVH does not really bother me, but a floppy suspension does. This is why I said that the individual would have to choose where the poly goes.

For instance, I will never have delrin RTABs...from what I gather, it is just too much of an annoyance (in the noise department) with little advantage over OE w/ limiters. A spherical RTAB has the same advantages without the noise. This is, of course, ignoring the fact that the RTAB needs a bushing capable of articulation on more than one axis.

Yes poly does increase compliance but at the cost of increased NVH. But you can achive the same thing with OEM type bushings of higher hardness ratings. Poly can let you feel closer to what the car is doing but the price you pay for this is a constant increase in NVH. If a poly bushing does not increase NVH then that bushing is not be capable of transmitting increased feedback. The relationship is 1:1.

With the exception of HD RTABs (which are not necessarily a stiffer compound, just compressed) and BW's GruppeN style motor mounts, there really are no affordable options for stiffer rubber OE mounts. There are inner control arm bushings for the rear... but have you priced them??

Don't forget... rubber wears out.

So what are the correct locations you think that poly bushings can be used on a street car if driver wants to maintain OEM like levles of NVH and what advantage do you think a poly bushing offers in this case?

In this particular case, it is best to use rubber, which is why the factory does.

To me, I only care about noise... not so much vibration and/or harshness. A poly bushings will increase NVH, yes... but in my case, my tolerance threshold for V & H is very high. It's the noise that I primarily care about.

Why, what is better about the AKG rear subframe bushings?

They incorporate the OE washers. They do not have a steel sleeve, but I see no disadvantage there. Maybe they will wear out faster than if they had sleeves.... but I doubt any of us will ever see that point.

[=BA=]

Some misinformation here.

Rubber suspension parts have not got a whole lot to do with durometer scale, it is the tooling that's behind rubber that makes it work. One of the key differences between rubber and polyurethane is that rubber cannot be compressed as a material, but it can only be deformed. The way polyurethane is made, it can be made compressable by adding in air bubbles, this is the way purple powerflex works for example. So if you use purple powerflex for subframes or other bushings, it is pretty useless as the material just gets compressed, this is why they wear out in such a high rate as well. Black powerflex for example is Shore 95D, so without air bubbles but this effectively makes it just as hard as delrin and nylon.

One of the better examples is the front, LCAB get one from a 96+ M3, rotate it 1/4 of a turn so that the openings are on top and bottom instead of the sides and the steering is much sharper, because the rubber does not have any play anymore. This effectively makes the bushing alot stiffer just by altering the place where the openings are.

Same for say a subframe, say you have rubber rear subframe bushings, if they have their openings on the front and back they are very stiff in lateral load but can still absorb vibration. If you use a soft polyurethane bushing like powerflex purple it will compress in all directions and will actually be worse than a proper rubber application.

Also one of the differences is that rubber wears out in open air, polyurethane will not but polyurethane has a very high wear rate in moving components. Components will move inside the polyurethane bushing, as polyurethane does not bond to metal parts. This also means the slightest wear on a very hard bushing will make it develop play in the bushing. Rubber bonds to metal, so when a component rotates the rubber bushing will twist along with it (this actually creates extra springrate in a suspension) and since it deforms, the piece along the metal part is pushed aside and you can use the excess material so that it feeds itself.

If you ask me polyurethane is bodge engineering, a manufacturer simply replaces everything with polyurethane but there is little to no engineering behind it. Polyurethane has no place in a car suspension if you ask me, the only place I would use it is in foundations etc, engine and gearbox mounts for example. Not the rear subframe as it sees a lot of lateral load.

If polyurethane was better, all manufacturers would use it but it is simply not

[Brent 930]

BA, what do you think is the best non all aluminum rear subframe bushing?

[=BA=]

It is hard to define something as best.

There is all sorts of materials to choose from, hard plastics like Delrin, Nylon or Teflon are also very stiff but also make a lot of noise, however as long as you don't have solid differential mounts I think it is not that bad. Probably goes the same for powerflex, the black ones are the stiffest but can also be noisy. But the diff bushings absorb a lot of noise.

Just make sure to never use the softer polyurethane ones (ie purple powerflex, or AKG 75D) as these are worst of all worlds in my opinion.

Subframe bushings are essentially a stationary part by themselves but need to resist lateral force on the subframe, and up and down movement due to torque in the driveline.

If it's a street driven verhicle I would just take new OEM ones but make sure the front ones are M3 items, the rear ones should be equal across the entire 3 series.

If you look at the actual design:



It is very stiff in lateral movement, but still allows some up and down movement, giving you the best of both, you get a stiff sideways assembly but a quiet car.

There is just one drawback, like any rubber piece exposed to the elements the rubber degrades so needs replacing in a number of years. But in reality, not many people keep a car that long Also you will notice an improvement since the part you are replacing is likely to be 15 years old or so. Going completely solid on subframe bushings will also eliminate up and down movement so should take some slack out of the driveline.

We replaced the rubber subframe bushings that came with it with nylon ones, the car is somewhat louder but I honestly did not notice much difference, also in driveline slack. The difference between stock and solid engine/gearbox mounts is like night and day in driveline responsiveness and also in noise.

I found the biggest differences in the rear suspension to be in the RTAB's and if you drive 95 M3 replace the lower outer rubber piece with the solid balljoint from the 96 M3.

[Brent 930]

Where do you get nylon rear subframe bushings at? Never heard of them.

I was thinking of changing from PF purple to AKG 95A, but...

Thanks

[=BA=]

The Nylon ones were made by a local company who fabricates a lot of E36 parts, specificly for the trackday car market and racing, as they rent out E36 trackcars themselves, they don't have any webshop or so.

But you might as well go with something like delrin if you wish to take that route.

[Brent 930]

^Delrin is harder than nylon 6, and it would be almost the same as going all aluminum.

You do realize that nylon 6 is =Poly 70D yet you don't care for Poly 75D.

[YAOGinanM3]

Whatever increase NVH I'm getting I could drive my car across the US and be just fine. More maintenance?

Frequent lubrication and replacement when used in locations that use poly incorrectly like RTABs.

[turbosporttsi]

^Delrin is harder than nylon 6, and it would be almost the same as going all aluminum.

You do realize that nylon 6 is =Poly 70D yet you don't care for Poly 75D.

He said that he doesn't care for the softer poly. It seems like the 75D was a typo. I am guessing he meant 95A....that's how I took it, anyway.



Oh, and to clarify my earlier statements, I will only run the "recommended for race use only" hard poly... not the soft stuff.

[=BA=]

Mean the softer poly yeah, that is 75-95A? Edit: went through the shore scales again and A is softer stuff and D is solid stuff

Not so much bothered by the Shore rating though, especially in a location like the subrfame. Shore rating is tested by using a springloaded indenter needle and looking at the size of the dent you will make with them. This will tell you something about the materials surface hardness but not much about how a bushing will perform in a car's suspension under load. There is some overlap to elasticity of the material but it does not go hand in hand in case of a subframe bushing.

Shore rating will only tell you something about wear rates in rotating bushings, ie the softer the shore rating the quicker the material will wear out when metal parts rotate in them. This is why Delrin is widely used in industrial applications, it has a high material hardness but is impregnated with teflon so it gives a very low fritcion.

I think if you take a location like the rear subframe there is not going to be a lot of difference weather you take a hardplastic like Delrin, Nylon, Teflon or aluminium to be honest, since it is a stationairy location. Mian interest is deformation. There is external forces acting on them but no moving parts. For a better comparison you would have to look at the young's modulus for materials in this application, rather than shore scale. In case of Nylon, it's about half that of Aluminium, this sounds like it is inferior, but these are big numbers So for ultimate stiffness you would want aluminium but I think it is not so relevant when you considder the size of the forces and the size of the bushing

Some figures I quickly found on Young's modulus (lbf/in2)

95A polyurethane = 10,000
Rubber = 15,000
75D polyurethane = 63,000
Teflon = 75,000
Delrin = 406,000
Nylon = 505,000
Aluminium = 10,000,000

Rubber compounds should actually be stiffer than 95A Polyurethane.

Pick up one of those purple powerflex ones and press your nail in, it's soft and easy compressible. Most of these bushings can be installed by hand, that is why people love them, but if they are so compressible that you can put them in by hand, would you put a 1000 - 1500 lbs lateral load on them? Take a hardplastic bushing and you have to put it in with a 10T shop press This is one of the reasons why I think the softer poly stuff is not suitable for bushings and in case of say a rear subframe, a OEM bushing is preferred over a soft poly one.

[Brent 930]

There is no doubt a made a big mistake by going PF purple for one reason you already mentioned. 80A is just too soft in that application. Then the whole cupping of the washers. I got around that for now but I'm going to change them either next month or next spring. So far I'm not completely satisfied with my choices, but I still think the AKG poly 95A's is overall my best pick of the group. Being mostly a street car. The one thing regarding the rear subframe is there are 4 bushing working together at the same time, not just one. This might be a consideration vs. for example; the RTAB's.

Otherwise I love delrin but the noise and stress on the subframe mounting points over time might be too much. I might get a set designed anyhow since I have resources for that sort of thing.

[Rob Levinson]

Poly bushings are very inexpensive to produce and require almost no tooling. The only reason they are expensive for BMWs is that the OEM bushings they replace are complex pieces that require tight tooling to produce so the poly bushing makers raised their retail prices to increase profit margins. There is not a huge market for these products in the first place and the market is full of poly bushings because people figured out how inexpensive it is to produce poly bushings.

Not to be disagreeable here, but that's pretty far from accurate.

Specifically because BMW OE bushings are complicated and precise, and there are substantial tooling/mold charges involved in making a duplicate, and because the quality level required for good long-term usage in a BMW is so critical, they are indeed expensive to make.

If you want cheap poly bushings, shop for Chinese parts. You'll be shopping pretty often as you will need frequent replacements.

The quality poly parts are made in USA... and in all reality, prices are fairly reasonable. These really don't seem expensive:

A full set of RTABs for $65? [ CLICK HERE ]
(OE price from BMW is about $80)

A full set of transmission mount bushings for $35? [ CLICK HERE ]
(OE price from BMW is about $45/set)

A full set of subframe bushings for $159? [ CLICK HERE ]
(OE price from BMW is about $300)

A pair of engine mounts for $215? [ CLICK HERE ]
(OE price is $150... okay, that one is cheaper, but different in performance)

Etc., etc. Trust me, nobody is getting rich off of poly bushing sales!

And as far as daily-driver use goes, many if not all of these parts are indeed suitable for street use, and will remain squeak-free when lubricated properly. Will the car feel or drive differently? YES! The idea of any performance upgrade is to make the car operate differently. For the enthusiast driver, this is usually a good thing. If this is your Grandma's car, then maybe she won't appreciate or even notice the changes.

But do expect any performance modification to change how your car drives - that's the whole idea!