I've been through several iterations of these and wanted to put some info in one place. There's lots of info spread out, some of which I wish I'd seen before having my subframe dropped 4+ times trying different solutions.
Firstly, there are two bushings in the front control arm. The forward one is the camber bushing, if it's offset, you will primarily change the camber setting. The rear one is the caster bushing, and an offset will thus change caster.
Secondly, there are about 3 types of bushings on the market, with some variations and at least one hybrid option. Rubber (OEM), polyurethane, and pillow ball (aka spherical bearing, solid bushing, ball joint, et.). Rubber is generally the most compliant and comfortable, urethane somewhere in the middle, and solid joints are generally harsher (particularly as they wear out). In general, urethane is cheaper to manufacture than rubber, and more resistant to breakdown from chemical exposure, but also more prone to deforming from high temperatures and elongating.
Lastly, there are both full replacement steel and aluminum arms on the market.
Rear bushing (big / caster)
This is the one that has caused me the most pain. The first set I tried were solid polyurethane bushings and they failed extremely quickly (a few hundred miles). I had a set of polyurethane bushings from another brand sent as warranty replacements, but due to a long backorder, I opted to order a set of stiff poly bushings from another brand, this time with the caster offset. These too, developed signs of failure within a few thousand miles. My assumption is that the axial tension is just not a good fit for polyurethane materials, though it is important to note that I'm using an aluminum subframe which may have been coming into contact with one of the bushings. Given that superpro seems to now be selling different bushings specific to each subframe, I suspect that may be part of my issue. FWIW I've talked with numerous people who've had bushings in that spot fail.
Folks doing heavy track miles, like regulars at the 'Ring, have noted needing to replace their rear bushing very often, much more than any others on the car.
I'd also note that while using very stiff poly bushings, it is much more difficult to push the arm down in order to facilitate servicing the front suspension, either changing the ball joint, knuckle, or strut.
Rubber:
OEM Mk7 - rubber, large voids, very pliable - 5Q0407183L
OEM 8V A3/S3/RS3/Mk8 R - rubber, small voids, less pliable - 81A407183
OEM 8Y S3/RS3 / 8S TT/TTS/TTRS - rubber, minimal/no voids, even less pliable - 8S0407183B
BFI "RS3" bushings - these appear to be non-OE replicas of the 8S0407183B p/n: 81A407183G
Hardrace "hardened" rubber (looks similar to BFI): 7824
Polyurethane:
Superpro stock geometry, steel subframe: SPF4176K
Superpro stock geometry, aluminum subframe: SPF5592K
Superpro caster offset, steel subframe: SPF4178K
Superpro caster offset, aluminum subframe: SPF5594K
Whiteline caster offset: KCA499
Powerflex offset bushing: PFF85-802 (purple or black) This has an offset bore similar to the others, you can add (or remove) caster at install.
Powerflex adjustable race bushing: PFF85-802GBLK. This is the first "hybrid" style, where it utilizes a ball joint inside a urethane bushing, with a flange to assist in adjustment while it's on the car. I have read positive reports about this style in hard usage, they seem to hold up better than a straight poly option.
Solid:
JXB: PTFE-lined aurora or FK bearings. These do not offer any sealing and probably wouldn't be a great idea for a street car due to maintenance/rebuilds. I've heard nothing but great things from a performance standpoint, however. Given they're a standard FK/Aurora bearing you can likely find replacements from your preferred bearing vendor.
Hardrace: Q0077. These appear to be a sealed ball joint, which should have more longevity, though I haven't seen anyone use them.
ECS Monoball: 008083LA01. They claim to use a sealed OEM Mercedes ball joint, but it's ECS so YMMV. I think these are interesting given the claimed OEM quality, combined with the articulation of a ball joint.
Front bushing (small / camber)
These have been fairly painless for me, both the solid poly as well as original rubber.
Rubber:
OEM: 5Q0407182 - This part is shared across the mk7, 8v, 8s, and 8y audis. If someone sells an "RS3" version of this, well, you already have one.
Hardrace: 8943. This looks like it has similar geometry, allegedly harder rubber.
Polyurethane:
Superpro stock geometry: SPF4175K
Superpro adjustable camber: SPF5552K
Whiteline adjustable camber: KCA539
Powerflex stock geometry: PFF85-501
Powerflex adjustable camber: PFF85-501G While adjustable, it doesn't seem very practical to adjust them while installed on the car, especially with DSG models.
Solid:
JXB (sold as part of a kit with their caster bushings)
Hardrace: Q0076
Full arms
There are 3-4 styles of these. OEM or OEM-replica stamped steel arms with pre-pressed bushings, aftermarket, one-piece aluminum arms, and fully adjustable tubular arms.
If you're in the market for a verkline arm, I assume you know whether you need modified kinematics and you own a $2,000 subframe so you must know what you're doing. Similarly, if you're buying ECS
Superpro steel arms: TRC1070. Appear to be stock geometry, with simple poly replacements.
Whiteline steel arms: WA302. Same thing, just black bushings. It's unclear if whiteline sells these bushings separately, they don't list stock geometry bushings and when I warrantied mine, they sent me superpro parts.
Superpro aluminum arms: ALOY0018K. A bit of extra caster and camber, with hybrid ball-in-socket urethane ball joints. In theory these are an improvement all around. The set I ordered arrived with a damaged bushing and the ball joint holes were machined incorrectly. Superpro used to sell one or two other arms, which had clearance problems on some subframes, and were thus discontinued.
Whiteline aluminum arms: KTA252 / KTA 262. First part is +2deg caster, second is +2.5deg caster.
Hardrace aluminum arms: Q0804 / Q0822. Rubber/pillow ball, respectively. I'm interested in these, they look like they might be a relatively durable/lightweight option, but without the geometry changes in the arm itself.
034 RCO arms: 034-401-1068. These appear to offer more camber than the others, with a rubber bushings. If 034 rubber bushings and mounts weren't generally trash, this would look like a great option.
It's worth noting that all of the OE steel arms have the same dimensions. Only difference from what I've found is the bushings themselves.
TL;DR
Personally, I wouldn't touch poly caster bushings again. The newer audi bushings I'm using have plenty of feedback, are obviously durable, and are pliable enough to make strut replacements bearable. I would use a good set of strut mounts/plates to add caster if needed. No one sells rubber offset bushings afaik.
The cookie-cutter option, at least for STH/STU autocross guys, is the "RS3" rear bushing combined with the powerflex offset camber bushing. My experience with having poly bushings on nearly every joint is that they hold up pretty well to torsional or radial loads, which would suit the front bushing.
If I'm missing anything notable, please let me know, especially if you've tried it and had different results. Thanks to @GoatAutomotive, @DerHase , @xXDavidCXx and others for their experiences and info in their threads. I'm especially curious if anyone has tried the new superpro bushings that are subframe-specific. I'd love to find out how those were revised.
Firstly, there are two bushings in the front control arm. The forward one is the camber bushing, if it's offset, you will primarily change the camber setting. The rear one is the caster bushing, and an offset will thus change caster.
Secondly, there are about 3 types of bushings on the market, with some variations and at least one hybrid option. Rubber (OEM), polyurethane, and pillow ball (aka spherical bearing, solid bushing, ball joint, et.). Rubber is generally the most compliant and comfortable, urethane somewhere in the middle, and solid joints are generally harsher (particularly as they wear out). In general, urethane is cheaper to manufacture than rubber, and more resistant to breakdown from chemical exposure, but also more prone to deforming from high temperatures and elongating.
Lastly, there are both full replacement steel and aluminum arms on the market.
Rear bushing (big / caster)
This is the one that has caused me the most pain. The first set I tried were solid polyurethane bushings and they failed extremely quickly (a few hundred miles). I had a set of polyurethane bushings from another brand sent as warranty replacements, but due to a long backorder, I opted to order a set of stiff poly bushings from another brand, this time with the caster offset. These too, developed signs of failure within a few thousand miles. My assumption is that the axial tension is just not a good fit for polyurethane materials, though it is important to note that I'm using an aluminum subframe which may have been coming into contact with one of the bushings. Given that superpro seems to now be selling different bushings specific to each subframe, I suspect that may be part of my issue. FWIW I've talked with numerous people who've had bushings in that spot fail.
Folks doing heavy track miles, like regulars at the 'Ring, have noted needing to replace their rear bushing very often, much more than any others on the car.
I'd also note that while using very stiff poly bushings, it is much more difficult to push the arm down in order to facilitate servicing the front suspension, either changing the ball joint, knuckle, or strut.
Rubber:
OEM Mk7 - rubber, large voids, very pliable - 5Q0407183L
OEM 8V A3/S3/RS3/Mk8 R - rubber, small voids, less pliable - 81A407183
OEM 8Y S3/RS3 / 8S TT/TTS/TTRS - rubber, minimal/no voids, even less pliable - 8S0407183B
BFI "RS3" bushings - these appear to be non-OE replicas of the 8S0407183B p/n: 81A407183G
Hardrace "hardened" rubber (looks similar to BFI): 7824
Polyurethane:
Superpro stock geometry, steel subframe: SPF4176K
Superpro stock geometry, aluminum subframe: SPF5592K
Superpro caster offset, steel subframe: SPF4178K
Superpro caster offset, aluminum subframe: SPF5594K
Whiteline caster offset: KCA499
Powerflex offset bushing: PFF85-802 (purple or black) This has an offset bore similar to the others, you can add (or remove) caster at install.
Powerflex adjustable race bushing: PFF85-802GBLK. This is the first "hybrid" style, where it utilizes a ball joint inside a urethane bushing, with a flange to assist in adjustment while it's on the car. I have read positive reports about this style in hard usage, they seem to hold up better than a straight poly option.
Solid:
JXB: PTFE-lined aurora or FK bearings. These do not offer any sealing and probably wouldn't be a great idea for a street car due to maintenance/rebuilds. I've heard nothing but great things from a performance standpoint, however. Given they're a standard FK/Aurora bearing you can likely find replacements from your preferred bearing vendor.
Hardrace: Q0077. These appear to be a sealed ball joint, which should have more longevity, though I haven't seen anyone use them.
ECS Monoball: 008083LA01. They claim to use a sealed OEM Mercedes ball joint, but it's ECS so YMMV. I think these are interesting given the claimed OEM quality, combined with the articulation of a ball joint.
Front bushing (small / camber)
These have been fairly painless for me, both the solid poly as well as original rubber.
Rubber:
OEM: 5Q0407182 - This part is shared across the mk7, 8v, 8s, and 8y audis. If someone sells an "RS3" version of this, well, you already have one.
Hardrace: 8943. This looks like it has similar geometry, allegedly harder rubber.
Polyurethane:
Superpro stock geometry: SPF4175K
Superpro adjustable camber: SPF5552K
Whiteline adjustable camber: KCA539
Powerflex stock geometry: PFF85-501
Powerflex adjustable camber: PFF85-501G While adjustable, it doesn't seem very practical to adjust them while installed on the car, especially with DSG models.
Solid:
JXB (sold as part of a kit with their caster bushings)
Hardrace: Q0076
Full arms
There are 3-4 styles of these. OEM or OEM-replica stamped steel arms with pre-pressed bushings, aftermarket, one-piece aluminum arms, and fully adjustable tubular arms.
If you're in the market for a verkline arm, I assume you know whether you need modified kinematics and you own a $2,000 subframe so you must know what you're doing. Similarly, if you're buying ECS
Superpro steel arms: TRC1070. Appear to be stock geometry, with simple poly replacements.
Whiteline steel arms: WA302. Same thing, just black bushings. It's unclear if whiteline sells these bushings separately, they don't list stock geometry bushings and when I warrantied mine, they sent me superpro parts.
Superpro aluminum arms: ALOY0018K. A bit of extra caster and camber, with hybrid ball-in-socket urethane ball joints. In theory these are an improvement all around. The set I ordered arrived with a damaged bushing and the ball joint holes were machined incorrectly. Superpro used to sell one or two other arms, which had clearance problems on some subframes, and were thus discontinued.
Whiteline aluminum arms: KTA252 / KTA 262. First part is +2deg caster, second is +2.5deg caster.
Hardrace aluminum arms: Q0804 / Q0822. Rubber/pillow ball, respectively. I'm interested in these, they look like they might be a relatively durable/lightweight option, but without the geometry changes in the arm itself.
034 RCO arms: 034-401-1068. These appear to offer more camber than the others, with a rubber bushings. If 034 rubber bushings and mounts weren't generally trash, this would look like a great option.
It's worth noting that all of the OE steel arms have the same dimensions. Only difference from what I've found is the bushings themselves.
TL;DR
Personally, I wouldn't touch poly caster bushings again. The newer audi bushings I'm using have plenty of feedback, are obviously durable, and are pliable enough to make strut replacements bearable. I would use a good set of strut mounts/plates to add caster if needed. No one sells rubber offset bushings afaik.
The cookie-cutter option, at least for STH/STU autocross guys, is the "RS3" rear bushing combined with the powerflex offset camber bushing. My experience with having poly bushings on nearly every joint is that they hold up pretty well to torsional or radial loads, which would suit the front bushing.
If I'm missing anything notable, please let me know, especially if you've tried it and had different results. Thanks to @GoatAutomotive, @DerHase , @xXDavidCXx and others for their experiences and info in their threads. I'm especially curious if anyone has tried the new superpro bushings that are subframe-specific. I'd love to find out how those were revised.
