Syncro Design Works RTAB

[cleanerPA]

Any interest in something like this:
https://syncrodesignworks.com/products/rtabs

They don't make this for our cars- I asked about it, but I think they would need more people to contact them to tell them that they want them.

Someone with an E46 M3 recommended these to me for my E46 M3- I had them installed and they're pretty great so far- rear end feels completely planted. Granted, my RTABs were definitely sketchy as they felt like they would randomly want to get the back end loose and it spooked the heck out of me more than once.

Sealed monoball bearings seem to be quite amazing. As they are sealed, they should not degrade like typical unsealed monoballs.

StimTech makes a monoball bearing RTAB for the E30, but it does not sound like it's sealed and requires the trailing arm to be removed from the car for installation. That makes it quite a time consuming and/or expensive job.

I'd love to get these into my shoe, but they're not made for our cars- yet.

[BimmerBreaker]

The E30 part should fit our vehicles as they use the same mounting types and trailing arms are compatible between E30 and Z3. Any RTAB bushing installation requires the trailing arm to be removed

I don't see why we would need monoballs at that location either on our specific suspension design to be honest - the E46 uses the Z-link style which started on the E36, which is a fundamentally different design

[dantheman7913]

I don't see why we would need monoballs at that location either on our specific suspension design to be honest

I recently spoke to the people over at Garagistic regarding their toe and camber kits for the rear subframe. For context, I was asking about the differences between their K0471 kit which uses serrated hardware and larger slotted brackets for additional adjustment range (and isn't explicitly recommended for us Z3 owners), vs their K0006-EH kit which uses eccentric hardware and smaller slotted brackets (and is compatible for our cars). They told me the following:

"When it comes to the K0471 vs K0006-EH, the main difference that can sometimes cause compatibility problems is that the serrated camber and toe brackets are almost double the size of the eccentric brackets, which when installed on the camber inside RTAB mount, can sometimes make contact with the trunk floor. With this being said, if you have around 2 in of room between your subframe and chassis, you should be able to run the serrated kit.

The eccentric kit can get you anywhere from 2-3 degrees change, but this really depends on the car and set up more than the brackets themselves. The serrated should be able to dial out 5+ degrees of camber, but like the eccentric, the car's suspension setup and welding of the brackets dictate how much change can be made.

This would work fine with polyurethane bushings, but if you can get some I would recommend monoball as they will allow for movement at extreme angles like what's seen with the trailing arms at max positive camber."

I'm assuming monoballs would add a ton of NVH but if you're going super low with the serrated correction kit, monoballs might be a worthwhile upgrade.

[cleanerPA]

The E30 part should fit our vehicles as they use the same mounting types and trailing arms are compatible between E30 and Z3. Any RTAB bushing installation requires the trailing arm to be removed

I don't see why we would need monoballs at that location either on our specific suspension design to be honest - the E46 uses the Z-link style which started on the E36, which is a fundamentally different design

Can you explain further? I didn't know you needed to remove the trailing arm to do the RTABs- you don't have to do that on the E46- I guess it's clear that I never have attempted to do the RTABs on the shoe.

Syncro doesn't make an E30 part.

- - - Updated - - -

I'm assuming monoballs would add a ton of NVH but if you're going super low with the serrated correction kit, monoballs might be a worthwhile upgrade.

So as I mentioned above, I have the SDW monoballs in my E46 M3 and they didn't really add any NVH at all. I don't notice the change other than the back end is really planted now. As bimmerbreaker mentioned, the rear suspension is a different design and I don't know how that impacts needing or not needing monoballs, but it was recommended to me for the E46, so I had them installed, and have been happy with them. I was very concerned about NVH as I've been driving the M3 a lot since I got it.

[dantheman7913]

Yea the Z3 has the same rear suspension as an E30. It's a pretty outdated design, the trailing arm mounts to the subframe at only two points that are along a shared axis, and the whole trailing arm pivots around that axis as you go over bumps. the bushings don't really move up or down or side to side, they just flex inside the bracket. Monoball bushings allow for 3d movement, which you wouldn't really need on this design since the bushings will normally just stay in place unless your trailing arm is at weird angles due to lowering the car or a camber/toe kit.

[dantheman7913]

And to add a lil more info, most people recommend using the regular rubber bushings for the RTABs but I installed powerflex purples for mine and it was a good upgrade, maybe a lil more NVH but the rear is definitely more stable.

[cleanerPA]

Thank you for the education, Dan.

I actually have the Powerflex purple RTABs sitting in a box in my garage for years, never installed them. Since the SDW monoballs worked so well on my E46, I thought I'd ask about how people thought of them for this application.

My RTABs are probably original, so a 21 year old rubber bushing probably needs replacement, along with the FCABs, front control arm ball joints, whatever other rubber bushings there are in the suspension.

I think I'm going to re-do all of the suspension bits, hopefully before '22 driving season.

[dantheman7913]

Yea I did the same when I first picked up my Z3, I went with powerflex purple fcab, rtab, and subframe bushings, and all the rest I went with regular rubber. I did use powerflex purple sway bar bushings for a short while but found that it added too much NVH straight to the steering wheel. Swapped it out w rubber ones and it felt so much better. I also picked up meyle hd front control arms, they swap the unremovable oem ball joint with a normal pressable one, which imo is worth it considering I plan on keeping it for awhile.

[TommyMaddox]

Any interest in something like this:
https://syncrodesignworks.com/products/rtabs

They don't make this for our cars- I asked about it, but I think they would need more people to contact them to tell them that they want them.

Someone with an E46 M3 recommended these to me for my E46 M3- I had them installed and they're pretty great so far- rear end feels completely planted. Granted, my RTABs were definitely sketchy as they felt like they would randomly want to get the back end loose and it spooked the heck out of me more than once.

Sealed monoball bearings seem to be quite amazing. As they are sealed, they should not degrade like typical unsealed monoballs.

StimTech makes a monoball bearing RTAB for the E30, but it does not sound like it's sealed and requires the trailing arm to be removed from the car for installation. That makes it quite a time consuming and/or expensive job.

I'd love to get these into my shoe, but they're not made for our cars- yet.

I believe I was US customer number 1 for the Stim.tech RTABs several years ago, and they are an absolute delight. The bearings are shielded with Spira-lock rings and are easy to replace. I went from poly to these and the difference in both performance improvement and noise reduction was substantial. When I got them, the early versions were a gunmetal gray passivated color. These work phenomenally well when you have the caster-camber adjustment kits welded in because they can tolerate and accommodate much greater axis misalignment than poly or rubber bushings which bind up.

For the front, I went with the greaseable Turner motorsport FCA spherical bearings after having front poly ones as well. Another big improvement. At this point there is no rubber in the suspension system (poly static mount bushings and sway bar bushings) and it works great surprisingly. the full and easy articulation of the components helps take up the bumps and allows the car to have better stability and hook up when pushing the limits.

[cleanerPA]

So are the StimTech bearings sealed or not?

[TommyMaddox]

So are the StimTech bearings sealed or not?

It's been over 3 years since I put them in, and received paper instructions only so my recollection is spotty. I believe the bearings are Aurora motorsport-spec PTFE lined and sealed spherical bearings. I believe one of the big challenges in design was fitment of a bearing, when a considerable amount of the trailing arm bore diameter is occupied by the bolt shaft and the RTAB body.

[lelandr]

I'm not sure that I would do something like this. First, I would guess that those are going to transmit a lot of banging into the chassis right under your seat--especially if you have hard subframe mounts. At worst, f those need greasing or any service it will be difficult. Note that the E30 and E46 RTAB layout is completely different.

I tried Urethane bushings from powerflex, AKG, and IE in that position on an E30 M3 track car, and quite frankly they were all trash.

In the end, if you HAVE to adjust the suspension in the rear (generally you don't), I would recommend one of the kits that welds to the subframe ears and just uses the factory rubber bushings.

For my E30 M3 track rat, I installed the Garagistic adjusters with a 5-series eccentric bolt and the factory rubber bushings and had everything aligned in 2016. Several thousand miles later and 40+ track days nothing has moved. This car runs high 1:42 @ Road Atlanta on Hoosiernentals which is a very respectable pace for a streetable E30 anything.

For my 2000 M Coupe, I just used the factory bushings for both the subframe and semi-trailing arms and the car aligned up beautifully and handles very nicely. Enormous improvement over worn-out stuff.

Even for my 2007 M Coupe (similar RTAB to your E46) which I'm building as a track car to replace the M3, I didn't use these bearings, even though the Z4's are reinforced enough not to have the chassis tear-out. I went with a factory bushing with the shims one either side to prevent play in the RTAB.

Using bearings instead of bushings for anything short of an all-out race car makes no sense to me. The bushings are, by design, supposed to be the weak link in the chain, even though BMW, especially in the M cars, uses solid bushings. On the street, which has potholes, bott's dots, speed bumps, bridge transitions, etc., replacement of the bushings is just going to transmit the considerable impact forces through the chassis, control arms, occupants, etc. I wonder how many used BMW owners would be really be impressed by the simple replacement of factory (OEM) bushings throughout the suspension? As I said, in developing my E30 M3 as a track car, I tried a lot of things and generally, this idea that all of these aftermarket bushings make the car handle better, IMO, don't really pan out in the real world--either on the street or on the track. Bearings, yes, but usually with other compromises.

Cliffs: On your car, the rubber is past it's useful lifespan. I would be willing to be a box of beers that simply getting new Lemförder bushings all around are going to make a shocking difference in the performance of your car. If you haven't done the shocks, I would probably address that as well.

[cleanerPA]

Fair enough, lelandr. I know I need to do the bushings on the shoe, just due to age and mileage.

I was asking because the SDW bearings work great on the E46, don't really transmit any noticeable NVH at all.

[MPowerZ32]

I'd be interested. I installed SDW RTAB on my E46 M3. https://syncrodesignworks.com/products/rtabs The rear end after the install feels more solid without any noticeable NVH. I would imagine the Z3M can receive similar benefits. The build quality is great too.

[mpire]

Yea the Z3 has the same rear suspension as an E30.

No, its the rear suspension from the E30 DTM race car.

It's a pretty outdated design

That has won more races than any other design, so it is what you make of it.

Its also used in countless other sports cars and does just fine for what we need of it.

[TommyMaddox]

I'd be interested. I installed SDW RTAB on my E46 M3. https://syncrodesignworks.com/products/rtabs The rear end after the install feels more solid without any noticeable NVH. I would imagine the Z3M can receive similar benefits. The build quality is great too.

Yeah that's my take away having bearings front and rear. I love it. It seems that most of the commentary against it is from people who don't have them actually installed.

[IndianaRoadster]

Yeah that's my take away having bearings front and rear. I love it. It seems that most of the commentary against it is from people who don't have them actually installed.

I have the Turner greaseable mono ball flca bushings and really like them. I didn't know about the rear one's when I replaced them a couple of years ago, wish I would have. Maybe down the road I'll swap out the rear one's.

[cleanerPA]

Yeah that's my take away having bearings front and rear. I love it. It seems that most of the commentary against it is from people who don't have them actually installed.

Yeah, the SDW RTAB work great. I'm very happy with mine. That's why I wanted to see how much interest there would be in getting these for the Z3 crowd.

Is it correct that the Z3 and E30 share the same RTAB dimensions? That would open it up to a lot more cars.

[TommyMaddox]

Yeah, the SDW RTAB work great. I'm very happy with mine. That's why I wanted to see how much interest there would be in getting these for the Z3 crowd.

Is it correct that the Z3 and E30 share the same RTAB dimensions? That would open it up to a lot more cars.

Yes, the stim.tech guys were primarily E30 focused, so the product was marketed more towards the E30 side.

As an engineer, I'm a big fan of bearings for pivot arms (FCAB and RTAB) or other suspension components that experience a substantial degree of rotation in use, over either rubber bushings or poly ones. I prefer softer poly for subframe and sway bar bushings to reduce unexpected shift of suspension assembly, and rubber for diff mounts, engine mounts, shock mounts or other items that need to damp high frequency constant vibration. I find using bearings with those two suspension components has improved handling dramatically, you don't need to worry about final torqueing at ride height, and they let the springs and shocks do more of the work of taking up the bumps, instead of depending on absorption and deflection through those components.