Solid FCABs for offset cars, for real.

[O-cha]

I have gone to do this once before but didn't have the resources at the time. Now it's pretty easy for me to do and I have been planning on making some for a while. I have several different designs all with different pros and cons as well as ultimate prices.

Press in aluminum bushing with nylon insert ~$100
Press in aluminum bushing with spherical bearing ~$200 (high grade bearings are ~$50 each x2)
New housing with nylon insert ~$200
New housing with spherical bearings ~$300

The press in aluminum bushing would press into the factory housing. I don't like this so much since I think the arm should be centered in the housing if it can be (CNCing new housing would allow this) but it's the most economical solution. The nylon allows the arm to still rotate (which is necessary) but it's not the beefiest material for the job and a spherical bearing is much better built and suited, but that is obviously reflected in the price.

CNCing a new housing all together would allow for the arm to be centered which is better as you don't have any load trying to rotate the bushing in the housing. (it would still be in the "offset" location, just centered in the new housing) This is a better design, but again, reflected in the price and not entirely necessary.



I would like to see if people would be interested in group buying these without seeing them on a car first, wanting to see them on my car first would increase costs by about $50 each. A run of at least 10 would be necessary.

If there is a consensus on what kind of bushing would be preferred I can go into more detail and show renderings.

[tikamak]

I am interested in such a development, however before voting, i would like to understand something.

When you say nylon insert, do you mean a urethane bushing?
What is the life of a spherical bearing that is supposed to see high stresses from being solid?

[inTgr8r]

JMO but I really don't see much demand for this when offset poly is already available.

[O-cha]

Originally Posted by tikamak

I am interested in such a development, however before voting, i would like to understand something.

When you say nylon insert, do you mean a urethane bushing?
What is the life of a spherical bearing that is supposed to see high stresses from being solid?

Nylon insert is a sleeve for the hexagonal arm to create a round surface to allow the arm to be able to rotate (which is necessary). The nylon is self lubricating oil impregnated. There's no "high stress from being solid" on the spherical bearing, that's what they are made for.

Originally Posted by inTgr8r

JMO but I really don't see much demand for this when offset poly is already available.

I saw in the other thread that you purchased those, and I am sure you will enjoy them.

However, there is a huge difference between solid and poly. That bushing is basically an OEM bushing with a longer service life. It won't provide the performance of a solid bushing.

Additionally, that design is a pressed in sleeve with no retention that is than bonded to urethane. That is a weak design and subject to failing, it probably has a low failure rate, but it should have been designed better to begin with.

[tikamak]

mmm, How would a solid FCAB behave on the street. let's say a bumpy street with uneven and broken pavement?

Would it upset the car?

i currently upgraded the coils of the KW V3 to the clubsport coils and i think a solid FCAB would go great with the upgrade.

[O-cha]

Originally Posted by tikamak

mmm, How would a solid FCAB behave on the street. let's say a bumpy street with uneven and broken pavement?

Would it upset the car?

i currently upgraded the coils of the KW V3 to the clubsport coils and i think a solid FCAB would go great with the upgrade.

It will not "upset" the car, it makes it more responsive. There can be an increase in harshness though if that's what you mean.

[Gallardo Rosso]

I built a set of solid aluminum bushings with spherical bearings about 12 years ago for my 2002 GTI. The bushing wasn't offset... I actually cut and rewelded the steel a-arm to move the outer lower ball joint out a half inch (making front track 1" wider and stiffer in roll) and a half inch forward (about 4 degrees more camber from the as built 0 degrees). Moving the outer ball joint would have a similar effect as the offset bearing.

The effect on the GTI was significant. But that was a much more compliant (soft/quiet) car. If you watch a MkIV GTI go thru a corner at race speed you can actually see the laden front wheel move fore and aft 4-5 inches total and moving sharply rearward during breaking. Basically when the wheel moves that much your suspension settings go out the window because your caster is varying by probably 10 degrees if not more. Obviously, the M is a much more rigid car to begin with and not as effected but I'm sharing my experience.

Since I dramatically changed the front geometry and bushing stiffness in one step it was a hard to say which change was more effective but the steering really came alive and had much more feed back and linear feel. It was easier to load the front end in corners and total grip was improved. On a timed skid pad at an scca test and tune with DOT race tires i took lateral grip from .98 to 1.05 (also remember the 1" track width is like adding roll bar in the front).

As for noise, vibration and harshness there was very little difference on the GTI install. Vertical hits like potholes are transferred up into the shock not really laterally into the a-arm. The spherical is more likely to transfer vibrations from coarse roads creating "road noise" in the cabin but the effect on the more isolated and insulated GTI was minimal.

With this said, I'll admit to only having a stock suspended M Coupe for a month and haven't experimented with it yet.

http://www.flickr.com/photos/noassmb...ed/8619177288/

[Z4-VILLA]

Im in

[beta]

I'm somewhat interested, but it's really hard to tell what to expect. I tried searching on the M3 forums for similar solutions, and people report either no increase in NVH, or horrible noise (for the same products even).

For the spherical bearings in a new housing, would there be an expected increase in noise? How often would these have to be replaced compared to OEM? Do they require any kind of servicing? Will dirt or other contaminants negatively affect more than stock?

[tikamak]

I'm also in. voted.

EDIT: i voted for New housing with spherical bearing. i think that this solution would be the best, especially that the steering in our cars can be worked on quite a bit. with the spherical bearing, i expect to see a steering feel similar to E92 M3 GTS feel.

[O-cha]

Originally Posted by beta

I'm somewhat interested, but it's really hard to tell what to expect. I tried searching on the M3 forums for similar solutions, and people report either no increase in NVH, or horrible noise (for the same products even).

For the spherical bearings in a new housing, would there be an expected increase in noise? How often would these have to be replaced compared to OEM? Do they require any kind of servicing? Will dirt or other contaminants negatively affect more than stock?

E46 or e36? The e36 solid one's a lot of people used were just delrin and were really hit or miss. Some people got no noise, some people had very loud popping noises when the arm rotated. That was a problem with that design as it was simply metal rotating in delrin.

There is an increase in NVH with any solid design, the problem is what a lot of people consider to be "horrible" is very different. I personally think it's barely noticeable, but I regularly increase the NVH in my cars in trade for performance.

As the OEM is a rubber bushing, dirt and contaminant will impact ANY other design more. The spherical bearings would be serviceable and replaceable. They would not require servicing unless they went bad.

Originally Posted by tikamak

I'm also in. voted.

EDIT: i voted for New housing with spherical bearing. i think that this solution would be the best, especially that the steering in our cars can be worked on quite a bit. with the spherical bearing, i expect to see a steering feel similar to E92 M3 GTS feel.

I agree it would be best, and it would probably be what I would make for myself if I was just making one, but it is a very expensive option and I'm not sure if there would be enough people interested at that price to come anywhere near recovering costs on it. I'm going to make one version one way or the other for myself, I am just trying to see what would sell the best to mitigate costs.

[beta]

Originally Posted by O-cha

I personally think it's barely noticeable

If it's barely noticeable I'm in. Worst case I'll sell it back on here to someone else if I hate it. Voted for housing + spherical. Only the best for my Z

[Finnegan]

Originally Posted by beta

If it's barely noticeable I'm in. Worst case I'll sell it back on here to someone else if I hate it. Voted for housing + spherical. Only the best for my Z

+1, voted same.

[tikamak]

Originally Posted by O-cha

E46 or e36? The e36 solid one's a lot of people used were just delrin and were really hit or miss. Some people got no noise, some people had very loud popping noises when the arm rotated. That was a problem with that design as it was simply metal rotating in delrin.

There is an increase in NVH with any solid design, the problem is what a lot of people consider to be "horrible" is very different. I personally think it's barely noticeable, but I regularly increase the NVH in my cars in trade for performance.

As the OEM is a rubber bushing, dirt and contaminant will impact ANY other design more. The spherical bearings would be serviceable and replaceable. They would not require servicing unless they went bad.



I agree it would be best, and it would probably be what I would make for myself if I was just making one, but it is a very expensive option and I'm not sure if there would be enough people interested at that price to come anywhere near recovering costs on it. I'm going to make one version one way or the other for myself, I am just trying to see what would sell the best to mitigate costs.

While designing the new housing with spherical bearing, you can simply design a thing rubber lining that would protect the bearing from dust and this will practically make the design maintenance free

[O-cha]

Alright, so I CADed the designs out using the actual dimensions and unfortunately one of my fears came true. There is simply no way to fit a spherical bearing into the design. There is not enough clearance between the control arm and the frame.

Even if I had the inner race of the bearing machined to function as the race and sleeve as one (HUGE money) and machined an entire new housing, it would still be about 1/4" too large.

I believe I am just going to proceed with the simplest design being the pressed in aluminum spacer with nylon sleeve.

[O-cha]

I need some more input guys. Current issue I am fighting with is the press fit of the bushing. The clearances to press fit metal are very tight, if I machine the bushing to the proper press of around 66mm +3 thousandths, some people might not be able to press it in. The housing gets galled up some when removing the stock bushing.

The solution that will work universally is not doing a full press fit, and using loctite retention compound. It's an adhesive made specifically for this purpose. It will fill a few thousandths of clearance and hold very strongly, stronger than a press fit even would have. It will also eliminate any worry of the bushing rotating in the housing.