944 Control arms

[Fast Guys]

So we are working on our 944 control arm designs and we have an idea, but wanted some feedback. Instead of pressing the ball joints in and effectively wearing the arm out every time you change one, we are considering using the bolt-on ball joint from the early steel arms. Not only will it be easier to change, but it will also offer bump-steer adjustment depending on where the ball joint is installed in the arm (different slots, per say).
Do you guys have any apprehension when it comes to the bolt on joint?

[harrisracing]

I'd like to see how they attach the the older control arms. Bump steer adjustment is a very sweet setup. If done by shims, blocks, etc between the ball joint.

Although I don't have a 944, offering bumpsteer correction at this location seems like a very innovative idea.

Patrick

[Fast Guys]

It is a bolt-on ball joint: a tab with three bolt holes that would be held in the bracket in double shear.

[Fast Guys]

This is it.

[turbot]

They worked good enough on steel arms so if the strength of the aluminum is at least equal to that, I don't see a problem with bolting.

If they could be shimmed to fix the problem of the inside bottom corner of the strut housing hitting the a-arm instead of the ball joint rebuild kits with the longer "geometry correcting" pin......that would be a plus.

Andy.....because of the bind....and probably the material construction, the aluminum arms are never supposed to be angled any more than perfectly horizontal during alignment and lowering if that helps any.

T

[Fast Guys]

I love it when you talk engineering talk.

Thanks for the opinion. Anyone else?

[lane]

I don't have a problem with the bolt in ball joint. I'm thinking thats better than the swivel joints that's on some control arms. Plus the bump steer thing would be great also.
Got any idea how much?

[Fast Guys]

May 27, 2010 7:54:25 GMT -6 lane said:

I don't have a problem with the bolt in ball joint. I'm thinking thats better than the swivel joints that's on some control arms. Plus the bump steer thing would be great also.
Got any idea how much?

I don't want to quote anything yet, but they will be on the near side of comparable prices. We will be prototyping them soon and testing them on track.

[Fast Guys]

I just realized that I was saying bump-steer when I really meant Roll Center Adjustments. If we could adjust bump-steer through the control arms, we'd REALLY be on to something.

My mistake, but we are also designing a Bump-Steer adjustment kit.

[Fast Guys]

Hey guys, this is russ. Just wanted to chime in.

Here is a rendering of the preliminary design. This is just to provide a basic idea of where we are currently heading with things. I have yet to optimize the design using FEA software, etc.

Basic rundown of features:
-Primary structure is hard anodized 6061-T6 Aluminum
-Uses one spherical bearing and one rod end on the inboard side
-Uses one studded spherical bearing on outboard side
-all bearings will have grease fittings
-ball joint pins will be available in 17mm and 19mm diameters and in multiple lengths for proper roll center adjustment
-all bearings will have rubber boots and seals to keep out contaminants
-ball joint pin will likely be made from 17-4ph stainless in h900 condition
-rod end can be threaded in and out for caster adjustment

I'll try to update this thread as the project develops.

~russ

Attachments:

[Fast Guys]

Alright, it's past my bed time. Enjoy the pictures.

Attachments:

[turbot]

Russ, Andy, ditch the rear rod end and just match the dimensions of the factory piece.

There are already spherical pillar block type bearings available from a number of sources for the rear which reuse the factory rear eccentric for caster.

What would this rod end attach to anyway....?

Y'all are on the right track and the rendering is a beautiful piece.

Don't botch it up with a cheesy rod end.

All people want is a billet replacement of the stock cast piece with replaceable ball joint at a reasonable price.

To use this, you're asking racers to ditch a $2-300 set of spherical rear caster blocks that, chances are, they already have, to change over to this adjustable rear eye joint.

I'd mimic the factory dimension of the front cross member mount to accept the already available sphericals for that position too and just offer the piece sans F/R sphericals.

This would make the entry price more attractive because your target customer has already invested in the parts that could just transfer onto your piece.

There are already several versions of a 944 arm with rod ends and heim joints, tubular steel, etc., etc., etc.

People still wait in line for Charley Arms because they are billet quality replacements that resemble the factory part.

Like I said from the get-go; make a billet replica of the factory arm and you'll have something unique that people will buy.

Y'all can cite studies of strength and sheer all day long, what will put people off these is the rear eye bolt setup.....trust me.

T

[lane]

I assume castor can be adjusted by screwing the rod end in or out on the a-arm? What kind of mount do you see for the rear of the a-arm, stock or custom?

[Fast Guys]

Lane, do you have a preference?

[Fast Guys]

Jun 2, 2010 4:40:02 GMT -6 turbot said:

Russ, Andy, ditch the rear rod end and just match the dimensions of the factory piece.

There are already spherical pillar block type bearings available from a number of sources for the rear which reuse the factory rear eccentric for caster.

What would this rod end attach to anyway....?

Y'all are on the right track and the rendering is a beautiful piece.

Don't botch it up with a cheesy rod end.

All people want is a billet replacement of the stock cast piece with replaceable ball joint at a reasonable price.

To use this, you're asking racers to ditch a $2-300 set of spherical rear caster blocks that, chances are, they already have, to change over to this adjustable rear eye joint.

I'd mimic the factory dimension of the front cross member mount to accept the already available sphericals for that position too and just offer the piece sans F/R sphericals.

This would make the entry price more attractive because your target customer has already invested in the parts that could just transfer onto your piece.

There are already several versions of a 944 arm with rod ends and heim joints, tubular steel, etc., etc., etc.

People still wait in line for Charley Arms because they are billet quality replacements that resemble the factory part.

Like I said from the get-go; make a billet replica of the factory arm and you'll have something unique that people will buy.

Y'all can cite studies of strength and sheer all day long, what will put people off these is the rear eye bolt setup.....trust me.

T

Terry, that's an interesting angle. Your argument against the adjustable rod end is fair. I'm not opposed to removing it, but the front inboard spherical joint likely isn't getting replaced for a factory (sized) piece. That requires a material thickness on the a-arm that would drive the price up quite a bit (bye bye $800/set MSRP). Plus, us installing a spherical joint there doesn't hurt our cost appreciably. Alternatively, we could opt for a 2-piece design to accommodate a smaller portion of thick stock for the inboard factory bushing, but I'm not keen on having the a-arm bolt together from 2 pieces.

We will be able to supply the a-arms with delrin inserts instead of the inboard spherical bearings as well, in case people want a little more damping.

In all fairness, you can also look at this from another angle...you've spent $300+ on your inboard spherical bearings for your stock LCA's, you're buying new LCA's one way or another, FastGuys LCA's are very affordable, much nicer than the competition, and already have built in spherical bearings, etc. So you say, "hey, I can get these new LCA's and sell off some of my upgraded spherical bushings!" I certainly wouldn't mind that situation over buying the LCA's AND needing to use the expensive bushings I had purchased.

Jun 2, 2010 7:05:58 GMT -6 lane said:

I assume castor can be adjusted by screwing the rod end in or out on the a-arm? What kind of mount do you see for the rear of the a-arm, stock or custom?

Yes, that's accurate. The a-arms would be included with a pretty simple, robust steel bracket that replaces the OEM caster block.


~russ