Had a chat with my CNC-buddy. He had a look at the images and asked if the collars was made in titanium when he heard the price

We will look into producing a prototype set in highgrade aluminium for a third of the price , will there be any interrest in this?

 

I'm sure the would be... Would you be able to somehow test them (like in the video in the 1st post...?)

 

I wont have any way of testing em like Spoon have, but as long as the design is fairly identical, the outcome should be pretty much the same?

The "point" in theese collars, is to eliminate the space between the subframe hole edge and the bolt, and by this eliminate the possibility of subframe movement. the built in "washer" is like a copper-ring between for ex. oilpan and oiltap-bolt.

 

Getting the subframe properly aligned has been on my todo list for some time now.

Subframe Movement and Camber

Definitely interested.

 

What kind of aluminum should be used? I'm going to make a set real quick and see if it does anything.

 

Are they re-usable? Since there forming to fit, does that mean if you ever take the subframe off again that you would need another set?

 

What kind of aluminum should be used? I'm going to make a set real quick and see if it does anything

Probably want an aluminum alloy such as 1100 or 3003 that is easy to anneal once machined.

You want these annealed "dead soft" so that they can function as shown in the video.

Are they re-usable? Since there forming to fit, does that mean if you ever take the subframe off again that you would need another set?

I imagine it would be like re-using fiber style gaskets. You can with proper preparation and if you are really careful on installation and removal.

In this case, perhaps apply liberal anti-seize when assembling and when removing be very careful to bring the subframe straight down off of any studs.

 

I don't see it. It is really just a bandaid for a poorly designed joint.

The proper way to design a bolted connection in shear is to use the friction of the mating surfaces to create the strength of the joint, not the shear strength of the bolt. Basically this means that unless the connection is improperly designed in the first place, sleeving the connection is defeating the whole purpose.

The shear strength of bolt+sleeve will likely still be less than the frictional force required to move the clamped connection. Additionally, this means that you are much more likely to reach the failure point of the bolt/sleeve because a much higher percentage of the resisting force is being transferred into the bolt.

One other thing is that as mentioned by others, fabricated sheet metal unibodies are not that precise, which means that by forcing the holes to be concentric, you are likely preloading the joint to some degree.

 

Patman are you saying that it might be a better idea to just machine the surfaces of the subframe and unibody so they clamp together flatly?

 

Before I did that, I would mark the subframe and either do a trackday or at least toss the car around hard in a parking lot, and see if it moves. I have my doubts as to whether this is an issue for the FD at all.

Assuming that it is found to move though, yes, you could do that, or you could increase the torque on the bolt. Or, what I would do, is drive the car and let the subframe get seated where it wants to be, then weld a pin or some keystock around the edges of the mounting location to remove the possibility of movement. That way you are not overstressing the bolt, nor are you forcing the subframe into a position it may not fit, but you are still constraining it fully.

 

Thank you, someone who really understands bolted connections. The bolt simply acts as a clamping force, as Pat mentioned the strength of the joint comes from the static friction of the two surfaces. There is effectively two ways to strengthen a bolted connection. Increase the surface area in contact, which these collars attempt or increase the clamping force (ie increase the torque on the bolt.) If a bolted connection separates it has effectively failed. Engineers will use a factor of safety against joint separation in the design, I don't know what Mazda used I typically use between 2 and 5 depending on the application. So that means you would need to at least double the forces the engineers envisioned to create joint separation. Assuming the bolts are properly torqued and the bolts aren't fatigued I doubt joint separation is much of an issue in the FD.

 

Interesting concept... I just can't see spending 300+ on these parts that might cost $10 to make in mass production.. And I'm sure bolt holes are interchangeable with other cars..

 

reviving an old thread, but I put these (rears) on my rx-8 and noticed an immediate difference. The rear end felt tighter without feeling any harsher. Kind of like going to Ohlins from OEM suspension. With those the car is stiffer, but somehow also more comfortable.

I would definitely give them a shot on an rx-8 if you're into suspension improvements. I've been told they're unnecessary on an FD because the suspension components are directly mounted and don't shift, but haven't looked deeper into it than that.

Good (promo) video on how these work: