I need some ideas to solve a problem. In T1 racing we are now allowed delrin OR poly bushings. Poly is available from many people. No one makes delrin. I don't want to get into a poly vs. delrin issue.

No one makes delrin bushings so I started cutting my own delrin bushings. It's not hard just time consuming on a manual lathe.

Two problems are the caster with the front upper control arm dogbones and the rear lower control arms bushings angles with camber. Both these areas rely on the compliance of the bending rubber bushings to achieve static rear camber and front caster. I thought the rear camber would be more of a problem and it is because delrin does not yield. Delrin is more like aluminum and poly is more like rubber.


There is no way install the rear lower control arm with delrin bushings because the delrin does not yield and therefore when you try and tighten it down you get severe binding. The design of how you set rear camber causes this problem. Rubber bends and delrin does not. Does anyone have ideas to solve this? I hate to use Delrin for the rear LCA camber plate area and then Poly which bends in the rear of the rear LCA. What do you think? I wonder if we are going to have to poly the rear LCA and the front upper control arms but poly always binds unless you constantly lube the heck out of it. Opinions?

 

Couldn't you shorten the length of the bushings and make shim washers once you know where it needs to be for the alignment, use shims to fill in the under length amount?

 

no that won't work. Maybe something along the lines of drilling the bushing hole 3* off axis might work. My guess is 3 degrees but my lathe only cuts at perfect 90* so I need the right tools.

 

I agree. I don't think it needs super precision, even some resistance to move really wouldn't be an issue. Resistance = damping.

What would be great is to have some type of pliable material that could be used to setup the arms and alignment before setting up hard. Remove the arms and then use these setup pieces to find the angles and shapes to machine your Delrin parts.

I'm really not that familiar with Delrin. What properties makes it desirable? I know the OEM are selected for their durometer and damping properties. I also know that once the durometer is too stiff there comes a point that unless the LCA attach points are stiffened there is no benefit from stiffer bushings. This means modifying the rear cradle as well.

I hope your experiment goes well. Even with the frustration that go with modifications like yours the end results can be fun.

 

Try shaving off some of the Delrin length so that it isn't such a tight fit, this makes the center aluminum bushing the load path when the assembly is bolted together. It also wouldn't hurt to taper the ends of the Delrin slightly leaving the center flat near the aluminum bushing end. The underwater grease that companies such as Pfadt include in their poly kits lasts the longest. I made some Delring bushings for a street car a long time ago, the ride was very harsh and they started squeeking when the chassis grease gave up.

 

Phoenix makes them.
I used them for the past year and did not experience the issues that you are describing.
I use no grease as they are quiet (Delrin is self-lubing).