My custom rear suspension redesign

[clarkspeed]

Here are a few pics of my redesign of the pick up points on the rear control arms.  I thought about this for such a long time before going this direction.  This car I am building is going to be dropped a large amount and I really wanted to bring the roll centers back up and also make them adjustable if possible  My design goals were to use the modified control arms I built a few years ago and avoid adding any additional weight.  Less weight even better.  Of course one possibility would be to add a tube to the bottom of the rear upright, but I didn't like adding unsprung weight and no way to make that adjustable. I just didn't like the Arizona Z solution either because that would require a different control arm and more rod ends.  Rather than modifying the control arm I decided to keep the 1" diameter shaft and designed my own bearings and bearing holders.  The bearing material is Delrin (acetal) that I 3d printed but you could also machine a set of these very easily using bar stock.  The bearing holders are 1-1/2" square tubing with a welded flange.  This required chopping up the existing bearing holders and adding some more support.  This mod raises the inner pivot point up roughly 0.8".   I can be brought back down using shims under the bearing holders.  In the highest position, the control arm interferes with the floor panels behind the rear seats.  So I cut a little bit of that out also.  Along with the bearing holders I designed by own forward cross member that holds the bearing plates down and also hard mounts to the differential. 

[AydinZ71]

Looks great! Delrin is pretty hard stuff, but it also surface hardens when friction is applied. We used it as an alternative to brass bushings when temperature was near ambient. If I understand your summary, you essentially raised your control arms in order to add more underbody clearance and lower the car further. How much more lowering capacity do you have on your coilovers? How are you routing your exhaust? Up and over the control arms? 

[JMortensen]

So you're not using the big ass bolts on the ends of the arms? I recall Jeromio and maybe one or two others had the experience of the bolts coming out and the arm slid back far enough to fall out of the bushing and disconnect itself from the car. I see you've made a cradle to capture both bushings. Lots of force there, just hope it's strong enough.

[clarkspeed]

No big ass bolts. I always wanted to center drill those things to lighten anyway. Yes the cradle is there to prevent fore and aft movement. It's kind of light, I could beef that up a little. 

 

Oh this car will be plenty low. I notched the cross bar above the diff to raise it up higher. The exhaust loops over the tranny, down the tunnel on passenger side, then cuts across for a side exit in the rocker panel below the passenger door handle. I'm starting to gather my photos to start a build thread when I realized I didnt have any of the rear suspension work.

[Mike Mileski]

Here's a picture of my current rear arms. The inner portion pivots on rod ends and both outer ends that attach to the upright are adjustable. I am currently designing another set that has the short outer adjustable arm towards the front of the car instead of at the rear. Absolutely no issues with these though.

 

Mike Mileski

Tucson, AZ

[clarkspeed]

Those look nice. I looked at something very similar with the brackets flipped to raise the pivot points. What size are those inner rod ends?

[AydinZ71]

On 3/8/2021 at 3:25 PM, clarkspeed said:

No big ass bolts. I always wanted to center drill those things to lighten anyway. Yes the cradle is there to prevent fore and aft movement. It's kind of light, I could beef that up a little. 

 

Oh this car will be plenty low. I notched the cross bar above the diff to raise it up higher. The exhaust loops over the tranny, down the tunnel on passenger side, then cuts across for a side exit in the rocker panel below the passenger door handle. I'm starting to gather my photos to start a build thread when I realized I didnt have any of the rear suspension work.

Sorry to distract from your main post topic, but what strategies are you employing to manage exhaust heat coming through your console/tunnel? Before I tore down this car, I had terrible issues getting engine/exhaust heat into the cabin. I have looked at so many different materials/strategies but I’m struggling with which one to move forward with. Latest thought is an aluminum heat shield offset from the underbody by 1/4” and urethane spacers.

 

I am running my fuel and brake lines down my tunnel now, and wold hate to forget some bracketing/attachment points before I reapply undercoating. 

[Mike Mileski]

The inner rod ends are 3/4" bore, 3/4" shank.

 

Mike Mileski

Tucson, AZ

[clarkspeed]

20 hours ago, AydinZ71 said:

Sorry to distract from your main post topic, but what strategies are you employing to manage exhaust heat coming through your console/tunnel? Before I tore down this car, I had terrible issues getting engine/exhaust heat into the cabin. I have looked at so many different materials/strategies but I’m struggling with which one to move forward with. Latest thought is an aluminum heat shield offset from the underbody by 1/4” and urethane spacers.

 

I am running my fuel and brake lines down my tunnel now, and wold hate to forget some bracketing/attachment points before I reapply undercoating. 

Good question. Especially since my tunnel is 40 thow aluminum sheet. Years ago I bought some insulation off Ebay that was aluminum on 1 side and roughly 1/4 thick adhesive foam on the other. I used it in 2 cars and it worked well, was cheap, and stuck permanently. Even let pipes ride on it.  Now I am trying to find more of it. The DEI stuff works well but is expensive and there are others. I intend to handle the heat with panel insulation, but will add pipe insulation if I need more.

 

The ex ITS car I race now had the entire driver area covered in some kind of insulation mat before I bought it. It was too hard to take out so I just painted over the shiny silver surface.  The paint has held up well. I suppose the car is cooler, but I cant tell in Florida.

[AydinZ71]

1 hour ago, clarkspeed said:

Good question. Especially since my tunnel is 40 thow aluminum sheet. Years ago I bought some insulation off Ebay that was aluminum on 1 side and roughly 1/4 thick adhesive foam on the other. I used it in 2 cars and it worked well, was cheap, and stuck permanently. Even let pipes ride on it.  Now I am trying to find more of it. The DEI stuff works well but is expensive and there are others. I intend to handle the heat with panel insulation, but will add pipe insulation if I need more.

 

The ex ITS car I race now had the entire driver area covered in some kind of insulation mat before I bought it. It was too hard to take out so I just painted over the shiny silver surface.  The paint has held up well. I suppose the car is cooler, but I cant tell in Florida.

 

thanks! Yeah I’m also looking for a stick-on solution I can add tot he underbody. There is just so much Crap on the market, it’s hard to tell what is quality and will last. No one wants to revisit the underbody more than once without a lift. If you find a source, please let me know! 

[clarkspeed]

The only place I have ever had issues with heat is in the gas pedal area. In think I burned some shoes one time. I just add roughly a 10 x 24 strip starting where the tunnel narrows down.  Usually does the trick. I have burned my hands on the shifter before, but since I always have gloves on I never worried about it.