95ONE

Agreed. I don't see any need for head studs.

Yes, you are correct, I have already added in a little anti dive where it sits. I have also placed that in my "best guess" spot to try to fix whatever I could. And caster is still adjustable, but not a whole helluva lot as Tony stated. I will fix if I need to later. The point for both of you is, I cannot / will not move the wheel further forward to do it. - using any further movement of this adjustment is not the best way. So leaving this limited travel with eccentric does not present a problem. I will certainly go after the strut mounts up top at this point to change it.

95ONE

All very close. Lets just say best educated guesses were calculated in based on old set up. Still, as Tony states, weight might be close to the same as the old set up, but now it's all in different areas of the car. That might change things.

After reading, I think that both Robsta and Tony are saying the same thing. It's almost just a semantic argument from what I read. Raising the A arm does both fix my poor geometry from being lowered, and helps the roll center at the same time.

The relocation of that mounting point did 3 things.

1.) Let me use my Spherical bearings.
2.) Corrected my Suspension Geometry / roll center from being lowered so damn much
3.) made room for my Collectors.

Priority in that order.

I had the bolt plates out of there, in my hands. It is a stamped "L" shaped plate that is thick. Folded up round the perimeter for strength. It does certainly have weld in "nuts" but they are square in shape. Mine were welded quite well, but differences in production can account for broken ones.

Amen to that statement. It took me a VERY long time to stare at that and design, and calculate and make compromises to get to that final arrangement. I started to miss life after work.

95ONE

duplicate post. won't let me delete? weird.

333pg333

Yeah there's no more delete post option for some reason?

So Bruce, why don't you want to move your wheel further forward to gain caster?
When you say you've improved the roll center what are you basing that on? In other words were you trying to raise or lower it, and why?

xschop

The drunk Germans spot welded only one spot on the failed inner nut. I used a 3" cut-off disc to peel back the top portion of the chassis sheetmetal, completely welded new nuts in at the 68mm C2C and then rewelded the chassis sheetmetal with an overlap.

95ONE

Good morning Patrick! You are up very early!

The front wheel is about as far forward as the wheel wells will allow. That's truly the main reason. That and just crazy adjustments that would have to be made to match everything else back in line.

As for the roll center. It's to raise it back up from underneath the ground! I will be doing the same for the rear and trying to balance the two.

JET951

Hi Bruce,
Thats some neat mods you have done there. What are your ideas about raising the height of the rear suspension to match the front? Are you thinking of cutting more into the body and raising the whole thing? any foreseen problems there?

I take it the body of the car is going to be quite low(hence you wanting to raise the roll Centre) what are you going to use as camber plates on the front? and what shocks are you thinking of. The reason i ask is that because it seems your car will be quite low you will be running out of shock on the front so you may need to look into some custom shock setup there to get enough travel back into the suspension.

I believe Tony is right with the front geometry correction is much much more important then correcting the Roll Centre. Basically with a low Roll Centre you are going to have more force present on the body(more roll). This is because your Centre of Gravity is going to be further away from the Roll Centre then what it normally is. Hence you will have more leverage on the body. This really isnt a problem as you can make up for that roll with stiffer springs and or sways. Going the other way(raising the Roll centre too much) could have a more dramatic effect on your suspension. If your Roll Centre gets too close to your Centre of Gravity you may start to get a jacking effect. Then we need to take into account that Roll will obtain more grip(to a point). Its basically a compromise to get the fastest setup

Sean

ausgeflippt951

Guys...you're all saying the same thing.

Changing the angle of the control arm (by moving the mounting point vertically) is, by definition, changing the roll center. Now, if you were also changing the ball joint location on the spindle WHILE changing the mounting point at the frame, then you would be doing more than simply changing the roll center. Unless you're specifically referring to changing the geometry w.r.t. anti-dive?

Speaking of which, how much anti-dive are you inducing? Due to the Mac Strut you should be able to get some anti-dive when lowering the car anyway. Plus you don't want to make the car twichy under bump. If you're unhappy with the amount of rear grip, dial out some low-speed rebound.



Bruce, I'm pretty sure you mentioned it earlier but you mentioned you'd also be modifying the tie rod angles as well, right? Inducing bump steer is actually the primary reason I tend to caution against modifying roll center height (for normal-ish height cars...yours doesn't apply...). If you change the control arm mounting points, definitely need to check the tie rods.

blodstrupmoen

Maybe it is possible to fit a anti-roll tank ?
brightbulb article

Interesting thread btw ..

odurandina

Q to all;

has anyone ever attempted a double wishbone setup ? seems doable if not for the $$$.

TonyG

I think.... to some degree, one cancels out the other in terms of the physical wheel location... that is... moving the wheel forward via the A arm/caster adjustment, then moving the top of the strut backwards.

I get like 8 degrees of caster by moving my strut top back, and using the factory eccentric + the range of adjustment via the slotted Racer's Edge caster blocks.

And FWIW... the big caster numbers really have a big effect on how the insides of the inside tire wear as these cars. With -3 (or more) degrees of camber these cars really drag the inside of the inside tire big time. The only solution I have found is to go big on the caster.

TonyG

ausgeflippt951

Interesting to hear, Tony. Are you running 8deg of caster?? Wooow. Are you running the GC camber plates?

Hell, the stock strut location usually limits us to <3 degrees. Lowering the car does help get a teensy bit more though.

95ONE

Sean,

Ans#1 That is exactly what I am doing. I will be building something that looks like the Kolken which raises the Rear arm mounting points. I will be raising them the exact same amount as the front. So, you nailed it. In the same action, I'm hoping to lose another 10-20lbs off the car.

Ans #2 I will probably be going with Moton adjustables. My travel with be something like Patricks. Very short. Edit: The word short is relative. Around 4-6" of total travel. Patrick's is only 3"

It is all a compromise. No doubt. My only advantage is that I know what handling traits I favor in my driving style and will be able to compromise in that general direction.


I only added a tiny bit of of anti dive. I LOVED the set up I had before. Perfect results. So I am truly just trying to keep the the same set up, but only with a disciplined tweak. Lowered car, but needed to change Arm angle to retain roll center. It's probably not actually raised, but the shorter travel / stiffer shocks will keep it in the "sweet spot" So it should "feel" like it has been raised.

I did not, however, like the way the car was braking with the old set up. With the new set up; bigger tires in the back, and the new brakes, I will try to adjust a little more bias towards the rear. I used that kind of bias to drive way back when, and I want it back. I added a small amount of anti dive to get this effect. I tried my hardest to only add a bit. I believe that will be all I need. The flip side effect of too much, which you described, is not an option. I cannot drive like that.

BUMPSTEER. Absolutely. I will have to find or make a bumpsteer kit. None of which I have found on the internet really encourage confidence. I will figure it out, but It might entail Heim joints and large bolts / spacers. Maybe reaming out the stock tie rod hole to match some better kits out there for other cars. I will get this worked out correctly. It's just a matter of getting to it at this point.

ONE problem. I am changing too many things to have a CLUE what will actually happen. I learned a long time ago to fine tune, changing only one thing at a time. I will be pulling my hair out for a long time messing with this suspension. So all this is just a best guess scenario.


I figure, if I was going to do something like this, I'll just start with a car that has one. That would be a 3rd Gen RX7 or an NSX. I just missed an NSX shell. I was ready to buy it. But it was sold. I'm pretty sure another NSX is in my future.

Im hoping the lighter car won't need as much camber, but tire temps will tell. I will adjust as the car "speaks" to me and "tells" me what she needs. But I have already added in more caster and anti dive with the mounting point of the bearings. They sit a bit further up and out than the stock caster (968) blocks. then I added a bit more with the eccentric adjustment bolt. I have the eccentric bolt aiming 45 deg out. They were pointing straight down on the set up I loved. This also adds a bit more anti dive into the mix.


With all that said, I got my aluminum torque tube "turned" .1" smaller on the end to slide easily, but within a tight tolerance. So I started welding it up. I can only weld this one flange on for now. Fit it in the car and slide the back "bell" on until it matches the mounting point of the trans. i will tack it in place and finish welding it. it will then be a complete piece at the proper length for this custom set up. I'm not happy with the consistency of my welds. It's been too long I think. But i know they are strong. I first inserted the machined tube into the machined flange for a perfect fit perpendicular and hubcentric. then I welded it. then I slipped a strengthening ring over it and welded it again. it is also welded on the inside of which I did not take a pic.

odurandina

if this is your idea of getting to the point it might be fair to state that you've accomplished this in spades.

TonyG

Yes. The GC camber plates moved all the way back. And the Racer's Edge caster blocks... which are slotted and allow you to get a lot more caster.

TonyG