Any interest in a camber adjustable rear coilover? s30/s130

[G-E]

I designed an interesting kit for the z31 front suspension that I'm convinced would do wonders for the rear of the early datsuns...

 

I've seen how seriously involved installing rear coilovers are, cutting out the strut tower top to weld in a new camber plate; what if you didn't have to do that? What if you could adjust camber at the spindle, and what if you could maintain that camber under compression (like a hard launch)? What if this would allow you to interchange/upgrade your coilover later, say to Fortuneauto 510's, Apexi N1 Revolution, Tein SuperDrift, or other premium brands?

 

To quote Scotty: Would that be worth something to ya laddy?

 

[G-E]

I guess my question is, who wants to be the lucky bunny? Who wants to help me develop the idea?

[RebekahsZ]

How much camber could you add before the tire rubbed the strut? I guess that would depend on the offset of the wheel?

[helghast7]

I think I'm in love.

[G-E]

Yea it would depend on your wheel as a starting point, but because the strut would be offset like in the case of the s13 front, you'd get extra clearance at the top. Now if you had the adjustable lower arm pushed further out at the same time, you could have wider wheels with bigger backspacing?

 

To give you an idea, the range for the z31 setup you see there is +2 to -9 or thereabouts on factory parts, so it can compensate for some really wild setups like extended flcas, or massive camber for the inside wheel for drifting. Obviously the goal is different but the device itself can do a lot.

Edited April 3, 2014 by G-E

[wheelman]

That's an interesting design but it isn't going to prevent camber change as the suspension moves through it's arc, on the rear of an S30 or the front of a Z31.

Picture the control arm as flat (parallel to the ground) as the starting point for an up or down movement, either direction it moves the hub will move toward the center of the car which will change the angle of the strut which in turn changes the camber.  The only way to prevent camber change is to eliminate the strut as a fixed mount point for the hub, in effect create a double arm arrangement with a pivot at the top and bottom of the hub.  Then you have to arrange the geometry in the correct way to eliminate differing horizontal movement of the two pivot points. 

[helghast7]

I just like the fact that it makes coilovers bolt in lol.

[G-E]

That's an interesting design but it isn't going to prevent camber change as the suspension moves through it's arc, on the rear of an S30 or the front of a Z31.

Picture the control arm as flat (parallel to the ground) as the starting point for an up or down movement, either direction it moves the hub will move toward the center of the car which will change the angle of the strut which in turn changes the camber.  The only way to prevent camber change is to eliminate the strut as a fixed mount point for the hub, in effect create a double arm arrangement with a pivot at the top and bottom of the hub.  Then you have to arrange the geometry in the correct way to eliminate differing horizontal movement of the two pivot points. 

 

While in the strictest sense that's true, it doesn't have to, it only has to operate at a specific range of travel... AND you have to keep in mind how it acts in relation to how everything else acts...

 

When you squat the semi-trailing arm, you gain too much camber, you could negate this by having the coilover go more positive under squat conditions, thereby giving you the best grip for launching at drag racing.

 

You could also have it set to maintain a specific negative camber in hard cornering on a car that doesn't normally squat (ie. stiff); if you had 3" of travel where there is next to no change, that would work well for road racing.

 

And like helghast says, you can swap coilovers in and out as needed, the adapters even have a set screw boss on the top, so prior to disassembly, you can mark the camber, then reassemble at the exact same position.

[helghast7]

Sooooo.... I say front and back kits and part numbers for which coilovers to buy and INTERESTED! 

[m1ghtymaxXx]

Interesting idea, I wonder is this method of camber adjustment in beneficial for performance in terms of camber curve, since the camber curve should stay the same, but allows you to change the static camber. A couple friends have KW coilovers in their FR-S' which have a slotted hole at the spindle to allow (IIRC) 2 degrees camber change in relation to the strut.

 

Also it should be noted that this won't work on S130 rear suspension, which is basically the same as the Z31 design but with with a coilover shock assembly. 

[G-E]

Doh yea same as z31 rear ... how's the height? Is it like the s12's where it's too short for a full coilover in the rear?

Edited April 9, 2014 by G-E

[socorob]

This is kind of like the way TTT has the slotted rear to get some camber adjustment.

[G-E]

This is kind of like the way TTT has the slotted rear to get some camber adjustment.

Link? All I've found is their weld-on sleeve and camber plates?

[johnc]

While in the strictest sense that's true, it doesn't have to, it only has to operate at a specific range of travel... AND you have to keep in mind how it acts in relation to how everything else acts...

 

 

In the broadest sense its completely true.  Its basic geometry for a strut suspension.  And yes you are correct regarding a limited total range of travel (typically 2" for a race car and 4" for a street car) but ideally that range of travel is near the 90 degree angle between the strut and the LCA so you move in the narrowest camber gain/lost range (by design).

 

When you squat the semi-trailing arm, you gain too much camber, you could negate this by having the coilover go more positive under squat conditions, thereby giving you the best grip for launching at drag racing.

 

 

How would a coil-over shock affect the suspension geometry of a trailing arm suspension design?  Its not a structural part of the suspension like it is on a MacPhereson or Champan strut design.

 

You could also have it set to maintain a specific negative camber in hard cornering on a car that doesn't normally squat (ie. stiff); if you had 3" of travel where there is next to no change, that would work well for road racing.

 

 

You are completely ignoring camber loss in roll.  You have to have some camber gain in bump to counteract that inherent flaw in strut suspension design.  I'm beginning to think you don't know a lot about suspension and even less about road racing.

 

And like helghast says, you can swap coilovers in and out as needed, the adapters even have a set screw boss on the top, so prior to disassembly, you can mark the camber, then reassemble at the exact same position.

 

 

Yeah, +/- a degree or two ain't no big thing.

[mal_tiempo]

Color me intrigued.  Any sketches of what a version for the S30 rear would look like?  

[seattlejester]

Interesting, so you cut the strut tube, and weld in an adapter so that the coil overs don't have to be modified.

 

I've got a spare strut assembly front and rear .

[tube80z]

I designed an interesting kit for the z31 front suspension that I'm convinced would do wonders for the rear of the early datsuns...

 

I've seen how seriously involved installing rear coilovers are, cutting out the strut tower top to weld in a new camber plate; what if you didn't have to do that? What if you could adjust camber at the spindle, and what if you could maintain that camber under compression (like a hard launch)? What if this would allow you to interchange/upgrade your coilover later, say to Fortuneauto 510's, Apexi N1 Revolution, Tein SuperDrift, or other premium brands?

 

To quote Scotty: Would that be worth something to ya laddy?

 

 

One reason I could see wanting to do this would be to set the steering axis angle and then adjust camber without changing this.  This would also fix your motion ratio when changing camber.  The question will be how much camber can you get this way.  The second issue is when you move to a two-piece spindle design then you have additional compliance under braking and cornering.  For a street car people don't care but for a hardcore racer this is something you want to make sure isn't a problem.

[G-E]

Wow so much to reply to...

 

johnc:

1. yea I meant the 240z rear in my example, not the 280zx one

2. the camber loss/gain has a dividing line, on one side you start more negative and go more positive, on the other side you start more positive and go more negative; in a case the control arm and spindle top move outwards similarly, camber is maintained rather than lost, and since there are adjustable control arms that allow moving the inner pivot up or out, I'm sure there's a compromise that will work well... 

 

seattlejester: exactly

 

tube80z:

1. are you talking about inherent flex in the system?

2. regarding sai for the front, a lot of drifters set their camber plate full positive, and the adapter negative enough to keep the leading wheel flat

 

I spoke to dave @ tougefactory who suggested an offset strut would make it more progressive damping, but without hard numbers and lots of complex math to be sure, his tentative opinion is that it shouldn't be significant if the side loads aren't too high -- I don't believe it is...

[G-E]

Ok, so I've been reviewing parts and angles, and it looks like there's a really good way to approach this...

 

If you see in the photos I posted, the front z31 kit contains negative camber rollcenter adjusters, this pushes the hub and strut out, which besides the obvious, helps minimize the strut offset from the steering axis.

 

The side effect of which is that you can run higher offset wheels (should be more readily available right?) or perhaps avoid the use of spacers, because you gain extra backspacing, and I expect using a longer arm in the rear would accomplish much the same thing.

 

It appears the dynamic camber curve can be kept in a good range, and any movement towards positive can be mitigated, while allowing the use of wider (and higher offset) wheels to fit

 

PS. It also looks like my z31 bbk should be possible to adapt with a new caliper bracket and changing the center bore on the hats

Edited April 12, 2014 by G-E

[JMortensen]

Wow so much to reply to...

 

johnc:

2. the camber loss/gain has a dividing line, on one side you start more negative and go more positive, on the other side you start more positive and go more negative; in a case the control arm and spindle top move outwards similarly, camber is maintained rather than lost, and since there are adjustable control arms that allow moving the inner pivot up or out, I'm sure there's a compromise that will work well... 

 

The point at which you change from gaining neg camber to gaining positive camber is when the control arm passes 90 degrees in relation to the STRUT TUBE, not the ground. Lots of people think that once the control arm passes horizontal to the ground then the strut loses neg camber. Not true. It would be difficult to run a car low enough to run into a situation where the car gains pos camber in bump. We have a really really good thread here that plots out camber curves, etc here:

http://forums.hybridz.org/topic/63492-suspension-tech-motion-ratio-unsprung-weight/

 

The camber gain is very linear throughout Dan's (74_5.0L_Z) range of motion, and he has an extremely low autox Z car.