Front suspension - the topic -
01-16-2004, 03:41 PM
#1
Race Director
Thread Starter
Front suspension - the topic -
Okay, I've been doing a lot of thinking about our front suspension and want to seriosuly make it better. However, instead of just fixing one or two things I'm thinking doing the best job possible, given what we have to work with. So, here I will give my view on the different aspects of the front suspension and what I feel needs to change. This is for front susp. I'm thinking about doing the same thing for the rear some time in the future.
1) camber: the camber curve is not good in stock form, instantaneous center is outside the car giving pos. camber gain on bump. This should be changed to neg. camber gain by altering the geometry so that the ic is inside the car. There are several methods of doing this. Solutions:
* shorter upper arm
> possibly adjustable arms
benefits are no shims so no messed up geometry (cross shaft axis) by shims
drawback is no bump rubber
* relocate upper arm mount
> lower mount
Not a whole lot of room without modding the complete mount.
> mount outside frame
Big drawback is that you are limited in the amount of neg. camber you can set. Will also need plating of suspension mount
2) Caster, I see no problem with out caster. I heard the VB&P arms area available with more offset on the upper arm to give more caster. Why is this? For those that like to know what caster does, caster is the angle that the kinpin makes when viewed from the side. This places the steering axis in fron (on neg caster) of the wheel to ground contract point. This makes that the tires are "dragging" giving stability (think of a cart with 2 wheels, if you pull it it will be more directionally stable than when you push it). So can VB&P or someone else chime in and tell me why more cater is desired?? For more stability (straight ahead) ??? See following points on kingpin angle for more on this.
3) Toe. Toe is what Norval and 427V8 have been addressing on their cars. Toe is jsut a setting and the only problem is toe control over bump & rebound, also called bump steer or toe steer.
Another point that falls under this little item is the steering setup. Everyone here has a rear steer rack. Some racjk & pinion, most the normal recirc. ball setup. I feel that some effort (or a lot of effort) should be made to try and create a front steer setup. I have found a woodward rack (power steering w/ slave cyl /mini cyl, highly expensive, over 800$!!) that will fit the stock geometry (eye to eye width of 16,25")
Why is front steer (end take off) so desireable? Because of deflection. When the bushings on the cross shaft deflect under heavy cornering (outside wheel) the kingpin and the 2 arms are forces to the inside of the car because of the resulting force of the centrifugal force (weight transfer to outside) and the grip or slip resistance of the tires. The steering arm however is not pushed inside. This means that on a rear steer setup this deflection results in more steering input or oversteer. This is highly undersireable. In a front steer setup you would get understeer, which is easy to make up for by the driver.
4) Kingpin inclination or angle.
Our kingpin has no angle and this is bad. Why is this bad? Because it gives a larger scrub radius or kingpin axis offset. This is the distance from the line through the kingpin (where it meets the ground) to the centerline of the tire.
0 scrub radius is not good, it will result in a sensation of no steering input, uit will be very easy to steer but you won't feel what's going on. Also it will be instable (see following point). Too large a scrub radius will make the car twitchy at higher speeds because the wheels will try to toe the front in. It will also make steering much harder.
As said, kingpin angle gives stability. Because of the scrub radius the wheels put a force on the tie rods, making them want to go straight ahead (cancel each other out)
Another thing is that kingpin inclination gives stability because of vehicle weight. When you turn the kingpin (one that has inclination, otherwise it's a moot point) the resulting "height" of the upper to lower ball joint changes. This one is kind of hard to explain, you might want to draw it out for yourself,.
If you turn the wheel the lower arms is pressed downward as the upper one can't become longer. This is because the resulting height changes. the angle on the kingpin is the same but the resulting vertical component changes. I find this one difficult to explain, study the drawing and you will probably see what I mean.
So, what this does is the vehicle weight gives the car the tendency to resist this raising, especially at higher speeds. this gives stability control too.
5) kick up and anti dive (these 2 are each others opposites)
The suspension we have has the tendency to kick up, no anti dive. When you draw lines through the cross shafts they meet facing the rear of the car, when facing the front you have anti dive. The problem with anti dive is that as the suspension goes into bump the wheels more forward in the horizontal plane, so when hitting a bump the wheel moves into the obstruction. With kick up the wheel moves back, absorbing some of the bump. This gives a comfortable ride. It is not possible to drive with a lot of anti dive on anything else but a super smooth track. The ride will get harsh. I think a little less kick up would be good, I heard from 71roadster that he heard from a company that they moved the upper arms rear mounting hole 1" upward, fiving less kick up and a bit more towards anti dive (it's not anti dive, it's still kick up but less then what's present in stock form). Maybe this is something we need to address too but I have no idea of how good or bad the stock setup is in that area. It does seem the car dives quite a bit under braking, something patched with stiff springs. When extending the lines through the cross shafts you find another instantaneous center, this point is the point where the brake torque acts on, giving the dive or kickup.
Conclusion so far:
What we need is:
A new kingpin (spindle) that is longer than stock and has a kingpin angle. This will allow wider tires, good stability control at high speeds.
After we have decided what the kingpin should be like we can choose the upper control arm length,because the kingpin angle moves the upper mount inboard we need a shorter arm, this combined with the camber curve that needs to be addressed we can select a length for the upper arm that allows us to run the angled spindle AND have a proper camber curve. This is also combined with the springs we want to run and the roll center & CG of the car. (stock or changed if someone wants to lower the tank, diff and that kind of stuff). The amount of roll will give an idea of how much camber we want to gain so that we maintain maximum contact patch with the street.
So now we have the spindle and the upper arm. Any caster change desired can be incorporated in the kingpin height and upper arm offset (adjustable arm is handy here too)
Last but not least, again the 0 bump steer stuff. It will be just as involving as what Norval and 427V8 have been doing. If a front steer rack is possible it would be a really really fine setup.
Some people may say front steer won't work because of the sway bar, there's a solution. Either mount the sway bar on the rear of the car (under the oil pan) like gregp has done or if you have a subframe in the engine you can mount it on that and connect it to the upper arms (subframe is relly nice in combination with upper coil over mounts)
That's about all I can come up with for now. Ideas? Input? Please!
1) camber: the camber curve is not good in stock form, instantaneous center is outside the car giving pos. camber gain on bump. This should be changed to neg. camber gain by altering the geometry so that the ic is inside the car. There are several methods of doing this. Solutions:
* shorter upper arm
> possibly adjustable arms
benefits are no shims so no messed up geometry (cross shaft axis) by shims
drawback is no bump rubber
* relocate upper arm mount
> lower mount
Not a whole lot of room without modding the complete mount.
> mount outside frame
Big drawback is that you are limited in the amount of neg. camber you can set. Will also need plating of suspension mount
2) Caster, I see no problem with out caster. I heard the VB&P arms area available with more offset on the upper arm to give more caster. Why is this? For those that like to know what caster does, caster is the angle that the kinpin makes when viewed from the side. This places the steering axis in fron (on neg caster) of the wheel to ground contract point. This makes that the tires are "dragging" giving stability (think of a cart with 2 wheels, if you pull it it will be more directionally stable than when you push it). So can VB&P or someone else chime in and tell me why more cater is desired?? For more stability (straight ahead) ??? See following points on kingpin angle for more on this.
3) Toe. Toe is what Norval and 427V8 have been addressing on their cars. Toe is jsut a setting and the only problem is toe control over bump & rebound, also called bump steer or toe steer.
Another point that falls under this little item is the steering setup. Everyone here has a rear steer rack. Some racjk & pinion, most the normal recirc. ball setup. I feel that some effort (or a lot of effort) should be made to try and create a front steer setup. I have found a woodward rack (power steering w/ slave cyl /mini cyl, highly expensive, over 800$!!) that will fit the stock geometry (eye to eye width of 16,25")
Why is front steer (end take off) so desireable? Because of deflection. When the bushings on the cross shaft deflect under heavy cornering (outside wheel) the kingpin and the 2 arms are forces to the inside of the car because of the resulting force of the centrifugal force (weight transfer to outside) and the grip or slip resistance of the tires. The steering arm however is not pushed inside. This means that on a rear steer setup this deflection results in more steering input or oversteer. This is highly undersireable. In a front steer setup you would get understeer, which is easy to make up for by the driver.
4) Kingpin inclination or angle.
Our kingpin has no angle and this is bad. Why is this bad? Because it gives a larger scrub radius or kingpin axis offset. This is the distance from the line through the kingpin (where it meets the ground) to the centerline of the tire.
0 scrub radius is not good, it will result in a sensation of no steering input, uit will be very easy to steer but you won't feel what's going on. Also it will be instable (see following point). Too large a scrub radius will make the car twitchy at higher speeds because the wheels will try to toe the front in. It will also make steering much harder.
As said, kingpin angle gives stability. Because of the scrub radius the wheels put a force on the tie rods, making them want to go straight ahead (cancel each other out)
Another thing is that kingpin inclination gives stability because of vehicle weight. When you turn the kingpin (one that has inclination, otherwise it's a moot point) the resulting "height" of the upper to lower ball joint changes. This one is kind of hard to explain, you might want to draw it out for yourself,.
If you turn the wheel the lower arms is pressed downward as the upper one can't become longer. This is because the resulting height changes. the angle on the kingpin is the same but the resulting vertical component changes. I find this one difficult to explain, study the drawing and you will probably see what I mean.
So, what this does is the vehicle weight gives the car the tendency to resist this raising, especially at higher speeds. this gives stability control too.
5) kick up and anti dive (these 2 are each others opposites)
The suspension we have has the tendency to kick up, no anti dive. When you draw lines through the cross shafts they meet facing the rear of the car, when facing the front you have anti dive. The problem with anti dive is that as the suspension goes into bump the wheels more forward in the horizontal plane, so when hitting a bump the wheel moves into the obstruction. With kick up the wheel moves back, absorbing some of the bump. This gives a comfortable ride. It is not possible to drive with a lot of anti dive on anything else but a super smooth track. The ride will get harsh. I think a little less kick up would be good, I heard from 71roadster that he heard from a company that they moved the upper arms rear mounting hole 1" upward, fiving less kick up and a bit more towards anti dive (it's not anti dive, it's still kick up but less then what's present in stock form). Maybe this is something we need to address too but I have no idea of how good or bad the stock setup is in that area. It does seem the car dives quite a bit under braking, something patched with stiff springs. When extending the lines through the cross shafts you find another instantaneous center, this point is the point where the brake torque acts on, giving the dive or kickup.
Conclusion so far:
What we need is:
A new kingpin (spindle) that is longer than stock and has a kingpin angle. This will allow wider tires, good stability control at high speeds.
After we have decided what the kingpin should be like we can choose the upper control arm length,because the kingpin angle moves the upper mount inboard we need a shorter arm, this combined with the camber curve that needs to be addressed we can select a length for the upper arm that allows us to run the angled spindle AND have a proper camber curve. This is also combined with the springs we want to run and the roll center & CG of the car. (stock or changed if someone wants to lower the tank, diff and that kind of stuff). The amount of roll will give an idea of how much camber we want to gain so that we maintain maximum contact patch with the street.
So now we have the spindle and the upper arm. Any caster change desired can be incorporated in the kingpin height and upper arm offset (adjustable arm is handy here too)
Last but not least, again the 0 bump steer stuff. It will be just as involving as what Norval and 427V8 have been doing. If a front steer rack is possible it would be a really really fine setup.
Some people may say front steer won't work because of the sway bar, there's a solution. Either mount the sway bar on the rear of the car (under the oil pan) like gregp has done or if you have a subframe in the engine you can mount it on that and connect it to the upper arms (subframe is relly nice in combination with upper coil over mounts)
That's about all I can come up with for now. Ideas? Input? Please!
01-16-2004, 04:00 PM
#2
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Re: Front suspension - the topic - (Twin_Turbo)
When you guys get done, can we make drawings for others to fabricate stuff?
01-16-2004, 04:43 PM
#3
Le Mans Master
Re: Front suspension - the topic - (Guru_4_hire)
Wow - I followed most of that, but my brain hurts now.
This is major fabrication. Remaking the spindle is a BIG deal. Maybe
Norval could pull that off - welding together a new one from three stock
spindles.
Do the C4 or C5 suspensions address these issues ? I have seen some
conversions, which may be easier than redesigning the C3 pieces.
Are these changes gonna be valid for my NCRS Bowtie inspection ? J/K :jester
This is major fabrication. Remaking the spindle is a BIG deal. Maybe
Norval could pull that off - welding together a new one from three stock
spindles.
Do the C4 or C5 suspensions address these issues ? I have seen some
conversions, which may be easier than redesigning the C3 pieces.
Are these changes gonna be valid for my NCRS Bowtie inspection ? J/K :jester
01-16-2004, 04:55 PM
#4
Race Director
Thread Starter
Re: Front suspension - the topic - (NHvette)
yes, C4 & C5 suspensions both have a kingpin angle and a better camber curve, as well as front steer. Only prob. with the C4 is that the upper arms mount on the outside so you're limited in the amount of camber.
I have been thinking about a C4 or C5 spindle. They both have the lower ball joint under the spindle, where our has the balljoint on the spindle and the spindle underside under the arm. Swapping to the C4 or C5 spindle would give the kingping angle AND do 2 other things. Because they mount on top of the lower arm the spindle will make the balljoint to balljoint height higher, thus giving a virtual longer spindle. I will also mount the spindle snout/axis higher up, giving a drop. The lower arm would need to be modified and the upper one drilled for mini ball joints. I think Norval did that to his, to my knowledge the extended coleman joints are mini ball joint pattern too.
But, the C4 & C5 give another problem, you'd have to use those brakes (not that much of a concern when it comes to C5 brakes but the C4 brakes are junk, I feel they are worse than ours)
Can someone supply measurements on the C4 & C5 spindles? That would be really usefull.
I have been thinking about a C4 or C5 spindle. They both have the lower ball joint under the spindle, where our has the balljoint on the spindle and the spindle underside under the arm. Swapping to the C4 or C5 spindle would give the kingping angle AND do 2 other things. Because they mount on top of the lower arm the spindle will make the balljoint to balljoint height higher, thus giving a virtual longer spindle. I will also mount the spindle snout/axis higher up, giving a drop. The lower arm would need to be modified and the upper one drilled for mini ball joints. I think Norval did that to his, to my knowledge the extended coleman joints are mini ball joint pattern too.
But, the C4 & C5 give another problem, you'd have to use those brakes (not that much of a concern when it comes to C5 brakes but the C4 brakes are junk, I feel they are worse than ours)
Can someone supply measurements on the C4 & C5 spindles? That would be really usefull.
01-16-2004, 04:58 PM
#5
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Re: Front suspension - the topic - (Twin_Turbo)
What about this new magnetic ride control. It appears that it is a set of shocks controled by a computer and 4 or so sensors. might be able to shoe horn them in if you can locate the computer(the article I read said standalone and it is an option so you may be able to pillage it out from a cadillac STS or a wrecked corvette)
Might have to make your own wiring harness too
here is an article about it.
http://corvetteactioncenter.com/specs/2003/msrc2.html
[Modified by Guru_4_hire, 5:07 PM 1/16/2004]
Might have to make your own wiring harness too
here is an article about it.
http://corvetteactioncenter.com/specs/2003/msrc2.html
[Modified by Guru_4_hire, 5:07 PM 1/16/2004]
01-16-2004, 05:07 PM
#6
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Re: Front suspension - the topic - (Twin_Turbo)
Holy cow - I need aspirin now. With regards to caster. I believe negative caster is where the wheel is canted behind centerline - like a shopping cart. This is more unstable. Think how a shopping cart front wheels wobbles like crazy but turns fast, not desirable in high speed driving. Positive caster cants the wheel forward of the centerline giving more high speed stability.
Extremely interesting topic. :thumbs:
Extremely interesting topic. :thumbs:
01-16-2004, 05:11 PM
#7
Race Director
Thread Starter
Re: Front suspension - the topic - (SAC)
shopping cart wheels have caster but no angle, when the upper ball joint is behind the lower the caster is positive. Negative caster is never used in cars as far as I know, it's very unstable. Caster is all about the amount the wheel contact patch is behind or in front of the steering axis.
[Modified by Twin_Turbo, 5:19 PM 1/16/2004]
[Modified by Twin_Turbo, 5:19 PM 1/16/2004]
01-16-2004, 05:12 PM
#8
Race Director
Re: Front suspension - the topic - (NHvette)
Just a comment regarding Caster: more Caster does make the car more stable at high speeds (desirable), increases steering effort (desirable for me atleast. I like feedback), and it creates camber gain on the outside wheel as the steering wheel is turned. For instance, when making a right hand turn, the left wheel will gain negative camber and the right wheel positive camber. This is good as it counteracts body lean. Most modern sportscars run a fair amount of caster for these reasons. Many Ferraris run upwards of 7 degrees.
01-16-2004, 05:30 PM
#9
Re: Front suspension - the topic - (Twin_Turbo)
I think this guy nailed most of it.
He modded the spindle to be taller to deal with the camber curve. He modded the spindle to move the upper mount inward to change the kingpin angle and spaced the upper A-arm inward an equal amount. And he moved the upper A-arm rearward to increase the caster. The only thing I cant tell if he did or not is raise the rear of the upper A-arm to increas anti-dive, tho this was highly recommended to me by a guy who builds racers.
I question the lack of any kingpin inclination in our cars. If you place a spindle on the ground with the ball joint mounts on the floor and the spindle pointing up, if there were no kingpin inclination, the spindle would point straight up (spindle angle perpendicular to line drawn through ball joint mounts). It doesn't. I know because the jig I built to help extend the spare spindles I have does essentially this. There is an eyeball estimate of 10 degrees of inclination. Maybe the guy in these photo's wanted more.
Chris
He modded the spindle to be taller to deal with the camber curve. He modded the spindle to move the upper mount inward to change the kingpin angle and spaced the upper A-arm inward an equal amount. And he moved the upper A-arm rearward to increase the caster. The only thing I cant tell if he did or not is raise the rear of the upper A-arm to increas anti-dive, tho this was highly recommended to me by a guy who builds racers.
I question the lack of any kingpin inclination in our cars. If you place a spindle on the ground with the ball joint mounts on the floor and the spindle pointing up, if there were no kingpin inclination, the spindle would point straight up (spindle angle perpendicular to line drawn through ball joint mounts). It doesn't. I know because the jig I built to help extend the spare spindles I have does essentially this. There is an eyeball estimate of 10 degrees of inclination. Maybe the guy in these photo's wanted more.
Chris
01-16-2004, 05:47 PM
#10
Race Director
Thread Starter
Re: Front suspension - the topic - (71roadster)
71roadster, yes that is exactly what I talked to you about in the IM :)
There si no kingpin angle in our spindles, kinda hard to see but look here:
There si no kingpin angle in our spindles, kinda hard to see but look here:
01-16-2004, 05:57 PM
#11
Re: Front suspension - the topic - (Twin_Turbo)
I disagree. Even in your photo I can see the the upper ball joint hole is lower to the ground than the lower ball joint hole and the spindle looks to be vertical. Assuming the spindle must be parallel to the ground when on the car, that means the upper ball joint is more inward than the lower. That means there is inclination. And in my fixture it is quite obvious that there is inclination. I'll get a picture when I have a chance.
C
C
01-16-2004, 06:00 PM
#12
Race Director
Thread Starter
Re: Front suspension - the topic - (71roadster)
I'll have to recheck but if there's an angle it is very small. Ideally the steering axis point on the ground is about 1-2" away from the wheel center line, in our cars it's much more than that.
EDIT
You are right, there is a couple of degrees of inclination. I was doing this from the top off my head but I just looked at the enxt pic again and there is indeed some inclination. Still I feel it's not nearly enough to get the steering axis within 1-2" of the tire centerline.
thanks for the heads up :)
[Modified by Twin_Turbo, 5:05 PM 1/16/2004]
EDIT
You are right, there is a couple of degrees of inclination. I was doing this from the top off my head but I just looked at the enxt pic again and there is indeed some inclination. Still I feel it's not nearly enough to get the steering axis within 1-2" of the tire centerline.
thanks for the heads up :)
[Modified by Twin_Turbo, 5:05 PM 1/16/2004]
01-16-2004, 06:04 PM
#13
Re: Front suspension - the topic - (Twin_Turbo)
Again, my eyeball estimate is ten degrees.
How do you figure that the ideal steering axis point is 1 - 2" inches from center of the wheel. Just curious.
Chris
How do you figure that the ideal steering axis point is 1 - 2" inches from center of the wheel. Just curious.
Chris
01-16-2004, 06:06 PM
#14
Race Director
Thread Starter
Re: Front suspension - the topic - (71roadster)
I got that from a book somewhere, will have to check what book it was. I think it was a race car engineering book.
01-16-2004, 06:10 PM
#15
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Re: Front suspension - the topic - (Twin_Turbo)
Twin Turbo what I you trying to do to me??? I just got my 4 A arms back from the powder coater and this weekend will start putting the front back together with new bushings, the extended spindles, the coil overs and bump steer correction parts. It is a simple bolt together deal.
Are you trying to give me more to think about, something I should have changed but missed??
I just printed out a hard copy to sit by the fire and read over.
I hope I don't get any more ideas :lol: :lol: :lol:
Are you trying to give me more to think about, something I should have changed but missed??
I just printed out a hard copy to sit by the fire and read over.
I hope I don't get any more ideas :lol: :lol: :lol:
01-16-2004, 06:13 PM
#16
Le Mans Master
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St. Jude Donor '09
Re: Front suspension - the topic - (Twin_Turbo)
Whoah!! Wait just a second!! I always thought that kingpin angle was the angle made thru the center of the balljoints, upper and lower.
Therefore the caster ANGLE would be between:
-- straight up and down, thru the center of the spindle when looking head-on to the tire from the side (reference at 0*), compared to
-- thru the center of the balljoints, upper and lower. (kingpin angle)
Kind of hard to picture with words, but I'm a lousy artist and no place to post pics, so I hope I've explained myself well enough!
Is that right? Please help me to understand the magical world of front suspensions!! I always wanted a Vette because I thought that was the pinnacle of American sports car handling, that no other car could compare. Now I'm finding out it's not much better than a CHEVette!!! :eek: :cry
Therefore the caster ANGLE would be between:
-- straight up and down, thru the center of the spindle when looking head-on to the tire from the side (reference at 0*), compared to
-- thru the center of the balljoints, upper and lower. (kingpin angle)
Kind of hard to picture with words, but I'm a lousy artist and no place to post pics, so I hope I've explained myself well enough!
Is that right? Please help me to understand the magical world of front suspensions!! I always wanted a Vette because I thought that was the pinnacle of American sports car handling, that no other car could compare. Now I'm finding out it's not much better than a CHEVette!!! :eek: :cry
01-16-2004, 06:14 PM
#17
Race Director
Thread Starter
Re: Front suspension - the topic - (norvalwilhelm)
Yup :) , but seriously I mentioned the kingpin angle before (in the extended spindle topic), I feel if we are gonna mod spindles why not do that at the same time and fix it too.
I powdercoated my parts too, a long time ago and will need a new set of used spindles and arms to work with, hate to mess up the nice coating. From now on I will not coatstuff untill I am positive it will go on as it is, that's the one major drawback with powdercoating. It's a pita to get off.
I powdercoated my parts too, a long time ago and will need a new set of used spindles and arms to work with, hate to mess up the nice coating. From now on I will not coatstuff untill I am positive it will go on as it is, that's the one major drawback with powdercoating. It's a pita to get off.
01-16-2004, 06:18 PM
#18
Race Director
Thread Starter
Re: Front suspension - the topic - (73sbvert)
Whoah!! Wait just a second!! I always thought that kingpin angle was the angle made thru the center of the balljoints, upper and lower.
Therefore the caster ANGLE would be between:
-- straight up and down, thru the center of the spindle when looking head-on to the tire from the side (reference at 0*), compared to
-- thru the center of the balljoints, upper and lower. (kingpin angle)
Kind of hard to picture with words, but I'm a lousy artist and no place to post pics, so I hope I've explained myself well enough!
Is that right? Please help me to understand the magical world of front suspensions!! I always wanted a Vette because I thought that was the pinnacle of American sports car handling, that no other car could compare. Now I'm finding out it's not much better than a CHEVette!!! :eek: :cry
Therefore the caster ANGLE would be between:
-- straight up and down, thru the center of the spindle when looking head-on to the tire from the side (reference at 0*), compared to
-- thru the center of the balljoints, upper and lower. (kingpin angle)
Kind of hard to picture with words, but I'm a lousy artist and no place to post pics, so I hope I've explained myself well enough!
Is that right? Please help me to understand the magical world of front suspensions!! I always wanted a Vette because I thought that was the pinnacle of American sports car handling, that no other car could compare. Now I'm finding out it's not much better than a CHEVette!!! :eek: :cry
caster:
kingpin angle (or inclination):
D = scrub radius or kingpin offset or steering axis offset (I bet there's even more english terms for this)
[Modified by Twin_Turbo, 5:22 PM 1/16/2004]
01-16-2004, 06:25 PM
#19
Re: Front suspension - the topic - (Twin_Turbo)
It's easy to check where the center of rotation is. Jack the wheel up, toss some sawdust under it, lower wheel, turn left and right a once or twice, jack wheel up, check where center of swirls are in the sawdust. I bet Norval has sawdust!
C
C
01-16-2004, 07:07 PM
#20
Melting Slicks
Re: Front suspension - the topic - (Twin_Turbo)
1) camber: the camber curve is not good in stock form, instantaneous center is outside the car giving pos. camber gain on bump. This should be changed to neg. camber gain by altering the geometry so that the ic is inside the car. There are several methods of doing this. Solutions:
* shorter upper arm
> possibly adjustable arms
benefits are no shims so no messed up geometry (cross shaft axis) by shims
drawback is no bump rubber
* relocate upper arm mount
> lower mount
Not a whole lot of room without modding the complete mount.
> mount outside frame
Big drawback is that you are limited in the amount of neg. camber you can set. Will also need plating of suspension mount
....................
What we need is:
A new kingpin (spindle) that is longer than stock and has a kingpin angle.
* shorter upper arm
> possibly adjustable arms
benefits are no shims so no messed up geometry (cross shaft axis) by shims
drawback is no bump rubber
* relocate upper arm mount
> lower mount
Not a whole lot of room without modding the complete mount.
> mount outside frame
Big drawback is that you are limited in the amount of neg. camber you can set. Will also need plating of suspension mount
....................
What we need is:
A new kingpin (spindle) that is longer than stock and has a kingpin angle.
EDIT: Looking at this again, it is apparent that the length of the A-arm to fix one problem likely wouldn't be the same to fix the other. Might there be an acceptable (subjective, I know) compromise? Once we decide on one of these, eg. the spindle first, will modelling software need to be used to decide the other?
[Modified by RUXperienced, 6:11 PM 1/16/2004]