King Pin Inclination Help?

[URTOAST]

I'm hoping some one on here can help me with this...

I'm working on a car that has less documentation then anything I have ever worked on, and to be honest it has turned into a VERY bad basket case. Never the less, I like it, and I'm going to finish it one way or the other.

Basically I have to get a SHO Spindle on a lower control arm of a Ford Festiva... I have talked to the original builder of this car, and he has been an inspiration to say he least... He is a Super nice guy, and is a wealth of knowledge, but he is very busy, so I hate to bug him with every problem I have on this car...

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Well here is my problem. I just found out about two days ago that the spindles to the SHO were milled where they accept the struts to reduce the Inclination of the king pin... This was done because the car was a FWD car, and now it's going to be RWD, he said he recalls from ~ 1991 or so that the original FWD set up was about 13 Deg. and you need to reduce it to about 8-9 Deg.

So here I am scratching my head wondering about this problem..

Will this be effected by the offset of my wheels?

Do the numbers of 8-9 Deg. make sense?

Can a set of caster camber plates help this?

Is there a better way? Not so much with the SHO spindle and the king pin problem but the set up of the tube in the Spindle that holds the Koni insert? This just seams bulky? Is there a strut that can just get clamped to the spindle, or is the steal tube the best way to reduce the flexing?

This car was setup about 17 years ago, and I just want to modernize what I can, some of it must stay to keep it similar to the original setup, but I'm open for improvments.... The car will be driven on the street about 98% of the time, and maybe some track day fun.

What I do know about this spindle swap is they used a spacer of sorts to join the lower ball joint of the Festi ( a one piece unit with the control arm) with the hole in the spindle... They also used a spacer to joint the SHO out tie rod to the inner tie rod of the Festiva.. I'm going to change this in favor of a custom inner tie rod that will directly hook to the SHO outer unit.

Thanks for the help in advance!

Brian

[MonzaRacer]

Ok so your asking about Steering Axis Inclination, not KPI as king pins havent been used in cars in decades.
SAI is actually the combination of the incline based off of the theoreticle center of the tire at 0 camber and the centerline through both ball joints or lower andbj and upper bearing plate.
If I understand what was done in the machining was to change the camber SAI has nothing to do with caster.
OK so just what kind of car is it your working on?
and why are you changing parts?
A little more info on the type of car your working on would help.
I am a 20+yr alignment tech so I understande a few things about suspensions.
Lee Abel
AFTERMARKET PERFORMANCE

[URTOAST]

Ok so your asking about Steering Axis Inclination, not KPI as king pins havent been used in cars in decades.
SAI is actually the combination of the incline based off of the theoreticle center of the tire at 0 camber and the centerline through both ball joints or lower andbj and upper bearing plate.
If I understand what was done in the machining was to change the camber SAI has nothing to do with caster.
OK so just what kind of car is it your working on?
and why are you changing parts?
A little more info on the type of car your working on would help.
I am a 20+yr alignment tech so I understande a few things about suspensions.
Lee Abel
AFTERMARKET PERFORMANCE

Lee,

Thanks for your help. The car is a Ford Shogun, witch in it's self will yield you nothing. Thats kinda why I left it out...There were only a hand full or so built. Basically they took a Ford Festiva FWD car and removed the engine, inserted a fuel cell, and placed a SHO drivetrane in the trunk, making it a mid engined RWD car. They were the hot ticket in the 90's and preformed very well for what they were. Some hate them, others like me love them... well some days :hmm:

Here is a link to Supercars.net

http://www.supercars.net/garages/Dodge%20Spirit%20RT/1v2.html

What the original builder of the car told me was he removed some of the Inclination of the FWD set up of the car because most FWD cars have a higher inclination rate then there RWD counterparts?

This problem is only on the front of the car... We are using the stock lower control arm, and the stock upper strut location so I'm have no doubt putting this thing together as is would work, but there were several people that worked on this car originally, and I'm sure they did this for a reason. Camber plates were, and still are available for the car, so I'm guessing this machining process had to provide some sort of benifit.... It doesn't look easy, well not as easy as some adjustable plates :)

So if this is based on the "center line of the tire" my wheel offset will efect this..... So when he used ...say 8-9 Deg. and one set of wheels, and I switch to another set... how do I know what angle to bore the spindles at?

Thanks

Brian

[Beige]

The SAI is used to change the scrub radius without changing the camber or the wheel offset.

Oversimplifying things:
FWD cars have different requirements for scrub radius because the steering wheels are also the drive wheels and the wheel torque can cause torque steer. The intersect point of the SAI and the ground is sometimes on the other side of the centerline of the tire than it would be on a RWD car.

Plot the scrub radius of the original wheels, then calculate a new SAI for the new wheels with the same scrub radius. Or you could just live with the change. People do it all the time.

I was gonna type this out yesterday but got caught up with something else. I was also gonna ask if it was a real SHOgun or a clone.

[URTOAST]

The SAI is used to change the scrub radius without changing the camber or the wheel offset.

Oversimplifying things:
FWD cars have different requirements for scrub radius because the steering wheels are also the drive wheels and the wheel torque can cause torque steer. The intersect point of the SAI and the ground is sometimes on the other side of the centerline of the tire than it would be on a RWD car.

Plot the scrub radius of the original wheels, then calculate a new SAI for the new wheels with the same scrub radius. Or you could just live with the change. People do it all the time.

I was gonna type this out yesterday but got caught up with something else. I was also gonna ask if it was a real SHOgun or a clone.

Well.... I dont have the origional wheels, so thats not going to work out. :pat:

So me saying 8-9 Deg. can neather sound good or bad till you see the wheels on the car and figure out the scrub radius.

Do you see anything wrong with going with his 8-9 Deg. if I'm off just a bit by changing the wheels? What does this effect, handling?

Is there a sweet spot set of numbers I should shoot for?

AS for the car... well... I bought it after being told it was the left over # 007 Shogun that was never finished, I recently talked to a guy that clames he had made an extra set of parts from all the molds prior to selling them... So its definatly not built by Special Editions in CA, but at the same time it all came from the same molds, I have the special subframe, and roll bars, interior pieces, stickers, and a lot of origional paperwork. Even a Serial number tag with 007 on it. So it's going to be as close as you can get to the real thing.... It took me about 1 year to find an all origional Festiva from 91 in CA with 30K origional miles on it.. So.. I'm trying my best to do everything to make this one sharp car... No rusty worn out old Festi here :)

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[MonzaRacer]

OK if I had my druthers I would fab up a better idea by doing some custome lower control arms, and try using a "custom" built spindle with a similar mount like the Mustangs do.
The problem with moding the monting hole in any of those spindles sound real scary.
To me it sounds like a more custom set up would be a better set up.
I'll do some digging as I saw some things done to a Taurus making it rear wheel drive.
Sounds very different.
Lee

[URTOAST]

OK if I had my druthers I would fab up a better idea by doing some custome lower control arms, and try using a "custom" built spindle with a similar mount like the Mustangs do.
The problem with moding the monting hole in any of those spindles sound real scary.
To me it sounds like a more custom set up would be a better set up.
I'll do some digging as I saw some things done to a Taurus making it rear wheel drive.
Sounds very different.
Lee

Oh I have no doubt that switching it up would yeald better results, but then again I need to keep it some what origional? The Blue # 2 Shogun competed several times in the "One Lap of America" race, and it did fine, even with this setup. So I guess I'm going to try to find a set of wheels I like, and then figure out this "Scrub" formula.... Argg... This will be my last basket case! :hand: