http://www.carrollsmith.com

 

Gene don't give up. I have the software to run a program but find getting the numbers to plug in is the hardest part. To me it is easier to just check on the car.
[/QUOTE]

Naaah, I"m not giving up just yet, but getting under that car to do things is very weather and arthritis depandant....these daze it's not so good no matter what...I do want to adjust the tow in a bit though, but I"ll get there yet....

GENE

 

OK I've been away a few days, so I'm going back a few posts here...

Pete;
My wording wasn't perfect. the authors statement was that the importance of bump steer is still misunderstood by many circle track racers.

Also I think you are being too pickey to say you cannot check BS for dynamic conditions, all you have to do is to check it at the steering angle and roll angle you expect to see in a turn. For circle track it's a lot easier than for road race with varying turns, but you can still do it. Besides, my frame flexes like a we noodle, so I just need to be kinda close :)

I agree that you should look at the system rather than just one measurement, that could make a horribly handling car.

Norval,
I really think you should be bumpsteering that car at the attituce you will see the most benifit. If you are doing a lot of circle track you will bumpsteer your car differently than if you run road course and different that if you run a lot of highspeed straight line stuff.

Gene,
It sounds like you're complaining untill I realise that you are settig the toe on the steering of a car that you built a rack and pinion for from junkyard parts!
Yea, you're no whiner! LMAO

 

427, I have been junkyard junky for decades.....

about 15 years ago an old friend commented that he loved going to junkyards as we happened to make a trip looking for Mitsubichi parts for his race cars...and I started browsing...seems there is a particular strange breed of cat that actually finds junkyards relaxing.....

I know, take a pill and chill.....

GENE

 

Norval, if the upper and lower a-arm cross shafts are parallel they will track the same when looking from the side (this would be with a slotted cross shaft). If the upper cross shaft is shimmed to get the same caster setting it wont be parallel to the lower cross shaft when looking at them from above. To get positive caster by shimming, the rear of the cross shaft will be further inboard than the forward bushing on the cross shaft. With the cross shaft at an angle, as the suspension moves in compression there will be a negative camber gain and a caster change in the negative direction. This doesn't happen when the two cross shafts are parallel. The top of the spindle will follow a line that is perpendicular to the cross shaft. If the cross shaft is angled with the aft bushing inboard then the top of the spindle will track towards the front of the car as the suspension travels in compression.

 

Speed Direct you sure gave me something to think about. :) I had to draw it out to get the picture but you are right the upper ball joints move different arcs if you shim to get the specs or machine the cross shafts for the same spec. The arms travel through different curves.

 

that's why shimming sucks IMO.

There's a couple of ways to get more neg. camber and that's by making the spindle longer or dropping the pivot on the upper arms (about 3/4 inch or so). There's also a way to change the camber curve and that's by changing the kingpin angle (this is built into the spinde, it's the angle between upper and lower balljoint as seen from the front) Since norval is going to mod his spindle anyway it just might be a good idea to add some kingpin angle to the top of the spindle so that the upper ball tapered hole is further inboard than the lower.

Then for the caster/camber changes, if you use adjustable upper arms like the ones from pole position racing products or similar you won't have that problem ever since the cross shaft stays in it's proper position and all you do is change the actual dimensions of the arm itself.


[Modified by Twin_Turbo, 1:15 PM 8/28/2003]

 

Twin Turbo you should go back and edit your post. You are talking about caster and camber and using the same camber for both. I will respond to this after you edit yours to make sure you are talking about the right thing. I have already experienced what you are talking about. I already have extended spindles.

 

I wasn't talking about caster, you can set caster w/ your slotted cross shafts perfectly.
If you sue adj. upper arms one can adjust camber without shimming so the cross shafts stay parralel, no weird caster changing because of different arc for upper and lower arm. W/ the adjustable arm you can also adjust the caster (to a certain degree).. jsut like stock but again no shimming.,

You have extended spindles already ???

 

Twin Turbo I have had extended spindles all summer. First thing in the spring I bought the adjustable ball joints. It is just a tall stud that you slide shims over to raise the pivot point on the upper A arm. The new upper A arm joint is just a heim like joint that bolts into the upper A arm. If I want 1 or 2 inches extension to the spindle I just add shims. A jack placed under the lower A arm takes the weight off the joint and I add of subtract shims.
This is not the way I want to keep it and will weld and extension to my existing sprindle to extend it and remove all the shims from the stud, still use the stud though because of easier take apart.
My slotted cross shafts did take care of the positive caster, 5 degrees but at the same time the extended ball joints adds negative camber, could be good might not. As it stands right now I have minus .75 camber with no shims so I could not run it at 0 if I wanted, not a good thing but I am happy with the minus .75 for now.
When I weld up the extension I will take a bit of camber out of the alignment of the ball joints so I can have some adjustablility.
I will jig the stock spindle that make the jig to be extended while maintaining the same location but it would be easy to make it also adjustable for alignment.
Sorry Twin Turbo, I though you were talking about caster.

 

oh, you have those coleman ball joints or a spindle extender??? I don't like those spindle extenders.
I meant to say that additional caster is not a problem w/ adjustable arms, just shorten one side and make the other side longer and the uppre ball joint moves to the rear (viewed from top). The caster can be handled by the arm too. So, I think I will go that route, no need for slots and seemingly endless adjustability without the need for shims.. the thing I don't like the most on the conventional setup.

I merely wanted to point out that if you are hoing to fab longer spindles you might want to increase kingpin inclination (ours is actually 0)


The kingpin inclination will add camber too, but the camber change will be more aggressive in the beginning, more initial camber. Might be something you'd want to have.

No need to jig the spindle since the kingpin angle is already 0, if you want to keep it that way just line up the holes and weld the whole deal up.




[Modified by Twin_Turbo, 2:41 PM 8/28/2003]

 

Twin Turbo. I have the coleman ball joints. They are adjustable but I like things more rigid then a stud with spacers on it so I will definitely go the extended spindles in the winter when the car is apart. I will use donor spindles so I can make only 1 weld and not 2 by adding a spacer. I went with the outer tie rod studs also but when I found out the car liked a 1 inch spacer I removed the steering arms and welded a 1 inch block to the bottom side of the steering arm. I also cleaned it up alot so it looks very neat.
Adjustable anything only gets me in the ballpark then I like to make it more permanent.
The adjustable upper A arms sound good but for me with already the specs I want in the front end machined right in there is no benefit.

As a side note the boss where the large nut is on the spindle needs machining down about 1/8th inch on my spindles to properly center the caliper over the rotor. At the bottom a 1/8th washer between the steering arm and the caliper bracket works for centering the bottom of the caliper.
Check this out guys and you will find the caliper is not centered.


[Modified by norvalwilhelm, 7:11 AM 8/29/2003]

 

Will the donor spindles have to be specificly from a '63-'82 Corvette or can they be from something else that will provide an appropriate upper stem and maybe promote the kingpin angle Marck is talking about? jim

 

Pro, guys, my thoughts are going back to my old Lemans/GTO project of years ago....and I am thinking of modding the suspension another way...keeping the upper arms, and modding a bit on the lower arms to allow another type more 'normal' BJ on bottom, instead of this inverted thing, this would allow the location of taller spindles from the factory, and maybe then I could ditch those annoying calipers also....just change the entire thing over for say a late Camaro??/A body setup?? late Monte?? Caddy???
anything common and available in junkyards.....being a budget/lazy guy this is the way to fly, I think....
Only problem is facing my welder's index finger when I show up with what may be 8 controll arms in hand asking for some cutting/welding....

GENE :eek: :eek:

 

Will the donor spindles have to be specificly from a '63-'82 Corvette or can they be from something else that will provide an appropriate upper stem and maybe promote the kingpin angle Marck is talking about? jim

No the donor spindle can be anything that has the proper taper. I will probably use and olsmobile spindle for a donor since that is what Roger my stock car friend uses but anthing will do. I will cut the stock spindle above the mounting boss for the brake caliper and as high up as possible then add the top end from the cut off donor spindle, jig it and weld it up. I could easily change the angle.

 

Gene what is wrong with our annoying calipers. If the system has the stainless sleeved calipers, a trued rotor and hydraboost what more do I need. I have absolutely no problems and fantastic brakes.

 

I dunno, Norval, wether to stary with the stock brakes or maybe put on something else, and as long as I"m thinking of dumping spindles, and changing stuff around, why not dump the entire system, maybe something lighter off a newer car??? aluminum,?? has to have a thick rotor, don't want any cheezy warpage, bad enough with what I consider a brake system that way over pickey about run out and such...so If I going to ditch something in the process, my mind says go all the way with it....sorta like the steering....

GENE

 

Gene our front calipers have 4 1 7/8th pistons, are a rigid construction and with stainless liners should last forever. As for pumping air if the rotors are trued and the bearings are set up properly they do not pump air.
Granted our calipers weigh more then aluminum but they work, pads are cheap and there is no dinking around with trying to make something else fit. The same with the spindles, the stock ones fit and a simple little weld and it bolts right back in. Any welding shop could mig weld the two peices back together.
Gene don't create problems by trying to graft something else to the front end. Sure you did a good job with the rack and pinion but it took alot of effort and I still believe that as the stock steering as it came from the factory and not 28 years of wear on it the stock system works fine.

 

Yeh, I hear you Norval, I"m not all THAT enthusiastic about the above, but the thought has been through my mind ever since first seeing these upside down lower ball joints for the first time some 7+ years ago.....nothing been acted on, just this nacent thought.....

My steering was tight as hell, everything, was new/fresh/rebuilt/ the tie rod ends I was using with the old system are still on the car...I never replaced them, saw no need...tight.....

I dunno, at this point if I do anything, it will be all the way or nothing....

GENE

 

Gene I often get the idea to start over on the front end and I can do it. In late September I will own my own machine shop so for me to build anything at home is easy. I would look forward to a winter of machining all the custom parts but WHY?
Why reinvent the wheel? Our steering with a little help and brakes work.
As for everything new in your stock front end did you rebuild the steering box? I don't mean install new bears and seal. That is just a recondition. I mean the pitman arm bushings. They are around .006 clearance after wear , replacement bushings put you aroun .003. You need .001 max and that is only through custom machined bushings.
I believe that almost all rebuild / new boxes are just reconditioned with the same sloppy pitman arm bushings.
Have a nice day Gene and stay out from under that car. :) :)