C5 suspension measurements?

[Scooter70]

Does anyone have C5 control arms and/or spindles available that they could take some measurements? I'm looking for arm lengths for upper and lower front and rear control arms from the pivot of the ball joint to the pivot of the bushings as well as a length from ball joint to ball joint on the spindle. Does anyone know the stock kingpin or upper control arm angles on an "off the showroom floor" C5?



I'm doing some thinking and want to model a few things in CAD. If I get good measurements, I'll post some annotated drawings for the community to use.

Thanks in advance.

-Matt

[boodlefoof]

Hey Matt,

Can't help you out, but I'm looking forward to your responses. I'm considering putting together a C5 component based suspension for my Datsun Z project.

[silver69camaro]

Front UCA/LCA Length (BJ Pivot to bushing centerline):
UCA: 8.55"
LCA: 15.96"

UBJ to LBJ: 12.614"

KPI depends on your own design, and can be improved from stock by changing the geometry. Stock is around 9, I think.

Off hand I don't know the angle of the upper control arm.

If you want, I can verify your drawings to what I have. Hope this helps!

[Travis B]

does anyone know what the anti dive angle is on the c4 or c5??

[Scooter70]

Thanks Matt. Are these front view dimensions or true length for each arm of the A? If I have time at work tomorrow I'll put those in a drawing and compare to what you have.

I was wondering what stock KPI was to compare to what Herb Adams says. (He says 7-9* is preferred.) Upper control arm angle is going to determine the instant center so it's a matter of design, right?

-Matt

[Mean 69]

KPI depends on your own design, and can be improved from stock by changing the geometry.

Really? How would you do that with a stock spindle?

The C5 spindle, as I have come to realize through close analysis, is one heck of a well designed piece. It's tall (as stated above), strong, steep KAI and shallow mounting width (i.e. very small scrub radius when used with the correct offset wheels), and (relatively) cheap. However, it has been stated several times here, there, and everywhere, that you can't "merely" swap a C5 setup into a car and expect it to work. One main issue is trying to locate the rack and pinion unit, the C5 uses a relatively high steering axis, so you have a couple options in order to make it work with a typcially placed American V8 engine in one of our cars: 1. Move the engine back several inches and leave the rack basically where it is relative to the factory intent, which is cool in that you move the center of gravity slightly reward for better front to rear weight balance (and this is exactl what has been done on one aftermarket subframe offering), but not so easy for most folks, or: 2. Raise the engine up a couple of inches(!!!!!) in order to clear the rack, the clearly obvious downside is a raised COG, and potentially less clearance under-hood (this too has been done, but one should question the overall benefit of an improved geometry versus a raised center of gravity?? We're scratching our heads!), or: 3. Use the C5 spindle, make certain that the suspension geometry is correct for the differing track/overall width relative the wide, low C5 cars while still allowing the use of all of the original layout pieces (clutch linkage, motor mounts, driveshaft, etc), and as importantly, FIX the STEERING.

Not so easy to find the best solution overall. Trust me. BUT! I would encourage anyone to model it all out, the education is priceless, you will learn more than you think. Good luck.

Mark

[Scooter70]

Not so easy to find the best solution overall. Trust me. BUT! I would encourage anyone to model it all out, the education is priceless, you will learn more than you think. Good luck.

Mark

Thanks for that Mark. The education is what I'm after right now.

[astroracer]

Not so easy to find the best solution overall. Trust me. BUT! I would encourage anyone to model it all out, the education is priceless, you will learn more than you think. Good luck.
Mark

Having the arm length really does no good as far as modeling the "suspension". You HAVE to know where the bushings, ball joints and tie rod points live in 3D space. Without the X,Y & Z points you have no way to locate the suspension components relative to one another as they were designed initially. This has to be done for the suspension to work properly.

When I designed the Bad Ast front suspension I started with C6 points but ended up with points entirely different from the Corvette in order to get my combination of spindle, tire/wheel size, steering rack and track width to work correctly.

You may want to download the demo program from Performance Trends...
http://www.performancetrends.com/SuspAnzr.htm
The demo has some canned suspension designs and I believe the C5 is one of them.
You can learn a lot by dinking around with the points but the program does not give you any help as far as what is good, bad or better for all of the results. I found that trying to match or improve on the Corvette numbers worked fine but I still needed some help and direction from a board member to get my suspension where I really wanted it to be.
Mark

[silver69camaro]

Really? How would you do that with a stock spindle?


Mark

Oops, sorry Mark, I wasn't clear. I was referring to a fabbed spindle I had seen a while back for C5 suspensions. That's what I meant by "your own design".

Mark is right on the C5 spindle. It's a darn good piece. It's easy to get the scrub down to .250", maybe less (but I haven't tried).

Matt, those measurements are from a top view. So, really, you could get the angle of the UCA if you set the UBJ the spec'd distance away from bushing centrline. Does that make sense?

[Mean 69]

Thanks for that Mark. The education is what I'm after right now.

Ast' suggestion to download Perf Trends suspension analyzer is a good one, they will let you try the full vehicle version for ten days, it is pretty easy to use once you figure out the peculiarities on data input, etc. One very cool thing is that they include the C4 Corvette front (and rear) suspension, as well as a good number of others (lots of circle track stuff, neat to see how they offset/bias for left hand turns only), you can make changes to any of them and see what the results are really efficiently. We use Bill Mitchell's WinGeo, but that is a preference of Katz', he has used it for years, both work really well. Get the available literature too, there are a number of posts that list some of the better books, they are invaluable. Like the other Mark stated, you will will ultimately end up with something that looks different anyway, if you don't restrict yourself to using specific parts, but you do need to start somewhere. The spindle is the hardest donor part to find, interestingly. I'd personally recommend choosing this first, then play around with control arms, and get the suspension where you'd like it for your application. After that, fit the steering in, this is where the fun begins and where you start iterating the design until you are ready to implode.

Oops, sorry Mark, I wasn't clear. I was referring to a fabbed spindle I had seen a while back for C5 suspensions.

Gotcha. Which one is this? Not sure I have seen it?
M

[Scooter70]

Having the arm length really does no good as far as modeling the "suspension". You HAVE to know where the bushings, ball joints and tie rod points live in 3D space. Without the X,Y & Z points you have no way to locate the suspension components relative to one another as they were designed initially. This has to be done for the suspension to work properly.

When I designed the Bad Ast front suspension I started with C6 points but ended up with points entirely different from the Corvette in order to get my combination of spindle, tire/wheel size, steering rack and track width to work correctly.

This is what I'm trying to learn.

You may want to download the demo program from Performance Trends...
http://www.performancetrends.com/SuspAnzr.htm
The demo has some canned suspension designs and I believe the C5 is one of them.
You can learn a lot by dinking around with the points but the program does not give you any help as far as what is good, bad or better for all of the results. I found that trying to match or improve on the Corvette numbers worked fine but I still needed some help and direction from a board member to get my suspension where I really wanted it to be.
Mark

Cool. I had already downloaded the program, I just hadn't installed it yet. I just did and you're right; it has everything that I didn't know I needed. Like Homer Simpson said, "There's just so much I don't know about astrophysics." ;)

I'll try to put all of the information into a usable format and post it here for future reference.

Thanks.
-Matt

[silver69camaro]

Gotcha. Which one is this? Not sure I have seen it?
M

The spindle was on a '67 Camaro I had seen had Pacific Raceways this past summer. I didn't get the guys name, but he had a 3x3 front subframe setup with C5 components, but a home-made spindle. It accepted the stock bolt-on hub, but everything else was steel tubing and gusseted. It looked impressive.

I don't know how many people are out there doing that, but I figure there's more than just what I have seen so far.

[B Schein]

I just am wondering how many people here have made there own spindles. I know I have it is no slight task to take on. I am fortunate enough to own my own CNC mill, and also work in a vary large machine shop that has just about every type of machine you could imagine. I took me a lot of time to figure out the right sequence of doing things and I also had to make a few fixtures. And this was working from Katz very detailed drawling. So I cant imagine how much of a task this would be to do all the design work do all of the analysis on and then also build. I am just being real here It is a lot of dam work don’t try and kid yourself it will be a much more daunting task than you think. I like Mark approach best pick you upright wisely and connect the dots from there.

[silver69camaro]

Brian,
Mark's idea for developing a suspension is the best choice for 99.99% of the people in the world!

IMO, the most daunting task of developing a spindle is not the manufacturing process...but the design process. Spindles should be designed such that they can have nearly unlimited miliage, and should survive the worst pothole in the world. These are some of the design parameters set by automotive engineers employed by major automakers. It must never, ever, ever experience catastrophic failure (e.g. pin fracture) in the real world.

That being said, how do you test a spindle for such parameters? Unfortunatly, the only real way to do it is real-world testing. It must be installed on a vehicle and driven, hard. I'm not talking about turning corners real fast, but loading down the vehicle while driving over a set of square speed-bumps at high speeds while turning a corner hard (C5 spindles were tested in this manner, and actually cased a cease production order when one spindle broke).

So here's Joe Blow, just like you and I...how do we test a spindle like that? Well, we can't. Guys like you and me, and everybody on this board (unless if you have the R&D resources like Ford or Toyota) typically do not have the ability to preform the proper tests. I've done my share of spindle testing, and any test except for real world tests just tell you "spindle A is probably stronger than spindle B in this ability". It's frusterating, but that's just the way it is.

In the end of this long winded post, be aware that if you do want to make your own spindle, be prepared to go through three major phases: geometry design, failure prevention & analysis, and manufacturing. When you're done, it will be one of the most rewarding objects you've ever created.

[B Schein]

I agree that the design is and was the hardest part, but with that said machining a upright from a very large and expensive piece of 7075 Al is can be nerve wrecking and a tedious process when you don’t have the same resources as the big three.

I see people throwing out the idea of making the there own custom uprights like it is no big deal every day thing, and I just don’t think it as easy as other may think.

[silver69camaro]

I see people throwing out the idea of making the there own custom uprights like it is no big deal every day thing, and I just don’t think it as easy as other may think.

True! Many have constructed their spindles of alloy bar, tube, and plate. Looks killer, and can be very reliable. Some circle track spindles are made this way, it's alot easier to do. Never seen one on the street though, but I guess it could be done.

Did you make any foam or machinable plastic/wax prototypes?

[B Schein]

No I didn’t make any prototypes types just went straight to the real thing I only need two but had enough material for four do to carefully cutting my stock.

[Scooter70]

I put all of the C5 suspension points (from Performance Trends Suspension Analyzer v1.1) into an Excel sheet. It also includes three views of the front and rear for easy reference.

Right Click -> Save As

-Matt

[70 LS1]

I put all of the C5 suspension points (from Performance Trends Suspension Analyzer v1.1) into an Excel sheet. It also includes three views of the front and rear for easy reference.

Right Click -> Save As

-Matt

Thanks, Matt, I'll take a look at it.

[Marcus SC&C]

Some more notes about C5 suspension parts. We`ve been using C5 steering knuckles (spindles) in our G-5 suspension packages for about 4 years now. We always have a few kicking around the shop. They`re great pieces but not without their problems (on cars other than a C5 or C6!). The steering arms,as Mark mentioned are much too high for most applications. The knuckles also have roughly 2.5" more "drop" than for example A body spindles. That can be on the verge of too much for some aplications. The upper ball joints are not available seperately (although I have LOTS of new ones it anyone needs any!) and unlike most other knuckles the body of the joint is pressed into the knuckle and the tapered stud points downward and fits into tapers in the arms. To achieve proper geometry on earlier cars it`s usually necessary to raise the upper control arm mounting points significantly.
We solved the steering arm issues by milling them off and designing new bolt on 7075 T-6 steering arms. We`ve got a lot of time in them because the design of the knuckles doesn`t lend itself to it easily. The arms also reinforce the hub/bearing mounting area. There were 7 machining steps applied to the spindles themselves to adapt them to the final overall configuration also. Little things like the fact that C5 lower ball joints have much taller tapers become real world anoyances. We looked into the arms also but the upper arms didn`t lend themselves easily to adaption because of the odd dual mini cross shaft configuration. The lowers would require a scratch built crossmember and mounts. It`s also worth considering that those arms were designed for a 3000lb sports car with 51/49 weight distribution,aluminum small block and rear transaxle. A 4000lb Chevelle with an iron big block (or even small block) could exceed the design load parameters of those arms by a very considerable margin. When you factor in higher amounts of weight transfer under hard braking from a higher CG etc. too....
The last few custom suspensions we did I built around tall ATS spindles. They`re stronger pieces (higher grade alloy,thicker cross section over shorter spans) and their overall configuration (steering arm mounting holes,less spindle drop,normal upper ball joint configuration ,interchangable ball joint tapers in typical sizes) makes them MUCH easier to work with.
It would be pretty neat to do a C5/C6 upgrade on an earlier Vette though,just to keep it all Vette. We actually did that with a `57 Vette subframe but due to steering arm/caliper clearance issues we ended up using AFX spindles on that anyway. It`s not as cool as using all Vette parts but it works better in this case and saved the customer a lot of money in custom machined parts. Mark SC&C