With coilover setups, why not relocate the LCA too?

[R.O.B.]

While doing research for differant setups to improve the handling of a 1967 mustang, I noticed a lot of strut and coilover setups. Yet these all use a new beefed up lower control arm still mounted in the stock location. Correct me if I'm wrong, but at a normal ride height, the stock set up has that LCA at like a 15* angle, not perfectly flat, say like newer mustangs. And all of the aftermarket setups put their new LCA in at this same angle. Doesn't this still cause lower quality handling? I mean, the whole strut coilover setup will vastly improve the handling, but with a relocated LCA, wouln't the handling be even better improved because the geometry will be improved?

Rob

 

[fast_back_gta]

Stuff like this is really interesting, I wish i had more knowledge on the matter.

I thought the old Trans-am race cars had their LC point lowered.. seem to recall i've read that somewhere.

I'm not sure though but is'nt for instance Global Wests lower control arm angled in a different way than the stock arm? Not sure what that would do to the geometry though.

What would you suggest be done to improve?

 

[R.O.B.]

I was thinking something like a K-member would be done. Either lowering the mounting point of the orginal lower control arm, or using newer style arms. For example, if were talking about switch over to a coil over setup, say like RRS. They will use a SN95 spindle. Well, why not use the SN95's lower control arms too, and have the suspension geometry mimmick a SN95.

 

[ron67fb]

Why would you lower the mounting point? Once the arm goes beyond horizontal in bump your camber curve is going the wrong way.

 

[R.O.B.]

Why would you lower the mounting point? Once the arm goes beyond horizontal in bump your camber curve is going the wrong way.

Well, I'm no engineer, but I'm looking at old vs new. My old '67 had the lower control arm's mounting point on the frame rail, and so when it reached the spindle, it was sitting at a serious angle. Now take a newer Mustang, say my buddy's 1995. It has the lower control arms mounted horizontal, and yet his will out handle my any given day of the week. I would assume if the old 1967 way was better, Ford and Chevy and the likes would still be doing it today, but their not, they and even the imports ALL have the lower control arm mounted horizontal. I can only assume that this must make for a superior geometry, but I could be wrong, hence why I'm asking here.

 

[R.O.B.]

I should add, the best way to prove/disprove this would be to have a suspension geometry program, and then plug in both ways and see who wins, but I cannot afford the $500+ for the program.

 

[Rusty67]

You would be surprized how good the geometry was on the classic suspension. If you want to convert to a lower A arm, that would be a nice upgrade but I think the possition it is in is fairly reasonable. You might like this setup:
Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks

I have it on my 67 and with the 17in SN95 rims I have with almost totally spent tires, my 67 takes the curves near my parents house almost as well as my SN95 daily driver and believe me, my DD is not stock.

The one thing that kit doesn't have is a set of OpenTracker roller perches. Definately a worth while addition.

 

[R.O.B.]

Thanks for the link, and it would appear that this reinforces my ideas of relocating the mounting point of the lower control arm. After all, your car handles better now.

 

[Rusty67]

This kit does not relocate the location where the lower arm bolts in, it adds a second mount to use an A-arm. The original mount location is used in conjunction with the added location on the crossmember. This gets rid of the strut rod and creats a full blown lower A-arm.

 

[R.O.B.]

Sorry, it was hard to tell. The link shows the picture for Nova's, and I can only find how to buy Mustang kits, not pics.

Well, does anyone have any more thoughts?

 

[Rusty67]

The early Nova's and the Classic Mustangs had almost identical suspension. The pic would look the same for both sets. If you want to see some pics of them installed on my 67 you can look here:
Untitled Document

 

[rbohm]

my advice is to leave the lower control arm points alone. any gain you get in handling are going to be minimal at best, and you will get worse bump steer. lowering the upper control arm pivot point is the best way to go for better suspension geometry.

 

[fast_back_gta]

Rusty67,
What's really the improvement with the Classic perform kit over an adjustable strut rod and "normal" lower control arm?

How do you set caster with that setup?

 

[Rusty67]

I think it depends on how the adjustable strut rod is put together. I think if you were to have one like OpenTracker's then you wouldn't see as much of a difference. The issue with the strut rod is that the rubber bushing allows the strut rod to move back and forth towards the front of the car and also towards the rear. This changes the true alignment of the car moment by moment in hard cornering and gives an unsure feel. If you look at video of a car from the profile view on hard cornering, the tire appears to be moving back and forth or possibly appears to be oval. This is from that play and it makes the car feel very unceartain. I know for a fact about this because I drive my cars around the curves near my house very hard quite often. After this setup was put on my car, that feeling in the front end is gone. The main issue I worry about now is my rear breaking loose.

The lower A-arm in this kit is a tublar setup which is extremely strong and stiff. It has a replacable ball joint and bushings made of a space age polymer which last longer then poly but don't ever squeek like poly. To get a stock arm to work almost as good as this one, you would have to have a boxed control arm, screw in ball joint (to match the serviceability) and replace the rubber bushing with a poly bushing. The poly bushing I had in my stock control arms seemed to contribute to harshness in the ride of the car.

I can't say for sure but I imagine the tubular a-arm would still be stiffer then an adjustable strut rod bolted to a boxed stock control arm.

Both mount points on the arms have cam bolts for adjustability. If you need more you can always put shims on the upper arms.

One kewl thing about this is they sell just the lower setup too so you can keep the stock upper control arm and just replace the lower half if thats all you need. There really isn't anything wrong with a boxed stock upper except the weight issue. A boxed stock control arm and some roller perches with the CPP lower setup should work as good as what I've got. Altho, I will say the upper they make does look rather sexy =)

 

[ron67fb]

I should add, the best way to prove/disprove this would be to have a suspension geometry program, and then plug in both ways and see who wins, but I cannot afford the $500+ for the program.

You don't need a $500 program, all you need is a pencil and piece of paper if it's so hard to understand the concept. Besides, how do you "win" on a suspension plotting program? It's already proven by simple geometry that a control arm angled down has a better camber curve than a horizontal one. Successful autocrossers using Fox-bodied cars and 3rd-Gen F-bodies have always known that lowering their cars past the arm going horizontal actually hurts handling, because of the geometry issue I pointed out. Saying X-car "handles better" just because of the LCA being horizontal proves nothing. A go-kart "handles better" having no suspension at all, so what? It all depends on the packaging and design of the entire suspension, not just moving one pickup point and calling it done.

 

[R.O.B.]

Hey Rusty67, thanks for the picks, that helps alot. I guess a good way to go would be using their lower kit, and then doing the strut coilover setup. Does anyone know if the ball joint from this kit (to fit a 1967), will fit a SN95 spindle?

 

[Rusty67]

You do know that the McPhearson strut setup on an SN95 Mustang is an inferior setup to the classics setup right ? Also, using that type of setup puts all the load of the spring and strut directly into the shock tower cap instead of into the shock tower. I would say away from this.

Another problem is you will now need to replace the top shock cap with some sort of camber caster plate setup as you will no longer have an upper control arm.

I'm totally serious when I say don't try to put an SN95 spindle on a classic Mustang. There are better ways to achieve a coil over setup.

 

[R.O.B.]

Well, I'm not totally into the coilover idea. What I really want to do, is improve the handling of this car, 1967 coupe, and have better steering and brake options too. All while doing this on the cheap (if possible). I have found that using the coil over setup with struts and SN95 spindles, gives me the options of Cobra brakes, and the option to do rack and pinon. I know that the handling of my coupe SUCKS! I also had a 1986 Trans AM, and that car handled like a corvette, and it was all stock! I want my Mustang to handle as well too. I'm looking at all possible ideas here.

I just always thought that although its better to do upper and lower control arms vs struts to build a better handling car, the eairly Mustangs were not designed good, and the camber curve is backwards. (tires swing out on the up and down, not in).

 

[Rusty67]

Trust me when I say these cars can handle. My friend use to circle track race Cougars which are basically the exact same car as a Mustang and he SPANKED the Chevy guys around the track ALL DAY LONG.

Its all in how you tweek the suspension.

The classic Mustang suspension is much better then you think. I think you should consider the CPP lower setup and a set of OpenTracker roller perches. Do the Shelby/Arning drop and get a good pair of shocks. If you want better handling then that then I'd say slap some good full length subframe connectors on there.

As far as the steering is concerned, do you have manual or power ?

 

[69gmachine]

Because it's not necessary

To answer your question, it's simply not necessary to relocate the lower arm because as you lower the car using the adjustable coil over, the lower arm straightens out to horizontal (or nearly so depending on how low you go) as a result. Mine are almost perfectly horizontal as it sits now.