Front A arms

Mike,

DeTomaso did it for the Si and Performance Automotive Technology (http://www.patsauto.com/) did it for their Si clone. I've seen photos of Si front control arms next to standard Pantera front control arms and the good news is, the extra 4" in length is all outside of the sway bar and shock mounts. If you wanted to fab' a set of longer front control arms, the way DeTomaso did it, the only other modifications required would be tie rod end extensions and longer brake flexible hoses. You might also need stiffer front springs and a stiffer front sway bar to compensate for the increased leverage of the longer control arms. Also, while you're fab'ing new front control arms, you'd want to move the upper ball joint rearward and lower ball joint forward, for increased caster. If I recall, the Si front wheels had +56mm offset vs the 15" x 8" Campi's 19mm. The Si also has one of the upper control arm chassis mounts higher than the other, in order to put some anti-dive geometry into the front suspension.

David,
Thanks for the reply. I just started this project last month and quickly realized that the front suspension needs modification. Fortunately, I am starting with a rust free shell. I have coilover shocks (adjustable) all around and big Wilwood brakes so far. My goal is to sort out the suspension geometry then dial in springs and shocks. Sway bars will be last to get the balance right. I believe an adjustable upper A-arm is in order for caster and camber adjustment. Not crazy for a lot of anti-dive. I'm trying to plot the suspension geometry to better make decisions about modifications. It is a street car so I need to not get too carried away.

I have modified a few sets of front upper A-arms to provide more caster adjustment. I run 6.5 degrees on my GT5, I also found tire brand choice made a big difference. I fabricated a jig to set the a-arms up in and ensure geometry.

The modification is well documented;
http://pantera.infopop.cc/eve/...0042044&m=9830021654

If you don't already have wheels and not using original style Campi's then you are more open to fabricating longer a-arms and modifying wheel offsets to compensate like the Si's had.

Julian

Joules,

Thanks for the photos. Nice work.
Have you ever extended the length of the upper and lower A-arms to deal with the excessive scrub radius? I haven't figured out the exact amount yet but am thinking they needs to be between 2" and 2.5" longer. Sway bar loading of the lower A-arm might necessitate some reinforcing.

Mike

I went through this exercise some time back. The first thing I did was build an adjustable jig. With the jig I mounted the original suspension and was marked and adjustable to incorporate changes before building another set of arms:



I have since given this away.

Second I approached it slightly different and laser cut arms. I was able to make the changes needed in the drawing program. Being able to draw meant I could add or change any parameter I wanted. The arms were cut and welded. There are several things I really liked about these arms:

1. Easy to change target specs

2. The arms look original!

3. The arms are adjustable in caster, width and caster.

Mine have 6.5 +/-1 degrees of caster. (I am running power steering).

Since getting the car running I have found I was a bit tight on the fenders. I was able to pull the a-arms in and gain more clearance. That kind of adjust ability is enormous. If I don't like the dimensions, modify drawing, re-cut! I have no spacers as the a-arms are cut to fit the car.

I am too swamped to make another set at this point but it is a different avenue to pursue. I also don't have other Pantera's here to test them on so the project has basically be shelved:

Nice work!
Thanks for the photos.
What gauge steel did you use?

Mike

Mike,

Another guy to talk to about having longer control arms made is Paul Chandler of Chandler Chassis Concepts. Here is a link to some of his work:

https://get.google.com/albumar.../5667219342518315842

http://chandlerchassisconcepts.blogspot.ca/

I made all new A arms for my narrow body car after looking at everything that was available in the aftermarket. I widened the front arms 1.5" and also compensated for the lack of caster by moving the ball joint locations. I also made them fully adjustable and used the much more common Chrysler ball joints.

Another pic

And another

Another way to handle excess front scrub radius is to use wheels with an extra 1" of negative offset. The stock 7" Campys have about 1" of scrub radius and the 8" Campys have virtually none.

Unknown what scrub radius the 10" wide Gr-4 or GR-5 front wheels have.

Beautiful job!! just finished refurbishing of front suspension, do you sell the A-arms?

quote:

Originally posted by randy37:
And another

Randy37,

Very nice work!
Do the Chrysler ball joints fit into the Pantera uprights (spindles) as is or do the uprights need to be reamed?
Do you make parts for others?

Thanks,
Mike

Well executed Randy, the only disadvantage I see is non adjustable caster, typically the narrow body cars are best at 4.5 degrees and wide body benefit from 6.5 degrees, although you could make them fixed for each body type.

Julian

Thanks for the compliments guys...as for making these for others I would be worried about the liability...unfortunately my own car has not seen the road yet so I don't even know if these are going to work or even stay in one piece.

I actually e-mailed the guy mentioned earlier (Chandler) to see if he was interested in making some for me but he never responded so I decided to give it a try.

Rc Mike, I had to ream the uprights to get the Chrysler ball joints to fit as the Pantera has an uncommon taper.

Here is a pic of the rears:

And another

quote:

Originally posted by Joules:
Well executed Randy, the only disadvantage I see is non adjustable caster, typically the narrow body cars are best at 4.5 degrees and wide body benefit from 6.5 degrees, although you could make them fixed for each body type.

Julian

Thanks Julian, I moved the upper and lower ball joint locations in my design to achieve 6 degrees caster and they are further adjustable by using spacers at the rod ends.

Superior craftsmanship. And sorry for next comments, but...

I've seen a Pantera almost crash totally when a home made a-arm came apart. I wouldn't dare run anything other than OEM on things that hold the wheels to the car.

Again, I'm impressed with what is done here, but consider what you're playing with it you use something built by a non-OEM: Your life

Mikael,
Your point is a good one. Good craftsmanship is only part of the equation. Good design and sound engineering is equally important. The entire system must be considered. For example: Are the stock suspension mounting points adequate to deal with the increased load spike caused by going from compliant bushings to spherical road ends? I'm not saying they aren't but all aspects should be considered. With my favorite fabricator now retired. I'm looking for a skilled fabricator to execute my design.

Mike, there are hundreds of Panteras driving around with fabricated rear upper control arms and many others with fully fabricated suspensions, including some machined from aluminum billet. The only suspension failures I've ever heard of were all caused by a failure of a suspension mount, either due to poor welding at the factory or corrosion. Keep in mind, when our cars were built, the manufacturer never anticipated the forces exerted on the chassis by our present day 18", 19" or even 20" tires and/or our modern brake upgrades.

Just got it all working the right way, sooo smooth, so stoked!