Rear Uprights

Ian Clark

Hi Guys,

Thought some pics of our new Rear Uprights mounted on a chassis would show what we're aiming at with these parts. They weigh the same as the cast aluminum/steel mounting blocks bolted together assembly while being much stronger and improved cooling for the brakes and wheel bearings.

Like the new Front Uprights, these parts are intended for the "100 Series" cars made by or with parts from the original Cape Advanced Vehicles. Owners of post 100 s/n cars already have upgrades from Autofutura so these parts aren't applicable.

The new Rear Uprights optimize the rear suspension geometry in several areas: Camber climb, Roll stiffness, Coil/Over Shock travel, and work in conjunction with our Revised Lower Control Arms to give adjustable Toe-in and elimination of all binding from the rubber bushings replaced with Aurora Spherical bearings and rod ends.

The new Rear Uprights won't work on the stock lower control arms however there is a package price for buying both. The Revised Lower Control Arms will work with the existing cast upright though.

About Camber Climb, we reduced the height of the upper pickup point on the upright to reduce the angle of the upper lateral link. This cuts the rate of camber climb by almost half, meaning if you're running wide tires (295 >) the contact patch is better on the exit of corners so you can put down more power. Also tire wear is more even across the tread face, especially at lower ride heights.

About Roll Stiffness, by lowering the pickup point of the lower control arm on the upright the axle center went up and the lower control arm becomes horizontal or droops slightly downward at the hubs depending on ride height. By making the lower control arms horizontal to slight droop we raise the instantaneous roll center, thereby reducing the lever arm length which the sway bar controls weight transfer side to side.

The result is a flatter cornering attitude without increased ride harshness that would come from stiffer bars or springs. The roll stiffness has improved geometrically rather than mechanically. Same effect, without adding NVH, noise, vibration and harshness.

About Coil/Over Shock travel, simply lowering the pickup point of the lower control arm extends the shock length, gives back almost .750" on our existing A-Arms. A shock absorber mount modification on the jig means our new production A-Arms will have a full inch more travel.

Note how the shock mount on the lower arm is angled to match the rear castor (anti squat angle). This keeps the bushings in the coil overs free.

There are pics of the stock uprights installed (with our billet mounting blocks to fit the new arms) so you can see the angles compared to the new parts.

We've also revised the tooling for the new upright since the last postings so any brand of brake caliper/rotor can be accomodated. Shown are the standard PBR mounts, however AP, Brembo, Wilwood... no problem.

Still three choices of colour, black, aluminum or charcoal metalic. Still a core credit for the old uprights too, but you do get new SKF bearings of course.

There's a lot of potential in the CAV monocoque chassis, it's a really strong part. The purpose of these new suspension components it is to give the pre 100 series cars the absolute maximum performance from the chassis using bolt on parts and only hand tools required.

If you're doing any lapping days or plan to track the car occassionaly, these are must have parts. Enough techno-bable, how do you like'm?



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Ian Clark

Hi Guys,

The Steel Rear Uprights have been a tremendous sucess and the feedback from car owners using them is very satisfying. They are however not inexpensive to make. In the previous post I mentioned a package price since the new rear uprights won't work with the stock CAV (pre 100 s/n only) lower control arms.

CAV Canada is offering, for a limited time, GT40s Forum members a 10% discount on the package of 2) Reversed Lower Control Arms, 2) Steel Rear Uprights, spacers and hardware.

The regular price of the rear uprights is 1495.00 each and the lower A-arms are 890.00 each. The set of four peices is 4,770.00 less 200.00 package discount equals 4,570.00. With the GT40s Forum members 10% discount that comes down to 4,113.00, now take off 300.00 per core credit for your old uprights - net 3,513.00 plus shipping for the set! (cores have to be rebuildable)

Wow, that's a great deal... I think I'll buy some for myself:) Actually, it's my pleasure to offer a break to the GT40s Forum members and CAV owners. The 10% discount applies to everything we manufacture, Suspension Arms, ZF Rod Shifters, ZF Transaxle Bracket, Front and Rear Uprights, Grilles, Steering Colum Quick Disconnects and the soon to be available Big Brake Kit for CAVs with 17" wheels.

The pictures below show in more detail the differences between our Steel Uprights and the old Cape Advanced Vehicle (pre Autofutura) cast upright. Also we are producing a Wide Track Rear Upright version that moves the 10" wide stock offset wheels out to fill the Gulf arches - no more Buick Roadmaster fender overhangs!

The unpainted part gives you an idea of what goes into these uprights, they are brutally strong yet weigh no more than the cast aluminum/steel bolt together parts they replace.



With regard to the 'Wide Track' version, why go this way rather than fabricate longer top/bottom links etc. With this 'new' upright the wheel/tyre combo will have more leverage over the upright under acceleration/braking resulting in higher loads on the outer rod ends and increase the tendency to toe in/out in these conditions, especially if the rear rims are not widened inboard. Just the same as fitting rims with a large outboard offset to the front- the scrub radius goes to pot.

Jac Mac
Hi Ian,

Wow, nicely thought out and fabricated parts.

I'm late to the thread here but was just wondering what problems (generally) were being experienced with the old/cast rear uprights? Were they failing under high loads? I know all about the history of the earlier front uprights issues but don't know any of the history of the rears. Thanks!

Ian Clark

Hi Jac, Cliff,

Jac, On the surface it would seem the simplest solution to track width while keeping 10" wide wheels would be to increase the length of the upper lateral link and reversed lower a-arm. In fact our control arm jig has the provision to make both lengths and we have cars so equipped. So our first version went as you suggest.

When the first wide track conversions were done we were still using the original old pre Autofutura uprights, our CNC Steel part didn't even exist.

After closer examination of the relationship between the change in suspension operating angles (as the inboard lower pickup points also have to be moved to keep the trailing arms from touching the sill boxes) keeping the arm lengths the same and manufacturing a dedicated upright made more sense.

Having done so, and used in combination with the new Lower A-Arms the suspension is optimized to the limit dictated by the chassis pickup points. Really a good working setup.


The original cast uprights from Cape Advanced Vehicles (pre Autofutura and pre s/n100 cars) are fine for pleasure drives when properly installed and maintained.

The problem is that in order to align the toe-in shims must be installed under the rear most mounting bolt of the steel block that goes across the bottom of the casting. Since both parts are machined flat and parallel something has to give to make up for the shims.

Deflection forces are absorbed by the casting and steel block, you can probably quess which metal fails first.

Anyways we designed the new Steel Uprights to improve the geomtery to improve traction, thereby performance and balance, as well as provide a stronger mount for the bearings (we've seen oversized and egg shaped bearing bores) at the same time.

In the process of making it light, the ring of holes around the bearing bore also reduces heat soak to the bearings from the brakes and improves cooling to the brake vents, both obvious benifits. Hopefully this will increase the life of the CV joint lube as there has been boiling of the lube which leads to a joint failure (under track conditions).

The new Steel Uprights came after the Reversed Lower A-Arms so you can see how one improvement creates opportunites to refine other components in the vehicle system.

A customer with all the all four corners on his car, and an experienced racer too, said that a completely stock CAV GT was "scary" to drive in comparison. It certainly underscores why the new Autofutura CAV GTs have been so impressively upgraded and owners of the early style (pre s/n 100) cars are opting for our performance upgrade parts.

To be fair "scary" would be at track speeds, although guys who never drive their cars in anger report the car feels better to drive just around town. CAV Canadas' Race Parts are designed first and foremost as performance improving components, in the case of the uprights, you get a vastly stronger part as well with no weight penalty on the rears, with the fronts being about 2lbs heavier for the pair.

Again, kudos to Jean and Jean for the fabulous work in taking the production CAV GTs to a higher level, our Race Parts are meant only for the pre s/n 100 cars.

Hi Ian,

Thank you, that's very helpful. Understood on all here. One more basic question: do the new rear lower A-arms and rear uprights somehow provide for conveniently and properly adjustable toe? In other words some kind of threaded adjustment rather than shims inelegantly placed between two machined parallel surfaces?

Ian Clark

Hi Cliff,

Your correct, the new Reversed Lower A-Arms include an Aurora PTFE lined rod end to adjust toe.

After considering the advice of a respected formula race car designer, provision was made to mount the toe-adjusting rod end in a slotted tab rather than in a fixed tube as per original.

The logic is thus: the toe-adjusting rod end is traveling an arc that changes length whereas the length of the upright and reversed a-arm itself are fixed. You can see the two tubes vee out from the centre mount and are tied with a cross tube. This creates a situation where shims of varying (very thin) sizes would have to be used to prevent side loading of the toe-adjusting rod end, hmmmm....

I really had to think about that one, not only because he was right but it meant deviating from the original layout. A .002" crush on the rod end would jam the ball, increase friction and no doubt lead to premature wear or possible failure.

I have to believe the original GT40s were carefully set up to avoid this and that all the suspension components where manufactured to a set and close tolerance. The suspension was set and stayed that way until an impact or routine maintainance ocurred.

Since the old style (pre Autofutura) rear upright castings and mounting blocks all varied in length, it made the choice easy.The goal was to acheive simple toe adjustment, eliminate the rubber joints and allow full suspension travel (including anti squat) without binding.

The new lower a-arms are the single biggest improvement you can make to an early (pre s/n100) CAV GT and are the building block for other upgrades like the steel uprights.

Although not as astonishing in handling improvements, the new front steel uprights are the next logical (and necessary part). Or of course you could opt for the Four Corner Kit which is a pretty good buy right now.

Thanks for asking about the toe-adjustment, gave me an opportunity to explain the "method in my madness" about that part. The pictures below show an early installation on the old upright and the new a-arms alone and the Four Corner Kit.



Hello Ian, Great looking parts! Can you send me a PM on the price now for the front kit, Also do you offer longer rear hub studs for the pin cap nuts? If so I will need the cost for them as well, Thanks, Ken J

Ian Clark

Hi Kenny,

You can still get the sale price on the Steel Front Uprights by ordering now. With rebuildable cores, the price nets down to 1050.00 per corner, down from 1500.00.

Also the longer studs are available, we have Moroso studs machined to fit the CAV hubs. You can have it done locally if you know a good machine shop or it normally costs 8.00 each for us to do it. Ordered with the uprights you price is 50.00 for the ten required.

Looking forward to your order, these are great parts.

Hi Ian,
We are interested in obtaining this set of parts for a CAV replica chassis #0027, and I am wondering if they are still available. It looks like an excellent upgrade the the original parts we have on our project. Any leads and help on finding a set would be very much appreciated!
Front and rear uprights, rear A arms and all related parts. Do the lower struts need to be replaced/ shortened? Can we still run our existing brakes or is there a recommended caliper/rotor upgrade as well?
Thanks for your support in the forum here!

Brian Kissel

Staff member
Lifetime Supporter
Doug, this thread is over 12 years old. Ian still visits, but is not as active as he once was. If he doesn't see this and respond, you may want to send him a PM.

Just a thought.

Regards Brian
Hi Doug, i've been in touch with Ian over the last few month on exactly the same topic. If you cant get in touch with him here, I have his email adres through which you could try to contact him. Send me a PM if you want to.
(I have CAV #22)