Rally car suspension project

[Chuck Moreland]

This car rolled off the transporter this AM. An interesting and unusual project, we will be building a rally suspension for this.

The customer is from St. Maarten VI and though he doesn't plan to race it, he has a couple reasons for the rally approach. Apparently road quality in St. Maarten is poor and wants the added height and travel to accomodate it. He's also been inspired by the Rothman's Paris Dakar cars.

However he'll be taking a milder approach on the appearance, passing on the Rothman's liviery. The car should still be strikingly unusual in appearance, with the wide body, turbo tail, and rally height. The customized suspension should be somewhat visible, poking out the bottom.


We'll be raising ride height about 2.5" from stock, and with customized struts up front to keep the geometry in check.

I'll post occasional updates on the project here.

We'll be posting near-realtime updates on twitter. Follow at http://twitter.com/elephantracing

[Zeke]

I'm all for cool improvements, but why didn't he just buy a Cayenne?

[Chuck Moreland]

I'm guessing he wants a Porsche, not a truck

[911st]

I have wondered about putting a Carrera Tail rubber on the turbos base. Bumper rubber delete and a set of hood lights would be cool to. Might make it look a little more like an SC/RS.


Enjoy.

[snbush67]

This is going to be good....I always liked the rally look, have you thought about all wheel drive? What tires are you going to use?

[RWebb]

yeh, maybe you can use Wayne's 959 as a parts car

[Rich Lambert]

I think "strikingly unusual" is an understatement. What's the plan for shock valving & T-bars (coil overs?) - a firm ride or something that sucks up the bumps? Quick-disconnect sway bar down links for really bad roads? What a neat project for you guys! I see an Excellence spread in your future.

[willtel]

This is going to be cool. I have had a few twisted visions of running my 930 in the Sandblast Rally (http://www.sandblastrally.com/2009/) but the thought of leaving my headers on a rut always gets the best of me.

[m110]

I would argue SUVs are neither sport, utility or reasonable vehicles. Turning a 911 into a real SUV is great...I have had this in the back of my head for some time. I think a 964 might be an easier application with coils and could be 4 wheel drive. Also pretty cheap right now.

This is going to be sweet.

How high would it need to be to need modified A-arms?
How high were the Paris-Dakar 954/3 at the fenders?

[Talewinds]

Speaking of understatements, calling the road quality in St. Maarten poor...., now THAT'S an understatement!

[Chuck Moreland]

We will be staying with torsion bars on this car, and they will be 18.8/25mm. The goal is to keep tires in contact with the road surface, and on a bumpy road surface that means soft springs and a lot of suspension travel.

The real challenge is to keep suspension geometry working right with the added height. Most of the cool mods are to the front struts.

We did discuss more radical modifications including relocated front and rear pickup points, and coilovers, but the customer opted to stay within a more manageable budget. 4wd was never considered due to cost considerations

[Kroggers]

This will be fun

[stevemfr]

Chuck,
Have you considered a combination of T-bars and coilovers - something along the lines of an SCRS? Wouldn't that make fine tuning a suspension with long travel easier? And, with a large portion of the springing being done by the T-bars, strengthening the shock mounts might not even be necessary for a non-competition car (aside from tying the front towers together - but you're prob doing that anyway).

Just curious because I've been mulling over this for my car for a couple of months - not because I want to go off-road, but to allow for quick adjustability from street to track for a dual-purpose car :-)

[911st]

Any skid plates planed?

[RWebb]

nice thing re coil overs is ability to have progressive spring rates

sounds too spendy for this owner tho

[Chuck Moreland]

Tired front suspension, with turbo brakes.



Control arm bushings are fairly deformed. The one on the right is noticably worse than the left. The car is an '84 and has only 4x,xxx miles on the clock. Still 25 years is enough to ruin the bushings just due to weight.



One of the torsion bars has been rubbing. This one will be replaced.




To the coilover ease-of-adjustment point, this car is getting QuickChange Spring plates so ride height is as easy (maybe easier) than coilovers.

[chris_seven]

We have used 18.8 and 26mm bars on gravel and Bilsteins set to '1000 Lakes' valving with quite reasonable results but the rules we run to minimise the changes we can make.

For the East African Safari I would use a good 3 way unit such as an Ohlins or Proflex which will probably be worth between 1 and 2 seconds per mile.

The Safari Rally cars of 73, 74 and 78 all suffered very badly with rear shocker breakages with Bilsteins which stopped them from them from winning and the manner in which the shocks are mounted needs some revision.

The shell will almost certainly need to be reinforced to stop it cracking and to maintain geometry and the front end tank guards assist with keeping good alignment. Rear guards are quite important as well and we also have Kevlar floor guards to reduce damage.

The roll cage is normally extended through the rear seat back to pick up on the chassis rails to reduce flex in this area and it is important to lift off the fuel tank support panel and fit some strengthening and tie the front control arm mounts together.

Steel trailing arms have a tendancy to bend on rough events and it is common practice to cut them open and strengthen internally. We have used aluminium arms quite successfully without any mods.

I would also tend to lose the rear sway bar and soften up the front end bar.

We run gravel cars on 6 x 15 front and 7 x 15 rear with 70 profile tyres from Dunlop Motorsport. The 70 profile is mandatory and I would like to try a 60 profile to see what happens.

We also fit early 2.7 turn steering racks and Turbo tie rods and Nylatron bushes with uprated rubber engine mounts.

Braking on gravel seems to be quite satisfactory with Aluminium S/RS/Turbo Calipers and standard vented discs on the front and M type rear along with a Bias Pedal Box to give adjustment. A hydraulic hanbrake is also very useful.

We fit 3.3 Turbo calipers for Tarmac when we need a bit more braking.

The transmission has quite a few mods as we have to use a 915. We always fit a teddy bear and 'our' box is an SC derived unit with an aluminium case and an 8:31 Ring & Pinion.

1st gear is stock and 2nd/3rd/4th and 5th have all been lowered. We run a 5th gear that gives about 120mph at 7500 rpm with 195 x 10 x 15 tyres. I also like the Wevo internal gate kit. A plate type LSD is fitted with about 50 lbft preload and 40/60 ramps.

[eimkeith]

Chris, are you with Tuthill?

[chris_seven]

Keith,

No we have our own business and our own bodyshop.

Cheers

Chris

[Chuck Moreland]

Front suspension freshly powder coated. You get a glimpse of the strut mods, lowered spindles, gussets, and double shear bump steer setup. The tie rod will be above the normal steering knuckle instead of the normal position below.

I'll post more on the struts later.