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If you come race with Club Fred at the ChampCar Laguna race this November, I can let you take a look at the G-force set-up that I installed in my car. I will email you separately with details on the race. There is still a seat open.
Unless your rules require it don’t build one of the classic tri link systems that fit entirely within the tunnel. It is much easier and better to go ahead and cut a hole in the floor for the top link to come through, install the front mount inside the car, and use a straight link for the top link. You can make the front mount adjustable so you can adjust your instant centers, you can make it strong by tying it into the roll cage, but most importantly you can use a straight upper link with a right hand and left hand rod end it makes it really easy to adjust your pinion angle.
When you mount the tri link in the tunnel you end up being very close to the drive shaft and it is easy to rub. You are also limited to the small OD stock RX7 drive shafts, many cheap aftermarket driveshafts could work but are too large to clear the tri link mount. Panhard bars are really simple in these cars, all you need is some angle iron and 1-inch square tubing. Do make sure you weld some extra angle iron stiffeners to the chassis points where you attach the Panhard mounts. 2 details you can see I did with my Panhard bar is I cut down the front back sides of the angle iron mount, you mostly need strength in the side to side plane. And I added a layer of steel in the area where the bar attaches to the fixed mount, so it is ¼ thick instead of just the 1/8 thick angle iron.
If you go look at Mustanghammer’s build thread you will see good pictures of both the straight tri link setup, and a much more elaborate Panhard bar system which uses toothed plates for adjustment.
Thanks gents. Assuming I continue this build, it would not be constrained by rules about where the 3d link is located. So inside the car is ok instead of the old school G-force setup.
Right now, I'm trying to decide whether to continue or whether to give up and get rid of it... Part of that is how much $ it's going to cost me to get it where I want.
Are you doing the fab-work yourself or paying to have it installed. If you are doing the work, parts are pretty cheap. Just takes time to get it set up and installed. If you are paying someone else.....well it would depend on who does the work.
One thing that I haven't seen discussed is that to optimize a 3 link you also need to think about the location of the lower control arms. Once you lower an RX7 more than a couple of inches, the lower control arm geometry gets all messed up. The mount for the arms needs to be lowered at the rear axle (easy) or raised at the chassis (hard) to get them in the proper geometry. Techno-Tuning makes drop brackets that make this easy or you can fab your own like I did. On my STU car, the lower control arms are connected 3" lower than stock. The EProduction cars I am familiar with had a "traction bars" that were 2.5" lower than stock.
Note I also lowered the shock mounts on the axle on my car because lowering a car eats into shock travel. Adjustable shocks that get bottomed out don't live long
I don't have welding skills so I'd need to pay for fabrication. Looks like at least 1 day of labor. Unless I were to stumble upon one of the old 3 links for sale.
Estimated cost for a 3rd link?
09-15-21, 07:14 AM
