Main British Car:
Brian Kraus's 1976 Midget with Mazda 13B - Front suspension project
Posted by: RX-Midget
Date: November 02, 2011 04:15PM
Owner: Brian Kraus
City: Westminster, MD
Car Model: RX-Midget
Engine: Mazda 13B rotary
Engine: Street Ported, Weber 48DCO, Racing Beat intake, locked timing, MSD direct fire for leading plugs, under drive pulleys, Fidanza aluminum flywheel, Racing Beat S/S clutch and PP
Cooling: VW radiator, Aux cooler mounted in drivers side fender well, 14" electric fan, 2 oil coolers
Exhaust: 2" custom Jet Hot coated header, two 2" to single 3" merg at rear axle, 3" in/out Dynomax muffler, 3" turndown
Transmission: Rebuilt '86 Mazda RX-7 trans, short shifter, Redline MT-90
Rear Axle: '85 Mazda RX-7 GSLSE axle, narrowed, vented disk brakes, LSD
Front Susp.: New double a-arm, coil over design using Wilwood 2" drop Pro spindle (Mustang II based), 3/4" sway bar, Afco remote double adjustable shocks, Carerra springs
Rear Susp.: Custome 4 link, Coil over shocks, adjustable 5/8" sway bar
(master) Stock '76 MG Midget
(front) Wilwood 11.75" x 1.25" Ultralight curved vane rotors, Dynalite calipers
(rear) Stock Mazda vented disks and calipers
Wheels/Tires: Superlite, 15x8, Hoosier
Body Mods: Spridgetech fiberglass fenders and hood
Interior: Kirkey seat(s), Custom carbon fiber dash, Autolite gauges
Electrical: EZ wiring harness, Small 14lb Harley motorcycle battery, stock RX-7 alternator w/ underdrive pulley, third brake light molded into rear sheet metal
Old front suspension. It worked OK, but I kept cracking spindles, even one of the stronger Winners Circle units. I needed a stronger spindle. I also wanted to reduce the amount of flex that was occouring under hard braking and generally update the suspension to use ball joints and coil over shocks. It also needed to be lighter...
Starting over using adjustable upper and lower arms, relocated pickup points, Wilwood 2" drop Pro spindles, double adjustable shocks (adjustable from inside the car while driving), and Speedway Engineering aluminum hubs. Brakes are still the same as before with 11.75"x1.25" rotors and Wilwood calipers. Suspension has 6" total travel, is much more adjustable, and ended up 6lbs lighter per side.
Was it worth it? Heck Yeah!! I never realized how much the suspension would improve the lap times. The last time I was at Summit Point I ran a 1:35 with the old suspension. This time I turned my fastest time of a 1:26 with the new hardware!! Now it has been a few years since I ran Summit Point's main circuit, and I think (hope?) I have improved my driving. So even if I drove 2 seconds better, the hardware was worth about 7 seconds per lap! Watch the video and see what you think. I am still having cooling issues when running the car hard for a few laps in a row, but plan to resolve that this winter with a new Howe radiator.
Here is a video from a great weekend of racing at VIR this summer. It was the first event running on the new suspension and the paint was still tacky! Nothing like thrashin' on a car up until it is time to leave for the track!
The "Jump" at 1:51 in the video was much easier to take with the new suspension:
Edited 8 time(s). Last edit at 11/03/2011 03:06PM by RX-Midget.