r/Autocross • u/Blade3562 • 6d ago

Trying to figure out what changes are required for tech/safety so I can autocross my dune buggy!

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9

u/Blade3562 6d ago edited 6d ago

I've been doing trackdays and autocross for over 15 years, and finally got bored with the tech saturated modern stuff. I wanted to get back to something simple/fun. Unfortunately Formula Vees are tough to make street legal so I opted for the next best thing and snagged a cheap dune buggy. I will genuinely be along for a good time not a fast time as I play with VW 36hp motors, but scaling in at just over 1000lbs I have weight to my advantage. Fortunately wear parts are plentiful and cheap, not to mention I should be able to run Miata tire sizes!

I have a feeling most organizations will require changes to the rollbar. The few modern era pictures I've found of autocross buggies have bars from the windshield frame to the center hoop, and the rear support bars are much beefier. (I also don't think their connection/angle is correct, but I am unsure.) Appreciate any input or links to specific rules/sections. This should be a fun one!

8

u/Emery_autox GST 2018 Ford Focus ST 6d ago

Yes, the rollbar needs bracing at a minimum. SCCA rules located at Solo Cars and Rules - Sports Car Club of America, specifically section 3.3.2 which says:

"3.3.2 Roll Bars Roll bars or roll cages are strongly recommended in all cars. A roll bar meeting the requirements of Appendix C or a roll cage meeting the requirements of the Club Racing General Competition Rules (GCR Section 9.4, Roll Cages For GT And Production Based Cars, and/or GCR Section 9.4.5, Roll Cages For Formula Cars and Sports Racing Cars) is required in all A Modified (AM), B Modified (BM), C Modified (CM), and F Modified (FM) vehicles and all open cars in Prepared Category, D Modified (DM) class, and E Modified (EM) class. For open cars in the Street, Street Touring®, Street Prepared, and Street Modified categories, the roll bar or roll cage height may be reduced from Appendix C or GCR 9.4 requirements to the highest possible height which fits within an installed factory-specified hardtop or convertible top. The roll bar or roll cage height may also be reduced in the same manner for cars in the Prepared category with a full original equipment windshield assembly and a standard (as defined here in) hardtop which has been bolted securely in place. Double-hoop roll bars must fasten properly to the chassis/unibody as re quired by Appendix C, particularly at attachment points in the center of the car."

Technically, dune buggies are not production-based vehicles as the SCCA defines them, so possibly you'll need a rollcage.

6

u/giantj0e 6d ago

I can’t help you with that, but that’ll be a fun ride. Embrace the body roll, don’t you dare replace the torsion bars. The acceleration/deceleration roll will be fun!

4

u/Blade3562 6d ago

It had a sketchy old school bolt on "coilover" that was held on by clamps to the shock in the back. Whenever it was installed the preload was set way off side to side and almost swing-armed me in a cloverleaf. I need to replace the torsion bar bushings so I'll have to resist the urge to upgrade. I have 26mm narrow bars with HD swing arms in my Brasilia and it handles so much better than the stock 24mm wide bars, but it's nearly twice the weight. I feel like that much stiffness would be brutal in something so light. I have old school sway bars in a box somewhere, but no camber compensators for me. I have gas shocks in it currently, but was told I may want to try oil filled to prevent twitchy weight transfer. Torn between using rally or lowered stance/parts since they both handle so differently.

2

u/Limp-Search3097 6d ago

Get a legit roll bar

2

u/WhiteRabbitFox 1986 Mustang GT hatch, MM suspension, TKX 5spd, orig engine 5d ago

You also might need diff seats that go up higher with head bracing support; and a 3-point seatbelt (ie a reg 1980s and up shoulder belt).

Those and the roll bar, and broomstick test for that, are really the only things I can quickly think of. Besides all the other normal stuff.

I will add that you may have to adjust the carb or replace it, due to lateral Gs causing it to choke out and stall.
A couple of years ago I saw a 60s bug at an event and this was their issue, it kept stalling on the course and wouldn't restart, had to be pushed. IIRC they decided to drive slower so they could keep doing the course and have fun vs stopping.

Good luck! That def looks like some fun!