'71 Super Beetle Autocross Build

[ChadH]

Hopefully this is a good sub-forum to post my project. Back in the '90s I ran a gutted '68 Beetle at the local events, and did surprisingly well with hand-me-down Hoosiers and some pretty basic suspension mods. A few decades later, Me, my wife and 2 kids started autocrossing again. Me with a Mk6 and now Mk7 GTI, my wife with her R56 Mini, and my kids in a JA/JB Kart.

Being a long time ACVW guy, I've succumb to the itch to build another Beetle racer and dragged home a '71 Super last week. I have rough plans on what I can do to the car within a pretty modest budget and am currently reading up on stickies and posts here to make better plans. With a 2110cc engine sitting in another car, awaiting transplant, the car will need to be in XP. Certainly, making a competitive XP car out of a Beetle is probably not do-able with my resources, but it will be fun making the car as quick as I can.

It looks like there's a few autocrossers and road racers here, so I'm hoping you can give me some practical advice as I go, and call me out If I'm proposing something stupid.

Here's some pictures of the car as it stands. It has a solid pan, and a few rough-spots on the body. I'll be spending the next month or two just getting the body in shape before tackling any of the mechanicals.

[Dale M.]

Big question is front struts ball joint, If ball joint its easy if struts it going to take a little more.... And YES some supers were ball joint (inports) while most were struts...

Dale

[ChadH]

It's a strut car. I already know I'll need to replace every bushing, ball joint and tie-rod end, and make adjustments to restore caster and get some negative camber out of it. I'm still not decided yet if I'll use a Versa-Strut or get the Maxx coilovers to lower the front end. I'm sure the coilovers are better, but they're more $$.

[Marc]

...And YES some supers were ball joint (inports) while most were struts...Dale

Citation required. There were some morphodite big-windshield cars with trailing-arm front suspension made in South Africa, but the term "Super Beetle" implies either the early 1302 or the later 1303 (negative scrub radius) MacPherson strut suspension. So far as I know, all "Supers" sent to North America were Mac strut; if I've got that wrong please educate me

http://jalopnik.com/5962574/the-freaky- ... uth-africa

[Marc]

It's a strut car. I already know I'll need to replace every bushing, ball joint and tie-rod end, and make adjustments to restore caster and get some negative camber out of it...

Besides the obvious liability of having the suspension anchor points split between the chassis and the body, a design frailty in the Super front end is that gangly single lower control arm. The rubber-bushed swaybar ends up being the only means of control over the wheelbase. It'd be SO much better if the lower arm had twin pivot points, as is the norm on most more-successful Mac strut cars, but it'd be an ambitious project to change the design that radically.
Back in the `70s one of my circle-track competitors campaigned the first Super and did surprisingly well with it (other than going through a minimum of two steering boxes a night - they don't stand up to wheel-to-wheel contact as well as the standard boxes). After he'd run it for a couple of years he sold it to a friend of one of my drivers and I got my first close look at it...he had added Heim-jointed links between the chassis and the outer ends of the control arms and nobody ever noticed (such a modification was specifically prohibited under the rules). We had to remove those to make it legal, and it never drove worth a damn after that...but that was with 10½" wide 15" slicks, the smaller/less-sticky tires you'll be using for autocross won't be as demanding.
Get rid of all the rubber you can; there's a bronze-bushed idler arm pivot available. Aluminum bushings at the control arm and swaybar pivots would be TOO stiff IMO, but I'd definitely go with urethane. Note that as you lower the front end (more than the rear) caster is lost...that may not necessarily be a bad thing for autocross where speeds are relatively low but eccentric swaybar bushings which shift it forward a little are available, as is an aftermarket bar that's built shorter...I wouldn't expect that to be necessary unless the car has a lot of rake, though.
We ran a Standard one season in SCCA - the first year you run as a "Novice" so the only rules that apply are safety - enginewise it's run-whatcha-brung and it worked best with the chassis about level: http://smg.photobucket.com/user/KaferCh ... x.jpg.html

[Jadewombat]

I campaigned my '73 for almost two years. Off the top of my head:

-Drum brakes on these cars are crap, get rid of them. 944 brakes are a relatively cheap and easy swap
-Switch to the '73.5 and later struts and the above brakes (More options as far as 924, 944, and 968 Porsche suspensions)
-A 40+ year old car has a lot of flex to it, I'd consider stitch welding some of the seams along the heater channels inside as well as tying the front strut towers to the rear with tubes along the tunnel--something like these pictures welded to the pan along with tubes to tie to the back of the front strut towers and the torsion housings at the rear. Just doing a Kafer brace at the rear of the car and a front strut bar still leaves a huge area in the middle of the car for flexing. https://www.google.com/webhp?sourceid=c ... stiffening
http://www.shoptalkforums.com/viewtopic.php?t=123860
-One step more is tying some bars to the front of the strut towers to the forward most front sway bar mounts inside the trunk
http://home.autodo.de/de/ah-wolfsburg-k ... 60419.html
-Rear kafer bar setup
-I got a lot of lift on the inner front wheel exiting corners (which sucks) to counter this add a rear sway bar or stiffer rear torsion bars
-I went with 220lb. 944 springs on the fronts (which was considered too stiff when I first bought them 15 years ago!) but guys are running near 400lb. with good success now.
-Rear shocks--I had great success with Bilsteins
-Don't go smaller than 14" on your steering wheel
-15" rims and tires are ideal, don't go wider than 205s (bugs are so light you have a ton of grip anyway). I ran 16" and they weren't really a good match to the gearing of the car.
-Consider a TBD diff. if you have the time and budget, every bit helps especially if you're running in XP
http://www.shoptalkforums.com/viewtopic.php?t=128682
-The center of gravity is just behind the two front seats near the floor, DON"T MOVE THE BATTERY UP INTO THE TRUNK ETC., its a myth that it helps balance things out. Just mount everything as close to this COG as you can like F1 cars do. My car was very neutral.
-I'd lower it about an 1" all around, then assess the front lower control arms angle. Mine were just slightly positive with the ground (you definitely don't want them negative)
-Stock camber on these cars sucks also (I think it's 1 degree positive for the factory settings--I had to use eccentered bushings on the lower control arms and camber plates to get it down to negative 0.5 degrees)
-Stock glass windows are really heavy, replace with lexan type windows
-As far as aero. the biggest benefit I saw was punching and flaring the rear of my fenders (stock fenders act like wings giving a little bit of lift to the car at speed--spinning wheels create a huge amount of turbulent air under there), splitters, windened fenders to match widened track width, etc. all of that stuff helps

These guys have two excellent supers they race:
viewtopic.php?f=51&t=101402

As well as this:
http://germanlook.net/forums/showthread.php?t=7848

My old car

[Dale M.]

...And YES some supers were ball joint (inports) while most were struts...Dale

Citation required. There were some morphodite big-windshield cars with trailing-arm front suspension made in South Africa, but the term "Super Beetle" implies either the early 1302 or the later 1303 (negative scrub radius) MacPherson strut suspension. So far as I know, all "Supers" sent to North America were Mac strut; if I've got that wrong please educate me :wink:

http://jalopnik.com/5962574/the-freaky- ... uth-africa

Never mind, my source may have been mistake or I misunderstood....I was under impression there were 71 beetles that had front BJ beams but they may not have been Supers.... Seems a 71 without front grill under bumper may have been tubes and BK... But then again I may be mistakes.... Guess I'm just stupid....

Dale

[Marc]

There were in fact 2 styles of Super front apron, one with "grille" slots (M-code 559) and one without - reproductions of either style are still available...that cosmetic difference has no significance to the mechanicals underneath.
Now that you mention it, I recall that myth circulating many years ago - you're not stupid or deluded, just a victim of misinformation.

There was a lot of confusion back in `71/`72 when Supers used the same 111xxxxxxx VIN series as Standards - no one outside the factory could tell them apart by the VIN. In `73 VW started using "3" as the second digit for Supers instead of "1"- that and the big curved windshield made it easy (although the "curved windshield" description still sometimes confuses a few who were aware that the last truly flat windshield was in `64).
All Convertibles were Super-based starting with the `71 model, so there was no need to change their VIN series...it remained "15xxxxxxxx"
The "flat-screened" Super body was designated the 1302 series; when the curved-windshield body was introduced for `73 it was called 1303.
In mid`73, under pressure from dealer/customer complaints about shimmying, a redesigned front suspension was introduced with negative scrub radius, That helped, but didn't totally cure the problem - it was just the best they could come up with in a hurry without having to redesign the chassis. Too bad they weren't allowed the budget to get it right. This too was dubbed "1303"...so the early `73s were unique in that they were 1303, but still had the 1302 front end.

Edit 4/09: While looking through the M-code list at theSamba I came across a curious one, M-108..."Custom Model with torsion bar front axle instead of suspension struts" which I suppose could be interpreted several ways. However, due to the different wheelbase and trunk-floor making it unfeasible to put a Super body on a Standard pan, I presume it just means a Standard with more "high-end" trim components than the basic "Export" model, probably something you'd either have to place a special order for or perhaps incorporated in some or all of the "Special Edition" cars: http://www.sebeetles.com/

[ChadH]

Wow - this is exactly the kind of input and advice I was hoping to get here! Some of the things you discussed, I've been thinking about on a conceptual level, but haven/t planned out specifics. Some I would really like to do, but being a budget build, I just won't be able to spend the money. I'm not afraid to spend time doing cheap welding and rudimentary fabrication work to make improvements though.

For the front end, I was planning on urethane bushings. I probably won't swap in a later strut setup, since this would pretty much require another donor car. I'll lower the car as much as possible to lower CG, but want to be sure I have enough travel that the suspension works properly.

For brakes, I'd like to swap in a disk conversion, but probably will just go with fresh drum setup to start. It won't be ideal, but if the project time frame and budget get too out of control, the project will die. I want to get the car in good running condition and feel out the rough spots before I throw too many dollars at it.

I do plan on reinforcing and bracing as much as the chassis as I reasonably can. I plan on installing a cage, and making ties to the front suspension and rear frame horns. I also plan on welding up body spot welds, following much of the advice in HIbbards classic "Baja Bugs and Buggies" book.

I have 181 rear torsion bars and springplates I planned on installing - these should be a little stiffer than stock. I'd love a TBD diff, but It'll be outside my budget for now. Back when I raced my swingaxle '68, the inside rear tire would lift in corners, and I had to wait until the car settled back down to apply power. Hopefully an IRS will be a little better than that.

Battery relocation advice is great. I had planned on relocating as far forward in the trunk as possible - it sounds like this is a bad idea. On my old '68, I had it in the front of the passenger foot well. Maybe this is better.

Advise on 15" rims and tire size is good to hear. Being a budget build, I'll probably start with 15"x5.5" steelies in the 195-205 range. 195's seem to be generally the cheapest of all tire sizes, so this appears to be a good starting point.

I'll run no side glass. Front windshield is cracked, so using Lexan as a replacement makes sense. I'll probably do glass in the rear though, since I have it.

I have OE German fenders that I'll use. Cutting holes in them will hurt - but I'll take your advice and do it.

Whew - that's quite a post. I'll need to read through your stuff a few more times before It all sinks in my head

..back out to the garage today. I'm scraping off undercoating and sealant so I can add some welds to the strut towers.

[H2OSB]

ChadH, check your PMs

[Ol'fogasaurus]

Are you guys allowed to do something like this?

[Marc]

...I have 181 rear torsion bars and springplates I planned on installing - these should be a little stiffer than stock...

Significantly stiffer. We never tried those (didn't have any around or we might have) but had good results from Squareback bars. Because the spring rate is proportional to the 4th power of the diameter, a small change makes a big difference. (compared to the stock Type I IRS 22mm bar) 23.5=> 30% stiffer, 24=> 41%, 24.5=> 54%, and 25.5=> 80%

Disc brakes are great for handling the heat of repeated/heavy use, but drums are underrated IMO. They offer the advantage of quick F-R bias change simply by fiddling with the adjusters, and in some cases are lighter as well.
Modification to consider would be semi-met linings. Full-metallic don't work well at all until hot. You can play with installing more-aggressive linings in the "primary" positions (front or top, the ones whose application is aided by drum rotation) and leaving softer ones in the secondary so you've got some stopping power when cold. Since we used to circle-track race in the rain - in Seattle that's roughly 40-45% of the events we'd go a step further and drill out the front circuit restrictors in the M/C so that when backed off the front brakes would have almost no effect on initial application but could be brought into play if needed by fanning the pedal. That only works if the driver has the presence of mind in an emergency to do so, of course...

Also note that Super front drum brakes were adapted from existing Type III rears. Type III rear brakes are a direct bolt-on to any`68-up Beetle should you want more rear bias, and with the right spring-holes drilled you can even use those shoes as Super fronts (allowing more options when playing with different friction material combinations). There are two different wheel cylinder bores which'll fit them and Super fronts too (23.8 and 22.2mm). The downside to them is the added weight, which is all unsprung to boot. If you stay with the stock rear drum brakes you can still fiddle with lining materials and wheel cylinder size (stock they're 17.46mm but the 22.05s from Standard Beetle front fit fine).

As a rule, any and all of these combinations will work just fine with the same stock 19.05mm M/C (good news since there aren't many options that'll fit in a Super).

[Jadewombat]

I really would stay away from drum brakes autocrossing. Brake fade will be an issue even with new brake components, there's not enough time between runs for them to cool down with all of the hard stomping. 3 or 4 of the SCORE offroad classes mandate drum brakes all around and there are brake shoes available with more bite to them, still though even 924 front disks would be an upgrade.

Swapping to 924 or 944 brakes and front suspension is really easy. The '73.5 and later/924/944 strut tops are identical and a direct bolt in on the super beetle body, the lower arms are also a direct bolt in, the only difficult part is a slightly bigger ball joint to accept the 924/944 front disk spindle. Years ago I used a Golf a-arm ball joint and had a plate welded on the lower control arm to accept this ball joint. I don't know how guys are doing it now, but I heard Kerscher (from Germany) makes a bigger diameter ball joint which simply presses in the lower arm. I also had to buy aluminum tie rods from an offroad VW/buggy place that were a couple of inches longer because the Porsche spindle sits a little too far out for the stock tie rods to reach.

VW bug rear trailing arms were actually used on the 924 and early 944s. Swapping rear disk brakes on my car was even easier than the front. I only had to make a clip to mate the bug e-brake cable to the inner brake shoes.

I got the brakes and rims off an '80 924T for $300 from the junkyard. This was years ago and nothing really has gone up in price since then. Check ebay and your local junkyards. I used an offroad drop-down pedal cluster (optional in your case) dual-master cylinders and a third because I was going with a hydraulic clutch on my car also. Vented disk brakes and huge calipers at all fours with 928S rims. The brakes were incredible and the pedal felt as solid as a Mercedes. I barely tapped the brakes to scrub off speed going into the corners and could brake very late, but I wouldn't do this setup the same though if I had to do it over again. It limits the size of the fuel tank you can use and where and I wasn't aware of remote reservoir setups at the time like volkdent used on his car. His setup didn't involve the cutting and mounting I did on my car:

http://germanlook.net/forums/showthread.php?t=10369

My old car:





As for VW (Ghia or T3 or aftermarket disk brake kits), they're OK but I autocrossed my friends '69 ghias (two different ghias, both '69s though) but there really was no comparison to my bug as far as braking.

[ChadH]

Are you guys allowed to do something like this?

I "think" it's allowable for Prepared, I'd need t read through the rules again. I believe anything goes, other than complete re-engineering the basic frame. I'm hoping to get by without completely removing the body off the pan though. If I do, it will be just to lift it enough to fully weld the cage near the roof.

For brakes, drums are likely going to be a necessity due to cost (at least initially.) I'll keep my eyes open for any good deals on 924/944 stuff though. It sounds like it might be cheaper than I thought. I'm planning on 18-months to get his done, so maybe something will come my way.

At our last autocross, there were only two areas that required heavy braking, one at the far end of the course, before a 180 turn around, and the second to get slowed down after the lights. Everything else was a light dab, or just letting the car scrub off speed. I would think dialing in bias would be critical though.

[H2OSB]

Swapping to 924 or 944 brakes and front suspension is really easy. The '73.5 and later/924/944 strut tops are identical and a direct bolt in on the super beetle body, the lower arms are also a direct bolt in, the only difficult part is a slightly bigger ball joint to accept the 924/944 front disk spindle. Years ago I used a Golf a-arm ball joint and had a plate welded on the lower control arm to accept this ball joint. I don't know how guys are doing it now, but I heard Kerscher (from Germany) makes a bigger diameter ball joint which simply presses in the lower arm.

I have the fortune (well, really, misfortune) to have two '74 Super Beetle projects going at the same time (one for myself and one for my 16 year old son). On my car I went the old school upgrade of using 944 brakes, although I used a Porsche "M" caliper on the front for better f/r brake bias. On my son's car I went with early Porsche 914 front rotors and BMW 320i calipers all on Porsche 924 spindles. The advantage of these spindles are, unlike the 944 spindles, they use 15mm ball joints like the 1303, they bolt to the Super Beetle/Golf mk1/944 strut at the bottom end, and they use the identical bearings and spacing as the Beetle/Ghia. The only issue I'm having right now is the adapter for the caliper to spindle, although I have Lanner Khan helping me sort that out (I believe he thinks I'm nuts).

If I were to do it again, I might just run the 924 brakes as they are and not try using the 914 parts. I originally went with 914 because my son wanted to retain the 4x130 bolt pattern. It is physically not possible to re-drill 924 rotors (4x108) to the Beetle 4 lug pattern. The only thing possible on a 1303 would be to run the 4x108 pattern or use some kind of adapter to get 4x130.

I've heard many times 924 brakes would be a waste of time as they're very similar to stock Super Beetle disc brakes (stock everywhere but the States), however I disagree. The disc brakes that came on the higher end Beetles had 9mm x 278mm rotors and calipers with 40mm pistons where the 924 had 13mm x 256mm rotors and calipers with 48mm pistons.

I suppose I could find another calipers. Anyone know of caliper that fits in place of a 924 stock caliper (BESIDES the VW Passat caliper...which is 54mm).

H2OSB