'71 Super Beetle Autocross Build

[Dale M.]

As for rear brakes if you can not go disks or do nor want to go with disks at this time, you may consider type 3 rear brakes if you can find them... They are about 1/2 wider and about 1 inch larger in diameter large increasing rear braking area by about 30% (+/-) ... And the nice thing is its all bolt on, no mods what so ever...Went that way on 69 chassis based fiberglass buggy I auto-crossed and was really pleases with extra braking...

Dale

[Jadewombat]

My friend and I put 914 rear calipers on his ghia, but I wouldn't do it again. Rear disks yes, but not those calipers. We did some testing before and after with the drum brakes and from 60mph it improved 10ft. less distance. The design of those calipers is pretty hokey, the mechanical adjustment of setting the pads from the rotor, etc. and it was A LOT of grinding and fitting to get those calipers to work. We didn't use a biasing cylinder either because the calipers are so small.

Setting up the bias of F to R on my bug was pretty easy. It had a balance bar to shift the bias on the two master cylinders, but it wound up being near 50-50 anyway. I set it up at like 80-20 or something, took the car out, stopped hard and locked the front brakes up very easily, then backed off the adjustment, took it out again, etc. I know what "they" say about front brakes doing most of the work on cars, but most cars aren't rear-engined either. My theory is, under a hard stop the center of gravity goes from the backseat near the floor to directly under the two fronts seats (unproven).

There's lots of 15" 4 x 108mm wheels out there, not from Audi/Porsche but used on other cars such as Fords. That's good to know about the 924 spindles, H2OSB. It would be good to grab the rear sway bar off of a donor car if you can find one. I bought a stock rear 924 bar for $30 from a guy on the Pelican Parts forums. Made the car very neutral, but I was still getting some lift on the front inner wheel exiting turns.

[ps2375]

I too, have the type3 rear drum, along with Ghia disks up front, the car has very good braking and I haven't had any issues with it during auto-x's, or anytime on the street. But, I am not using an "R" compound tire during the auto-x either.

[ChadH]

I think one of the more difficult things to do, once I eventually get the car mobile again, will be general setup of everything. Since it won't be street legal, I'll have very limited opportunities to test -n- tune the car. I might be able to sneak a few covert low-speed drives around the block, but will really be limited to race days to work out the bugs.

Engine tuning, handling tweaks, brake setup, etc. is likely going to be all over the place for quite a few races. I'm sure there will be many times in this process that I will regret not just buying a Miata and being done with it.

[H2OSB]

The rear brakes on my son's car are 914 rotors, over type 3 hubs that have been slightly turned down to fit inside the rotors. The calipers are typical Golf IV calipers mounted to slightly modified cast caliper adapters (the ones that come in most of the rear brake kits). With the front 48/rear 38 calipers the break bias ratio is the perfect 1.6:1 (per Eric of PMB Performance).

Going with the "using 924 brakes out of the box" theme, to match the front brakes to the rear, instead of using type 3 hubs or a Beetle rear drum turned down into a hub, one could simply use the 924 rear brake drum, turned down into a hub, with one of the Audi 90 rear brake rotors over it. I can't remember which Audi 90 model it is...I looked it up not too long ago. But is was closer in diameter to the Golf rotors that originally went with the Golf caliper. The front and rear combo, as I've described it, would allow the use of 14 inch wheels which could be a real acceleration advantage on an autocross course.

johnL (aka H2OSB)
www.superbeetlesonly.com

[H2OSB]

I'm sure there will be many times in this process that I will regret not just buying a Miata and being done with it.

I'm sure you're not wrong about this. My personal desire to autocross a Super is simply because I like Supers and I think it will be fun. I have no illusions the car will be competitive. That's why I'm going to run an upright converted 1911cc T4 engine and just not say anything >:)

johnL (aka H2OSB)
www.superbeetlesonly.com

[Jadewombat]

Speak of the devil, I just saw this. He's bracing the car in all of the right places:

viewtopic.php?f=15&t=147330

Mind you, a full cage isn't needed for EP or XP but the car would see a lot of benefits stiffening things up a bit to let the suspension (instead of the body and pan) do the work.

My car wasn't high-dollar either. I didn't win any big awards, but with some lightening and trial and error I was able to toss it around and keep with other cars that had two and three times as much power as I did. They didn't get nearly as much attention as I did though.

A welding machine, punch and flare tool, and dremel will get you the majority of what you need done to make a fun and fairly competitive car.

[ChadH]

Great link! I was just looking at mine yesterday, thinking I need to brace the very front of the frame horn, and wondering how I would get some tubes in there. I didn't think about removing the spare tire well. Not sure If I want remove mine, but it's an idea.

I guess I'm not clear on why he has so many adjustable turnbuckles - just to facilitate removal? I'll probably just hard weld to the frame, or use a spreader plate if it's joining thinner sheet metal.

The door bars are bit excessive for autocross, since it's not likely I'll get T-boned, but some triangles in that area will certainly help. I'm anxious to start on this fun stuff, but have a lot of bodywork cleanup to do first.

Oh ya, I have a neighbor with a water-jet in his garage. He does custom cuts for people as a side business. Looking at those camber plates is getting my gears turning. I better bring some beers over to the neighbor and make better freinds with him.

[Bruce2]

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

I wouldn't do it if you have genuine fenders. The effect of holes will be so microscopic you'll never be able to measure it at the slow speeds on an autocross course.

[Jadewombat]

I wouldn't do it if you have genuine fenders. The effect of holes will be so microscopic you'll never be able to measure it at the slow speeds on an autocross course.

Not true, it made a big difference on my car. It was much more stable at all speeds, but definitely noticeable at highway speeds and autocross speeds. I ran a CF spoiler under my car, rear splitter on the roof, deflectors on the front fenders, side skirts--measured it all with vacuum (manometer) before and afterwards to be scientific about it and venting the fenders by far made the most difference in handling. I was able to hold slaloms and long sweepers much tighter on the courses--the downforce was significant and our cars need all the help they can get. I agree though, cutting german metal is a bit of a toss-up--still though. My fenders were fairly rusty on the insides and it was long past show car status of a car that had been sitting for 15 years so I didn't mind quite a few holes.

Spinning wheels create a huge amount of turbulence and VW fenders act like wings. Look at all modern cars (some trucks, too) and they have fender liners to close that gap.

[ChadH]

I'm not really that worried about hacking up the fenders - they all have dents to be pounded out and slathered with bondo. Whether or not there's a real benefit, I'll do it "Because Racecar"

I got a lead on a 944 that's being parted out. I'm too broke right now to persue it, but if it's still available in a few weeks, maybe all the discussion on Porsche swaps will come in handy.

[ChadH]

Progress: Finished scraping undercoat and seam sealant from the front fender area, and stitched up the strut towers. Scraping sealant from the deep recesses is a PITA. I got most of it out, but still had some "dirty" welds.





I also removed the gas filler door and patched it with sheet metal. I'ts not pretty, so no pictures until I fill the area.

[ChadH]

Starting to think about transmission and gearing. Here's the delema...I have a relatively fresh 002 three-rib Bus 'box I could use. I know it's a solid transmission, and shifts well. I also have 3 Type 1 transmissions, but I have no history on then, and don't know if any of them are any good.

The 002 has really low gearing, with a 5.38 R&P. Add that to small diameter tires (probably 195/50/15), and I'll have tractor gears. First would probably be useful only for driving slow in the pits...but I'd end up with some close ratios, and 2-3 look pretty good for autocross.

The type 1 boxes probably have a better ratio in 2nd, and I'd probably only need to get into 3rd on long straights. But, then again, I don't know the condition of any of them.

The left chart shows RPM/speed for the 002, and the right is a type 1 with a 4.13 R&P. Any thoughts or opinions? Remember, "Budget Build."

[Marc]

Lots more work to graft the 002 in, not to mention the expense of the custom-length axles that are needed...and have you ever taken a look at the silly internal shift linkage in those things? Prone to breakage and harder to snap-shift than a Type I. It can be upgraded using 091 parts, but you did say "budget".....

I'd run the 4.125 Type I trans for now, and find out how far off it is. You may end up wanting to go with a 3.875 trans (stronger 1st gear and that'll make 1st & 2nd 6% taller, about all you can do without a $$$ aftermarket mainshaft & gears) with a close-ratio 3rd. Perhaps even close 3rd AND 4th so it'll be more versatile - or, you can get 4ths that are shorter than the stock 3rd, so it's even feasible to leave 3rd alone and use a 1.43 4th, for example...that'd give you 3.80/2.06/1.43/1.26 with a goofy shift pattern

[ChadH]

I guess what I'm thinking is, I've been through the sweat and tears in fitting the 002 into my Thing, which is now one of two donor/parts cars I'm going to use for this build. I was just looking at an old thread I did for that, re-living the experience.

http://www.thesamba.com/vw/forum/viewto ... ?p=4398651

FWIW, It has nearly new type 2 CV's, shorter axles, 100mm stub axles and flanges etc. that are just sitting in my yard rotting away. It would be a lot of work to get it installed, but I do know what's involved. I found the shifting on the bus trans to be no better or worse than a beetle trans. The problem is, once I install it, it's going to be a big PITA to go back to a Type 1 trans if I want.

I suppose I could install the Type 1 transmissions (and reinstall one of the others I have, until I found the best one.) This would expedite getting the car mobile, and let me assess if I want to pursue a rebuild, modified type 1, or the bus box.

I hope me sharing my random train of though is OK. Honestly, I don't know really what I want to do until I can get a motor in the car, drive it, and see what it needs.