Super Beetle Racer

[Tim]

Hi everybody,
I am planning to build a circuit racer based on a 1303 to race in Zhuhai, a city in Southern China. the event is called Collectable Car Racing which takes place averagely once in a month. Most cars are 70'/80' Japaneses makes and some are even retired Group N racers, such as Toyota AE86, Honda EG9. The rules are basically simple - under 3000cc natural air-intake and has no restriction on modifications. Of course have to be 100% safety in mind. If I can build it successfully, perhaps I am the first one to race a Beetle in China.

My project will be a German looker with Porsche suspension and brakes, not to mention the T4 engine and 901/915 transmission. In the preliminary stage, I want to mainly focus on suspension and brakes, and stay with the stock transaxle and the 1641 T1 from my another Cal-looker. So, I would like to ask if anyone can give me some advices on my following questions.

1) Can I adapt '88 or later Porsche 944S2 front spindles and rear trailing arms/CV joints/axles to 1303? (I noticed in the forum seem everyone was talking about only early 944 suspension for the conversion). The reason that I prefer 944S2 parts is because it is difficult to get used Porsche 944 parts in Hong Kong but I think the post '88 may be relatively easlier to obtain.

2) I will use the 17mm ball joints from Kerscher to install the late Porsche front spindles (if I can find). Do they fit each other?

3) I also want to convert the rear suspension into coilover spring setup. Does anyone know where can I get something like the 935 style spring plate to eliminate the torsion bar?

4) If the above modifications can be done, I guess I can easily adapt the 944S2 brake system. I understand that the track will be widened but I plan to have flared widened fenders with 7.5x17 front and 9x17 rear Cup wheels. Is it enough for the fenders 40mm widened in the front and 70mm at the back?

5) If I can use the S2 four-pot brake calipers, what size of the master cylinder should I use? I plan to use the Tilton pedals setup with separate MC for the front and rear brakes. The pedal kit comes either in one 7/8" & one 1" MC or two 1" MC. Which kit will fit better for the S2 brake system?

Thank you!
Tim

[Oliver Knuf]

At fist, a question back, what building year is your 1303? It's possible to adapt the complete 944 S2 front to the superbeetle, but you have to change quite a bit. I know conversions with the spindle from the 944 S2, but on the superbeetlesonly site, there's a complete conversion with the axle parts to the frame end.
The rear is easy to change, as you can use all the S2 parts, including the torsion bars, but in case of modifying the complete car to an adjustable spring setup, I would use spring plates with CNC-machined mounts, unibal mount in front and completely adjustable. There are different front and rear coilovers available. I think, we have three different front setups and two different rear setups. A complete race version is also available, with spring tension rates by demand and exchange springs, to work a bit on the setup.
Your fenders will be too wide with 40mm and 70mm, but when you use the complete new axle setup with rack&pinion in front and the aluminum rear IRS parts, then it would be good to be so wide. Hopefully you'll use the hollow original cup wheels and no copies, as these ones where to heavy for track racing.
Use at fisr the same master cylinder from the 944 and if you do it tricky, use a brake module to get more power on the brake from a Mini Cooper or something in that style. Mike Ghia, also a participant of this forum has a servo controlled brake on his beetle, if I remember that right. Ask him for pictures!

[Tim]

Hi Oliver,
The base car which I plan to use is a pre-'74 1303. It has early type McPharson struts. I do not intend to swap for a complete 944 front setup. I just want to adapt the 944 spindles with late super beetle control arms and the Kerscher 17mm ball joints (Kerscher webpage mentioned that it is for fitting the 944 spindle. I just guess the meaning because it is in German). I just wonder if the 944 S2 spindles and early 944 spindles are using the same size ball joint.

As for the rear, I am not sure how to make the spring plates with CNC-machined mounts and unibal mount in front from sketch. Do you think I can use some real or aftermarket 935 spring plates and modify to fit the bolt pattern of the 944 trailing arms? Does the bolt pattern of 935 torsion bar cover fit beetle rear torsion tube bolt pattern?

Is the Kerscher front coilover struts suitable for track racing? Any good suggestion for both front and rear racing coilover? What spring rates should be used?

The race organizer told me that the circuit which I intend to race is not quite suitable for a Beetle because there are many corners. He said an average group N race car, such as Honda Civic EG9 can do 2 min per lap (4.4km a lap). A Porsche 993 racer can only do similar time due to its heavy tail. He guessed that a Beetle with a very unbalanced front/rear weight distribution can't do better than 2.5 min. So, I think I should pay more attention on front/rear balance. I will move the weight torwards the front by using fuel cell which can be fitted in the front spare wheel well and by relocating the battery to the front end, and will also lighten the rear end by using carbon fibre decklid, etc. Do you think this will work? Also, I guess I need the best brake system to allow late braking in corners. Which system do you think is the best to do the job?

Thanks for your professional advices.

Tim

[Chris Percival]

I would say a circuit with many corners is to your advantage, my reason being that you won't need all out top speed as much..

However you are right to try and balance the weight out a bit. Would you put the battery behind the fuel cell (ie where the metal tank would have been?)..

I would say the kerscher coil over front struts are the best you are going to get for your bug, and that goes for the rears too.

I would have thought that a fairly basic vented disk up front and a basic disk out back would do the job. Remember you are going for function over form. There is no need to have huge disks, just make sure they keep cool enough and are correctly balanced, predicatable and reliable.

You might want to think about aero-dymamics too. I don't know what kind of modifications you are allowed to do, but think about a rear wing, a front airdam, smooth underside etc..

Good luck with your development/racing and keep us posted!

Chris

[Tim]

Yeah, thanks for reminding me the aero-dynamics. I would go for a Remmele roof spoiler and a small front spoiler. I read a article before (can't remember from where) saying that a big rear wing, at high speed can create a heavy down force at the back and cause the front to lift up. The car will become very unstable at high speed. I am not sure though. Does anyone have such experience?

One more question, is the space under the 1303 spare wheel well big enough to acommodate an aftermarket racing rack and pinion system (such as BRT)? www.brt-racing.com

Tim

[Superman]

Not to take you from these forums but the forums on my Super site have some racers that post.

Look for Jak Rizzo, Steve C, Plumbugracer, & Chris Percival

www.superbeetlesonly.com/forums

Steve C has done a R&P conversion.

[Superman]

Also note: the 944 Turbo (not the Turbo S) and the 944 S2 have the same suspension and brakes.

*my posts are based on what is offered in the USA, I have no idea what is offered in Hong Kong, being that is where you are from

[Chris Percival]

Tim, you are right to be cautious about large rear spoilers. Although I have never heard of a bug lifting up at the front, anything that reduces the weight at the front wheels is a bad thing. Just reduce the lift generated at the rear with a small spoiler will be fine..

Not sure about the stearing rack, I think the same issues would be there as with fitting a 1303 stearing rack into a pre-rack car...