I'm looking at buying/building a vw beetle based purvis eureka. I only really want to attempt this if I can in some way improve handling and performance of the standard car.
I'm guessing that for such a light car, finding an engine with adequate performance should be relatively easy, & I hoping that I can upgrade the brakes fairly easily.
The big problem will be the imbalanced handling from the placement of engine behind the rear axle & next to no weight over the front wheels.
I would be very keen to hear any opinions and experience you may have regarding overcoming this problem.
At this stage I am thinking about looking for the smallest & lightest engine I can find for the rear, and possibly adding some weight to the front if need be.
Does anyone have experience in addressing this problem?
The biggest single cheap improvement I made to the handling of my 68 beetle was re-locating the battery to the front of the car. The scrutineers at Autocross were also happier to see it removed from the passenger compartment.
I'd also recommend practising on the go karts at a hire track. I always tried to pick a hire kart with evil oversteering tendencies. After you get the hang of that, the beetle seems relatively tame!
There are heaps of things that can be done to get a Beetle to handle better, and most would map across to a Eureka too.
Even just careful selection/adjusting of shocks, springs, swaybars etc. can make a world of difference... basic theory being that stiffening the front brings in understeer, while stiffening the rear gives more oversteer. From there even subtle changes in camber, castor and alignment can mean big things for turn in, high speed stability etc.
Going with just the weight aspect tho, things different on Jezebel that affect front to rear balance are:
- battery up the front... depending on size, could be 15kg or more
- fuel pump, filter etc. up the front... realistically only about 2-3kg tho
- dry sump tank up the front... 2-3 kg for the tank itself, 1-2kg more for lines and breather, about 4.5 kg of oil (5L)... and 3kg or so of weight (oil) REMOVED from the sump
- lightened flywheel... about 3-4kg I think... which is a bit considering a VW engine is about 85kg stock
Next on the list is the cooler and thermostat going up the front... another 2-3kg... but that's mainly about cooling and plumbing than weight distribution.
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Hi, there is a great book that explains all the mods that you can do to the beetle, (how to modify volkswagenbeetle suspension, brakes and chassis for high performance) ISBN 1-901295-80-x , this will tell you what parts, IE brakes and suspension parts that can be retrofitted to a beetle from a porsche, if you build a car you will need to research what type of vw suspension that you would like to use, generally it would be ball joint front end a independent rear end, for example you can substitute the rear trailing arms on the IRS with a set from a 944 porsche,there are 3 different widths availabe and bolt right into the car,2 of them are alloy and go a long way to improve the unsprung weight of the IRS rear end, in doing this you will inheret the porsch rear brakes of which there are about 4 variants, all of this is detailed in the book above, i would not be to concerned about the rear weight bias as i have 2 car which i have modified that have no problems staying with a WRX
I"m sure that you're not going to like it....
How about learning to drive it and make the best out of it? Many rally drivers von the championships with rear engined cars, many circuit drvers did the same....why cant you ?
You don't need that kind of reinforcement unless you are going to do some serious and abusive off road bashing. Given that a Eureka is an on road car, I see no need for it.
VW makes/made a front suspension support kit like that. They are part number 111 498 001 for link pin front ends and 111 498 001A for ball joint front ends
mrtom.
I've just recently built an Meyers Manx SR on a shortened Type 1 chassis and with a Subaru EJ20 single cam, non-turbo engine in it. It's heavier than a Beetle engine. I fitted the radiators in the rear wheel wells and the battery, fuel tank and spare wheel in the front.
It weighs 850 kilos and has a 36/64, front /rear weight bias. So far I've not noticed any problems with over/under steering when I'm hooning/fanging. I don't think that you need to take desperate measures about your weight bias.
Sure, put the battery in the front and if you fit a water cooled engine, try to fit the radiator, fuel tank and spare wheel in the front.
What I strongly suggest that you do is to fit adjusters to the front suspension to soften it. Every Eureka that I've bounced has been rock hard and unmoving in the front and soft and nicely bouncy in the rear. You want to be nicely bouncy in the front to balance the rear, which will be soft when it is adjusted correctly.
What you have to understand is that you are dealing with a VW Beetle which has the most supple suspension in the world under it. Sports cars built on Beetles are not like other sports cars which have hard, jiggly suspensions, you need a soft, supple, well shock absorbed suspension, that bounces evenly, front and rear. Stock shockers are just right. You do not need hard gas or air shockers.
Fit oversized tyres with low air pressures (10 to 15 psi front and 15 to 20 psi rear) and you will have a ride as soft as a limousine and the cornering and braking of a 1970s Grand Prix racing car.
Mazda rotary engines are light and powerful. I know of at least one in a Eureka and it goes well. That one has the radiator in the rear.
I don't reccommend radiators in the rear as you have difficulty getting good air flow to them for good cooling in hot weather.
Have you test driven a Eureka? I could not drive one as I sit tall and the top of the windscreen is right in front of my eyes. I'd have to scrunch right down to see under the top. Don't spend your money until you have test driven one. They seem to be the right size for short people.
Another problem with Eurekas is that the headlights are right on the lower legal limit. The front needs to be raised a bit. Adjusters will do that. They have a nose down look anyway.
I agree with what vwo60 says. That's good advice.
Apart from all that, I like Eurekas and I hope you get yours on the road soon.
cb john wrote:I"m sure that you're not going to like it....
How about learning to drive it and make the best out of it? Many rally drivers von the championships with rear engined cars, many circuit drvers did the same....why cant you ?
Pretty good advice, John.
There's nothing like lots of time behind the steering wheel to get to know the VW's handling traits. When you can tell the difference after you have made an adjustment, then you will be on the right track to improvement.
If you can make it to the 2010 Supersprint - 22nd May - you could pick up a wealth of information in one day!
Cheers, Greg
I'd rather wear a Beetle out by racing it than by polishing it!
I've ordered vwo60's book recommendation above & that has been quite helpful. I'm going to try to get a look at a Eureka in the next week or so also....
Thanks for the tips.
Cheers,
Tom
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
You don't need that kind of reinforcement unless you are going to do some serious and abusive off road bashing. Given that a Eureka is an on road car, I see no need for it.
Have you ever seen how much a VW beam can flex under heavy braking and cornering with tyres that have grip ?
Front beam supports ARE a benefit for anyone that is starting to really push their cars IMO
Hi, try to keep the unsprung weight as low as possible, i had my 3 piece wheels made to suite the car,they are are light weight wheel with an ET that keeps as close as possible the suspension geometry of the original, do not overtyre the car as they are light weight, you can balance out some of the oversteer issues by tyre sizes, i run 205/45/17 front and 235/45/17 rear and find this set to be quite nuteral , i use KYB gas ajust shocks all round and find them very good, on both of my cars the ride is excellent even with the low profile tyres
Craig Torrens wrote:Front beam supports ARE a benefit for anyone that is starting to really push their cars IMO
I removed mine, saving a lot of weight. The 'struts' that I made to replace them work really well, and are much lighter. Have a look at Wakefield Park - Nationals Supersprint.
Cheers, Greg
I'd rather wear a Beetle out by racing it than by polishing it!
Craig Torrens wrote:Front beam supports ARE a benefit for anyone that is starting to really push their cars IMO
I removed mine, saving a lot of weight. The 'struts' that I made to replace them work really well, and are much lighter. Have a look at Wakefield Park - Nationals Supersprint.
shaihulud wrote:...the 1975 Porsche 911 Turbo 3 litre. It has a 40/60 front/rear weight bias.
I've never heard that that is a problem....
Sorry, that's just hilarious. In England (where they were rather more common than in Oz, especially in the affluent '80s) they were called "doctor killers" because so many well-heeled doctors bought 911 turbos and then left this world going backwards. I've personally seen a couple in London wrapped around telephone poles on the exit to bends, especially on Sunday mornings.
From the '90s onward, behaviour of the 911 at the limit was greatly improved despite the continiued rearward weight bias, but the early examples were unchatchable if you entered too fast.
Not sure if will work - I'm no good at this stuff - but here goes. The 'strut' (known as the 'Mackie Strut' to a select few, Ha,Ha), connects to the lower link-pin (yes I rather like link-pins) via a special clevis. This clevis replaces the locking bolt & nut. An adjustable rod-end at the outer end of the strut is attached to the clevis, and the other end of the strut fits into a hole, drilled in the frame head.
It's probably not much of a description, but what these struts (there's one each side, of course) do is hold the lower trailing arms 'out', reducing front wheel tuck-under - if thats a word - on hard cornering to almost nil. I have known about this problem for about 50 years, but have only recently thought of a simple - and cheap - fix!
If the pics don't work, send me an email, and I'll send pics back. greg@kirrapak.com
Cheers, Greg
I'd rather wear a Beetle out by racing it than by polishing it!
shaihulud wrote:...the 1975 Porsche 911 Turbo 3 litre. It has a 40/60 front/rear weight bias.
I've never heard that that is a problem....
Sorry, that's just hilarious. In England (where they were rather more common than in Oz, especially in the affluent '80s) they were called "doctor killers" because so many well-heeled doctors bought 911 turbos and then left this world going backwards. I've personally seen a couple in London wrapped around telephone poles on the exit to bends, especially on Sunday mornings.
From the '90s onward, behaviour of the 911 at the limit was greatly improved despite the continiued rearward weight bias, but the early examples were unchatchable if you entered too fast.
No car is a problem, if you learn how to drive it PROPERLY!
Cheers, Greg
I'd rather wear a Beetle out by racing it than by polishing it!
greg what size front bar do you run? A mentor of mine allways reinforced that your driving style was more important in a vw with constant remarks about swing axle driving, brake, back on the power, late apex, juggle it on the wayout, keep those back wheels flat!
Not sure if size matters, as they say. My front bar was a freebie - from my son's Lotus Elise. It's about 19mm dia. x 1.6 wall (tube). The rear compensating spring is far more important -IMVHO!
Your mentor sounds like he? knows what he is talking about, the OUTSIDE back wheel must be almost vertical when cornering hard. The 'jiggle' on the way out (most likely caused by lower/front trailing arm flex) has almost been eliminated on my car after the 'strut' mod.
Cheers, Greg
I'd rather wear a Beetle out by racing it than by polishing it!
