356 Race Car

[roy mawbey]

Barry was the one who finally convinced me years ago that my experiences with 'A' diaphragm clutches were correct. He sold me a complete normal standard type spring clutch assembly which when I fitted it, transformed my car its still on there, and operates perfectly. I tried everything with the other set up.

Pleased he is okay, never forgot his helpful conversation a good technical sales man with excellent technical ability. No doubt of course he would have sorted the diaphragm, but I have sometimes this stupid notion I have to repair everything myself.

Roy

[steve wright]

And so the winter rebuild starts. This car has spent more time apart than going round in circles! We're focusing on a few areas of development over this winter: the gearbox, improving the handling, a freshen up of the motor, and lightening the car.

Ian did a non-championship race in early November and had a brilliant race: passed 4 cars from a standing start and then had a right old ding dong with an MGB for 15 of the 17 laps race, managing to stay ahead of him… until he suddenly couldn't find any gears. Broken hockey stick meant a DNF which was a real shame. A drag-racing spec replacement is going in as this is apparently a weak component in the 356 box when racing. Wish I'd known that when we rebuilt it five months ago! We're currently running BBAA ratios – all are brilliant, and perfectly matched to the motor, except 4th which is just too short. I think that's a consequence of the short, twisty courses the SCCA run in the US. Given the longer circuits here in the UK we're on the redline in top on three different circuits for extended periods, so we're going to raise 4th to a B. Ian measured the rear tyre and did some calc's for the new 4th B gear (26:23..0.89) and we'll get approx. an extra 10mph at 7,000rpm with only a 400rpm extra drop when shifting (i.e.dropping to 5000rpm rather than 5400rpm when shifting at 7K) so should still be in the power-band.

In terms of handling we're focusing on installing a camber compensator, which were fitted to the Super 90. The camber compensator stops the inside rear wheel dropping when cornering, effectively acting as a load transfer mechanism across the car so it remains flat through the corner. We still need to play with front sway-bar thicknesses. The other area of focus is solid mounting the drivetrain. The rear suspension of the 356 really is antiquated, and pretty rudimentary when it comes to handling. No-one would deny it's robust, but it's hardly race-car sophisticated. So the best approach is to limit it as much to minimise any camber, toe or castor change, without giving away all vertical movement. Again we're applying VW drag-racing theory here by solid mounting everything: I'm not sure if it's common practice in the 356 racing fraternity but there's nothing in the rulebook to say you can't do it, so we're going to try it and see what difference it makes. As you know the engine and gearbox are located on rubber mounts at the front of the gearbox and on a cradle that hangs from the chassis under the gearbox. The other locating point is the trailing arm where again rubber bushes locate the torsion bar/trailing arm joint into end of the torsion tube. When you put the stress of lifting off the accelerator at 100mph and stand on the brakes, the momentum literally pulls the rear wheels backwards in the body. It's not much, but then you don't need much to shift the rear toe from static zero to negative, and that's a Bad Thing. All of a sudden the rear wheels are pointing out slightly, making the car try and corner, just when you want it to stay nice and stable. Solid mounting these three areas removes any play, although it puts drivetrain vibration through the car. Not an issue with a race car but you wouldn't want to do it to a road car. Take a look under a 1973 911 RSR and you'll see they've done exactly the same: solid mounting the torsion bar with an ally block. So we'll try it and see what happens - Martin Taylor of Taylor Machining has made up beautiful ally replacements of the standard units (thanks to Paul at PRS for loaning us standard ones for copying while we were running the car in the latter part of the season).

The motor is probably the biggest area of focus over the winter, at least for Ian. It might seem crazy to pull something apart when it's running perfectly fine, but race engines take a real pounding, so frequent maintenance and an annual freshen up is wise insurance to stop them going bang. In this case the motor was also a bit of an unknown quantity, so stripping it down and seeing what we've got was important. It's basically a warmed over standard motor with a SC non-counterweighted crank and Carrillo rods, with a Webcam 86A cam (oh my god so mild!!!!!), 9:1 pistons and Feramic (i.e. Copper) clutch. The case has been boat-tailed which is nice (polished and de-burred to reduce oil windage) but the cam is slightly worn, and the barrels need diamond-honing as they're also slightly worn. The heads are completely stock. Ian reckons with all this we're probably getting 120hp, if we're lucky. No wonder we were getting passed so much!



So where do we go from here? Well I've set a budget of £5,000. When you add a rebuilt gearbox, running costs, etc, etc, it's at the top of what I can budget unfortunately. I was hoping to build a full-on race motor but that will have to wait until 2014. First up is a freshen up of the bottom end with a polish to the crank, new bearings, etc. We'll lighten the flywheel a little and weld the fan - the last thing you want on a race engine is a fan coming apart: errant fans literally saw engines into pieces. Ian will do a bit of minimal porting to the heads but mainly around the valve guides and concentrate on a very accurate valve job to the seats and new valves as this is where most gains will be made as the standard ports are already pretty big for a 1600cc engine, so it's all about airspeed not just CFM (flow).

And finally lightening the car. We corner weighted it at the beginning of the season and it came in at 806kg's dry. The FIA Appendix K specified weight for the 356A Super is 780kg's, so we've got some way to go to make this. There's no limit to ballasting the car so I'm going to focus on getting the weight distribution optimised. This means getting weight out the rear of the car and moved forward and to the passenger side. With 75-90kg's of driver it's a big old lump of driver that needs to be balanced out! Cars generally weigh more on the drivers side as well because of the seat, steering wheel and column, pedals, master cylinder, etc. And on a LHD car with all the circuits running clockwise this is a distinct disadvantage as all the weight is being loaded on the already stressed outside (drivers-side) tyre. So I've bought my Christmas presents to myself early: a set of 27kg digital scales and a lovely German drill press. I've also bought a load of lovely ally panels from Karmann Konnection, and I'm busy looking at what I can drill and lighten. More on lightening later when I start getting stuff drilled



I've realised racing never stops, you just take a breath over winter…. More to come soon: off to see Pete at Cogbox on Friday evening to talk about the gearbox details.

Cheers,
Steve

[neilbardsley]

What a great post Steve. Nice to see some different thinking on how to make the car quicker.

What cars are you generally racing against? I had a quick look and I could mostly see 60s endurance racing for a car of this type and that seems to match with you talking about beat some 911s? If that the category you are racing in? If so aren't you running uphill, so to speak, since it's tough to take on a late 60's car?

[Bootsy]

Neil, if you have a read of the thread you'll see plenty of the cars that Steve is racing against.

[sladey]

Fantastic post Steve - really interesting reading. I'd love to do this some day.

[neilbardsley]

Neil, if you have a read of the thread you'll see plenty of the cars that Steve is racing against.

Sry I asked the wrong question. I was trying to ask that categories are you racing in or can you race? My knowledge of the different racing categories is pretty weak Ian had spoke in another thread about 65/66 cars being the cut off for Group F (I suspect I've got that letter completely) wrong but when I did a search on line I could mostly see 60s and pre 60s cars grouped together? I realise that you have to optimize the car you have but did you consider the optimial car for the available categories too?

[steve wright]

Hi Neil,

there are two different things at play here: Appendix K regulations put the cars into classes. This is the regulation the car must be built to, but not necessarily race under. We're in Class E which is 1947 to 1961, and Class F is 1962 to 1965. In practice what this means is that some of the Appendix K reg's apply differently to classes of car. For example the use of electronic rev limiters, roll cages, etc.

BUT, most championships run classes too, so the HSCC runs two main races in one in the Guards Trophy race series: The Sports Racers (Chevron's Porsche 910's, etc), and the GT (production sports cars). For the GT, which we're in, there are then classes based essentially on capacity: up to and including 2 litres, 2.0 litres to 2.5 litres, and more than 2.5 litres. Unfortunately this puts us squarely in competition in our class with the 1965 911 because it's 1,991cc, which is why Ian was referring to "racing against them".

A lot of other championships distinguish on the basis of an up to 1,600cc class, which would be perfect for us, and some do it on age, say pre-63 or pre-61, which again would be perfect for us. This is one of the reasons Robert Barrie said we were going in the deep end, because you're up against the big boys. Nothing quite like having a Chevron pass you at 130mph! Having said we always knew racing a 356 was going to be as underdog, but there's something quite satisfying about beating larger capacity and technically more sophisticated cars. That's where the term "Giant-Killer" came from and a label I dearly hope we'll be able to proudly wear in years to come....

Hope that clarifies things. This is why it's very, very important to read the regulations and understand how they apply to your car, but also to be REALLY clear about which race series you plum for! In reality what this means is that in the Guards races where there are usually 35 to 40 cars scrapping it out, you aren't racing against the Chevron's (staying out their way more likely) but against your class, which is typically where you end up qualifying. It all evens itself out on the grid but it does mean you've got to be clear about who you're really racing against.

Cheers,
Steve

[neilbardsley]

Thanks Steve that explains alot. Races within races You will have to keep your eyes/ears open for another Porsche Flat 4 race. There was one in Pau, France (beautiful part of the world btw) last year but I didn't think the organisers are putting it on next year but you never now.

http://www.peter-auto-racing.com/index. ... ang=dpx_uk

[Darren65]

Having not caught up with this thread for a while I really enjoyed the updates…

… hardly understood anything that was mentioned but suitably impressed, great fun!

[steve wright]

Hi Darren. let me translate: lighten car plus make more horsepower equals go faster As Mav, our pit crew chief says when we go out onto the grid "go fast, overtake everyone, and don't hit anything"!! That's what it all boils down to!!!

[neilbardsley]

Steve is the engine running a dry, or wet, slump? May understanding is that with a dry slump get you some more hp but is heavier and generally prefered for race engines?

[steve wright]

Hi Neil, wet sump as this is standard to the car. I can't recall off the top of my head but I don't think we're allowed to convert it. To be honest there's not much point as the extra tank, oil, pipes and pump are all located in the rear of the car which is not good. We've not had any issues with oil starvation from the standard pick up tube but Ian will extend it anyway and likely go with a wide deep sump to put more oil in circulation. Dry sump means less oil being moved about by the crank, rods, etc, etc, but that's a whole different kettle of fish for another day

[Mike Smith]

Steve,

Dry Sump is NOT allowed, except for Carrera Motors and as you elude to, the disadvantage outweighs any gain

I know, from reading your write ups that you are switched-on to all the possible problems

However, be aware that with modern tyres and on very long flat out corners you can get oil starvation - make sure you have a nice big Oil Pressure Idiot light and make sure it works

I have not been to Thruxton for a good many years but that track caught us out and cost us a motor

[steve wright]

Thanks Mike. Yes we've two VERY large warning lights on the dash, one obviously for the fanbelt/generator, and the other for oil. We're looking for a sump at the moment, a wide cast version so it's nice and light, but with little depth so there's no risk of destroying it on a kerb.

Christmas has come early for me with the purchase of a bunch of bits, so will post pictures over xmas/new years.

Cheers,
Steve

[Mike Smith]

I have a couple of diffrent types in stock

Cannot remember much about them but could haul them out and send you some comments and measurments