'56 Oval

See cars and bikes being built for the salt

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David Leikvold
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skinny

Post by David Leikvold » Sat Nov 21, 2009 9:59 am

It depends on what sort of tyre you decide to use. You won't find a VR or ZR road tyre in 135 or even 145 in any rim diameter. The best you could hope for would be an H rated something in a smaller diameter rim. Don't go so small that you can't run front brakes, if you ever catch fire at high speed you'll be mighty glad you kept those discs. If you go to one of those skinny Goodyear Front Runners you might, just might, be stretching the friendship regarding load carrying capacity and their grip and handling characteristics would be pretty ordinary. Maybe check out what Pro Stockers run on the front, they'd have more nose weight than your VW so they'd be up to the job. I don't know what width they are. Perhaps someone else can enlighten us.
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T-34
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Post by T-34 » Sun Nov 22, 2009 1:19 pm

Trying to get my head around this a little better, but cannot figure out what is best.

I will retain the 15" rims and front brakes as this is easiest (and cheapest as stock parts can be retained), this may limit tyre choices, but there is still a fair choice, so would like to choose wisely.

Given the choice, drag cars / rails usually use a fairly large diameter front tyre with a small contact area to help reduce contact friction and lower the speed of the wheel, which helps to get it moving quicker. But then with drag racing it's all about getting something stationary moving as quick as possible, this isn't quite the same with the salt.

I can perceive a benefit in running a narrower front tyre - to reduce contact friction, but then there is an obvious trade off with grip - which is necessary for steering. Also salt is pretty slippery (right?) so would more grip be an advantage? I can also imagine a really wide tyre 'aquaplaning' on the salt - is this an issue? Is there an optimum width, somewhere between the two extremes?

Thoughts? Experiences?

Cheers,

Mick.
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David Leikvold
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hmm

Post by David Leikvold » Mon Nov 23, 2009 12:43 pm

Mick,
Staying with 15" makes a lot of sense for the reasons you just mentioned. I'm still a fan of the 185/50ZR15 because of its diameter, width, construction and speed rating. Here's why: the diameter lowers the car about 50mm and improves clearance between the top of the tyre and the mudguard by the same amount. That could get the car 100mm closer to the ground by lowering the suspension 50mm and still retain the original clearance to the guard. Then you could keep lowering the suspension until the clearance was negligible, remembering that you want very hard suspension and very little body roll. The extra 20mm of width is only 10mm each side so with standard rims you could probably still turn the car lock to lock without rubbing the tyre on anything. You'd have to check that yourself, don't take that as gospel. Tyres of that size and type have a grippy rubber compound and a great tread pattern for unloading water (as I said previously look for a tyre in any brand with a tread pattern that looks like a wet weather race tyre. I don't think it's necessarily all about an optimum width, it's more about a contact patch size that works well. Don't forget also that the high tyre pressure will tend to round off the tyre ever so slightly thus improving the removal of water from the contact patch. I don't think the Goodyear LSR's very simple tread pattern would do much of anything and the contact patch would be very small too. Good grip is more important than reducing negligible amounts of rolling resistance. Cars that are built to handle well are more useful than cars that are running on a wing and a prayer.

The car won't necessarily aquaplane on the salt, it depends on the amount of standing water. If we get rain there'll be some but if racing is allowed to continue there shouldn't be enough to be dangerous. If too many cars spin out they'll suspend proceedings until conditions improve. The sun does a very good job of evaporating small amounts of standing water quickly. Obviously it's always better if it hasn't rained in a while. Grip problems at speed are usually caused by a number of factors, usually either poor aero and/or weight balance. The car should not get light and start to lift at speed, that lift is causing drag and getting dangerous, if you have to have drag it should at least be working for you and generating downforce. By the way make sure you use a front air dam to keep air out from under the car. Weight balance front to rear is also very important for high speed stability. A lot of people use lead ballast to push the car into the salt without using drag inducing wings. This is very sensible but only if you put it all between the front and rear axles and close to the centre of gravity, not hanging beyond the axle lines either front or rear. Weight close to the CG helps, weight that causes a pendulum effect does not. A few years back Rod Hadfield ran a couple of tons(!) of lead in his Bronze Aussie Commodore (which had a kazillion horsepower) and when the car did spin on a wet patch he managed to spin it 14 full circles before it stopped. The number of spins isn't important, it's the fact that the lead ballast kept the car firmly on the ground every time it went sideways.

Is the salt slippery? Yes, no, yes, no. I've never raced on salt (bitumen and dirt only) but others who have have told me that it changes all the time and that some parts of the course can be damper than others. Apparently there are a few underground streams across the lake that make the salt softer and wetter in places. Prior to visiting Speedweek I had imagined that it was like concrete and either wet or dry, but that's not the case at all. The best way to describe it is to say that it's alive. The moisture content changes all the time even when it hasn't rained, new pressure ridges are forming as temperature and moisture change, water gathers in tiny new puddles formed by the pressure ridges. Mostly it's rock hard, so hard that you can't drive a tent peg into it to save your life. Everyone brings cordless drills and long roofing screws to put up their pit and shade structures. And then when it rains water trickles down the tent ropes and literally dissolves the salt around the peg plate leaving a hole surrounded by rock hard salt. Figure that out! The salt is scraped flat on the course and return road so that the water doesn't get a chance to pool in significant quantities and also to provide a smooth and reasonably consistent racing surface. In a road car it feels like tiny vibrations through the car at speed (like you would get from big dirt tyres on a 4x4) but isn't at all disconcerting and doesn't affect the car. Despite all that you'll still see photos of cars with the sills caked in salt just from the spin off from the tyres. Wheel arches gather large amounts too but it mostly falls off. Still leaves enough behind to rust anything it touches!

Just a thought for the future. VW gearbox ratios aren't kind to you for the salt, so maybe you could hunt around for a Mark9 Hewland gearbox from an old Formula Ford (at least 20 years old, a Hewland LD200 is a Hewland case and no use to you). The case for the Mk9 was actually a VW tunnel case machined internally to accept Hewland gears, etc. There is a large selection of ratios available for them and I'm pretty sure (hoping) the diff ratio would be in the 3's, not the VW's 4 somethings. The selector housing is a Hewland piece and will be pointing in the wrong direction for a Beetle but fixing that wouldn't be impossible. Hewland also did custom side plates and output shafts but they bolt directly to standard VW CV joints anyway so the conversion is just about as simple as it could be. Changing ratios would be a biggish job in the beetle, you'd have to drop the motor and box every time.

So there you have it. Sorry there aren't any absolutes but at least you have more to ponder now. Good luck.
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Post by T-34 » Mon Nov 23, 2009 1:21 pm

Wow information overload - lol

Just to clarify - I mentioned "aquaplaning" for want of a better expression, but was referring to the salt lifting the tyre - not water, but I think you've answered the question anyway - wet weather tyres.

I'm sorting the ride height out with a 2" narrowed beam and 2 1/2" dropped spindles - the beam also has adjusters so hopefully I will be able to dial in the height pretty well. With lower profile tyres and the narrowed beam, should hopefully eliminate wheel rub and so let me get it as low as required without having to resort to wider guards.

I have thought about the hewland gearboxes - they would be an ideal choice - although they are not cheap. But must admit I didn;t consider trying to source one from a formula ford - this might be an option. As far as 2010 is concerned, I've decided to stick with the 915 and see where it takes me.

I've just ordered the beam + new brakes + two new floor pan halves , so hopefully will have some more progress to report soon. I will mull over the info regarding tyres - there's lots to digest.

Cheers.

Mick.
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Rob
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Post by Rob » Tue Dec 01, 2009 4:47 pm

Mick,

I found some stuff for you today on yet another read of the rulebook.

Make sure you check out fire systems in the rulebook RE front mounted fuel tanks and (from memory) scatter shields as there is a section regarding extra engine mounts for engines mounted solely by bolts to trans axles.

If you can't find it I will look again and post the paragraph numbers for you.

Cheers,
Rob
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Post by T-34 » Wed Dec 02, 2009 10:58 am

Cheers for the heads up, I will have a gander when I get back to Adelaide as my copy is back in the office.

I was planning on running a foam filled race style tank with rollover vents - the original tank has a nice rusty hole in the bottom and is about as much use as a chocolate teapot. I could patch it up but would also have to mod it for a larger feed and add in a return line from the fuel pump, plus I wouldn't trust the integrity of it on a roll or a collision so it's easiest just to replace it.

There is always the possibility of relocating the fuel tank somewhere else, but the only place that there is any room to relocate it is within the passenger compartment itself, not sure if that's a good or bad thing? (gut feeling tells me bad).

I was also planning full fire suppression, although haven't looked into that yet.
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Post by T-34 » Wed Dec 02, 2009 11:16 am

Suppose whilst I'm here I should give an update...

Still waiting for the parts supplier to get back to me and got to admit it's quite a bit frustrating. I think being a POM, I've been spoilt with the UK suppliers, where you can drive 10 mins down the road and get the stuff off of the shelf, if they don't have it, the shop another 10 mins down the road probably will. I can't recall ever having to order stuff in.

It just don't happen like that here in SA. Half of me wants to be angry that the supplier is so slack, but then I remember that the reason I love SA so much is the fact that it is so laid back.

"you can please some of the people some of the time..."

LOL

Anyhows, it's something like 97 days to go (not that I'm counting) so I've spoken to another supplier in case this one fails to deliver.

Aint got no time to waste :D
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Rob
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Post by Rob » Wed Dec 02, 2009 12:25 pm

Mick,

You can download the current rulebook from the web page. It's a heap faster to search through and assuming you have a Ntebook, is with you all the time.

Cheers,
Rob
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Post by T-34 » Wed Dec 02, 2009 12:52 pm

Rob wrote:Mick,

You can download the current rulebook from the web page. It's a heap faster to search through and assuming you have a Ntebook, is with you all the time.

Cheers,
Rob


LOL then I will NEVER get any work done.
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Post by T-34 » Sun Dec 20, 2009 10:38 pm

Been doing a bit of swatting up on the rulebook, and also making a bit of progress on the build too, which is a good job as the little widget thingo on my desktop tells me that it's only 78 days to go.

:shock:

The new running gear parts have been ordered and should be with me next week, the pans are already here. The body is off of the pan and the old pan halves have been cut out ready for the new ones. I've sourced the IRS components for the rear IRS conversion and have made a start by stripping the old front and rear suspension components off of the pan. Had a set of steel double banded wheels lined up but lost the guys number - D'Oh!

Next job is to get the gearbox fitted in and check clearances with the engine fitted. This will obviously require the body on, so the next week will probably involve fitting and removing the body a few times until things are sorted.

I've cut the rear valence to allow for easier engine fitting and removal and will be fitting some dzus fastners to hold this in place. This saves having to lift the car over the engine to fit it, and also provides better access to the engine for maintenance.

I've a Kirkey bucket seat on order from the states, and will be talking to CB performance tomorrow to get the induction system components sorted out. They have off the shelf plenum chambers for their own turbo kits that will suit my build perfectly and will save lots of fabricating time, although I intend to use a single throttle body rather than two 48IDA style throttle bodies they normally use. They also have a lot of other stuff that I simply cannot get locally, I just hope that they can ship it relatively quickly.

The car is booked in to have the cage made at Donegal engineering in the new year, one big prob with this is that the turnaround I've been given is about a month, which is simply too long. So I'm currently investigating other alternatives - top of my list is to see if I can buy a cage from another bug, or buy an off the shelf kit. hopefully I will know more in the next couple of days.

Also paid a visit to the local race shop and had a look at race-wear packages - gloves + boots + suit + underwear + helmets. Also had a look at fuel tanks, fire suppression and other such stuff. Picked up a few goodies to get on with.

The pan should be mostly finished this week, hopefully I can get it painted, assembled and rolling before the new year, then I can get the cage sorted (somehow) and start fabricating the header system. Still lots to do, and I might hopefully make it - provided I don't lose a month to getting the cage made up.

Anyhows - here's some pics...

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The body off of the pan

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One of the new pan halves. Much easier to replace the whole pan half, then try to patch the old one up.

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The old suspension removed and one of the IRS arms offered up.

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The Rear IRS suspension setup I sourced. This is basically from a later model bug and fits right on. The only modification is that the inner pivot housings need to be added to the swingaxle pan - these are available off the shelf.

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Pan halves removed and pan completely stripped.

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Pan halves trial fitted. I will leave these off for the time being as it makes the pan a little easier to handle on my own.

There's some more pics, vids etc over at my site (see below).

Mick.
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Post by Rob » Mon Dec 21, 2009 2:40 pm

Now that's what you call striping to the bare bones!

Be careful buying a cage from another bug RE pipe diameter and wall thickness.

Cheers,
Rob
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Post by T-34 » Mon Dec 21, 2009 4:36 pm

Rob wrote:Now that's what you call striping to the bare bones!

Be careful buying a cage from another bug RE pipe diameter and wall thickness.

Cheers,
Rob


Yeah, stripping right back is the easiest way to do it, plus the body has to come off to replace the pan halves. The pan carries all of the strength in a bug, so it needs to be 100%. It should hopefully end up something like a new pan - new bearings, brakes, hoses, brake lines, cylinders, rubbers, ball joints, etc etc... A good basis to build from.

The cage will obviously have to meet specs, and if one's not available, plan B will have to come into play - just not sure what that is yet - lol.
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Post by momec » Wed Dec 23, 2009 9:58 am

Plan B is find out what they drink at Donegal Engineering or bribe with whatever is required to jump the queue.
Good luck Chris
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Post by T-34 » Wed Dec 23, 2009 3:43 pm

Hehehe, I think I've already jumped the queue, it's just the sheer time it will take to put together. The guy who is building it works on his own so it's simply not possible to get him to do it any faster, and as I've already committed to getting him do it, I don't really want to change horse half way through the race.

One option is to just build hoop type cage as class is open and so full cage is not required - this is less work and possibly a time saving. I can then get cage added to later.

This is obviously a compromise (of sorts), but then a full cage may be overkill for a car that may struggle to reach 120 / 130mph.

Unfortunately I wasn't able to source an alternative, so i just need to follow the path I am on.

I might be able to borrow another car to fit my engine in to get headers made up - this will save some time as it can happen at same time as cage is getting fitted.

Fingers crossed..........
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Post by T-34 » Mon Dec 28, 2009 12:08 am

Fitted the 915 box in today, it sits pretty good. Had to cut out old front gearbox mount to get enough clearance. Still got to make up mountings but will fab some custom ones to fit. I've also cut the pan for the shift linkage, everything seems to line up better than expected. It is a bit of a tight squeeze in between the frame horns, but it all fits. There is only one place that really needs a bit of clearancing as it is a little close to the case, but not really a massive issue as the box shouldn't be moving around too much. I am very tempted to hard mount the engine and box in, as this will certainly be easier, but not 100% at the moment.

Also started the IRS conversion by clearancing the frame ready for the pivot housings to be welded in. These need some clearancing to fit the rear torsion bar tubes, which considering that they are laser cut is a poor show. If I had known that they would be so poor quality I would have fabbed some myself, especially as now I have to waste time putting them right. The IRS arms are fitted to the pan and the brakes and hubs stripped off to allow the earlier style drums to be fitted - this way the original bolt pattern can be retained.

I really need to finish off IRS conversion and 915 mounts tomorrow so that I can flip the pan and get the body back on - then I can trial fit the engine to see if it fits. This will allow me to take LOTS of measurements so that I can fab headers up without body and pan whilst it is off having the cage made. I might make a temporary frame to hold rear valence and rear wings in position relative to the engine to make life easier

I took a load of snaps but will post them up tomorrow, and add them to the post.
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