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260DET

The Z31 Project - Race Car

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The hardest part is done, I now have a left and a right trailing arm finished. They are set up to accept two lateral links and a coilover each side all rod ended, even the coilover botton end. Work has started on chassis brackets to accept the inner lateral links ends, have some nice swaged aluminium radius rods made for speed cars of some sort which are getting modded as suitable lateral links, with L and R threaded rod ends it's all adjustable by simply rotating the links. 

 

Could go on about the numerous design changes, fabricated parts that didn't work out, the difficulty in getting both sides the same but pfft, I know what the fans want, pics!!!!

 

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Edited by 260DET

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Wheels, what a PITA. Anyway have ordered a set of 18x10's, that size dictated by the biggest 18" 275/35 Hankook semi slicks available. After a lot of research I decided on Koya's because they custom fit them to your offset etc requirements, they are light and well priced. Fit at the back should be OK with a bit of guard rolling, the front may take a bit more work than that.

 

Pic is of the MCA race car.

 

 

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Paul Newman driving, 2+2's were also raced when the longer wheelbase was an advantage. Stock Z31's may look and drive pretty ordinary but there is no arguing with the race versions. 80's cool to the max.

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Lots of little things being done, sooner or later they will all be able to be put together to make something complete and picture worthy. In the meantime pic of a 2+2 race car, the longer wheelbase was an advantage on most circuits. Should mine use the same colour scheme?

 

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The 2+2 will always be uglier though... I think definitely go with the retro race theme.

This '86 Paul Neuman scheme is my favourite:
220px-Racing300ZX.jpg

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OK then, thanks, the car is already white so the underneath can just be touched up before it is flipped back on to wheels. None of the American ads but maybe a cool permanent number would be good. I guess that there is no register somewhere of the permanent numbers in use. Instead of 33 maybe 88?  

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CAMS Qld office has a register for car race numbers.

This is for cars that are intended for acing purposes.

CAMS Competition license holders advise Qld State office of their desired number.

I used to have 28, 66 and 13

However, none of the above applies,so stick whatever numbers you want on it, and at your first Sprint/Lapdash day, they'll allocate youa number that goes on top left corner of screen, and require you to put a bit of tape over your painted on numbe, so that the stopwatch guy doesn't get confused.

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Thanks for that Jason, last time I checked at least some sprint entry forms catered for a permanent number so seeing that the car will be log booked such a number will be useful as well as being part of the overall paint job.

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Waiting for some specialist welding to be done before moving along, front aero redo on the 280ZX for 2017 Challenge Bathurst is keeping me off the streets though. Underneath body reinforcement of the Z31 is complete as far as possible where it can be reached without rotating the car 180*, pic of that below. Been concentrating on the front chassis members and where they meet the passenger compartment which it seems obvious to me is a weak part, the cage will mostly take care of the passenger compartment itself and back, although sill reinforcement/jacking support from front to back has also been added.

 

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Ummmm

Why dont you just seam weld it,,,, properly, like all other competition cars have done.

10 or so metres of that pallaver, it'll be lucky to come in under2 tonnes!

That,and, the flag marshalls meatball flagging you for the trail of snapped off chunks of rhs!

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Obviously you don't understand what this is about Jason, my third Z car build and the most ambitious whereas you mainly bought your cars already done by someone else and then spent as little as possible on them. So I don't consider you very knowledgable on what is being done here going also by your mainly sniping comments.

 

After a lot of thought and research I'm pretty sure what is being done will turn into a decent race car which includes having a reasonably stiff body, seam welding won't do it if the required structure is not already there to be seam welded. Sure some weight will be added, the SHS in the various  sizes used would average out at about 2kg per metre, but look at the chassis strength of modern cars and how quick the best ones are. It's no secret, for good handling and grip stiff components and structures are essential, light wet noodle chassis do not cut it. 

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Actually weight is very much a priority consideration, there are plenty of weight saving ideas to come, big non structural ones like doors, bonnet and hatch. The cage will probably be pretty basic too, a taxi bar is the only extra I can think of right now, the cage will be tied into the body at multiple extra points though, the significance of which seems to be ignored in a lot of caged cars.

 

The 280ZX has taught me a couple of things, for a start the front removable X member must rock under stress because the retaining bolts keep wanting to come loose as do the bolts that retain the triangular engine bay brace I made. The message is clear, add strength to these areas because there is flex there. It's pretty significant that modern cars have a heavy sub frame in the front suspension area, my response is much lighter.

 

Ooooh, just thought of an extra brace that could go in the front, must resist must resist must resist, temptation you fat witch  >:D

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Auto transmission. The present GM 4L85E in the 280ZX works great but it is over kill for the relatively low power of my V8, it weighs, yes, 115kg. So lots of internal weight to get rotating as well as the overall weight penalty. As the proven 280ZX will be the vehicle of choice to race this year, the Z31 project is proceeding but the 280ZX has been to Bathurst and I know exactly what has to be done to it to make it truly Bathurst fit.

 

So 280ZX auto, eventually Z31 project car auto. 115kg is just unacceptable for the reasons given so there must be an alternative. To cut a very long story and an epic adventure of internet searching short I've found the most promising solution yet. Which is to use a GM Powerglide 2 speed auto with a Gear Vendors 2 speed unit behind to give a total of 4 gears which is all that's needed, that was confirmed by the 2016 Bathurst experience. Present info is that this combination will weigh between 60 to 75kg, compared with the present unit's weight of 115kg, plus a lot better internal efficiency meaning more power to the ground and better dynamics on the track.

 

Waiting to hear form Gear Vendors but I am getting just a little bit excited :)

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Do you have many ratios to choose from in a powerglide?

Why not fit the 6 speed manual box from LS?

Mick, dont go there !!!

Richard likes to be,,,,, different,,,,,

 

Powerglides only have one ratio, Low

Top is direct, and doesn't lock in, but they are very strong.

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Don't think that ratios will be a problem overall Mick, I'm not up on Powerglides yet but because they are popular for drag racing (Jason knows all about that lol) there are a heap of options available for them including new light weight cases would you believe. Will know more when GV get back to me too.

 

On the 'more than four speeds question' with the four speed auto at Bathurst all that was needed was a touch higher 2nd gear, below that only a low 1st gear for trailer loading and pit driving is needed. The engine is cammed only and has a very useable 3,000rpm power spread which covers all the present gears. The less shifting to be done the better, allows more concentration on lines, traffic and so on. Good brakes are needed but this allows you to easily outbrake those who have to down shift lots. No, 4 speeds is perfect, less weight too.

Edited by 260DET

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Mick, dont go there !!!

Richard likes to be,,,,, different,,,,,

 

Powerglides only have one ratio, Low

Top is direct, and doesn't lock in, but they are very strong.

 

Being different involves a complete rethink of what's best for me, what works and what doesn't. There is no 'one size fits all' in racing either, over time I've found that a lot of amateurs like me just copy what others have done, other than playing it safe I can't see the point in that. Sure it's good to learn from those with experience but don't be bound by their opinions.

 

To finish the lecture :) no high end race cars these days have a clutch pedal, there are applicable reasons for that.

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The Gear Vendors system works by replacing the main transmission's rear housing with an extension housing to which is bolted the GV unit. So this brings the weight back a bit which is good and also means a shorter tailshaft which is also good. 

 

The whole auto thing has been a PITA ever since it was decided to do it, mainly because drag racing rules as far as autos go so all the equipment and knowledge is based around that. And so there is little incentive to make aftermarket gear for circuit racing except where the big dollars are of course and that usually involves the manufacturers anyway. So I'm a bit lucky that the arrangement I'm considering is available and at an affordable price.

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For anyone interested in the GV option, their unit shifts between 1.00 and 0.78 so behind a two speed Powerglide the gears may be described as 1, 1+, 2 and 2+. Using the Powerglide OE 1.76 1st gear gives the final ratios of 1.76, 1.33, 1.0 and 0.78 which is great for circuit racing but with the high 1.76 1st gear I'm not sure if the car will be slow enough to trailer load, drive around the pits, etc., 1st gear in the present auto is 2.48 which is practical. 

 

Will have to have a chat with my drag racing mate and a good torque converter builder. On the one hand 1.76 will require plenty of low revs slip while on the other a low stall, high efficiency converter works great on the track. At Bathurst I found that the lock up clutch was not essential as the trans ran cool, no hint of overheating after 20 minutes use. Deleting the lock up clutch would probably cost 5 to 10 kph top speed but slightly improve all round performance.

 

Anyone with knowledge of this sort of stuff please comment.

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1.76 hey!

Not to far from the Datsun Sports Option box first gear ratio of 1.85

Now thats a cracker of a box to go real racing in especially matedto thecorrect diffratio for blinding off the start line acceleration, and also have a gear ratio for every corner, to maximise corner exit speeds.

 

Did I tellyou about my early/mid 1980's days when I ran what was known as "Dial your own" bracket drag racing?

Attended Fairbain ACT, Catlereagh NSW, Calder Vic, strips, ran Datos and GM cars

Used to playarround with different stall converters, and manualised valve bodies in the GM trans, to good effect.

 

Sounds like you have an expert Auto trans bloke to get you sorted though,,,,,,

Ask him about fitting a Lenco, one of those old dinosaurs would suit you perfectly

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I guess that if you Jason can trailer load etc with a 1.85 manual then I should be able to manage a 1.76 auto.

 

Pic of a special cased Powerglide but otherwise identical setup to what I'm considering.

 

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