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GT40 Tech - Chassis,Brakes,Tires,&Wheels Chassis and Handling.

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Old 15th April 2017, 10:49 AM   #1
phase5
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GTD sway bar info needed please

hello everyone,
I am rearranging the GTD that I now have and I am relocating the swaybar to the top side above the trans., from where it is now which is behind the trans way down below the body. after moving it I discovered the bend on the sway bar is too far wide to fit between the correct mounting hole on the frame support. Also it is a bit on the thin side and would like to upgrade the diameter. Any info on where to purchase a sway bar that is more correct for the correct mounting location?

Thanks,
Ken
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Old 15th April 2017, 11:03 AM   #2
phase5
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Re: GTD sway bar info needed please

Here are some quick pictures.
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GTD sway bar info needed please-20170415_075849-jpg   GTD sway bar info needed please-20170415_075922-jpg  
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Old 16th April 2017, 08:09 PM   #3
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Bobs 9401
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Re: GTD sway bar info needed please

Ha Ken,
Where do I start, I owned a GTD also and redesigned just what your looking to do and also got ride of the bump steer in the process. I can send you pictures or drawings or you can look up my build thread Bob's GTD build I'll be more than happy to help you out anyway I can.
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Old 19th April 2017, 10:11 AM   #4
phase5
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Re: GTD sway bar info needed please

Thanks Bob,
Great job on all of your work and rework.
1. I need a new sway bar, where do I get one?
2. Where did I get myself a quick latch to remove the rear and front lids? Do need to machine one myself?

Thanks for the help
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Old 19th April 2017, 10:05 PM   #5
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Re: GTD sway bar info needed please

One of the kit company's should have one that will work. As far as the quick latch I'm not sure I understand what you mean?
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Old 20th April 2017, 10:18 AM   #6
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Re: GTD sway bar info needed please

You may be able to get one from someone like Southern GT or Frank at Wealden Engineering may have one left from an upgrade. As you are in the USA it may be easier to fabricate one. Buy a length of spring steel round bar of suitable diameter. Bend where necessary by heating with an oxy torch while red hot to the gentlest possible radius. The steel will need to be rehardened. Heat treating the annealed stock requires first getting the part red hot and water quenching it. That is the hardening part of the heat treatment. which will make it brittle and then it must be tempered. Clean off the scale and temper it by heating at around 450-500 degrees F. to a uniform blue color and let it cool slowly. You may find a local spring works who will do the heat treatment for you. I have a local place that does leaf springs for trucks.

The bar diameter on my GTD is 15mm and you can get the shape and size from the attached pics. If you want a stiffer bar you can get thicker bar but note that the stiffness goes up dramatically with increased thickness. You can get a formula to calculate this from Mr Google.
The standard GTD rear antiroll or sway bar is non adjustable but you can make it adjustable using the sliders as in the attached pic.
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Old 20th April 2017, 10:25 AM   #7
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Re: GTD sway bar info needed please

Part 2

The stiffness of the anti roll bar
increases with thickness
Increases with stiffer steel. (You can look up the modulus on Google)
Increases as you move the sliding links closer to the bar pivots.
Decreases if you make sections of the bar smaller in diameter

Drop links can be made up from steel bar or tube and some rose joints.

Cheers
Mike
Attached Thumbnails
GTD sway bar info needed please-gtd-rear-antiroll-bar-jpg   GTD sway bar info needed please-gtd-anti-roll-bar-rear-jpg   GTD sway bar info needed please-gtd-rear-antiroll-bar-jpg  
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File Type: jpg Screen Shot 2017-04-20 at 14.57.30.jpg (5.7 KB, 2 views)
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Old 20th April 2017, 10:27 AM   #8
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Re: GTD sway bar info needed please

Pic of round anti roll bar slider. Usually available from kit or racer shops.
Cheers
Mike
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File Type: jpg Screen Shot 2017-04-20 at 14.57.30.jpg (5.7 KB, 15 views)
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Old 20th April 2017, 11:11 AM   #9
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Re: GTD sway bar info needed please

There are many different ways of engineering this, and we have several preferred ways of doing it, depending on the type of use the car is likely to have. See the attached pictures, this is my preference for a track car, because it has two main benefits, adjustability and torsional balance. The centre straight can be either a solid rod or a tube beam, I prefer the solid rod, usually 22mm dia high specification mild steel, which accepts a torsional twist, acting as an additional spring in the cross car transfer of load, this makes the load transfer a little more progressive and, for me gives a better feel in hard cornering. The tubular cross beam will perform as a rigid bar , great if you are a race driver but gives no feel to the handling as it transfers the load instantly. At each end I use Ford adjustable blades, which can be rotated to give degree of personal tuning to the roll bar. I have used these on a lot of cars successfully, but have to admit you need to be a very good driver indeed to really benefit from them. Considering that the original GT40 race cars ran with a bit of bent wire for an antiroll bar at the rear, these are light years ahead of those , but if you are building a true replica, go buy some bent wire ! Frank
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GTD sway bar info needed please-anti-roll-bar-3-jpg   GTD sway bar info needed please-antiroll-bar-4-jpg  
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Old 20th April 2017, 11:17 AM   #10
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Re: GTD sway bar info needed please

Another picture
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GTD sway bar info needed please-dscf0552-jpg  
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Old 20th April 2017, 11:31 AM   #11
phase5
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Re: GTD sway bar info needed please

Quote:
Originally Posted by MikeP View Post
Part 2

The stiffness of the anti roll bar
increases with thickness
Increases with stiffer steel. (You can look up the modulus on Google)
Increases as you move the sliding links closer to the bar pivots.
Decreases if you make sections of the bar smaller in diameter

Drop links can be made up from steel bar or tube and some rose joints.

Cheers
Mike
Awesome info, thank you for the pictures and the help. makes the decision much easier.
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Old 20th April 2017, 11:34 AM   #12
phase5
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Re: GTD sway bar info needed please

Quote:
Originally Posted by wealdenengineer View Post
There are many different ways of engineering this, and we have several preferred ways of doing it, depending on the type of use the car is likely to have. See the attached pictures, this is my preference for a track car, because it has two main benefits, adjustability and torsional balance. The centre straight can be either a solid rod or a tube beam, I prefer the solid rod, usually 22mm dia high specification mild steel, which accepts a torsional twist, acting as an additional spring in the cross car transfer of load, this makes the load transfer a little more progressive and, for me gives a better feel in hard cornering. The tubular cross beam will perform as a rigid bar , great if you are a race driver but gives no feel to the handling as it transfers the load instantly. At each end I use Ford adjustable blades, which can be rotated to give degree of personal tuning to the roll bar. I have used these on a lot of cars successfully, but have to admit you need to be a very good driver indeed to really benefit from them. Considering that the original GT40 race cars ran with a bit of bent wire for an antiroll bar at the rear, these are light years ahead of those , but if you are building a true replica, go buy some bent wire ! Frank
Who makes these bars? I think that is the route ill go. I have a full CNC machine shop but for the bar, I think simply ordering one is a better route.
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