GT-Forty.com

GT-Forty.com http://www.gt-forty.com/GT-Forty/Suspension.html Disclaimer: These section is dedicated to the suspension and alignment of this GT40. Doing the initial alignment is required to get the body alignment correct. I started on the Right Front corner - primarily since it was the easiest. I want the front suspension set to 6 degrees positive caster and 1 degree of negative camber and 1/16” toe out. Rear Suspension - This was actually easier than I thought. Like the front suspension, I set the rear ride height by raising the outboard side of the lower control arm until it is level to the ground. I wanted Zero Toe and Zero Camber. The rear uprights need to be canted to the rear at 6.5 degrees. The pictures below show you how I got there. Note - you might notice that many shots of heim joints show the locking nuts backed off. That is intentional to illustrate how many threads are exposed. Rest assured that they will be appropriately tightened and torqued before this car hits the road. All racing suspensions are designed to have the lower control arm parallel to the ground when at ride height. http://www.gt-forty.com/GT-Forty/Suspension.html#0 1f7c3890-602c-4ed9-b554-1b5623d6110b http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1415/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1415/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">All racing suspensions are designed to have the lower control arm parallel to the ground when at ride height.</p></div></div> We set the LCA at 0 degrees to simulate ride height for our alignment. http://www.gt-forty.com/GT-Forty/Suspension.html#1 c804a7ba-4094-4b74-ab33-3c57772d1261 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1417/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1417/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">We set the LCA at 0 degrees to simulate ride height for our alignment.</p></div></div> I use a bubble type caster camber gauge. There are some nice digital ones but these are pretty fool proof if kept in good condition. http://www.gt-forty.com/GT-Forty/Suspension.html#2 189bfd70-671b-4ef8-8758-f5bcaa2c9f31 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1419/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1419/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">I use a bubble type caster camber gauge. There are some nice digital ones but these are pretty fool proof if kept in good condition.</p></div></div> The Magnetic mount works perfectly well on the face of the rotor for both camber and caster setting. Caster is tested by turning 20 degrees to both right and left of center. http://www.gt-forty.com/GT-Forty/Suspension.html#3 fc0b0b92-d6aa-42b5-b074-a1b8ba346360 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1421/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1421/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">The Magnetic mount works perfectly well on the face of the rotor for both camber and caster setting. Caster is tested by turning 20 degrees to both right and left of center.</p></div></div> I had to turn the upper control arm (UCA) heims all the way in and remove the outer jam nut on the ball joint to get to -1 degree camber http://www.gt-forty.com/GT-Forty/Suspension.html#4 838fae18-9f5d-4acf-9159-fdc2c927cc42 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1423/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1423/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">I had to turn the upper control arm (UCA) heims all the way in and remove the outer jam nut on the ball joint to get to -1 degree camber</p></div></div> To get the +6 caster, I had to move the UCA as far to the rear as possible. This is the rear heim/mount http://www.gt-forty.com/GT-Forty/Suspension.html#5 2ac6ae85-2d07-42a5-b26e-c3d021c555e5 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1425/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1425/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">To get the +6 caster, I had to move the UCA as far to the rear as possible. This is the rear heim/mount</p></div></div> This is the UCA front heim/mount http://www.gt-forty.com/GT-Forty/Suspension.html#6 ca021b59-d14d-4181-a3df-c3f6705f15d7 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1424/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1424/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">This is the UCA front heim/mount</p></div></div> LCA Rear shim pack had to be modified to move the LCA as far forward as possible. This is the rear mount (spaces shown below) http://www.gt-forty.com/GT-Forty/Suspension.html#7 f11b97f6-bbcb-446c-93a9-cb3d88e94839 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1429/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1429/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">LCA Rear shim pack had to be modified to move the LCA as far forward as possible. This is the rear mount (spaces shown below)</p></div></div> This is the front of the LCA. Note that it took 5 washers to the rear and one to the front. http://www.gt-forty.com/GT-Forty/Suspension.html#8 54b9854f-6391-4959-a554-6552314af7dd http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1431/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1431/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">This is the front of the LCA. Note that it took 5 washers to the rear and one to the front.</p></div></div> Spacer Stack for the LCA Rear http://www.gt-forty.com/GT-Forty/Suspension.html#9 58958890-d23c-4503-b423-b2b3e567fb8f http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1427/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1427/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Spacer Stack for the LCA Rear</p></div></div> I used a piece of tubing for the spacer http://www.gt-forty.com/GT-Forty/Suspension.html#10 496b576c-dffe-44ed-962a-45b15549c139 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1428/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1428/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">I used a piece of tubing for the spacer</p></div></div> The LCA and QA1 shock http://www.gt-forty.com/GT-Forty/Suspension.html#11 9568fe60-6272-44a2-9181-66f1aec7a4eb http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1433/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1433/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">The LCA and QA1 shock</p></div></div> Showing the angle between upper and lower balljoints http://www.gt-forty.com/GT-Forty/Suspension.html#12 1d1e812d-501a-4abf-92e2-a7f0c47f6f12 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1434/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1434/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Showing the angle between upper and lower balljoints</p></div></div> Another offset revealing picture. http://www.gt-forty.com/GT-Forty/Suspension.html#13 00896e39-000c-4d7c-9a6e-8b932e366687 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1436/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1436/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Another offset revealing picture.</p></div></div> Right Rear - Lower Radius Rod is as short as it will go. http://www.gt-forty.com/GT-Forty/Suspension.html#14 2f5062e7-f334-4a7b-965a-eff53cbf993c http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1509/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1509/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Right Rear - Lower Radius Rod is as short as it will go.</p></div></div> Right Rear - Upper Radius Rod is lengthened to roughly half the total length of the heim joint’s threaded shank. This was done to get the right cant angle to the rear upright and to straighten out the upper control arm http://www.gt-forty.com/GT-Forty/Suspension.html#15 18c6c145-b4b8-4c2d-8002-cd3d88ff1273 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1510/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1510/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Right Rear - Upper Radius Rod is lengthened to roughly half the total length of the heim joint’s threaded shank.  This was done to get the right cant angle to the rear upright and to straighten out the upper control arm</p></div></div> Right-Rear - Upper control arm must be parallel to the rear chassis’ Horseshoe. This means that it is 90 degrees to the centerline of the car. http://www.gt-forty.com/GT-Forty/Suspension.html#16 6c86389c-0024-4dce-931a-a81a02046b82 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1511/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1511/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Right-Rear - Upper control arm must be parallel to the rear chassis’ Horseshoe. This means that it is 90 degrees to the centerline of the car.</p></div></div> Right Rear - Upper control arm heims are adjusted almost all the way in to shorten the control arm to bring the camber to Zero. http://www.gt-forty.com/GT-Forty/Suspension.html#17 b04851ca-ef48-43fd-bb5d-2b86f103567c http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1512/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1512/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Right Rear - Upper control arm heims are adjusted almost all the way in to shorten the control arm to bring the camber to Zero. </p></div></div> Right Rear - Lower control arm inner heim. I needed to turn it out a little more than half the length of the threaded shank and then shimmed to the rear to help dial out most of the Toe-Out condition that the car had. http://www.gt-forty.com/GT-Forty/Suspension.html#18 14b76912-ec5f-4ad0-9568-e64eb009767d http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1513/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1513/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Right Rear - Lower control arm inner heim. I needed to turn it out a little more than half the length of the threaded shank and then shimmed to the rear to help dial out most of the Toe-Out condition that the car had.</p></div></div> Right Rear - lower control arm shims on the inner heim were replaced with 3 - 5/8” flat washers. Notice the stack of washers here is almost 1/2” thick. I will fabricate a better spacer. http://www.gt-forty.com/GT-Forty/Suspension.html#19 6eac688b-2405-4ff5-8226-664635cc4b31 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1517/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1517/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Right Rear - lower control arm shims on the inner heim were replaced with 3 - 5/8” flat washers. Notice the stack of washers here is almost 1/2” thick. I will fabricate a better spacer.</p></div></div> Right Rear - Lower control arm Rear-Outer heim - about 4 threads showing to the inside of the locking nut. http://www.gt-forty.com/GT-Forty/Suspension.html#20 78e033bc-d574-49a0-adad-88c5758e19ca http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1514/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1514/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Right Rear - Lower control arm Rear-Outer heim - about 4 threads showing to the inside of the locking nut.</p></div></div> Right Rear - lower control arm Front-Outer heim - about 4 threads exposed to the inside of the locking nut. http://www.gt-forty.com/GT-Forty/Suspension.html#21 af36eed8-1ba7-44a4-a3ea-eb3581cec5bb http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1515/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1515/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">Right Rear - lower control arm Front-Outer heim - about 4 threads exposed to the inside of the locking nut.</p></div></div> Alignment Props When suspensions are designed, the lower control arms are designed to be parallel to the ground at fully loaded ride height http://www.gt-forty.com/GT-Forty/Suspension.html#22 c52790f3-d912-46a5-8ed3-ebf093b3fadf http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1592/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1592/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-top: 0pt; " class="paragraph_style_2">Alignment Props<br/></p><p style="padding-bottom: 0pt; " class="paragraph_style_2">When suspensions are designed, the lower control arms are designed to be parallel to the ground at fully loaded ride height</p></div></div> I made these props from 2x4 lumber. Notched to prevent the props from moving if bumped. http://www.gt-forty.com/GT-Forty/Suspension.html#23 63d7c235-bf56-4c6c-9f97-3aefaf01b94f http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1593/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1593/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-top: 0pt; " class="Caption">I made these props from 2x4 lumber. Notched to prevent the props from moving if bumped.<br/></p></div></div> With the Coil-Over springs relaxed, the props can easily hold up the weight of the wheels and suspension. http://www.gt-forty.com/GT-Forty/Suspension.html#24 6738ead7-f09d-471d-8f24-adfd27f7bb63 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1594/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1594/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">With the Coil-Over springs relaxed, the props can easily hold up the weight of the wheels and suspension.</p></div></div> By setting up the suspension in this manner, we can put am almost perfect alignment on the car before it’s ever ready to hit the road. http://www.gt-forty.com/GT-Forty/Suspension.html#25 b7de8c77-728c-4a61-9509-2bacd02425d3 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1598/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1598/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="Caption">By setting up the suspension in this manner, we can put am almost perfect alignment on the car before it’s ever ready to hit the road.</p></div></div> Since the GT40 is not a symmetrical car, it’s necessary to have the basic alignment done in order to do the initial body positioning. http://www.gt-forty.com/GT-Forty/Suspension.html#26 73c2d068-9d28-427c-bdac-321e64194676 http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1597/thumb.jpg http://www.gt-forty.com/GT-Forty/Suspension_files/Media/IMG_1597/micro.jpg <div style="padding: 0px; " class="image_cluster_layout_style_default_External_182_135"><div class="image_cluster_layout_style_default"><p style="padding-bottom: 0pt; padding-top: 0pt; " class="paragraph_style_2">Since the GT40 is not a symmetrical car, it’s necessary to have the basic alignment done in order to do the initial body positioning. </p></div></div>