SL-C Manual: Door and Body Installation
Proper body and door fitment begins with setting the center body section or spider correctly. Don’t try to lock down one part of the body and work your way around to the other side; follow the directions in this section for best results. Take your time on this step, as it will determine the overall body and door fit on the completed car.
It should be obvious, but the suspension can only be setup with the car resting on the suspension. The toe, camber, etc. of wheels while the car is lifted up is irrelevant- don’t be concerned about how it looks when on jackstands- the only meaningful measurements are taken when the car is resting on the wheels and tires (or ones of the same offset, diameters, and tire size and brand).
For best results, loosely install the windshield first. You can completely install the windshield, or just tape it in place if you want greater access during the build (this is recommended). This ensures that the spider isn’t warped, and setting the windshield in place will dictate the door opening to which the doors must conform. Don’t make the common mistake of getting the door fitment right and then finding that the windshield no
longer fits the body correctly. The rest of the car body can be somewhat massaged, but the windshield cannot, so don’t try to force it- the usual result of that approach is a broken windshield. If you don’t tape it in place for this step, but actually glue it in, you may want to leave it in for fitment purposes, then remove and re-install it later, as the last step in building the car. This has some risk, as removing a windshield without breaking it takes some skill, so it may be best to entrust this to the professionals at a competent auto glass shop.
This process assumes you are building the car on a level floor. For the best body fit, install the body only when the car is on a level surface.
To begin the process, install the wheels and tires on the car. Make sure the tires have approximately the correct amount of air in them (start at 25 PSI if you haven’t selected a final tire pressure yet).
Later cars come from the factory already configured this way, but make sure your car has the suspension arms approximately equally spaced at the threads to begin. In other words, you don’t want the left side arms all the way in and the right side ones spaced out, or any other combination except equal spacing on all arms. This is essential for a later step when the body is squared on the chassis.
Then set the ride height to approximately 4” on the front, and 4.5” in the rear. This measurement is obtained by measuring the distance from the bottom of the chassis to the floor below. For the front, take the measurement between the two ends of the lower control arm, roughly centered under the front axle line (an imaginary line across the width of the car, where an axle would be if it the car had a solid axle). For the rear, take the measurement from the bottom of the chassis, again, where the axle centerline would be if the car had a solid rear axle.
It should be obvious, but ride height is adjusted by moving the springs up or down on the coilovers, by raising or lowering the coil over lock rings.
Do not use the rear suspension pushrods to adjust ride height. Doing so will adversely affect the effective side-to-side wheel rate, as pushrods that are of different lengths will cause slightly different wheel rates from side to side. This will result in odd handling characteristics, and possibly a safety issue. The only correct way to adjust ride height is to adjust the spring position by moving the collars on the coilovers. If you feel you must adjust the pushrods, make sure that at the end of the adjustment, they are both the same length.
Adjust the rear suspension pushrods so that they don’t hit the upper suspension arm in full droop. In many cars, that means the rods have about 1/2” of exposed threads- but this is only a starting point, and your car may vary. In any case, measure the installed length of the pushrods and ensure that they are the same length on each side.
Use a coilover wrench to adjust the springs quickly. You can obtain a coilover wrench inexpensively at Jegs. Summit also has a similar wrench from QA1. The use of regular waterpump pliers on the coil over adjuster rings is discouraged as they will mar the surface of the rings and promote corrosion.
When setting ride height, you may have to keep adjusting things, as, for example, a change in ride height on the left front will have an effect on the left rear, etc. Keep working the height on the car until you have the right height on all 4 corners, and do one final check without making changes to be sure the last change hasn’t altered the other heights.
After setting the ride height and spacing the suspension arms, do a rough toe check on the car. Small errors in toe that may not be apparent by visual inspection will have a large effect on how the wheels fit into the wheel openings. The rear toe is adjusted by moving the rear toe links in or out as needed (making the links shorter makes the wheels toe OUT more, while lengthening them makes the rear wheels toe IN more. Each wheel needs to be adjusted separately in the rear, and the trick here is not to get an average or overall setting, but to set each wheel independently to the correct setting. Shoot for about 1/16” or less toe IN for each of the rear wheels.
The front wheels should also be set for toe, but since they are connected by the steering rack and tie rods, changes can nominally be made by adjusting only one toe rod, assuming you can adjust the steering wheel. Try to adjust both tie rods however, as this will make steering wheel alignment easier when the car is final aligned later.
Please don’t skip the chassis alignment steps above and try to go right to aligning the body. If the chassis isn’t setup correctly, there is no basis for aligning the body.
Once the suspension and ride height is set, locate the center section of the car body (called the “spider”) on the chassis so that it is centered on the car, front and center, left and right. If you have the interior tub option, the tub will properly dictate the fit for the rest of the spider- this is a key benefit of the tub, as it makes it very hard to get the spider installed incorrectly.
If you don’t have the interior tub option, mount the spider on the chassis without the roll cage in place to prevent the cage from distorting the spider and adjust the spider so that the wheel openings are approximately even on all 4 corners. Allow the spider to float forward and backward as needed.
If necessary use plastic shims (for example, cut from plastic milk bottle material) to level the spider left to right. Note the number and location of the needed shims so if necessary you can replace them.
Older bodies may need to be ground in the front where the body contacts the footbox area. To determine if this is needed in your car, use modeling clay to check clearances. Interference here is typically due to varying body thickness due to production variances. New chassis (beginning in mid 2012) are actually narrowed 1 inch in the footbox to eliminate this potential problem. If necessary, you may need to carefully grind the INSIDE of the spider in the footbox area to make it sit properly on the chassis. Do repeated fits, checking for clearance with modeling clay until there is no interference.
Now install the front and rear clams, locating them on the factory-provided stainless steel pins. For alignment purposes, you will want to hold the rear clip up with shims or other stock in the rear as the hinging for them is in another step.
The wheel and tire combo should be centered in each wheel well. If not, adjust the suspension until it is correct. Some cars may need the spacers on the suspension arms to be moved around so that the arms can be slid forward or backward as needed in order to center the tire in the wheel opening in the body.
The front clam should sit flat on the splitter. If not, investigate and resolve the problem, making sure that the splitter is level. Adjust as needed. The splitter should be attached to the chassis using the provided hardware as shown in the picture below. This car has an extra set of side hardware.
Once the entire body is on, insert the driver door into the door opening and space it evenly so that a uniform gap of about 1/8” is maintained all over in the opening. Use paint sticks or similar shim stock to hold the openings to validate the fit. If necessary, move the spider to make the fit perfect. Don’t try to bend the doors to fit- instead, move the spider slowly and carefully until both doors are gapped in their openings, and the front and rear clams fit perfectly. You may need to add or remove shims, or grind the body (on the INSIDE only) around the footbox part of the chassis.
Repeat this process for the other door.
Validate that the wheels are centered in the openings, and if necessary, adjust the suspension to bring the wheel/tire combination in line with the openings. Be especially aware of how even small changes in one area affect other pieces of the alignment puzzle.
Once you have the door gaps and fit perfect, and the fit of the front and rear clams correct, you can lock down the spider. As discussed elsewhere, use the small recessed areas on the body to insert a bolt and any necessary shims/washers/etc. to hold the body in place. You can drill and tap a hole in the chassis for this purpose, or use rivnuts. The picture below shows how the spider is locked to the chassis on the passenger side near the fuel filler.
Use a washer as shown (bigger is better, here). As shown in this picture, there may be shims or body washers under the body held in place by the bolt as shown, as needed to properly locate the spider for a perfect door opening.
In the picture above, the side needed about 1/8” of spacers to get the alignment correct, as seen by the washer stack between the chassis and body.
The car comes with side skirts in fiberglass (or as an option, in carbon fiber). They are delivered as one part, which needs to be cut lengthwise to create two parts. Cut down the middle carefully and trim to fit.
To mount them, place them on the body and align them so they are centered. The assembly order is, from the bottom, skirt, body, aluminum chassis extensions.
Drill holes through them and the sheet metal chassis extensions that are welded to the chassis. Remove the skirts and install Rivnuts in the aluminum chassis extensions, then re-install the skirts. The use of Rivnuts makes it much easier to remove and re-install them while you are building the car, as it may be difficult to reach nuts or bolts deep inside the area between the chassis and the body.
Once the spider is correctly located, use the provided templates to cut the holes in the spider for the lower door hinges. There are two parts on each side that need to be cut as shown in the photos below, which shows a spider upside down, looking at the hinge area.
The first area to be cut is on top of the spider (at the bottom of this picture) for the top of the hinge to protrude (this is covered by the front shell or clam in use, so it is only seen when the front clam is opened). The second area is for the actual hinge to come out, along with the holes for the attaching hardware. Cut these holes carefully, and plan to massage them later with body filler if you are painting the car. The holes are covered by the front clam when closed, but doing a neat job here will pay benefits later. You can see the hole in question in the picture below, at the upper left:
Note that the hinge area has been reinforced with a metal plate. The same approach is used for the doors as well, in order to spread the load across the greatest area possible. You can fabricate these plates from aluminum- thicker is better- and if you use flat pieces, ¼” is very strong. Lighter gauges can be used if you want to roll the panel around as is shown in the picture above. When the doors are completely aligned, you can epoxy the metal plates to the doors, or run bolts through the plates to create a sort of sandwich effect which is very strong.
Mount the hinges and check for free swing. It’s normal for the hinges to ride in the metal bracket attached to the body, so don’t be alarmed at that.
Using the template shown below, drill the holes for the gas spring, and install it to prove that all clearances work. Then remove the end that bolts to the body and let the spring float unattached while performing the next step
To use this template, print out the page so that the squares measure exactly 1 inch per side. Alternatively, make one up using the measurements taken off the template above.
The gas spring on each door is designed to hold the door open, not to open the door when unlatched- the operator is expected to use some small effort to open the door.
Install the gas spring with the provided spacers so there is clearance between it and the chassis. You'll find that the alignment process is easier without the gas spring attached, but that the force provided by the spring affects the alignment, so plan accordingly.
Once you have validated that the door openings are correct for the doors, and the hinges have been mounted you need to attach the doors to the hinges. This process is simple in concept- you just run the long studs on the end of the hinge into the doors, adjust the upper hinges if needed, and tighten on both sides of the door when you have the gaps correct- but in practice there are a few things that make the process easier.
This process assumes you have already bolted the hinges to the spider as described above.
If you haven’t already done so, make a rough cut of the door panel opening, leaving at least a 1” lip. The opening enables you to get your hands and tools into the door cavity, which is required for the next steps. Leaving a lip makes it easier to install door panels later if you are not using the optional factory set.
If you have the gas springs on the hinges, pull one end off of them now so you won’t have to fight the spring as you align. You can snap them back on when alignment is complete.
To begin, you’ll need to drill holes in the door where the hinge studs will penetrate the door. With the door in place, and the hinge mounted on the car but with the studs on the hinge removed, mark the approximate place on the door where the studs will penetrate the door edge. Drill holes to allow the studs access. It’s OK to make these a little bigger than the studs, as you will be making plates, or using fender washers to cover holes that are a little big. Making the holes a little oversize gives you the ability to move the door around on the hinges so you adjust the alignment. Try not to go more than about ¼” larger than needed.
Once you have the holes for the hinge studs to penetrate the doors, make up metal plates on both sides of the door to bolt the hinge studs through. This relieves stress on the fiberglass door, and makes it easier to keep perfect alignment, once it is obtained. Use cardboard to make patterns, then cut them out of ¼” aluminum or possibly thinner steel. The inside of the door has all the room you need for thickness, and the outside has sufficient as well. Take care when making the outer plate as it will be visible when the doors are open.
With the outer metal plate loose on the hinge studs, place the door in place and repeat the alignment using paint sticks or whatever you used to make the door fit perfectly. Now install nuts and washers on the OUTSIDE of the door so the door is properly aligned when shut. You’ll have to go through several iterations to get this right, so take your time and creep up on it.
Once you get the outer nuts and washers position set, you can install and tighten up the nuts and washers on the inside of the door.
Now just carefully adjust the nuts and washers until the door opens and closes without rubbing, maintaining the fitment you want. With experience, this process takes about an hour per door. First timers will always take longer, until the geometry in the hinges and the amount of adjustment becomes second nature. Repeat for the second door.
When both doors are hinged and swinging correctly, install the gas spring and validate the fit again. It is common for the force of the gas spring to slightly distort the door fit, so you may need to make small adjustments in the nuts and washers on the door to account for that.
The Le Mans
The doors are different in the Le Mans, as are the hinges. In the Le Mans, the door hinges straight up. More details are forthcoming on the hinge details on the Le Mans.