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Fender Kit Installation Guidance

280YZ, 940Z , Subtle Z Fender Kits for the 1970-1978 Datsun Z




Thanks for your interest in, or your purchase of this Z Fender Kit. This kit was designed to improve traction by allowing larger wheels and tires to be mounted on your Datsun, and to enhance its appearance by widening the track and making the body more muscular.

This Z Fender Kit is designed to fit on 1970-1978 Datsun Z coupes (2-seater cars). With minor modifications the rear quarter panels can be used on 2+2 cars, and the front fenders, hood, air dam, and spoiler will fit without modification.

280YZ complete kit280YZ kit. Photo courtesy of Tim McClanahan, Big O Tires, Anaheim CA

The kit consists of bolt-on front quarter panels, hood and air dam. The rear quarter panels and the spoiler bond on after minor preparation. Please note: The cowl hood pictured with the kit above is NOT included as part of the basic kit. Please let me know if you want a hood with your kit. Also, you can buy any of the parts separately.

Since some customers don’t install the front quarters, this guide is written in back-to-front format. However, it is not absolutely necessary to install the kit in this order.

Get a medium size box to hold all the parts you will remove and/or reuse. It’s amazing how quickly they grow legs, especially when you have to work on your car between domestic chores.

You may have difficulty removing the bolts, as they tend to resist due to age and rust. It will be difficult to get WD-40 into the threads, but try it anyway. Also, It may help to tighten them an eighth of a turn before loosening them.

For some particularly difficult bolts it is necessary to back them out a little, spray the exposed threads with penetrating oil and retighten them to get the oil into the nut or threaded hole, before the bolt can be completely removed.

Reinforcing, Rotisserie

Many builders reinforce their donor cars before installing the body kits. If you’ve stripped your car out completely to repair hidden collision damage or rust, this is as good a time as any to reinforce it. 

A roll cage is a good way to stiffen the car. This can improve handling performance, as well as help resist the torque of whatever engine you are going to install. It also provides much improved crash protection.

Matt Benson 280yz passenger sidePhoto courtesy of Matt Benson, Zephyr Cove NV

If your car is completely stripped, the body shell is pretty light. You should  consider mounting it on a rotisserie. You can easily fabricate one from steel tube and plate, and use an engine stand on either end of the car. This will give you a pivot point for rolling the car over to weld on the floor pan and/or sub-frame reinforcement. It will also allow you to roll the car around a little bit, make more room in your garage when needed, and facilitate better access to all sides of the car.

240z 280z s30 rotisseriePhoto courtesy of Tim McClanahan, Big O Tires, Anaheim CA

240z 280z s30 reinforcing on rotisseriePhoto courtesy of Tim McClanahan, Big O Tires, Anaheim CA

Rear End 


Remove the rear side marker lights. You can re-use these later, if you desire. We also offer a more subdued, flush-mount side marker for a cleaner look.

Remove the antenna.

If your car had the dealer-added or aftermarket side moldings, you'll have to remove these also. Pry out the rubber strip (if installed) and drill the rivets (or remove the screws, as applicable).

You could get away with removing only the bumper ends (on the 280s), but the installation will go a lot easier if you remove the bumpers entirely.

Remove the fuel filler door. This would probably be a good time to enlarge the mounting holes for the door. Slot them outboard to allow the door to line up with the surface of the new, wider quarter panel.

CAUTION: Before you begin the next section, make yourself aware of the location of the wiring harness and antenna cable that run through the fenders in the areas you are going to cut. The antenna cable is on the driver’s side, and the wiring harness to the rear of the car for the tail lights, fuel pump and sender, etc, runs through the passenger side. If you don’t make some provision for pulling them up and well clear of your cuts, you are going to create a lot of extra work for yourself in the form of sorting out the connections and hooking the wires up again.

The antenna cable should be fairly easy to maneuver out of the way, especially since the antenna is loosened or removed already. However, the wiring harness on the other side doesn’t have a lot of extra slack in it. You may have to pull some interior panels in the rear deck area and loosen the wiring harness from the hold downs in order to generate enough slack.

If you can tape or zip tie the wire harness and antenna cable up and well out of the way, you will not have to worry about it any more…like when you start to weld the wheel well and the quarter panel back together. A little too much heat can do as much damage as cutting through the bundle.

Removing the interior panels inside the car is a very good idea. This will help you visualize all your cuts and watch for things you may unintentionally hit with the saw blade. It will also help keep you from setting your car on fire when you start to weld, and allow you to access the interior of the quarter panel should a spark go astray.

Some of the interior panels overlap in such a way as to require a sequenced removal. The dome light panel has to come off first, followed by the quarter window panel, and then the panel inside the quarter panel.

These are held on with push-pin style fasteners. Use an ice pick or similar pointed instrument to push the rod in the center of the fastener all the way through. They will drop down inside the unibody, lost forever, but this is the only way to do it. You can get new ones at the body shop supply house.

Before you can do all this, you will also have to remove the raised pressboard floor above the space saver spare, if you own a later 280Z.

Trimming the wheel arches

USE EXTREME CAUTION when cutting your quarters. Cutting processes inevitably involve heat, sparks, flame, or a combination of two or more. Be aware of the location of the fuel tank (under the car), the fuel vapor expansion tank (inside the car, behind the right rear strut tower), the lines that connect them, the fuel filler neck, and combustible materials inside and under the car.

Under coating burns quite well, and you may not notice it right away. Therefore it is always good to have a “fire marshal” looking over your shoulder and standing by with an extinguisher or a pail of water.

The two best tools you can use for this process are a cutoff wheel on a die grinder and a Sawz-All (big reciprocating saw). Each works better in some situations than the other. However, both can be dangerous and loud. Wear your safety goggles and your ear muffs (the hearing protection kind, not the cold weather kind). I like to wear a dust mask, too, as both operations put a lot of fine metal dust and body filler in the air, and knock a lot of dirt out from under the wheel wells.

The rear wheel arches have to be trimmed out for the larger wheels and tires. This is done by making two cuts, one right at the edge of the wheel arch to separate the inner (wheel well) and outer (quarter) panels. The second is done through the quarter panel only.

Quarter Panel Trim Measurements

At the bottom, front and rear of the wheel arch, the second cut is pretty close to the first. However, as you go up and toward the apex of the wheel arch, the second cut peaks at a point that corresponds with the highest point inside the wheel arch

Then, the portion of the wheel well panel that extends below the edge of the quarter panel is slotted radially, about every two inches. The "tabs" that are formed should be bent up and tack welded to the quarter panel edge, to "re-connect" the two panels for greater rigidity.

This is a photo after the quarter panel is cut and the tabs bent up. You can see the outer cut needs to go up well above the crease line on the quarter panel:fiberglass fender installation 1

At this point you can cut off the tabs, depending upon how you are going to finish the wheel well. Read that section and make your decision before you do, however.fiberglass fender installation 2fiberglass fender installation 3

The following photo shows the tabs welded and finished off, in preparation for mounting the fiberglass rear quarter panel.fiberglass fender installation 4

Bonding the quarter panels

You may want to trim away the "returns", or curved-in front and rear edges of the fiberglass rear quarter panel, in order to get the panel to seat down fully over the metal. Then, we use Duraglass (by Evercoat) or MarGlass to bond the glass to the metal. You can use a variety of products including epoxies (like MarineTex), or others made specifically for bonding fiberglass to metal.

Once you've completed the wheel arch modification, scuff the paint on the quarter panels down to metal with a heavy-grit sanding disc. Also scuff the inside of the fiberglass around the edges (that's where the bond line will be) about three inches wide.

On the right quarter, scuff the area around the gas cap and the corresponding area inside the fiberglass quarter panel.

One of the easiest ways to mount the quarter panels is with short drywall screws. These screws are self- drilling so you don’t need to pre-drill the holes for them. 

You can also use Cleco aircraft fasteners to hold the fiberglass in place, as shown here:

Cleco aircraft fasteners to hold the z quarter panelPhoto courtesy of Tom Johnson, Airpower Insurance, Phoenix AZ

Once you have achieved best fit of the quarters, dry fit them into place with the screws and trial fit the fuel filler door. If you like the way they look and you are satisfied with the alignment of the fuel filler door, pull them off, mix your bonding agent and re-install them. As you tighten the screws, the glue will ooze out around the edges. When you have completely tightened them, wipe off the excess using a putty knife or Bondo spreader. Leave a little of the excess above the level of the fiberglass so you can later sand it down and feather it out into the metal.

For the gas cap area, you can use your putty knife, Bondo spreader, or your finger to force Dura Glass into the gap between the old panel and the new fiberglass. As before, leave a little above the surface. Sand to a smooth finish when it is hard.

This is a photo of a bonded panels that is ready for final body work prior to painting:

bonded panels that is ready for final body workPhoto courtesy of Tom Johnson, Airpower Insurance, Phoenix AZ

On the kits designed for race car use, the quarter panels are usually fastened with quarter-turn Dzuz-style fasteners. You may be able to see imprints of Dzuz heads in the gel coat which indicate where the Dzuz fasteners are used. If you are using these panels on a street car, you may find it helpful to do a wet lay-up of a strip of fiberglass across the edge of the quarter panel and onto the sheet metal. 

If this is the case, make sure you prep all the surfaces with a heavy grit sanding disk to ensure proper adhesion of the fiberglass resin.

The fuel filler door can be re-mounted at this point, or you can wait until after painting the car…but don’t forget to paint the door, too! 

Le Mans fuel filler pocket

I now offer the option of a Le Mans fuel filler pocket pre-bonded into the quarter panel for slightly more cost. This photo of Dan Juday’s car shows that option, plus the optional wheel well lips for the YZ quarter panels. The lips are nice if you want to use the YZ quarter panels with the slightly less wide Subtle fenders, which have the factory wheel well lips.

Finishing the wheel wells

In the rear, we have used an aerosol urethane foam to fill the gap between the metal quarter panel and the fiberglass. This can be finished with Bondo, or covered with fiberglass. It's a little tricky to glass, particularly around the top of the arch, but it is a nice way to close out the gap.

You can also fabricate a narrow piece of thin sheet metal to span this gap. This can be screwed or riveted into place. However, don’t forget to seal the screws or rivets with caulking, and under coat the whole area to prevent water intrusion and rust.

Front Fenders

Note: If you are installing the front quarters, install them before the hood, because the hood is supplied slightly oversize. Therefore, it needs to be trimmed to fit the opening and since the fiberglass quarters will result in slightly tighter gaps they should be in place before the hood is trimmed.


As for the front-end parts, removal is pretty idiot-proof (no offense intended!). The trickiest part will probably be sequence and making sure you get all the hidden bolts! Save all the bolts.

Remove the hood first. Then remove the cowl at the base of the windshield. You’ll reuse the cowl, but there are a couple of fender bolts underneath it.

Remove the inspection panels. You will also reuse them. The metal loops on the stock fenders to which the inspection panels latch are not duplicated on the fiberglass fenders. If you want latching capability there are a variety of latches available at the hardware store. The inspection panels are captured by the hood anyway, but you may need a bump stop of some sort (I typically use a small bolt screwed into the fender recess at the front of the inspection panel) to make sure it stays level with the fender.

Remove the fender liners. You may have difficulty removing the bolts, as they tend to resist due to age and rust. It will be difficult to get WD-40 into the threads, but try it anyway. Also, It may help to tighten them an eighth of a turn before loosening them.

Remove the grill pieces and the lower valance. Remove the side pieces that connect the lower valance to the fenders.

You can now begin to remove the fenders. There are two bolts at the bottom near the door, one in the door jamb, two under the cowl, and several along the top of the fenders. Once they are loose, slide the fender forward and off the car.

Remove the headlight extensions. You will reuse them. Also, dismantle the headlights out of the extensions.

Remove the headlights and buckets from the old fenders. You will bolt these on to your new front fenders. 

Remove the side markers. 

Remove the turn signals/parking lights. You may or may not want to reuse them, depending on the year of your car (and thus the shape of the turn signals). There are a variety of aftermarket lights you can use or you can get something you like from the wreck yard.

Here’s what your car will look like when you have removed everything:

Z no fendersPhoto courtesy of Tim McClanahan, Big O Tires, Anaheim CAWhile you have the front of the car stripped, it's a good time to inspect for and repair any rusted areas, especially the areas just inboard of the headlights, and beneath the battery tray. Also, if you are planning brake and/or suspension upgrades, it's much easier to do them now while you have good access. I strongly suggest the Toyota brake upgrade, and detailed info can be found in our excellent V-8 Conversion Manual, as well as important suspension upgrade and modification information.

Mounting the new fenders

Cut the headlight openings before you mount the fenders. Trace the cutout from the headlight extension openings. Drill a hole (or a couple of connecting holes) large enough to get a saber saw blade started. Don’t forget to drill the holes for the bolts to mount the extensions. Also, be careful that you line the extensions up flush with the outer surface of the fender.

The Subtle Z fenders are designed to work with your stock headlight buckets. However, I now offer replacement fiberglass headlight buckets that work nicely with them, as well.

replacement fiberglass headlight buckets

For the 280YZ, customers have done a variety of headlight installations:

280yz headlight locationsPhoto courtesy of James Lodder, Surrey, UK.

280yz headlight locations small squarePhoto courtesy of Ted Fisher, Primarily Japanese Motorsports, Tucson AZ

I also now offer a reasonably-priced option to include factory-style headlight buckets in the front  end of the YZ fenders:

z headligth buckets included with z fenders


When locating the holes to mount the fenders, I suggest drilling the fender them SLIGHTLY oversize. That will allow you to move the panels a little to achieve optimum fit before you snug the bolts down. All of the edges are a little "long" and may need to be trimmed for best fit. We are intentionally generous on the edges, because (at least with fiberglass) it's a lot easier to trim off than add on!

The old wheel well liners can be stretched to fit the front fenders, but are not absolutely necessary. The two primary reasons for them are keeping water out of the little nooks and crannies (including the fender mounting areas, door hinges, and the headlights) and to prevent rocks thrown off the tires from dinging the fender from the inside. A good layer of sprayed-on undercoating can eliminate most of the rock damage and fiberglass is much less prone to this anyway.

mounted 280yz fendersPhoto courtesy of Tim McClanahan, Big O Tires, Anaheim CA


Mounting the air dam

The air dam should be bolted to the bottom edge of the front fenders 1/4" by 1" bolts. Use oversize “fender" washers to distribute the clamping load over a larger area.

The bottom edge of the air dam is a lot lower and further forward than stock, so be VERY CAREFUL in parking your car. It only takes a small impact against the curb to break the air dam...not because the air dam isn't sturdy (the same would be true of metal, but it would bend instead of breaking), but because of the way it mounts.

Also, be careful when driving into dips (like when exiting parking lots) or over large bumps (like speed bumps). The degree of care you need to take is proportional to how much you have lowered your car!

You can also mount the airdam on a bracket that you can disconnect from the car quickly. This really helps for loading on and off a trailer at the track, for getting a jack under the front of the car, or just for accessing the lower radiator support area if you have an oil cooler or turbo intercooler. Here’s an example:

removable z airdamPhoto courtesy of Ron Redden, Mira Loma CA
 removable z airdam bracketsPhoto courtesy of Ron Redden, Mira Loma CA

This photo shows the bottom of Dan Juday’s airdam. He installed a chin plate, made from a thin sheet of aluminum, to stiffen the airdam and help protect it from damage.

Dan Juday airdam


Mounting the Hood

Mounting the hood can be a little tricky. Here is a brief description:

The hood bolts on just like the stock hood. The two metal plates supplied with the hood serve the same purpose as the built-in tabs on the metal hood. You just have to bolt them on with the bolts supplied. There are two metal plates bonded inside the hood reinforcement and they have threaded holes to accept the mounting bolts.

If it looks like the bolts will bottom out before they become snug, drill through the back side of the fiberglass reinforcement to allow the bolts to protrude through.

z hood mount bracketsThe holes in the metal plates are slightly oversize to allow some adjustment. If more adjustment is needed, drill them a little larger. Be careful not to get them too big to prevent 

Make sure you remove the hood spring from the front end of your car. The fiberglass hood is so light, the spring is not necessary, and it will apply a constant (and unnecessary) load to the hood, even when it is in the down position.

Remove the latch striker from your old hood. You can drill two slightly oversize holes to mount the striker on the new hood. Adjust the location to make the hood close "just right", but it’s worth a little time and effort. Just use a couple of nuts inside the reinforcement to bolt the latch on.

Note: the hood latch mount on the firewall is typically bent downward from years of neglect and abuse. If the striker ever gets out of adjustment, or the action gets stiff from lack of lubrication, simply shutting the hood can cause the mount to be bent. This makes the alignment worse, etc, etc.

You may have to pry the mount upward. The best way is to use a hoist (engine hoist, or a come-along attached to an overhead beam or tree limb, or even a rope over a limb...the force required is not much) to gently tug the mount back into position. Obviously, lubricate the action...and while you are at it, lube all the pivots on the hood hinge.

The alignment of the hood is sometimes problematic. I could spend an hour telling you how to do it, but it boils down to "play with it until you get it right." I know that's a bit of a cop out on my part, but that's what I do when I mount one. AND that's what you have to do if you ever remove and then replace a stock hood. However, some things to keep in mind:

The hood is a little "big" in width and length. Therefore, you can trim it to fit just as you did with the fenders. However, this should be a final step. Get it as close as you can using the bolts before you trim it. There is a lot of adjustment available, and if you don't have enough, it's very easy to slot the mounting holes to give you a little more.

There are slotted holes under the hinge-body mount as well.

You also have to be mindful that it's possible to have excessive "play" in the hinging mechanism, even though the hood looks right when it is closed. In other words, if the hood is mounted and in the down-and-latched position and you grab the front edge and lift, it shouldn't rise more than a TINY amount. If it does, you need to go back and adjust the mounting location.

When mounting a hood with the hood springs still in place, they naturally place a little "pre-load" on the hood mounts. You won't have this pre-load once the springs are removed, and you may have to lift the hinge a little when mounting the hood.

One important note about the hood: It is fiberglass and is located over the hottest part of the car. Therefore, left to it's own devices it will want to change shape with age. It is important that it be properly mounted and supported so as to prevent this shape change. You may want to consider couple of angle brackets bolted to the fender mounting bolts to provide support along the sides of the hood. These can be made of aluminum bent to a 90-degree angle and drilled in the appropriate locations to allow the hood to JUST rest on them when it is fully latched. Also, a blanket of insulating material (like on the later model ZXs) applied to the underside of the hood can help this problem.


Once you've got all the panels mounted and you are satisfied with the fit, you can cut the holes for the headlights and side markers (if you are going to re-use them) as well as the antenna-mounting hole. Having done all that, painting the fiberglass is just about the same as painting metal. You’ll want to scuff the entire gel coat then apply "high-build" primer. This can be block sanded down to perfect smoothness to eliminate waves and texture. Don’t forget to prep and paint the fuel door, inspection panels and anything else you have removed from the car for that purpose!

A catalyzed polyester or urethane primer can help prevent the body filler from shrinking and causing the texture of the fiberglass from showing up in the paint later. It will also aid in reducing “staining” when applying base coat/clear coat paint. Duratech is a good brand.

You will probably want to apply these steps to the rest of the car and paint the whole thing at the same time for best match. Just make sure you've done a good job on your rust repair and that you have fixed all the little dings and dents.

If you have to replace the windshield, it is a good idea to pull the old one before doing your paint work. That way you will have fresh paint underneath the new windshield seal. Otherwise the new seal may shrink back, exposing the old paint at the edge.

Once your paint is done and you’ve finished any post-paint work (color sanding or buffing), you can re-install your bumpers, lights and exterior trim.

Wheels and Tires

Wide wheels with 4-bolt mounting can be hard to find. You can check with your local wheel shops, but the correct size and offset are getting hard to find in off-the-shelf wheels with the Z bolt pattern. There are a lot of race shops that offer modular (multi-piece) wheels that can be assembled in different ways to achieve the width you need. A few companies do pretty reasonably-priced custom-built wheels, as well. 

For the Subtle Z and 940Z , 8-inch wide wheels work best. If you have trouble finding 8-inch wheels, I sell a nice hub extender (adapter) that will add an inch or more of backspacing to allow you to use a front-wheel-drive-style wheel. They have a 4 on 4.5 hole pattern, with the protruding studs set at 4 on 100mm. This will allow you to use the most common Honda and Mazda wheels. 

z hub extender adapter

The 280YZ can take 10 to 12-inch wide wheels. The stock Z bolt pattern in 4 on 4.5 inches. The stock backspace or backset (NOT offset) is 3-7/16 inch. 

I’m NOT a big fan of re-drilling the hubs to a 5-bolt pattern. If you must have 5 lugs, buy racing hubs that are set up for that. However, there’s no strength reason to go from 4 to 5. The Zs have been racing for years with 4 lug wheels and I’ve never seen one fall off.

You can get away with a little more backspace, especially on the 240’s. With coilover conversions (which usually have a smaller diameter spring and lower spring perch) you can increase the backspace even more, maybe as much as 4 inches or more. This is more like the backspace on a front wheel drive vehicle, and there are a lot more wheels available in this backspace.

Best thing to do is go to a professional wheel and tire shop, one that caters to performance drivers. Let them help you make the measurements and find a combination that works for you. Make sure you check the tires for fit and clearance before you drive off!

You can adjust tire size to fill out the wheel well. You may have to trim the return—or lip at the edge—of the fenders. Keep in mind that the fit will depend highly upon the ride height of the car. Therefore, if possible have your car at its final ride height prior to fitting wheels and tires. 

z no fenders wide tiresPhoto courtesy of Tim McClanahan, Big O Tires, Anaheim CA

While 16- and 17-inch wheels and ultra-low profile tires look cool, they make the ride a bit harsh for my taste. I also feel that a 15” tire with a moderately low profile tire is such a huge improvement over the stock tall, skinny 14’s, AND the difference between 15’s or 16’s and 17’s is so small, AND the expense is so much greater, I personally prefer to stick with 15’s or 16’s.

Don’t forget to take into account the extra width you may need to clear upgraded or aftermarket brakes.

Other Notes

If you have any other questions about mounting your Z Fender Kit, feel free to give us a buzz!

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